1. s T. Bauschert 11.05.2001 1 IP Network Engineering Challenges Senior Consultant Network Planning and Design Siemens AG, München Email: thomas.bauschert@icn.siemens.de Dr. Thomas Bauschert IP Network Engineering Challenges

2. s T. Bauschert 11.05.2001 2 IP Network Engineering Challenges 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. s T. Bauschert 11.05.2001 3 IP Network Engineering Challenges Network Architecture

4. s T. Bauschert 11.05.2001 4 IP Network Engineering Challenges Network Architecture State-of-the-art network architecture: switched (MPLS) IP core network (highly meshed) multiple homed distribution/access routers

5. s T. Bauschert 11.05.2001 5 IP Network Engineering Challenges 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) ATM virtual meshing via ATM PVCs router throughput < 1 Gbit/s, STM-16 I/F router throughput < 1 Tbit/s, STM-64 I/F physical meshing ASON router throughput < 1 Tbit/s n x STM-64 DWDM I/F virtual meshing via wavelenghts state-of-the-artfuture

6. s T. Bauschert 11.05.2001 6 IP Network Engineering Challenges IP Traffic Specification

7. s T. Bauschert 11.05.2001 7 IP Network Engineering Challenges 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. s T. Bauschert 11.05.2001 8 IP Network Engineering Challenges IP Network Dimensioning

9. s T. Bauschert 11.05.2001 9 IP Network Engineering Challenges 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. s T. Bauschert 11.05.2001 10 IP Network Engineering Challenges IP Network Dimensioning Challenges: link dimensioning model improvements: - dimensioning formula for short flows - M/G/R-PS extension for multiple r peak - 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. s T. Bauschert 11.05.2001 11 IP Network Engineering Challenges IP Traffic Engineering and QoS Provisioning

12. s T. Bauschert 11.05.2001 12 IP Network Engineering Challenges 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. s T. Bauschert 11.05.2001 13 IP Network Engineering Challenges Further important Engineering Issues

14. s T. Bauschert 11.05.2001 14 IP Network Engineering Challenges 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. s T. Bauschert 11.05.2001 15 IP Network Engineering Challenges Special Topic: MPLS-DiffServ* *partially taken from MPLS2000 Conference material

16. s T. Bauschert 11.05.2001 16 IP Network Engineering Challenges MPLS-DiffServ

17. s T. Bauschert 11.05.2001 17 IP Network Engineering Challenges MPLS-DiffServ

18. s T. Bauschert 11.05.2001 18 IP Network Engineering Challenges MPLS-DiffServ

19. s T. Bauschert 11.05.2001 19 IP Network Engineering Challenges MPLSDiffServ (DS) DS over MPLS (or: MPLS - DS): E-LSP L-LSP TE not CoS aware! DS aware MPLS TE: TE is CoS aware OMP MPLS-OMP DS aware MPLS TE + RSVP CAC for rt- Traffic (e.g. voice) reinvention of ATM! IntServ increasing complexity! MPLS-DiffServ Overview

20. s T. Bauschert 11.05.2001 20 IP Network Engineering Challenges DS over MPLS: “MPLS Support of Diff-Serv” draft-ietf-mpls-diff-ext-07.txt, Aug 2000 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 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 MPLS-DiffServ IETF Drafts

21. s T. Bauschert 11.05.2001 21 IP Network Engineering Challenges MPLS-DiffServ Example: MPLS TE

22. s T. Bauschert 11.05.2001 22 IP Network Engineering Challenges MPLS-DiffServ Example: DS over MPLS

23. s T. Bauschert 11.05.2001 23 IP Network Engineering Challenges MPLS-DiffServ Example: DS aware MPLS TE

24. s T. Bauschert 11.05.2001 24 IP Network Engineering Challenges MPLS-DiffServ Example: DS aware MPLS TE

25. s T. Bauschert 11.05.2001 25 IP Network Engineering Challenges MPLS-DiffServ Example: VoMPLS - DS aware MPLS TE with RSVP CAC

26. s T. Bauschert 11.05.2001 26 IP Network Engineering Challenges  “ultimate QoS” solution for VoMPLS:  QoS never degrades  automatic/dynamic traffic engineering of voice (exceeds today’s TDM TE capabilities)  excess calls get rejected if/when EF-capacity exceeded  traffic patterns do not have to be known before  This level of sophistication is only useful in some environments  Under construction at IETF MPLS-DiffServ VoMPLS: DS aware MPLS TE with RSVP CAC

27. s T. Bauschert 11.05.2001 27 IP Network Engineering Challenges MPLS-DiffServ

28. s T. Bauschert 11.05.2001 28 IP Network Engineering Challenges Additional Slides

29. s T. Bauschert 11.05.2001 29 IP Network Engineering Challenges MPLS-DiffServ IP VPN-Concepts: HOSE Model

30. s T. Bauschert 11.05.2001 30 IP Network Engineering Challenges MPLS-DiffServ IP VPN Concepts: PIPE Model

31. s T. Bauschert 11.05.2001 31 IP Network Engineering Challenges Current IGP extensions for TE: advertise “unreserved TE bandwidth” (at each preemption level) Proposed IGP extensions for DS aware TE:  Class-Types= group of Diff-Serv classes sharing the same bandwidth constraint (eg AF1x and AF2x)  advertise “unreserved TE bandwidth” (at each preemption level) for each Class-Type Current LSP-signalling extensions for TE:  at LSP establishment signal TE tunnel parameters (label, explicit route, affinity, preemption,…) Proposed LSP-signalling extensions for DS aware TE:  also signal the Class-Type  perform Class-Type aware CAC Current Constraint Based Routing for TE: compute a path such that on every link there is sufficient “unreserved TE bandwidth” Proposed Constraint Based Routing for DS aware TE: same CBR algorithm but satisfy bandwidth constraint over the “unreserved bandwidth for the relevant Class-Type” (instead of aggregate TE bandwidth) MPLS-DiffServ Necessary Enhancements for DS aware MPLS TE