Bob Briscoe's publications

Contents

Future Communications Architecture

• Flow Rate Fairness: Dismantling a Religion (Jul 2007)
• Internet: Fairer is Faster (May 2009)
• A Fairer Faster Internet Protocol (Dec 2008)
• The Need for Congestion Exposure in the Internet (Oct 2009)
• Problem Statement: Transport Protocols Don't Have To Do Fairness (Jul 2008)
• Policing Congestion Response in an Inter-Network Using Re-Feedback (Sep 2005)
• Policing Freedom to Use the Internet Resource Pool (Dec 2008)
• Re-feedback: Freedom with Accountability for Causing Congestion in a Connectionless Internetwork (May 2009)
  
• Re-ECN: Adding Accountability for Causing Congestion to TCP/IP (Sep 2009)
• Re-ECN: The Motivation for Adding Accountability for Causing Congestion to TCP/IP (Sep 2009)
• Architecting the Future Internet; Re-Capturing the Internet Value Chain (May 2009)
• Emulating Border Flow Policing using Re-PCN on Bulk Data (Oct 2009)
• Pre-Congestion Notification (PCN) Architecture (Jun 2009)
• A Survey of PCN-Based Admission Control and Flow Termination (Jul 2009)
• Is There a Problem With Peer-to-peer Traffic? (May 2008)
• Solving this traffic management problem... and the next, and the next (May 2008)
• Byte and Packet Congestion Notification (Oct 2009)
• Tunnelling of Explicit Congestion Notification (Dec 2009)
  
• Layered Encapsulation of Congestion Notification (Nov 2008)
• A path-aware rate policer: design and comparative evaluation (Oct 2005)
• Dagstuhl Perspectives Workshop on End-to-End Protocols for the Future Internet (Apr 2009)
• Open Research Issues in Internet Congestion Control (Aug 2009)
• Review: Quick-Start for TCP and IP (Nov 2005)
• The Implications of Pervasive Computing on Network Design (Jul 2004)
  
• Market Managed Multi-service Internet (M3I): Architecture (Aug 2003)
  
• The Direction of Value Flow in Open Multi-service Connectionless Networks (Nov 1999)

Myth-slaying

• Internet: Fairer is Faster (May 2009)
  
• A Fairer Faster Internet Protocol (Dec 2008)
• Flow Rate Fairness: Dismantling a Religion (Jul 2007)
• Problem Statement: Transport Protocols Don't Have To Do Fairness (Jul 2008)
• Metcalfe's Law is Wrong (Jul 2006)
• When a ‘law’ isn’t a law at all (to appear 2010)

Denial of Service Resistance

• Grand Strategy - Rationale; towards a Denial of Service Resistant Internet (Nov 2005)
• Using Self-interest to Prevent Malice; Fixing the Denial of Service Flaw of the Internet (Oct 2006)
• Policing Congestion Response in an Inter-Network Using Re-Feedback (Sep 2005)
• A TCP Test to Allow Senders to Identify Receiver Non-Compliance (Nov 2007)
• Byte and Packet Congestion Notification (Oct 2009)

Charging & security: Multicast streams

• TESLA: Multicast Source Authentication Transform Introduction (Jun 2005)
  
• MARKS: Zero side-effect multicast key management using arbitrarily revealed key sequences (Nov 1999)
  
• Nark: Receiver-based Multicast Non-repudiation and Key Management (Nov 1999)
  

Internet Quality of Service

• Flow Rate Fairness: Dismantling a Religion (Jul 2007)
• The Need for Congestion Exposure in the Internet (Oct 2009)
• Problem Statement: Transport Protocols Don't Have To Do Fairness (Jul 2008)
• Problem Statement: We Don't Have To Do Fairness Ourselves (Jul 2008)
• Internet: Fairer is Faster (May 2009)
• A Fairer Faster Internet Protocol (Dec 2008)
• Commercial Models for IP Quality of Service Interconnect (Apr 2005)
  
• Policing Congestion Response in an Inter-Network Using Re-Feedback (Sep 2005)
• Re-ECN: Adding Accountability for Causing Congestion to TCP/IP (Sep 2009)
• Re-ECN: The Motivation for Adding Accountability for Causing Congestion to TCP/IP (Sep 2009)
• Policing Freedom to Use the Internet Resource Pool (Dec 2008)
• Pre-Congestion Notification (PCN) Architecture (Jun 2009)
• A Survey of PCN-Based Admission Control and Flow Termination (Jul 2009)
  
• Baseline Encoding and Transport of Pre-Congestion Information (Nov 2009)
• Encoding and Transport of (Pre-)Congestion Information from Within a DiffServ Domain to the Egress (May 2008)
• PCN 3-State Encoding Extension in a single DSCP (Oct 2008)
• A PCN encoding using 2 DSCPs to provide 3 or more states (Apr 2009)
• A three state extended PCN encoding scheme (Jun 2008)
• PCN Encoding for Packet-Specific Dual Marking (PSDM) (Jul 2008)
  
• Emulating Border Flow Policing using Re-PCN on Bulk Data (Oct 2009)
• Emulating Border Flow Policing using Re-ECN on Bulk Data (Sep 2008)
• An edge-to-edge Deployment Model for Pre-Congestion Notification: Admission Control over a DiffServ Region (Oct 2006)
• A Framework for Admission Control over DiffServ using Pre-Congestion Notification (Oct 2006)
• An architecture for edge-to-edge controlled load service using distributed measurement-based admission control (Oct 2006)
• Metering and Marking behaviour of PCN-nodes (Nov 2009)
• Pre-congestion Notification Marking (Oct 2006)
  
• The Controlled Load per hop behaviour (Oct 2006)
• RSVP Extensions for Admission Control over Diffserv using Pre-congestion Notification (Jun 2006)
• Byte and Packet Congestion Notification (Oct 2009)
• Tunnelling of Explicit Congestion Notification (Dec 2009)
• Layered Encapsulation of Congestion Notification (Nov 2008)
  
• Explicit Congestion Marking in MPLS (Jan 2008)
• Guaranteed QoS Synthesis for Admission Control with Shared Capacity (Feb 2006)
• Guaranteed QoS Synthesis - an example of a scalable core IP quality of service solution (Apr 2005)
  
• Guaranteed QoS Synthesis (GQS): Outline (Oct 2002)
• Review: Quick-Start for TCP and IP (Nov 2005)
• Market Managed Multi-service Internet (M3I); Economics Driving Network Design (Oct 2002)
• Service Differentiation in Third Generation Mobile Networks (Oct 2002)
  
• Economic Models for Resource Control in Wireless Networks (Sep 2002)
  
• An Open ECN Service in the IP layer (Feb 2001)
  

Managing IP transmission, Quality of Service and sessions through shadow pricing

• Flow Rate Fairness: Dismantling a Religion (Jul 2007)
• Internet: Fairer is Faster (May 2009)
• A Fairer Faster Internet Protocol (Dec 2008)
• Commercial Models for IP Quality of Service Interconnect (Apr 2005)
• Policing Congestion Response in an Inter-Network Using Re-Feedback (Sep 2005)
  
• Re-ECN: Adding Accountability for Causing Congestion to TCP/IP (Sep 2009)
• Re-ECN: The Motivation for Adding Accountability for Causing Congestion to TCP/IP (Sep 2009)
• Policing Freedom to Use the Internet Resource Pool (Dec 2008)
• Re-feedback: Freedom with Accountability for Causing Congestion in a Connectionless Internetwork (May 2009)
• Emulating Border Flow Policing using Re-PCN on Bulk Data (Oct 2009)
• Emulating Border Flow Policing using Re-ECN on Bulk Data (Sep 2008)
• Using Self-interest to Prevent Malice; Fixing the Denial of Service Flaw of the Internet (Aug 2006)
• A path-aware rate policer: design and comparative evaluation (Oct 2005)
• Pre-Congestion Notification (PCN) Architecture (Jun 2009)
• Baseline Encoding and Transport of Pre-Congestion Information (Nov 2009)
• An edge-to-edge Deployment Model for Pre-Congestion Notification: Admission Control over a DiffServ Region (Oct 2006)
• A Framework for Admission Control over DiffServ using Pre-Congestion Notification (Oct 2006)
• An architecture for edge-to-edge controlled load service using distributed measurement-based admission control (Oct 2006)
• Guaranteed QoS Synthesis for Admission Control with Shared Capacity (Feb 2006)
• Market Managed Multi-service Internet (M3I); Economics Driving Network Design (Oct 2002)
• Metering and Marking behaviour of PCN-nodes (Nov 2009)
• Service Differentiation in Third Generation Mobile Networks (Oct 2002)
• Economic Models for Resource Control in Wireless Networks (Sep 2002)
  
• A Market Managed Multi-service Internet (M3I) (Feb 2003)
  
• Tariff Dissemination Protocol (Mar 2002)
  
• Market Managed Multi-service Internet (M3I): Architecture (Aug 2003)
  
• Market Managed Multi-service Internet (M3I): ISP Business Model Report; Prototype Descriptions (Feb 2002)
  
• Market Managed Multi-service Internet (M3I): ISP Business Model Report (Feb 2002)
• Market Managed Multi-service Internet (M3I): Charging and Accounting System (CAS) Design (Jul 2000)
  
• Market Managed Multi-service Internet (M3I): Pricing Mechanisms; Price Reaction Design (Jul 2000)
  
• Market Managed Multi-service Internet (M3I): Requirements Specification Reference Model (Jul 2000)
• Intelligent Client Based Charging Middleware (Jan 2000)
  
• The Direction of Value Flow in Open Multi-service Connectionless Networks (Nov 1999)
  
• Lightweight Policing and Charging for Packet Networks (Mar 2000)
  
• A Dynamic Pricing Framework to Support a Scalable, Usage-based Charging Model for Packet-switched Networks (Jun 1999)
  
• A charging model for Sessions on the Internet (Jul 1999)
  
• An End to End Price-Based QoS Control Component Using Reflective Java (Dec 1997)
  

Loosely coupled distributed object systems & multicast

• The Implications of Pervasive Computing on Network Design (Jul 2004)
  
• GAP: The Generic Announcement Protocol for Event Messaging (Sep 2003)
• End to End Aggregation of Multicast Addresses (Nov 1997)
  
• Taxonomy of Communications Requirements for Large-scale Multicast Applications (Dec 1997)
  
• Distributed Objects on the Web (Apr 1997)
  
• Service Discovery in Massive Scale Federations - The Web Analysed in Open Distributed Processing Terms (Mar 1996)
  

Industry roadmapping

• Grand Strategy - Rationale; towards a Denial of Service Resistant Internet (Nov 2005)
• Commercial Models for IP Quality of Service Interconnect (Apr 2005)
  
• The Implications of Pervasive Computing on Network Design (Jul 2004)
  
• Market Managed Multi-service Internet (M3I): ISP Business Model Report (Feb 2002)
• The Direction of Value Flow in Open Multi-service Connectionless Networks (Nov 1999)
  
• Distributed Objects on the Web (Mar 1996)

Most recent papers first
(based on date of first version).

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The Need for Congestion Exposure in the Internet, Toby Moncaster (Ed., BT), Louise Krug (BT), Michael Menth (Uni Wuerzburg), João Taveira Araújo (UCL), Steven Blake (Extreme Networks) and Richard Woundy (Comcast),  IETF Internet-Draft <draft-moncaster-congestion-exposure-problem-03.txt> (Oct 2009). (22pp, 21 refs) [BibTeX]

Differences between drafts: [ ]

Presentations: [ ]

Abstract:    Today's Internet is a product of its history.  TCP is the main transport protocol responsible for sharing out bandwidth and preventing a recurrence of congestion collapse while packet drop is the primary signal of congestion at bottlenecks.  Since packet drop (and increased delay) impacts all their customers negatively, network operators would like to be able to distinguish between overly aggressive congestion control and a confluence of many low-bandwidth, low-impact flows.  But they are unable to see the actual congestion signal and thus, they have to implement bandwidth and/or usage limits based on the only information they can see or measure (the contents of the packet headers and the rate of the traffic).  Such measures don't solve the packet-drop problems effectively and are leading to calls for government regulation (which also won't solve the problem).

We propose congestion exposure as a possible solution.  This allows packets to carry an accurate prediction of the congestion they expect to cause downstream thus allowing it to be visible to ISPs and network operators.  This memo sets out the motivations for congestion exposure and introduces a strawman protocol designed to achieve congestion exposure.

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Architecting the Future Internet; Re-Capturing the Internet Value Chain, Andrea Soppera, Toby Moncaster, Bob Briscoe (BT), Institute of Telecommunications Professionals (ITP) Journal (May 2009). (7pp, 4 figs, 9 refs) [BibTeX]

Abstract: Many people believe the Internet is perfect and are amazed to find researchers working on the so-called Future Internet. However, what these researchers realise is that users and application writers are locked in an endless battle over the allocation of resources in the network.  Often they don’t even know they are fighting this battle – users simply want the fastest service they can get and application writers have responded. Many ISPs seek to control the resulting Internet congestion by imposing volume caps or rate limiting certain types of traffic at peak times. These are only palliative measures that lead to a breakdown in trust between users and their ISPs and limit the space for innovation in the network. Our strategic innovation is based on providing better visibility of the underlying congestion in the network, with separation of accounting mechanisms and resource control. Within the IETF we are pushing for “Re-Feedback”; a small modification to TCP-IP to reveal the Internet’s congestion to all users. Our aim is an economic incentive framework that incentivises the various players to design efficient resource control mechanisms to maximize the value of the Internet, thus ensuring a sustainable evolution towards the Future Internet.

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A Survey of PCN-Based Admission Control and Flow Termination, Michael Menth, Frank Lehrieder (University of Würzburg), Bob Briscoe, Philip Eardley, Toby Moncaster (BT Research), Jozef Babiarz (Nortel Networks), Anna Charny, Xinyang [Joy] Zhang (Cisco), Tom Taylor, Kwok-Ho Chan (Huawei Technologies), Daisuke Satoh (NTT) and Georgios Karagiannis (University of Twente), IEEE Communications Surveys and Tutorials, 11(3) (to appear) (Jul 2009). (18pp, 9 figs, 65 refs) [BibTeX]

Abstract: Pre-congestion notification (PCN) provides feedback about load conditions in a network to its boundary nodes. The PCN working group of the IETF discusses the use of PCN to implement admission control (AC) and flow termination (FT) for prioritized realtime traffic in a DiffServ domain. Admission control (AC) is a well-known flow control function that blocks admission requests of new flows when they need to be carried over a link whose admitted PCN rate already exceeds an admissible rate. Flow termination (FT) is a new flow control function that terminates already some admitted flows when they are carried over a link whose admitted PCN rate exceeds a supportable rate. The latter condition can occur in spite of AC, e.g., when traffic is rerouted due to network failures.

This survey gives an introduction to PCN in an early stage of the standardization process. It presents and discusses the multitude of architectural design options for PCN in a comprehensive and streamlined way before only a subset of them is standardized by the IETF. It brings PCN from the IETF to the research community and serves as historical record.

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Re-feedback: Freedom with Accountability for Causing Congestion in a Connectionless Internetwork, Bob Briscoe (BT & UCL) UCL PhD dissertation (to appear—available on request) (May 2009). (256pp, 39 figs, 173 refs) [BibTeX]

Abstract: This dissertation concerns adding resource accountability to a simplex internetwork such as the Internet, with only necessary but sufficient constraint on freedom. That is, both freedom for applications to evolve new innovative behaviours while still responding responsibly to congestion; and freedom for network providers to structure their pricing in any way, including flat pricing.

The big idea on which the research is built is a novel feedback arrangement termed `re-feedback'. A general form is defined, as well as a specific proposal (re-ECN) to alter the Internet protocol so that self-contained datagrams carry a metric of expected downstream congestion. Congestion is chosen because of its central economic role as the marginal cost of network usage. The aim is to ensure Internet resource allocation can be controlled either by local policies or by market selection (or indeed local lack of any control).

The current Internet architecture is designed to only reveal path congestion to end-points, not networks. The collective actions of self-interested consumers and providers should drive Internet resource allocations towards maximisation of total social welfare. But without visibility of a cost-metric, network operators are violating the architecture to improve their customer's experience. The resulting fight against the architecture is destroying the Internet's simplicity and ability to evolve.

Although accountability with freedom is the goal, the focus is the congestion metric, and whether an incentive system is possible that assures its integrity as it is passed between parties around the system, despite proposed attacks motivated by self-interest and malice. This dissertation defines the protocol and canonical examples of accountability mechanisms. Designs are all derived from carefully motivated principles. The resulting system is evaluated by analysis and simulation against the constraints and principles originally set. The mechanisms are proven to be agnostic to specific transport behaviours, but they could not be made flow-ID-oblivious.

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Dagstuhl Perspectives Workshop on End-to-End Protocols for the Future Internet, Jari Arkko (Ericsson) Bob Briscoe (BT), Lars Eggert (Nokia), Anja Feldmann (TU Berlin & DT) and Mark Handley (UCL), ACM Computer Communications Review (Editorial Zone) 39(2) 42--46 (Apr 2009). (6pp, 1 fig, 20 refs) [BibTeX]

Workshop: description and materials

Abstract: This article summarises the presentations and discussions during a workshop on end-to-end protocols for the future Internet in June 2008. The aim of the workshop was to establish a dialogue at the interface between two otherwise fairly distinct communities working on future Internet protocols: those developing internetworking functions and those developing end-to-end transport protocols. The discussion established near-consensus on some of the open issues, such as the preferred placement of traffic engineering functionality, whereas other questions remained controversial. New research agenda items were also identified.

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Internet: Fairer is Faster,  Bob Briscoe (BT), BT White Paper TR-CXR9-2009-001 (May 2009). (7pp, 5 figs) [BibTeX]

Abstract: The Internet is founded on a very simple premise: shared communications links are more efficient than dedicated channels that lie idle much of the time. We share local area networks at work and neighbourhood links from home. Indeed, a multi-gigabit backbone cable is shared among thousands of folks surfing the Web, downloading videos, and talking on Internet phones. But there’s a profound flaw in the protocol that governs how people share the Internet’s capacity. The protocol allows you to seem to be polite, even as you take far more resources than others.

Network providers like Verizon or BT either throw capacity at the problem or patch over it with homebrewed attempts to penalize so-called bandwidth hogs or the software they tend to use. From the start it needs to be crystal clear that those with an appetite for huge volumes of data are not the problem.  There is no need to stop them downloading vast amounts of material, if they can do so without starving others.

But no network provider can solve this on their own. At the Internet standards body, work has started on fixing the deeply entrenched underlying problem. A leading proposal claims to have found a way to deploy a tweak to the Internet protocol itself—the Internet’s ‘genetic material’. The intent is to encourage a profound shift in the incentives that drive capacity sharing.

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The following 6pp article for IEEE Spectrum magazine is adapted for an engineering audience from the above 7pp white paper—it has some of the economic motivation and figures edited out.

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(Remote IEEE original) A Fairer, Faster Internet Protocol, Bob Briscoe (BT), Illustrations by QuickHoney, IEEE Spectrum, Dec 2008 pp38-43, alternative remote URL: <http://www.spectrum.ieee.org/dec08/7027> (2008). (6pp, 3 figs) [BibTeX]

Abstract:  The Internet is founded on a very simple premise: shared communications links are more efficient than dedicated channels that lie idle much of the time. ¶ And so we share. We share local area networks at work and neighborhood links from home. And then we share again—at any given time, a terabit backbone cable is shared among thousands of folks surfing the Web, downloading videos, and talking on Internet phones. ¶ But there’s a profound flaw in the protocol that governs how people share the Internet’s capacity. The protocol allows you to seem to be polite, even as you elbow others aside, taking far more resources than they do. ¶ Network providers like Verizon and BT either throw capacity at the problem or improvise formulas that attempt to penalize so-called bandwidth hogs. Let me speak up for this much-maligned beast right away: bandwidth hogs are not the problem. There is no need to prevent customers from downloading huge amounts of material, so long as they aren’t starving others. ¶ Rather than patching over the problem, my colleagues and I at BT (formerly British Telecom) have worked out how to fix the root cause: the Internet’s sharing protocol itself. It turns out that this solution will make the Internet not just simpler but much faster too.

 

Internet—Fairer is Faster, Bob Briscoe (BT), In Proc Qualität im Internet; 41. Freiburger Verkehrsseminar  (Quality on the Internet, 41st Freiburger Traffic Seminar) Sep 2008 pp23--68. (6pp, 4 figs) [BibTeX]

Presentations: [ Freiburg'08 | links to all seminar slides (Deutsch | English) ]

Abstract: (see the IEEE Spectrum article above—a variant of the same article, but with more figures and covering network interconnection in addition).

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PCN 3-State Encoding Extension in a single DSCP, Bob Briscoe (BT) Internet Engineering Task Force (IETF) Internet Draft <draft-ietf-pcn-3-in-1-encoding-00.txt> (Jul 2009) (8pp, 9 refs) [BibTeX]

Differences between drafts: [ IETF document history ]

Presentations: [ IETF-73 ]

Abstract: The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain.  The overall rate of the PCN-traffic is metered on every link in the PCN-domain, and PCN-packets are appropriately marked when certain configured rates are exceeded.  The level of marking allows the boundary nodes to make decisions about whether to admit or block a new flow request, and (in abnormal circumstances) whether to terminate some of the existing flows, thereby protecting the QoS of previously admitted flows.  This document specifies how such marks are to be encoded into the IP header by re-using the Explicit Congestion Notification (ECN) codepoints within this controlled domain.  This encoding builds on the baseline encoding and provides for three PCN encoding states: Not-marked, Threshold-marked and Excess-traffic-marked.

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Policing Freedom to Use the Internet Resource Pool, Arnaud Jacquet (BT), Bob Briscoe (BT & UCL) & Toby Moncaster (BT), Workshop on Re-Architecting the Internet (ReArch'08) (Dec 2008) (6pp, 6 figs, 14 refs) [BibTeX]

Presentations: [ NGN Interconnection Strategies'08 ]

Abstract:  Ideally, everyone should be free to use as much of the Internet resource pool as they can take. But, whenever too much load meets too little capacity, everyone's freedoms collide. We show that attempts to isolate users from each other have corrosive side-effects - discouraging mutually beneficial ways of sharing the resource pool and harming the Internet's evolvability. We describe an unusual form of traffic policing which only pushes back against those who use their freedom to limit the freedom of others. This offers a vision of how much better the Internet could be. But there are subtle aspects missing from the current Internet architecture that prevent this form of policing being deployed. This paper aims to shift the research agenda onto those issues, and away from earlier attempts to isolate users from each other.

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PCN Encoding for Packet-Specific Dual Marking (PSDM), Michael Menth (Uni Wuertzburg), Jozef Babiarz (Nortel), Toby Moncaster and Bob Briscoe (BT) Internet Engineering Task Force (IETF) Internet Draft <draft-menth-pcn-psdm-encoding-00.txt> (Jul 2008) (13pp, 8 refs) [BibTeX]

Differences between drafts: [ ]

Abstract: This document proposes how PCN marks can be encoded into the IP header.  The presented encoding reuses the ECN field of the Voice-Admit DSCP in a single PCN domain.  The encoding of unmarked PCN packets indicates whether they are subject to either excess- orexhaustive-marking.  This is useful, e.g., when data and probe packets require different marking mechanisms.

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A PCN encoding using 2 DSCPs to provide 3 or more states, Toby Moncaster, Bob Briscoe (BT) and Michael Menth (Uni Wuertzburg), Internet Engineering Task Force (IETF) Internet Draft <draft-ietf-pcn-3-state-encoding-00.txt> (Apr 2009) (14pp, 13 refs) [BibTeX]

Differences between drafts: [ IETF document history ]

Presentations: []

Abstract: Pre-congestion notification (PCN) is a mechanism designed to protect the Quality of Service of inelastic flows within a controlled domain. It does this by marking packets when traffic load on a link is approaching or has exceeded a threshold below the physical link rate. This experimental encoding scheme specifies how three encoding states can be carried in the IP header using a combination of two DSCPs and the ECN bits.  The Basic scheme only allows for three encoding states.  The Full scheme additionally provides limited end-to-end support for ECN.

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Baseline Encoding and Transport of Pre-Congestion Information, Toby Moncaster, Bob Briscoe (BT) and Michael Menth (Uni Wuerzburg), Internet Engineering Task Force (IETF) RFC <rfc5696.txt> (Nov 2009) (15pp, 14 refs) [BibTeX]

Differences between drafts: [ IETF document history | moncaster-02-01 | moncaster-01-00 ]

Presentations: [ IETF-73 | IETF-72 ]

Abstract: The objective of the pre-congestion notification (PCN) architecture is to protect the QoS of inelastic flows within a Diffserv domain. It achieves this by marking packets belonging to PCN-flows when the rate of traffic exceeds certain configured thresholds on links in the domain.  These marks can then be evaluated to determine how close the domain is to being congested.  This document specifies how such marks are encoded into the IP header by redefining the Explicit Congestion Notification (ECN) codepoints within such domains.  The baseline encoding described here provides only two PCN encoding states: not- marked and PCN-marked.  Future extensions to this encoding may be needed in order to provide more than one level of marking severity.

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Is There a Problem With Peer-to-peer Traffic? Why ISPs and their customers can seem to be in conflict, Toby Moncaster (BT), Bob Briscoe (BT & UCL) & Lou Burness, (BT), Position Paper for IETF workshop on p2p infrastructure (May 2008). (2pp, 1 ref) [BibTeX]

Abstract:  Peer-to-peer (P2P) applications, especially BitTorrent, have been one of the great success stories on the Internet. Unfortunately that success brings with it a downside for end-users that don’t use P2P. This memo seeks to more precisely understand the nature of this problem and thus hopefully make some progress towards solving it.

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Solving this traffic management problem... and the next, and the next, Bob Briscoe (BT & UCL), Lou Burness, Toby Moncaster & Phil Eardley (BT), Position Paper for IETF workshop on p2p infrastructure (May 2008). (4pp, 1 fig, 7 refs) [BibTeX]

Presentation: [ IETF p2p infrastructure wkshp ]

Abstract:  A Challenge: Some ISPs say they throttle p2p file-sharing sessions to protect lighter usage like Web. Actually we could make lighter apps go much faster without prolonging p2p transfers. Basic scheduling theory says if shorter jobs go faster they finish earlier, leaving the same capacity on average for longer jobs. As Figure 1 shows, rather than throttling p2p bit-rate, the key is for p2p file-sharing to have a lower weighted share. Then it would be much less aggressive to real-time streaming(e.g. VoIP) as well.

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Open Research Issues in Internet Congestion Control, Michael Welzl (Uni Oslo), Dimitri Papadimitriou (Alcatel-Lucent), Michael Scharf (Uni Stuttgart) and Bob Briscoe (BT) IRTF Internet-Draft <draft-irtf-iccrg-welzl-congestion-control-open-research-05.txt> (Aug 2009). (46pp, 100 refs) [BibTeX]

Differences between drafts: [ 05-04 | 04-03 | 03-02 | 02-01 | 01-00 ]

Abstract: This document describes some of the open problems in Internet congestion control that are known today. This includes several new challenges that are becoming important as the network grows, as well as some issues that have been known for many years. These challenges are generally considered to be open research topics that may require more study or application of innovative techniques before Internet-scale solutions can be confidently engineered and deployed.

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Problem Statement: Transport Protocols Don't Have To Do Fairness, Bob Briscoe (BT & UCL), Toby Moncaster and Lou Burness (BT), IETF Internet-Draft <draft-briscoe-tsvwg-relax-fairness-01.txt> (Expired) (Jul 2008). (27pp, 27 refs) [BibTeX]

Differences between drafts: [ 01-00 ]

Presentations: [ NGN Interconnection Strategies'08 | IETF-70 ]

Abstract: The Internet is an amazing achievement - any of the thousand million hosts can freely use any of the resources anywhere on the public network.  At least that was the original theory.  Recently issues with how these resources are shared among these hosts have come to the fore.  Applications are innocently exploring the limits of protocol design to get larger shares of available bandwidth. Increasingly we are seeing ISPs imposing restrictions on heavier usage in order to try to preserve the level of service they can offer to lighter customers. We believe that these are symptoms of an underlying problem: fair resource sharing is an issue that can only be resolved at run-time, but for years attempts have been made to solve it at design time.  In this document we show that fairness is not the preserve of transport protocols, rather the design of such protocols should be such that fairness can be controlled between users and ISPs at run-time.

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Tunnelling of Explicit Congestion Notification, Bob Briscoe (BT), IETF Internet-Draft <draft-ietf-tsvwg-ecn-tunnel-06.txt> (Dec 2009). (40pp, 7 figs, 21 refs) [BibTeX]

Differences between drafts [ IETF document history | 06-04 ]

Presentations: [ IETF-76 | IETF-75 | IETF-74 | IETF-73 | IETF-72 | IETF-69 ]

Abstract: This document redefines how the explicit congestion notification (ECN) field of the IP header should be constructed on entry to and exit from any IP in IP tunnel. On encapsulation it updates RFC3168 to bring all IP in IP tunnels (v4 or v6) into line with RFC4301 IPsec ECN processing. On decapsulation it updates both RFC3168 and RFC4301 to add new behaviours for previously unused combinations of inner and outer header. The new rules propagate the ECN field whether it is used to signal one or two severity levels of congestion, whereas before they propagated only one. Tunnel endpoints can be updated in any order without affecting pre-existing uses of the ECN field (backward compatible). Nonetheless, operators wanting to support two severity levels (e.g. for pre-congestion notification—PCN) can require compliance with this new specification. A thorough analysis of the reasoning for these changes and the implications is included.

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Byte and Packet Congestion Notification, Bob Briscoe (BT), IETF Internet-Draft <draft-ietf-tsvwg-byte-pkt-congest-01.txt> (Oct 2009). (37pp, 34 refs) [BibTeX]

Differences between drafts: [ IETF document history | ietf00-briscoe02  | briscoe02-01 | briscoe01-00]

Presentations: [ IETF-76 | IETF-73 | IETF-71 | IETF-70 | IETF-69 ]

Abstract: This memo concerns dropping or marking packets using active queue management (AQM) such as random early detection (RED) or pre-congestion notification (PCN). The primary conclusion is that packet size should be taken into account when transports read congestion indications, not when network equipment writes them. Reducing drop of small packets has some tempting advantages: i) it drops less control packets, which tend to be small and ii) it makes TCP's bit-rate less dependent on packet size. However, there are ways of addressing these issues at the transport layer, rather than reverse engineering network forwarding to fix specific transport problems. Network layer algorithms like the byte-mode packet drop variant of RED should not be used to drop fewer small packets, because that creates a perverse incentive for transports to use tiny segments, consequently also opening up a DoS vulnerability.

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A TCP Test to Allow Senders to Identify Receiver Non-Compliance, Toby Moncaster (BT), Bob Briscoe (BT & UCL) and Arnaud Jacquet (BT), <draft-moncaster-tcpm-rcv-cheat-02.txt> (Expired) (Nov 2007). (31pp, 4 figs, 17 refs) [BibTeX]

Differences between drafts: [ 02-01 | 01-00]

Presentations: [ IETF-69 | IETF-68 ]

Abstract:  The TCP protocol relies on receivers sending accurate and timely feedback to the sender.  Currently the sender has no means to verify that a receiver is correctly sending this feedback according to the protocol. A receiver that is non-compliant has the potential to disrupt a sender's resource allocation, increasing its transmission rate on that connection which in turn could adversely affect the network itself. This document presents a two stage test process that can be used to identify whether a receiver is non-compliant. The tests enshrine the principle that one shouldn't attribute to malice that which may be accidental. The first stage test causes minimum impact to the receiver but raises a suspicion of non-compliance. The second stage test can then be used to verify that the receiver is non-compliant.  This specification does not modify the core TCP protocol - the tests can either be implemented as a test suite or as a stand-alone test through a simple modification to the sender implementation.

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Flow Rate Fairness: Dismantling a Religion, Bob Briscoe (BT & UCL), ACM Computer Communications Review 37(2) 63--74 (Apr 2007). (10pp, 2 figs, 35 refs) [BibTeX]

Flow Rate Fairness: Dismantling a Religion, Bob Briscoe (BT & UCL), IETF Internet-Draft <draft-briscoe-tsvarea-fair-02.pdf> (Jul 2007 - Allowed to Expire). (44pp, 2 figs, 62 refs) [BibTeX]

Differences between drafts: [ 02-01 | 01-00 ]

Presentations: [ PFLDnet'09 | NGN Interconnection Strategies'08 | IETF-69 | IETF-68 | IRTF-E2ERG'0702 | IRTF-ICCRG'0702 | PFLDnet'07 | IETF-67 ]

Abstract: Resource allocation and accountability have been major unresolved problems with the Internet ever since its inception. The reason we never resolve these issues is a broken idea of what the problem is. The applied research and standards communities are using completely unrealistic and impractical fairness criteria. The resulting mechanisms don't even allocate the right thing and they don't allocate it between the right entities. We explain as bluntly as we can that thinking about fairness mechanisms like TCP in terms of sharing out flow rates has no intellectual heritage from any concept of fairness in philosophy or social science, or indeed real life. Comparing flow rates should never again be used for claims of fairness in production networks. Instead, we should judge fairness mechanisms on how they share out the `cost' of each user's actions on others.

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Using Self-interest to Prevent Malice; Fixing the Denial of Service Flaw of the Internet, Bob Briscoe (BT & UCL), The Workshop on the Economics of Securing the Information Infrastructure (Oct 2006). (16pp, 34 refs, 5 figs) [BibTeX]

Presentation: [ WESII'06 | CRN_DoS'06 | CRN_DoS_Nov'05 | CRN_DoS_Jan'05 ]

Abstract: This paper describes the economic intent of a proposed change to the Internet protocol. Denial of service is the extreme of a spectrum of anti-social behaviour problems it aims to solve, but without unduly restricting unexpected new uses of the Internet. By internalising externalities and removing information asymmetries it should trigger evolutionary deployment of protections for Internet users. To be worthwhile architectural change must solve the last stages of the arms race, not just the next. So we work through the competitive process to show the solution will eventually block attacks that other researchers consider unsolvable, and that it creates the right incentives to drive its own deployment, from bootstrap through to completion. It also encourages deployment of complementary solutions, not just our own. Interestingly, small incentives in the lower layer infrastructure market amplify to ensure operators block attacks worth huge sums on the black market in the upper layers.

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(Remote IEEE original) Metcalfe's Law is Wrong, Bob Briscoe (BT) and Andrew Odlyzko (Uni Minnesota) and Benjamin Tilly (Rent.com), Illustrations by Serge Bloch, IEEE Spectrum, Jul 2006 pp26-31, alternative remote URL: <http://spectrum.ieee.org/jul06/4109> (2006). (6pp, 2 figs) [BibTeX]

Presentations: [ NGN Interconnection Strategies'08 ]

Abstract: Of all the popular ideas of the internet boom, one of the most dangerously influential was Metcalfe’s law. simply put, it says that the value of a communications network is proportional to the square of the number of its users. We propose, instead, that the value of a network of size n grows in proportion to n log(n).

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When a ‘law’ isn’t a law at all, Bob Briscoe (BT) and Andrew Odlyzko (Uni Minnesota) and Benjamin Tilly (Rent.com), International Commerce Review 10(1) Springer (2010). [BibTeX]

Abstract: Of all the popular ideas of the Internet boom, one of the most dangerously influential was Metcalfe’s law. Simply put, it states that the value of a communications network is proportionalto the square of the number of its users.

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Explicit Congestion Marking in MPLS, Bruce Davie (Cisco), Bob Briscoe and June Tay (BT), IETF standards track RFC <rfc5129.txt> (Jan 2008). (21pp, 18 refs) [BibTeX]

Differences between drafts: [ IETF document history | rfc-02 | ietf02-01 | ietf01-00 | ietf00-davie01 | davie01-00]

Presentations: [ IETF-69 | IETF-68 | IETF-67 | IETF-66 ]

Abstract: RFC 3270 defines how to support the Diffserv architecture in MPLS networks, including how to encode Diffserv Code Points (DSCPs) in an MPLS header. DSCPs may be encoded in the EXP field, while other uses of that field are not precluded. RFC3270 makes no statement about how Explicit Congestion Notification (ECN) marking might be encoded in the MPLS header. This document defines how an operator might define some of the EXP codepoints for explicit congestion notification, without precluding other uses.

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Emulating Border Flow Policing using Re-PCN on Bulk Data, Bob Briscoe (BT), IETF Internet-Draft <draft-briscoe-re-pcn-border-cheat-03.txt> (Oct 2009). (59pp, 31 refs, 4 figs) [BibTeX]

Differences between drafts: [ pcn03-pcn02 | pcn02-pcn01 | pcn01-pcn00 | pcn00-tsvwg01 | tsvwg01-tsvwg00]

Presentations: [ IETF-66 | IETF-65 ]

Abstract: Scaling per flow admission control to the Internet is a hard problem. The approach of combining Diffserv and pre-congestion notification (PCN) provides a service slightly better than Intserv controlled load that scales to networks of any size without needing Diffserv's usual overprovisioning, but only if domains trust each other to comply with admission control and rate policing.  This memo claims to solve this trust problem without losing scalability.  It provides a sufficient emulation of per-flow policing at borders but with only passive bulk metering rather than per-flow processing.  Measurements are sufficient to apply penalties against cheating neighbour networks.

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Guaranteed QoS Synthesis for Admission Control with Shared Capacity, David J. Songhurst, Phil L. Eardley, Bob Briscoe, Carla Di Cairano Gilfedder and June Tay (BT), BT Technical Report TR-CXR9-2006-001 (Feb 2006) [BibTeX]

Abstract: Guaranteed QoS Synthesis (GQS) is a distributed measurement-based admission control scheme. It is designed as a simple and scalable approach to providing strong service guarantees using bulk packet congestion marking across a core network region. We describe the operation and performance of GQS, with particular reference to its use for fair resource-sharing between guaranteed traffic and a rate-responsive non-guaranteed class. This analysis includes a detailed simulation study which fully represents the interactions between events at packet and session timescales. Results confirm that GQS provides strong guarantees under normal conditions, is robust to different traffic configurations, and readily recovers from network failure events.

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Grand Strategy - Rationale; towards a Denial of Service Resistant Internet, Bob Briscoe, working document, draft B (Nov 2005)

Presentations [ CFP Jan 06 | CRN Jun 06 ]

Goal of this document: To lay out the space of possible activity across the technical, economic, contractual and regulatory fields in order to prioritise activity. In particular:

• to identify approaches that require less co-ordination between companies, between industries, between disciplines or between jurisdictions
• to identify gaps where such co-ordination is unavoidably necessary
  
• to identify approaches that are not worth pursuing. 

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Review: Quick-Start for TCP and IP, Bob Briscoe (BT & UCL), IETF Internet-Draft <draft-briscoe-tsvwg-quickstart-rvw-00.txt> (Nov 2005 - Expired). (35pp, 20 refs) [BibTeX]

Abstract: This review thoroughly analyses draft 01 of the Quick-Start proposal, focusing mostly on security issues. It is argued that the recent new QS nonce proposal gives insufficient protection against misbehaving receivers, and a new approach is suggested. But it would be perverse to strengthen protection against malicious receivers too much when the protocol only works if all senders can be trusted to comply. The review argues this is an inevitable result of choosing to have routers allocate rate to senders without keeping per-flow state. The paper also questions whether Quick-Start's under-utilisation assumption defines a distinct range of operation where fairness can be ignored. Because traffic variance will always blur the boundary, we argue that under-utilisation should be treated as the extreme of a spectrum where fairness is always an issue to some extent.

If we are to avoid per-flow state on routers, the review points to an alternative direction where endpoints allocate rate to themselves. Counter-intuitively, this allows scalable security and a spectrum of fairness to be built in from the start, but rate allocation is less deterministic.

Issues not related to security are also raised, including the possibility of a catastrophic overload if path delays are atypical. A solution to this is offered, as well as solutions to scalability issues with the range and precision of the Rate Request field. Many other more minor review comments are given.

Review: Quick-Start for TCP and IP, Bob Briscoe (BT & UCL), BT Technical Report TR-CXR9-2005-007 (Nov 2005). (18pp, 20 refs) [BibTeX]

<Identical body text to the above IETF Internet Draft>

Re-ECN: Adding Accountability for Causing Congestion to TCP/IP, Bob Briscoe, Arnaud Jacquet, Toby Moncaster and Alan Smith (BT), IETF Internet-Draft <draft-briscoe-tsvwg-re-ecn-tcp-08.txt> (Sep 2009). (51pp, 28 refs, 7 figs) [BibTeX]

Differences between drafts: [ 08-07 | 07-06 | 06-05 | 05-04 | 04-03 | 03-02 | 02-01 ]

Presentations: [ IETF-76 | ECOC-FID'07 | IETF-69 | IETF-68 | CMU'06 | IETF-67 | IETF-66 | IETF-65 | IETF-64 ]

Abstract: This document introduces a new protocol for explicit congestion notification (ECN), termed re-ECN, which can be deployed incrementally around unmodified routers.  The protocol works by arranging an extended ECN field in each packet so that, as it crosses any interface in an internetwork, it will carry a truthful prediction of congestion on the remainder of its path.  The purpose of this document is to specify the re-ECN protocol at the IP layer and to give guidelines on any consequent changes required to transport protocols.  It includes the changes required to TCP both as an example and as a specification.  It briefly gives examples of mechanisms that can use the protocol to ensure data sources respond correctly to congestion,and these are described more fully in a companion document [re-ecn-motive].

Re-ECN: The Motivation for Adding Accountability for Causing Congestion to TCP/IP, Bob Briscoe (BT & UCL), Arnaud Jacquet, Toby Moncaster and Alan Smith (BT), IETF Internet-Draft <draft-briscoe-tsvwg-re-ecn-tcp-motivation-01.txt> (Sep 2009). (53pp, 28 refs, 2 figs) [BibTeX]

Differences between drafts:  [ 01-00 ]

Presentations: [ ECOC-FID'07 | IETF-69 | ParisNetNeutrality'07 | IETF-68 | CRN_NetNeutrality'06 | CMU'06 | IETF-67 | IETF-66 | IETF-65 | IETF-64 ]

Abstract: This document describes the motivation for a new protocol for explicit congestion notification (ECN), termed re-ECN, which can be deployed incrementally around unmodified routers.  Re-ECN allows accurate congestion monitoring throughout the network thus enabling the upstream party at any trust boundary in the internetwork to be held responsible for the congestion they cause, or allow to be caused.  So, networks can introduce straightforward accountability for congestion and policing mechanisms for incoming traffic from end- customers or from neighbouring network domains.  As well as giving the motivation for re-ECN this document also gives examples of mechanisms that can use the protocol to ensure data sources respond correctly to congestion.  And it describes example mechanisms that ensure the dominant selfish strategy of both network domains and end- points will be to use the protocol honestly.

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A path-aware rate policer: design and comparative evaluation, Arnaud Jacquet, Alessandro Salvatori (BT) and Bob Briscoe (BT & UCL), BT Technical Report TR-CXR9-2005-006 (Oct 2005). (12pp, 15 refs, 13 figs) [BibTeX]

Abstract: In the current Internet, congestion control is voluntary and not responding sufficiently to congestion is becoming a growing problem. Rate policers in the literature are based on the assumption of placement at a single bottleneck and a known minimum round trip time. We aim to characterise the limitations of these policers in many practical scenarios where we believe these assumptions break down. We present the design of a policer based on a novel feedback architecture that transcends these assumptions. The new arrangement places our policer at the interface with the sender. The sender is trapped into sending packets through the policer that honestly declare the congestion and round trip time of the whole downstream path. We compare the theoretical limits of these different classes of policers.

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RSVP Extensions for Admission Control over Diffserv using Pre-congestion Notification, Francois Le Faucheur, Anna Charny (Cisco), Bob Briscoe, Philip Eardley (BT), Jozef Babiarz and Kwok-Ho Chan (Nortel), Internet Engineering Task Force (IETF) Transport Services working group Internet Draft <draft-lefaucheur-rsvp-ecn-01.txt> (Expired) (Jun 2006) (13pp, 9 refs, 1 fig) [BibTeX]

Presentations: [ IETF-66 | IETF-63 ]

Abstract: This document specifies the extensions to RSVP for support of the Controlled Load (CL) service over a Diffserv cloud using Pre-Congestion Notification as defined in [CL-DEPLOY].

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Pre-Congestion Notification (PCN) Architecture, Philip Eardley (BT) (Editor), IETF RFC <rfc5559.txt> (Jun 2009). (54pp, 56 refs, 4 figs) [BibTeX]

Differences between drafts: [ IETF document history ]

Presentations: [ IETF-72 | IETF-71 ]

Abstract:  This document describes a general architecture for flow admission and termination based on pre-congestion information in order to protect the quality of service of established, inelastic flows within a single Diffserv domain.

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An edge-to-edge Deployment Model for Pre-Congestion Notification: Admission Control over a DiffServ Region (superceded by Pre-Congestion Notification Architecture), Bob Briscoe, Philip Eardley, David Songhurst (BT), Francois Le Faucheur, Anna Charny (Cisco), Jozef Babiarz, Kwok-Ho Chan, Stephen Dudley (Nortel), Georgios Karagiannis (Uni Twente), Attila Bader and Lars Westberg (Ericsson), Internet Engineering Task Force (IETF) Transport Services working group Internet Draft <draft-briscoe-tsvwg-cl-architecture-04.txt> (Oct 2006) (Expired) (63pp, 44 refs, 7 figs) [BibTeX]

Differences between drafts: [ 04-03 ]

Presentations: [ IETF-66 | IETF-65 | IETF-64 | IETF-63 ]

Abstract: This document describes a deployment model for pre-congestion notification (PCN) operating in a large DiffServ-based region of the Internet. PCN-based admission control protects the quality of service of existing flows in normal circumstances, whilst if necessary (eg after a large failure) pre-emption of some flows preserves the quality of service of the remaining flows. Each link has a configured-admission-rate and a configured-pre-emption-rate, and a router marks packets that exceed these rates. Hence routers give an early warning of their own potential congestion, before packets need to be dropped. Gateways around the edges of the PCN-region convert measurements of packet rates and their markings into decisions about whether to admit new flows, and (if necessary) into the rate of excess traffic that should be pre-empted. Per-flow admission states are kept at the gateways only, while the PCN markers that are required for all routers operate on the aggregate traffic - hence there is no scalability impact on interior routers.

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Metering and Marking behaviour of PCN-nodes, Philip Eardley (BT) (Editor), IETF RFC <rfc5670.txt> (Nov 2009). (20pp, 1 Fig, 15 refs) [BibTeX]

Differences between drafts: [ IETF document history | eardley01-00 ]

Abstract: The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain in a simple, scalable, and robust fashion.  This document defines the two metering and marking behaviours of PCN-nodes.  Threshold-metering and -marking marks all PCN-packets if the rate of PCN-traffic is greater than a configured rate ("PCN-threshold-rate").  Excess-traffic-metering and -marking marks a proportion of PCN-packets, such that the amount marked equals the rate of PCN-traffic in excess of a configured rate ("PCN-excess-rate").  The level of marking allows PCN-boundary-nodes to make decisions about whether to admit or terminate PCN-flows.

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Pre-Congestion Notification marking (superceded by Metering and Marking behaviour of PCN-nodes), Bob Briscoe, Philip Eardley, David Songhurst (BT), Francois Le Faucheur, Anna Charny, Vassilis Liatsos (Cisco), Jozef Babiarz, Kwok-Ho Chan, Stephen Dudley (Nortel), Georgios Karagiannis (Uni Twente / Ericsson), Attila Bader and Lars Westberg (Ericsson), Internet Engineering Task Force (IETF) Transport Services working group Internet Draft <draft-briscoe-tsvwg-cl-phb-03.txt> (Expired) (Oct 2006) (48pp, 20 refs, 14 figs) [BibTeX]

Differences between drafts: [ 03-02 ]

Presentations: [ IETF-66 | IETF-65 | IETF-63 ]

Abstract: Pre-Congestion Notification (PCN) builds on the concepts of RFC 3168, "The addition of Explicit Congestion Notification to IP". However, Pre-Congestion Notification aims at providing notification before any congestion actually occurs. Pre-Congestion Notification is applied to real-time flows (such as voice, video and multimedia streaming) in DiffServ networks. As described in [CL-DEPLOY], it enables "pre" congestion control through two procedures, flow admission control and flow pre-emption. The draft proposes algorithms that determine when a PCN-enabled router writes Admission Marking and Pre-emption Marking in a packet header, depending on the traffic level. The draft also proposes how to encode these markings. We present simulation results with PCN working in an edge-to-edge scenario using the marking algorithms described. Other marking algorithms will be investigated in the future.

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Commercial Models for IP Quality of Service Interconnect, Bob Briscoe & Steve Rudkin (BT), in BTTJ Special Edition on IP Quality of Service, 23(2) (Apr 2005). (26pp, 44 refs, 8 figs; pre-print) [BibTeX]

Presentations: [ NGN Interconnection Strategies'08 | IP Interconnection Forum | CFP ]

Abstract: Interconnection of IP QoS capabilities between networks releases considerable value. In this paper we show where this value will be realised. We give technical and economic arguments for why QoS will be provided in core and backbone networks as a bulk QoS facility incapable of distinguishing or charging differentially between sessions. While between edge networks a vibrant mix of retail QoS solutions will be possible, including Internet-wide per flow guarantees.

We outline cutting edge research on how to coordinate QoS between networks, using a session-based overlay between the edges that will extract most surplus value, underpinned by a bulk QoS layer coordinating the whole. We survey today's interconnect tariffs and the current disconnected state of IP QoS. Then we describe a commercial `model of models' that allows incremental evolution towards an interconnected future.

The paper covers intertwined engineering and economic/commercial issues in some depth, but considerable effort has been made to allow both communities to understand the whole paper.

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Guaranteed QoS synthesis - an example of a scalable core IP quality of service solution, Peter Hovell, Bob Briscoe and Gabriele Corlianò (BT), in BTTJ Special Edition on IP Quality of Service, 23(2) (Apr 2005). (11pp, 6 refs, 4 figs; pre-print) [BibTeX]

Presentation

Abstract: With the transition of services like IP telephony to be carried over IP networks there is the potential for catastrophic numbers of calls to fail whenever sufficient demand is focused on unpredictable points in the core IP network. This is well-known; Service differentiation helps but does not alleviate the problem - call admission control is required but seems expensive for the few occasions it is required.This paper describes a BT-developed experimental mechanism called guaranteed QoS synthesis (GQS) that performs call admission control for core IP networks for constant bit-rate streams (voice and video). The mechanism is primarily aimed at Internet services  but it may be possible to extend it for VPN applications. The GQS mechanisms is economic to deploy and operate , and scales without any increase in complexity.  It achieves these properties by keeping no flow state in the network and basing call admission decisions on the measured congestion across the network. The paper describes the high-level GQS architecture as well as some of the deployment issues and potential savings in the operational support area. How GQS enables the separation of the interconnect QoS and retail business models is also explained.

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Policing Congestion Response in an Internetwork using Re-feedback, Bob Briscoe (BT & UCL), Arnaud Jacquet (BT), Carla Di Cairano-Gilfedder (BT), Alessandro Salvatori (Eurécom & BT), Andrea Soppera (BT) and Martin Koyabe (BT) in Proc ACM SIGCOMM'05, Computer Communications Review 35(4) (Sep 2005) (12pp, 21 refs, 8 figs; pre-print) [BibTeX]

Presentation: [ SIGCOMM'05 | CFP_BB'05 | UCL'04 | Cam'04 | ICSI'04 ]

Abstract: This paper introduces a novel feedback arrangement, termed re-feedback. It ensures metrics in data headers such as time to live and congestion notification will arrive at each relay carrying a truthful prediction of the remainder of their path. We propose mechanisms at the network edge that ensure thedominant selfish strategy of both network domains and endpoints will be to set these headers honestly and to respond correctly to path congestion and delay, despite conflicting interests. Although these mechanisms influence incentives, they don’t involve tampering with end-user pricing. We describe a TCP rate policer as a specific example of this new capability. We show it can be generalised to police various qualities of service. We also sketch how a limited form of re-feedback could be deployed incrementally around unmodified routers without changing IP.

Shared Control of Networks using Re-feedback; An Outline, Bob Briscoe, Sébastien Cazalet, Andrea Soppera and Arnaud Jacquet (BT), BT Technical Report TR-CXR9-2004-001 (Sep 2004) (9pp, 16 refs, 5 figs) [BibTeX]

Presentation

Abstract: Properly characterising paths is an important foundation for resource sharing and routing in packet networks. We realign metrics so that fields in packet headers characterise the path downstream of any point, rather than upstream. Then closed loop control is possible for either end-points or network nodes. We show how incentives can be arranged to ensure that honest reporting and responsible behaviour will be the dominant strategies of selfish parties, even for short flows. This opens the way for solutions to a number of problems we encounter in data networking, such as congestion control, routing and denial of service.

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The Implications of Pervasive Computing on Network Design, Bob Briscoe (BT), chapter in Alan Steventon and Steve Wright (Eds.) Intelligent spaces (2006), Springer Verlag, ISBN: 1-84628-002-8 (25pp, 66 refs, 13 figs; pre-print) [BibTeX]

Presentation

The above document supercedes the article below

The Implications of Pervasive Computing on Network Design, Bob Briscoe (BT), in BTTJ Special Edition Intelligent spaces, vol.22 no.3 (Jul 2004) (21pp, 65refs, 3 figs; pre-print) [BibTeX]

Abstract: This paper concerns how computing devices will impact on how we design networking as they increasingly pervade the fabric of the world. We identify the pressure points where pervasive computing will push current approaches to their limits, covering both technical and business implications. We use a broad definition of communications technology, to include not only infrastructure equipment and services, but also communications facilities within the devices themselves.

We outline progress redesigning the Internet for pervasive computing. We cover components of communications such as transport, routing and security. But
we also consider how the industry will be arranged; explaining why new modes of communications (e.g. publish-subscribe) will become prevalent, where functions will be placed and how their deployment will happen. We give the rationale behind the most respected approaches being adopted. We give reasoned, if sometimes controversial, views of what should happen, built on our own research. We dispel some myths and outline the research agenda that still stands between us and realisation of the vision of ubiquitous computing.

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(Remote LCS copy) GAP: The Generic Announcement Protocol for Event Messaging, Andrea Soppera, Trevor Burbridge, Bob Briscoe and Mike Rizzo (BT), in Proc. London Communication Symposium (Sep 2003) [BibTeX]

Presentation

Abstract: We describe the Generic Announcement Protocol (GAP), a two-tier generic multicast transport designed for scalable event notification. GAP requires no extra central infrastructure or administra-tion beyond a multicast enabled network or an equivalent overlay. GAP’s scalability arises from the
use of announcement indexes, which exploit the underlying openness and flexibility of the raw GAP protocol. Event notifications can be massively multiplexed onto a multicast group channel, with in-terested receivers only joining the group for the brief duration of the announcement, coordinated by
an acyclic graph of indexes, which are themselves announcements on other channels. This indexing technique, combined with the GAP protocol is particularly efficient when waiting for events to occur, since the network resources (for addressing and filtering) are kept to a minimum.

Abstract: We present and analyse an approach to service differentiation in third generation mobile networks based on Wideband CDMA, that exposes a new weighting parameter designed to reflect allocation of the congestible resource. The approach naturally takes into account the difference in resource scarcity for the uplink and downlink, because it is grounded on fundamental economic models for efficient utilization of resources in WCDMA. If required, discrete values of this weight parameter can be presented as different service classes. Finally we present numerical experiments demonstrating the effectiveness of our approach, and investigate its performance and transient behaviour under power control and signal quality estimation errors. Keywords: resource usage, class-based, power control, congestion control.

Abstract: We present a model based on congestion pricing for resource control in wireless CDMA networks carrying traffic streams that have fixed rate requirements, but can adapt their signal quality. Our model is based on resource usage in the uplink direction of CDMA networks, and does not differentiate users based on their distance from the base station. We compare our model with other economic models that have appeared in the literature, identifying their similarities and differences. Our investigations include the effects of a mobile's distance and the wireless network's load on the target signal quality, the transmission power and the user's benefit and charge.

Abstract: In this paper, we describe our approach to managing quality of service (QoS) using pricing. We show how it is possible to synthesise network QoS in the end-systems along the lines of the end to end design principle, as one of many possible business models. We have: i) developed an architecture for market management; ii) invented new business models to test and demonstrate its flexibility; iii) implemented generic mechanisms that not only enable these models but also many others; iv) modelled selected features of the resulting systems & markets and v) conducted experiments on users to assess acceptability and the feasibility of the overall approach. Each of these aspects is outlined in brief overview, with numerous references to more
detailed work.

Abstract: This draft describes a very flexible and efficient protocol for distributing price information (tariffs) inside an Internet Service Provider's management system and to its customers. It is designed to work with multiple QoS architectures, for example Intserv [2] and Diffserv [4]. It can also be used for dynamic pricing. It can use a number of different transport mechanisms, e.g. embedding tariff messages as policy objects in RSVP [9] messages. As tariffs can get very complex, it is possible but not necessary to send tariffs as code (e.g. Java).  The draft also contains clear definitions of tariff and related terms.

Abstract: This document introduces Timed Efficient Stream Loss-tolerant Authentication (TESLA). TESLA allows all receivers to check the integrity and authenticate the source of each packet in multicast or broadcast data streams. TESLA requires no trust between receivers, uses low-cost operations per packet at both sender and receiver, can tolerate any level of loss without retransmissions, and requires no per-receiver state at the sender. TESLA can protect receivers against denial of service attacks in certain circumstances. Each receiver must be loosely time-synchronized with the source in order to verify messages, but otherwise receivers do not have to send any messages. TESLA alone cannot support non-repudiation of the data source to third parties.

This informational document is intended to assist in writing standardizable and secure specifications for protocols based on TESLA in different contexts.

Presentation

Abstract: This document contributes to the effort to add explicit congestion notification (ECN) to IP. In the current effort to standardise ECN for TCP it is unavoidably necessary to standardise certain new aspects of IP. However, the IP aspects will not and cannot only be specific to TCP. We specify interaction with features of IP such as fragmentation, differentiated services, multicast forwarding, and a definition of the service offered to higher layer congestion control protocols. This document only concerns aspects related to the IP layer, but includes any aspects likely to be common to all higher layer protocols. Any specification of ECN support in higher layer protocols is expected to appear in a separate specification for each such protocol.

[Full report, on which the above paper is based]

(Remote M3I copy)Market Managed Multi-service Internet: Pricing Mechanisms; Price Reaction Design, Bob Briscoe, Konstantinos Damianakis and Jérôme Tassel (BT), Panayotis Antoniadis & George Stamoulis (Athens UEB), M3I Consortium Deliverable D3PtII, 10 Jul 2000 (24pp, 12 Figs, 19 refs) [BibTeX]

Presentation

Abstract: Some applications only make sense within a very tightly bounded range of quality of service (QoS) from the network. Others are far more adaptive. For the former type of application, it is relatively easy to determine their QoS requirements. This document primarily concerns how to determine the QoS requirement of the latter type of application, given a tariff for
network quality of service. We also cover how an application might describe its policy for determining QoS with respect to price. This description can then be used as policy for another entity controlling QoS, whether a middleware function on the same host, or a remote application being communicated with through a protocol.

Abstract: This document presents our architecture for a market managed multi-service Internet (M3I). As explained in Part I, the task is to encompass all multi-service Internet architectures simultaneously in one architecture. To avoid confusion, we therefore term these sub-architectures ‘service plans’. A service plan is a combination of a network control architecture and the business model used to offer it as a service. The architecture is open, not only encompassing current and proposed service plans, but also facilitating the creation of new ones.

This document is an ‘architecture’ not a ‘design’. We define architecture as a specification of:
• why certain functions are best provided separately;
• what service they each offer and what their interfaces are;
• information structures that will have common use across the system such as identifiers.

The M3I Architecture is delivered in two parts: Principles (Part I [8]) and Construction (Part II — this part). Part I is designed to be readable alone. It goes to the core of what a multi-service Internet is and extracts fundamental principles from this exercise. It then gives a high level overview of the building blocks described in this second part in order to describe sensible ways to put them together. In contrast, this second part cannot
be read alone — part I is an essential pre-requisite. This second part describes the construction kit of the architecture — the building blocks and their interfaces. Indeed, it will be seen that the building blocks are very rudimentary — much as the principles were very fundamental. Specification is high level, but relatively precise. Because the building blocks are so rudimentary, we also introduce various compositions of the building blocks into useful sub-systems — themselves building blocks, but molecular rather than atomic. Each building block has the types of its possible inputs and outputs
tied down, so that it is impossible to put the pieces together in illegal ways. However, what is legal is not always sensible, hence the need for the principles in Part I.

Abstract: In this paper we describe an intelligent, client based charging middleware that can be used to enable customers' self policing over the access of network resources in a multi service network like Internet (and ultimately higher level services). By intelligence we mean the charging software, data stores and the human or agent based reaction to dynamic pricing. The middleware components described in this paper are part of the MWARE client based middleware being researched and developed at the BT Advanced Communications Technology Centre [mware].

Abstract: In this paper we present a novel scalable accounting infrastructure to support charging for network usage and Quality of Service (QoS) in an Internet context. Measurement and accounting are two core processes of a charging mechanism that make heavy demand on resources. They reduce the resource available for the core processes of the network i.e. routing and forwarding packets. Increasing the processing power and data storage capacity of the affected network elements lead to an increment in the cost of the network. The underlying principle of the infrastructure we propose is the transfer of these processes onto the edge systems to reduce their impact on the cost of the network. The measurement, accounting, applying pricing and billing processes and related sets of data are relocated on the edge systems of the network while allowing the provider to retain control over them. This paper focuses on the measurement and accounting aspects of this infrastructure. To achieve scalability we propose not to meter all the data or QoS control packet but only samples of them. We also discuss which controls both users and network providers could desire over the relocated processes. Early implementation of this work is introduced as a practical example of the concepts we present.

MARKS: Zero side-effect multicast key management using arbitrarily revealed key sequences, Bob Briscoe (BT), in Proc First International Workshop on Networked Group Communication (NGC'99) (LNCS pub. Springer-Verlag ), Pisa, Italy  (17-20 Nov 1999) (13pp, 3 figs, 20 refs) [BibTeX]

Presentation

Abstract: The goal of this work is to separately control individual secure sessions between unlimited pairs of multicast receivers and senders. At the same time, the solution given preserves the scalability of receiver initiated Internet multicast for the data transfer itself. Unlike other multicast key management solutions, there are absolutely no side effects on other receivers when a single receiver joins or leaves a session and no smartcards are required. The cost per receiver-session is typically just one short set-up message exchange with a key manager. Key managers can be replicated without limit because they are only loosely coupled to the senders who can remainoblivious to members being added or removed. The technique is a general solution for access to an arbitrary sub-range of a sequence of information and for its revocation,as long as the end of each sub-range can be planned at the time each access is requested.

Keywords: Multicast, Group Key management, Internet.

[A full length report describing five variations on the solution to the problem and a mathematical model encompassing them all. The above NGC'99 paper is a brief extract describing one solution]

Abstract: The goal of this work is to separately control individual secure sessions between unlimited pairs of multicast receivers and senders. At the same time, the solution given preserves the scalability of receiver initiated Internet multicast for the data transfer itself. Unlike other multicast key management solutions, there are absolutely no side effects on other receivers when a single receiver joins or leaves a session and no smartcards are required. Solutions are presented for single and for multi-sender multicast. Further, we show how each receiver's data can be subject to an individual, watermarked audit trail. The cost per receiver-session is typically just one short set-up message exchange with a key manager. Key managers can be replicated without limit because they are only loosely coupled to the senders who can remain oblivious to members being added or removed. The technique is a general solution for access to an arbitrary sub-range of a sequence of information and for its revocation, as long as each session end can be planned at the time each access is requested. It might therefore also be appropriate for virtual private networks or for information distribution on other duplicated media such as DVD.

Presentation

Abstract: The goal of this work is to separately control individual secure sessions between unlimited pairs of multicast receivers and senders while preserving the scalability of receiver initiated Internet multicast for the data transfer itself. Unlike other secure multicast solutions, there are absolutely no side-effects on other receivers when a single receiver joins or leaves a session. Each individual receiver can also reliably prove whether any fragment of the data hasn't been delivered or wasn't delivered on time (e.g. late video frames). Further, each receiver's data can be subject to an individual, watermarked audit trail. The cost per receiver-session is typically just one set-up message exchange with a key manager. Key managers can be replicated without limit because they are only loosely coupled to the senders who can remain oblivious to members being added or removed. The solution requires a tamper-resistant processor such as a smartcard at each receiver. However, generic cards supplied by a trusted third party are used rather than cards specific to each information provider. The technique can be applied to other bulk data distribution channels instead of multicast, such as DVD.

Keywords: Multicast, Non-repudiation, Key management, Smartcard, Watermark, Audit trail, Internet

[Full report, on which the above paper is based]

The Direction of Value Flow in Open Multi-service Connectionless Networks, Bob Briscoe (BT), BT Technical Report TR-NZG12-2000-001 (20 Aug 2000) (20pp (inc 6pp appendices), 7 figs, 24 refs) [BibTeX]

Abstract: [The union of the two papers below]

The Direction of Value Flow in Connectionless Networks, Bob Briscoe (BT & UCL), invited paper, First International Workshop on Networked Group Communication (NGC'99) (LNCS pub. Springer-Verlag ), Pisa, Italy (17-20 Nov 1999) (17pp (inc 3pp appendices), 7 figs, 23 refs) [BibTeX]

Presentation

Abstract: [A modified version of the ICTEC'99 paper below (with just a summary of the maths, but highlighting the multicast aspects of the work)].

The Direction of Value Flow in Multi-service Connectionless Networks, Bob Briscoe (BT & UCL), Second International Conference on Telecommunications and Electronic Commerce (ICTEC'99), Nashville, TN, US, (6-8 Oct 1999) (19pp (inc 6pp appendices), 7 figs, 22 refs) [BibTeX]

Presentation
 

Abstract: This paper argues that, for scalability, all network providers in a connectionless multi-service network should offer each class of their service to each neighbour for each direction at a single price. This is called 'split-edge pricing'. To preserve scalability, if sets of customers wish to reapportion their networking charges between themselves, this should be tackled end-to-end. Edge reapportionment should not be muddled with networking charges, as is the case in the telephony market. Avoiding the telephony approach is shown to offer full reapportionment flexibility, but avoids the otherwise inevitable network complexity. 'Split-edge pricing' is recursive, applying as much to relationships between providers as to edge-customers. Various scenarios are discussed, showing the advantage of the approach. These include phone to Internet gateways and even inter-domain multicast conferences with heterogeneous QoS. The business model analysis suggests a new, purely financial role of end-to-end intermediary in the Internet industry.

Keywords: Charging, pricing, end-to-end, clearing, multicast, Internet, business models.

Abstract: The underlying objective of the work presented in this paper is to create an active multi-service network which uses pricing to manage supply and demand of resources. The paper describes a dynamic pricing framework designed to support a radical approach to usage-based charging for packet-switched networks. This approach addresses the scalability problem normally associated with usage-based charging by shifting responsibility for accounting over to customer systems, which are also assigned the task of applying tariffs to create a bill.

In this context, the role of the dynamic pricing framework is to enable a provider to establish `active tariffs' and communicate them to customer systems. These tariffs take the form of mobile code for maximum flexibility, and the framework uses an auditing process to provide a level of protection against incorrect execution of this code on customer systems. In contrast to many active networks proposals, the processing load is moved away from routers to the edge of the network.

Keywords: usage-based charging, mobile code, self-billing, pricing, resource management.

Presentation

Abstract: This paper suggests that a multi-service packet network might be achieved by adding classification and scheduling to routers, but not policing. Instead, a lightweight, packet-granularity charging system is presented that emulates a highly open policing function and is completely separated from the data path. A high proportion of charging operations runs on customer systems to achieve this, the proportion being configurable per-customer. Functions dispersible to customers include not only metering, accounting and billing but also per-packet or per-flow policing and admission control. Lower cost is achieved through simplicity without sacrificing commercial flexibility or security. Inter-provider charging, multicast charging and open bundling of network charges with those for higher class services are all catered for within the same, simple design. The paper is primarily architectural, referring to supporting papers for reports of early implementation experience in an Internet context.

Keywords: Charging, pricing, congestion control, quality of service, policing, operational support, active networks, Internet.

Abstract: A chargeable session on the Internet may consist of more than one underlying chargeable service.  Typically there will be two, one at the network layer and one at the session layer.  Since different applications can have different demands from the Network, a generic charging scheme has to separate the service provided by the network from the service provided by an application/service provider.
In this paper we propose a pricing model which is session based and we look at the impact of this on  real-time multimedia conferencing over the Internet. In this model, we are trying to allow for the optional integration of charging at the network layer with charging at the session layer, while keeping the underlying technologies still cleanly apart. This paper also highlights the fact that the main problem of pricing application on the Internet is not just a simple case of analyzing the most technically feasible pricing mechanism but also making the solution acceptable to users.  We take the position that session based pricing is easier for end users to accept and understand and show why this is the case in this paper.

Abstract: [near-identical to the above ISCC'99 paper]

End to End Aggregation of Multicast Addresses, Bob Briscoe & Martin Tatham (BT), 21 Nov 1997, BT Technical Report TR-NAA12-1997-001 (source of the above Internet Draft) [BibTeX]

Abstract: This paper presents an approach for solving the inherent problem with multicast routing scalability - by co-operation between end-systems and the network. We introduce an extremely efficient, elegant way to name arbitrary sized inter-meshed aggregations of multicast addresses. This is done in such a way that it is easy to calculate how to change the name to encompass many more related names. We describe how these aggregate names could be used anywhere in place of the set of addresses to which they refer, not by resolving them into multiple operations, but by a single bulk action throughout the routing tree, and in session descriptions potentially including those for reservations. Initial aggregation in end-systems might only reduce the problem by an order of magnitude, but it is believed that this will provide sufficient structure for routers to be able to recognise further aggregation potential.  To improve the chances of router aggregation, address set allocation schemes must fulfil certain criteria that are laid down in this paper.

Presentation

Abstract: The main objective of the model we describe in this paper is to allow easy, flexible addition of quality of service (QoS) control to Java Internet applications. In this work the QoS is expressed in terms of network and host resources, the network QoS being controlled with RSVP. Flexibility is provided by a prototype product from the ANSA research consortium; Reflective Java which uses the Meta Object Protocol (MOP) to separate functional requirements (what the application does) from non-functional requirements (how it does it). This protocol permits the design and implementation of a generic QoS control element which can be added to an application for which QoS control is required. Alternatively, an existing application with rudimentary QoS control can be modified to use a set of QoS control classes designed by a specialist intended to reconcile competition for QoS between applications. The QoS control element we have designed also has scope for QoS adaptation, moving decisions on the introduction of QoS control from build-time to run-time when best-effort degrades below a useful point. Charging is also considered in this work.

Presentation to IETF LSMA working group, Pete Bagnall, Munich, Aug 1997, Washington, Dec 1997 [broken link - presentation lost]

Abstract: The intention of this memo is to define a classification system for the communication requirements of any large-scale multicast application (LSMA). It is very unlikely one protocol can achieve a compromise between the diverse requirements of all the parties involved in any LSMA. It is therefore necessary to understand the worst-case scenarios in order to minimize the range of protocols needed. Dynamic protocol adaptation is likely to be necessary which will require logic to map particular combinations of requirements to particular mechanisms.  Standardizing the way that applications define their requirements is a necessary step towards this. Classification is a first step towards standardization.

Abstract: Various distributed object technologies have traditionally been seen as necessary to protect us from the uncertainties of a world where there is a perpetual state of partial failure. The World-Wide Web is the second largest distributed system in the world, behind only the telephone network which has far simpler ambitions. This paper discusses various approaches to the task of integrating the Web with more deterministic distributed object technologies to create islands of reliability (or to add other specific capabilities) without compromising the global scale of the Web. However, it is dangerous to take the view that a globally popular system such as the Web wasn’t designed correctly. The paper goes on to explore the essence of the Web’s success and discusses whether other distributed object systems would benefit from being less obsessed with deterministic behaviour.

Abstract: The marriage between distributed object technology (the real men) and Web technology (the earth mothers) has been announced. From the groom's point of view, preparations for the marriage will be complete once he's taught the bride how to speak IIOP, learnt a bit of HTTP to make her comfortable and finished work on some important object services in the shed at the bottom of the OMG. However, by some mysterious organic process, she has amassed knowledge of all things. Whatever question he has, he must discover the spell that will draw out the answer. He needs to get in touch with her inner feelings. Consummation will be delayed until this chauvinistic gap is breached.

It is fashionable to criticise how well the Web achieves this or that goal then invent a "proper" service to do it better. It is tempting to suppose that technology for structured applications from the traditions of the distributed object world should be inserted into the Web on the day of their marriage. This paper aims to show that, in the field of service discovery, the Web deserves a long hard look before we click on the button marked "Fixed in the Next Release". As such, no new technology is proposed, merely some optimistic thoughts leading to the insight that the Web is a "proper" system for resource discovery (well, nearly).