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Diffserv deployment in the wide area: network design and testing

This article by Tiziana Ferrari delves into the motivation, benefits, and testing of Diffserv deployment in wide area networks. It covers classification, marking, policing, QoS measurement, and more.

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Diffserv deployment in the wide area: network design and testing

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  1. Diffserv deployment in the wide area: network design and testing Tiziana Ferrari Italian National Institute for Nuclear Physics ferrari@cnaf.infn.it TF-TANT task force http://www.dante.net/tf-tant/ Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  2. Overview • Why diffserv? • Test programme • testbed • interim results: • classification and marking • policing • scheduling • QoS measurement • services: • VLL Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  3. Motivation • Why diffserv? • independent of layer 2 technologies • interoperability: • diffserv domains  National Research Networks (NRN) • diffserv region: NRN + 1 diffserv core domain • independent diffserv implementation in each diffserv domain • traffic aggregation • scalability • transparency to the application Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  4. Motivation (cont) • (some) benefits: • network layer: • VLL service, a potential replacement of ATM permanent connections • resource allocation on congested links • QoS support in/to NRN which are not ATM based • application layer: • QoS support for mission critical applications (RSVP - diffserv) e.g.: good QoS support to client-server distributed applications thanks to traffic aggregation Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  5. Diffserv and the European network model DS domain DS domain MPLS NRN NRN Non DS capable domain NRN Marking policing scheduling TEN-155 DS domain NRN (marking) shaping NRN DS domain DS domain Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  6. Overview of test programme • Diffserv • DSCP: class selectors, EF, AF • test of basic QoS features in diffserv platforms • parameter tuning • interoperability • services: definition, implementation, validation through test applications (video streaming, IP telephony, distributed applications) • diffserv and intserv (end-to-end QoS) • diffserv and MPLS • QoS measurement • Policy management Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  7. Work accomplished (June 99-Oct 99) • network configuration • baseline performance testing • marking • policing: • functionality, token bucket parameter tuning (normal and exceed burst size) with TCP traffic • CB-WFQ (Class Based WFQ): traffic isolation • scheduling: • CB-WFQ: traffic isolation, VLL service in the wide area • SCFQ (Self Clocked Fair Queuing): EF, AF and best-effort Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  8. Work accomplished (cont) • QoS measurement (ongoing): • parameters: one-way delay and one-way delay variation • LAN and WAN (VLL service implementation and validation) • traffic generators with GPS antennas • NTP • definition of test services: • point to point virtual leased line • one-to-many virtual leased line • resource allocation on congested links • better than best-effort • services for remote instrumentation control (AF) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  9. Diffserv test network Uni. Bologna CSELT EPFL Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  10. LAN layout (example) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  11. Equipment • Test workstations (ATM, Ethernet, Fast Ethernet, Giga Ethernet interfaces) • traffic generators (3 SmartBits, Netcom Systems) connected to GPS rx • ATM switch(es) in each test sites • 2 Cabletron Ethernet switches • DS capable routers: • CISCO C7200 and/or C7500 • IBM 2212 and IBM 2216 (in 5 sites, 2 routers per site) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  12. Interim Results Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  13. Classification, marking and policing • Multi-field classification: OK • packet marking: OK • testing of different “exceed actions”: OK • policing (at a configurable rate): • token bucket: parameter tuning for TCP traffic performance optimisation • normal burst • exceed burst Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  14. Policing: test of exceed actions drop precedence 0 Throughput: SWITCH: 1.20 Mbps DANTE: 0.38 Mbps (drop effect) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  15. Policing: TCP burst tolerance • Normal and exceed burst tuning with TCP traffic • single and multiple TCP streams optimum values are functions of the rate R at which traffic is policed, in particular: • normal burst = 0.5 sec * R independently of the platform • exceed burst = 2 * normal burst Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  16. Policing: TCP burst tolerance (cont) • CISCO platforms • Target rate: 1.25 Mbps Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  17. Policing: TCP burst tolerance (cont) • IBM platforms (IBM 2212) • Small TCP burst tolerance in a policer can completely starve a TCP stream. • Token bucket depth is function of the rate at which traffic is policed •  tuning needed Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  18. Policing: TCP burst tolerance (cont) EF behaviour aggregate of TCP traffic, target rate = 163 Kbps (IBM 2212) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  19. Policing, two-parameter TB:optimum burst size for different traffic rates IBM 2212 • Small TCP burst tolerance: it can completely starve a TCP stream • optimum token bucket size: function of the policing rate Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  20. Scheduling and policing:two-parameter TB and premium buffer size Recommendation: token bucket size < premium buffer size (for low packet loss probability) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  21. Scheduling: CB-WFQ Scheduling implementation to provide minimum bandwidth guarantees to classes • tested on CISCO platforms - C7200, IOS 12.0(5)T - • class definition: based on class selectors for aggregation  OK • bandwidth allocation: no starvation, dynamic allocation in case of classes which are not fully deploying the capacity guaranteed to them  OK • traffic isolation between EF BA and best-effort: • several combinations of TCP and UDP traffic • variable number of TCP streams (different aggregation degrees) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  22. CB-WFQ: set-up Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  23. CB-WFQ: traffic isolation, 1 TCP stream • Inconsistent results, for some sites TCP throughput < 1.25 Mbps • different ATM burst tolerances on the WAN connections seem seem to be • the cause  traffic isolation on WAN connections can be an issue Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  24. CB-WFQ: traffic isolation, multiple TCP streams • Overall TCP performance of the behaviour aggregate improves when the • aggregation degree increases • TCP performance of a single connection still low •  problem under investigation Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  25. Scheduling: Self Clocked Fair Queuing • IBM 2212 • Policy = (traffic profile, validity period, diffserv action) • Diffserv action = (type of marking, queue type, bandwidth) • optimum traffic isolation (tests only with UDP) Premium: 163.8 Kbps guaranteed (8% PPP link bw) Assured: 819.2 Kbps (40% PPP bw) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  26. QoS measurement • Resource allocation monitoring • for resource allocation and network dimensioning • performance measurement • passive • active (invasive traffic) • for service validation • to understand the effect on end-to-end performance of buffering in one router or in a chain Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  27. Parameters • parameters of interest: • one-way delay, requirements: clock synchronisation • GPS based synchronisation • SmartBits (Netcom Systems) • NTP (Network Time Protocol) • NTP client / server hierarchy • one-way delay variation • deployment of inter packet gap at rx and tx • packet loss probability • throughput Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  28. tx rx SmartBits QoS measurement: 1-way delay and instantaneous delay variation (LAN) Goal : VLL service implementation and validation Metric: Type-P-One-way-Delay (RFC 2679), type-P-one-way-ipdv Variables: • WFQ/SCFQ EF queue depth • packet size • EF queue “weight” • traffic volume Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  29. One-way delay: average vs packet size Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  30. Latency in time Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  31. ipdv (*without* best-effort) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  32. ipdv (*with* best-effort) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  33. Services • Virtual leased line: • point to point • one to many • capacity allocation on congested links (e.g. US links) • better-than-best-effort (qualitative definition) Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  34. VLL Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  35. VLL: implementation Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  36. Future work • Weighted Random Early Discard (WRED) testing • completion of IBM testing • study of TCP related issues: ACK colouring, TCP and UDP aggregations with AF • interoperability testing (other future platforms: NORTEL, TELEBIT, TORRENT, Linux) • service implementation and validation • diffserv and MPLS • diffserv and intserv • policy management and bandwidth brokerage Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

  37. To know more • Activities of the TF-TANT task force: • http://www.dante.net/tf-tant • Diffserv test programme and interim test results: • http://www.cnaf.infn.it/~ferrari/tfng/ds • QoS measurement test programme: • http://www.cnaf.infn.it/~ferrari/tfng/qosmon Tiziana Ferrari Diffserv deployment in the wide area: network design and testing

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