Segment Routing: MPLS & Ethernet World Congress 2013

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Segment Routing: MPLS & Ethernet World Congress 2013

  1. 1. Segment RoutingClarence Filsfils – cf@cisco.comDistinguished Engineer© 2013 Cisco and/or its affiliates. All rights reserved. 1
  2. 2. •  Introduction•  Technology•  Use Cases•  Conclusion© 2013 Cisco and/or its affiliates. All rights reserved. 2
  3. 3. Introduction© 2013 Cisco and/or its affiliates. All rights reserved. 3
  4. 4. •  Leverage the efficient MPLS dataplane•  Leverage all the services supported over MPLS© 2013 Cisco and/or its affiliates. All rights reserved. 4
  5. 5. •  Simplicity –  less protocols to operate –  less protocol interactions to troubleshoot –  avoid directed LDP sessions between core routers –  deliver automated FRR for any topology•  Scale –  avoid millions of labels in LDP database –  avoid millions of TE LSP’s in the network –  avoid millions of tunnels to configure© 2013 Cisco and/or its affiliates. All rights reserved. 5
  6. 6. •  Applications must be able to interact with the network –  cloud based delivery –  internet of everything•  Programmatic interfaces and Orchestration –  Necessary but not sufficient•  The network must respond to application interaction –  Rapidly-changing application requirements –  Virtualization –  Guaranteed SLA and Network Efficiency© 2013 Cisco and/or its affiliates. All rights reserved. 6
  7. 7. •  Simple to deploy and operate –  Leverage MPLS services & hardware –  straightforward ISIS/OSPF extension to distribute labels –  LDP/RSVP not required•  Provide for optimum scalability, resiliency and virtualization•  Perfect integration with application –  simple network, highly programmable –  highly responsive© 2013 Cisco and/or its affiliates. All rights reserved. 7
  8. 8. •  SR EFT is available! –  12k, ASR9k, CRS1, CRS3 –  ask to test it at the Cisco/Cariden booth on Thursday –  get it to your lab•  Working aggressively with lead customers towards productization© 2013 Cisco and/or its affiliates. All rights reserved. 8
  9. 9. •  Simple ISIS/OSPF extension•  Welcoming contribution© 2013 Cisco and/or its affiliates. All rights reserved. 9
  10. 10. •  Ahmed Bashandy•  Bertrand Duvivier•  Clarence Filsfils•  Dan Frost•  David Ward•  Stefano Previdi•  Stewart Bryant© 2013 Cisco and/or its affiliates. All rights reserved. 10
  11. 11. Segment Routing© 2013 Cisco and/or its affiliates. All rights reserved. 11
  12. 12. •  Forwarding state (segment) is established by IGP –  LDP and RSVP-TE are not required –  Agnostic to forwarding dataplane: IPv6 or MPLS•  MPLS Dataplane is leveraged without any modification –  push, swap and pop: all what we need –  segment = label•  Source Routing –  source encodes path as a label or stack of segments –  two segments: node or adjacency© 2013 Cisco and/or its affiliates. All rights reserved. 12
  13. 13. A packet injected at A B C D node C with label Pop Z 65 9003 is forced 9003 through datalink CO M N O P•  C allocates a local label•  C advertises the adjacency label in ISIS –  simple sub-TLV extension•  C is the only node to install the adjacency segment in MPLS dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 13
  14. 14. 9105 9107 9107 9101 9103 9103 9105 9105 9105 9107 B C D 9103 9101 9105 9105 A 9107 Z N O P 9105 9103 9103 9105 9105•  Source routing along any explicit path –  stack of adjacency labels•  SR provides for entire path control© 2013 Cisco and/or its affiliates. All rights reserved. 14
  15. 15. Pop 9003 9001 switches on blue member Pop 9001 B C 9002 switches on green member Pop 9002 9003 load-balances on any Pop 9003 member of the adj•  Adjacency segment represents a specific datalink to an adjacent node•  Adjacency segment represents a set of datalinks to the adjacent node© 2013 Cisco and/or its affiliates. All rights reserved. 15
  16. 16. •  SR requires only 1 label per node in the IGP domain –  insignificant: < 1% of label space•  Node SR Range –  a range of labels allocated to the SR control-plane –  e.g. [64, 5000]•  Each node gets one unique label from SR Range –  Node Z gets label 65© 2013 Cisco and/or its affiliates. All rights reserved. 16
  17. 17. FEC Z swap 65 swap 65 push 65 to 65 to 65 pop 65 A B C D A packet injected Z 65 anywhere with top label 65 will reach Z via shortest-path•  Z advertises its node segment –  simple ISIS sub-TLV extension•  All remote nodes install the node segment to Z in the MPLS dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 17
  18. 18. FEC Z swap 65 swap 65 push 65 to 65 to 65 pop 65 A B C D A packet injected Z 65 anywhere with top 65 65 65 label 65 will reach Z Packet to Z Packet to Z Packet to Z Packet to Z Packet to Z via shortest-path•  Z advertises its node segment –  simple ISIS sub-TLV extension•  All remote nodes install the node segment to Z in the MPLS dataplane© 2013 Cisco and/or its affiliates. All rights reserved. 18
  19. 19. 72 72 9003 9003 9003 65 65 65 Packet to Z Packet to Z Packet to Z 72 72 A B C D Pop Z 9003 65 M N O P 65 Packet to Z 65 65 Packet to Z Packet to Z•  Source Routing•  Any explicit path can be expressed: ABCOPZ© 2013 Cisco and/or its affiliates. All rights reserved. 19
  20. 20. 72 72 78 78 78 65 65 65 Packet to Z Packet to Z Packet to Z 72 72 A B C D 78 Z 65 M N O P 65 Packet to Z 65 65 Packet to Z Packet to Z•  Node Segment is at the heart of the proposal –  ecmp multi-hop shortest-path –  in most topologies, any path can be expressed as list of node segments© 2013 Cisco and/or its affiliates. All rights reserved. 20
  21. 21. Nodal segment to C Nodal segment to C A B C D Adj Segment Z M N O P Nodal segment to Z•  Simple extension•  Excellent Scale: a node installs N+A FIB entries –  N node segments and A adjacency segments© 2013 Cisco and/or its affiliates. All rights reserved. 21
  22. 22. •  IP-based FRR is guaranted in Backbone any topology –  2002, LFA FRR project at Cisco C1 C2 –  draft-bryant-ipfrr-tunnels-03.txt•  Directed LFA (DLFA) is E1 E4 guaranteed when metrics are symetric 1000 E2 E3•  No extra computation (RLFA) Adj segment Node segment to P node to Q node•  Simple repair stack –  node segment to P node –  adjacency segment from P to Q Default metric: 10© 2013 Cisco and/or its affiliates. All rights reserved. 22
  23. 23. Use Cases© 2013 Cisco and/or its affiliates. All rights reserved. 23
  24. 24. A B PE1 PE2 M N All VPN services ride on the node segment to PE2•  Efficient packet networks leverage ecmp-aware shortest-path! –  node segment!•  Simplicity –  no complex LDP/ISIS synchronization to troubleshoot –  one less protocol to operate© 2013 Cisco and/or its affiliates. All rights reserved. 24
  25. 25. •  An SR core router scales much than with RSVP-TE –  The state is not in the router but in the packet –  N+A vs N^2 N: # of nodes in the network A: # of adjacencies per node © 2013 Cisco and/or its affiliates. All rights reserved. 25
  26. 26. SR avoids state in the core SR avoids enumerating RSVP-TE tunnels for each ECMP paths•  A sends traffic with [65] Classic ecmp “a la IP”•  A sends traffic with [111, 65] Packet gets attracted in blue plane and then uses classic ecmp “a la IP”© 2013 Cisco and/or its affiliates. All rights reserved. 26
  27. 27. •  Tokyo to Brussels –  data: via US: cheap capacity –  voip: via russia: low latency•  CoS-based TE with SR –  IGP metric set such as >  Tokyo to Russia: via Russia Node segment to Brussels >  Tokyo to Brussels: via US Node segment to Russia >  Russia to Brussels: via Europe –  Anycast segment “Russia” advertised by Russia core routers•  Tokyo CoS-based policy –  Data and Brussels: push the node segment to Brussels –  VoIP and Brussels: push the anycast node to Russia, push Brussels© 2013 Cisco and/or its affiliates. All rights reserved. 27
  28. 28. B C D 9101 9101 9101 9105 9105 9107 A 9107 Z 9105 9103 9105 N O P 9101 9103•  For Traffic Engineering•  or for OAM Nanog57, Feb 2013© 2013 Cisco and/or its affiliates. All rights reserved. 28
  29. 29. 65 2G from A to Z please FULL 65 Link CD is full, I cannot use the shortest-path 65 straight to Z•  The network is simple, highly programmable and responsive to rapid changes –  perfect support for centralized optimization efficiency, if required© 2013 Cisco and/or its affiliates. All rights reserved. 29
  30. 30. Tunnel AZ onto {66, 68, 65} 66 FULL 68 65 Path ABCOPZ is ok. I account the BW. Then I steer the traffic on this path•  The network is simple, highly programmable and responsive to rapid changes© 2013 Cisco and/or its affiliates. All rights reserved. 30
  31. 31. Millions of Applications•  Each engineered application flow is flows mapped on a path –  millions of paths A path is•  A path is expressed as an ordered list mapped on a list of of segments segments•  The network maintains segments The network –  thousands of segments only maintains segments –  completely independent of application No application size/frequency state•  Excellent scaling and virtualization –  the application state is no longer within the router but within the packet© 2013 Cisco and/or its affiliates. All rights reserved. 31
  32. 32. Conclusion© 2013 Cisco and/or its affiliates. All rights reserved. 32
  33. 33. •  Simple to deploy and operate –  Leverage MPLS services & hardware –  straightforward ISIS/OSPF extension•  Provide for optimum scalability, resiliency and virtualization•  Perfect integration with application•  EFT and IETF available – test and contribute© 2013 Cisco and/or its affiliates. All rights reserved. 33

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