Senior Consultant Network Planning and Design Siemens AG, München

1. IP Network Engineering Challenges Dr. Thomas Bauschert Senior Consultant Network Planning and Design Siemens AG, München Email: thomas.bauschert@icn.siemens.de

2. Outline • Network Architecture • IP Traffic Specification • IP Network Dimensioning • IP Traffic Engineering and QoS Provisioning • Further important Engineering Issues • Special Topic: MPLS - DiffServ: Combination of Traffic Engineering and QoS Provisioning

3. Network Architecture

4. Network Architecture • State-of-the-art network architecture: • switched (MPLS) IP core network (highly meshed) • multiple homed distribution/access routers

5. ASON ATM virtual meshing via wavelenghts virtual meshing via ATM PVCs router throughput < 1 Tbit/s n x STM-64 DWDM I/F router throughput < 1 Gbit/s, STM-16 I/F physical meshing router throughput < 1 Tbit/s, STM-64 I/F Network Architecture • Future challenges: • scaleable/reliable network architecture (to accommodate huge IP traffic growth): Tbit/s-routers required in near future • switched (MPS) optical core network (ASON): interaction of IP and optical layer (similar to IPoATM) state-of-the-art future

6. IP Traffic Specification

7. IP Traffic Specification (for Network Planning Purposes) • State-of-the-art: • traffic model stream/elastic traffic: stream traffic parameters: offered traffic + effective bitrate elastic traffic parameters: flow arrival rate + average flow size • traffic matrix generation methodology • Challenges: • traffic classification: how many classes are really necessary? • which QoS metrics should be applied? (e.g. blocking probability for stream traffic is only reasonable in case of CAC) • point-to-multipoint traffic description strong relationship to QoS mechanisms

8. IP Network Dimensioning

9. IP Network Dimensioning • State-of-the-art: • single link dimensioning with multirate Erlang-B (stream) and M/G/R-PS (elastic, ideal TCP behavior) model • dimensioning for tree-type access networks • separate dimensioning for elastic / stream traffic portions

10. IP Network Dimensioning • Challenges: • link dimensioning model improvements: - dimensioning formula for short flows - M/G/R-PS extension for multiple rpeak - consideration of QoS mechanisms and multiple QoS levels • network dimensioning algorithm (similar to the well-known unified algorithm for PSTN and ATM networks) with following features: - integrated (IGP) routing optimization - consideration of constraints imposed by TE and QoS mechanisms like MPLS, OMP, DiffServ - multiple load period dimensioning - point-to-any dimensioning (for DiffServ networks) - consideration of restoration capabilities (e.g. via MPLS) - dimensioning for multiple QoS metrics • integration of dimensioning algorithm and TE system in automated planning and engineering system

11. IP Traffic Engineering and QoS Provisioning

12. IP Traffic Engineering and QoS Provisioning • State-of-the-art: • separate application of Traffic Engineering and QoS mechanisms (multipath routing (OMP), MPLS LSP adaption, DiffServ, IntServ) in IP networks • Challenges: • performance evaluation of TE / QoS mechanisms • use of TE for fast load adaption and restoration • development of optimum TE control algorithm (objectives/constraints of TE?) • information exchange/interaction of TE mechanism and routing • combination of different mechanisms: MPLS-OMP, MPLS-DS - requires protocol enhancements > new IETF drafts - driver: search for optimum tradeoff between overprovisioning and complexity - strong relationship to SLA formulation - will admission control be really neccessary? • end-to-end QoS provisioning: reasonable scenarios

13. Further important Engineering Issues

14. Further important Engineering Issues • Optimization tasks concerning routing protocols: • IGP (OSPF, ISIS) design / optimization rules • EGP (BGP-4) design / optimization rules (e.g. application and # of route reflectors, confederations etc.) • traffic induced by routing protocol • performance evaluation of routing protocols • Optimization of Data Center (server site) locations • Engineering of Data Centers

15. Special Topic: MPLS-DiffServ* *partially taken from MPLS2000 Conference material

16. MPLS-DiffServ

17. MPLS-DiffServ

18. MPLS-DiffServ

19. MPLS-DiffServOverview OMP MPLS DiffServ (DS) IntServ MPLS-OMP • DS over MPLS • (or: MPLS - DS): • E-LSP • L-LSP • TE not CoS aware! increasing complexity! • DS aware MPLS TE: • TE is CoS aware DS aware MPLS TE + RSVP CAC for rt-Traffic (e.g. voice) reinvention of ATM!

20. MPLS-DiffServIETF Drafts MPLS TE: • “Requirements for Traffic Engineering Over MPLS” • RFC2702, Informational RFC • “RSVP-TE: Extensions to RSVP for LSP Tunnels” • draft-ietf-mpls-rsvp-lsp-tunnel-07.txt, Aug 2000 • “Constraint-Based LSP Setup using LDP” • draft-ietf-mpls-cr-ldp-04.txt, Jul 2000 • “Extensions to ISIS for TE” • draft-ietf-isis-traffic-03.txt, Sept 2000 • “TE extensions to OSPF” • draft-katz-yeung-ospf-traffic-03.txt, Oct 2000 DS over MPLS: • “MPLS Support of Diff-Serv” • draft-ietf-mpls-diff-ext-07.txt, Aug 2000 DS aware MPLS TE: • “Requirements for support of Diff-Serv-aware MPLS Traffic Engineering” • draft-lefaucheur-diff-te-reqts-00.txt, Jul 2000 • “Extensions to IS-IS, OSPF, RSVP and CR-LDP for support of Diff-Serv-aware MPLS TE” • draft-lefaucheur-diff-te-ext-00.txt, Jul 2000

21. MPLS-DiffServExample: MPLS TE

22. MPLS-DiffServExample: DS over MPLS

23. MPLS-DiffServExample: DS aware MPLS TE

24. MPLS-DiffServExample: DS aware MPLS TE

25. MPLS-DiffServExample: VoMPLS - DS aware MPLS TE with RSVP CAC

26. MPLS-DiffServVoMPLS: DS aware MPLS TE with RSVP CAC n “ultimate QoS” solution for VoMPLS: n QoS never degrades n automatic/dynamic traffic engineering of voice (exceeds today’s TDM TE capabilities) n excess calls get rejected if/when EF-capacity exceeded n traffic patterns do not have to be known before n This level of sophistication is only useful in some environments n Under construction at IETF

27. MPLS-DiffServ

28. Additional Slides

29. MPLS-DiffServIP VPN-Concepts: HOSE Model

30. MPLS-DiffServIP VPN Concepts: PIPE Model

31. MPLS-DiffServNecessary Enhancements for DS aware MPLS TE Current IGP extensions for TE: n advertise “unreserved TE bandwidth” (at each preemption level) Proposed IGP extensions for DS aware TE: n Class-Types= group of Diff-Serv classes sharing the same bandwidth constraint (eg AF1x and AF2x) n advertise “unreserved TE bandwidth” (at each preemption level) for each Class-Type Current LSP-signalling extensions for TE: n at LSP establishment signal TE tunnel parameters (label, explicit route, affinity , preemption,…) Proposed LSP-signalling extensions for DS aware TE: n also signal the Class-Type n perform Class-Type aware CAC Current Constraint Based Routing for TE: n compute a path such that on every link there is sufficient “unreserved TE bandwidth” Proposed Constraint Based Routing for DS aware TE: n same CBR algorithm but satisfy bandwidth constraint over the “unreserved bandwidth for the relevant Class-Type” (instead of aggregate TE bandwidth)