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Introduction to Segment Routing

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Introduction to Segment Routing
Ismail Ali
Technical Consultant (Cisco Systems (M) Sdn Bhd)

Published in: Internet
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Introduction to Segment Routing

  1. 1. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 1Cisco  Confidential 1©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Ismail  Ali Technical   Consultant,   Cisco  Systems  Malaysia
  2. 2. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 2 • Introduction • Incremental  Deployment  Use  Cases • Standardization • Conclusion
  3. 3. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 3
  4. 4. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 4 • Source Routing:  source  chooses  a  path  and  encodes  it  in  packet  header  as  an   ordered  list  of  segments. • Segment:  an  identifier  for  any  type  of  instruction Service Context Locator IGP-­based  forwarding  construct BGP-­based  forwarding  construct Local  value  or  Global  Index Segment   =  Instructions   such  as   "go  to  node   N  using   the  shortest  path"
  5. 5. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 5 • MPLS:  an  ordered  list  of  segments  is   represented  as  a  stack  of  labels SR  re-­uses  MPLS   data  plane   without   any   change • IPv6:  an  ordered  list  of  segments  is   represented  as  a  routing  extension   header This presentation focuses on MPLS data plane IPv6 IPv6 IPv6 Control   Plane IPv4 MPLS Data   Plane
  6. 6. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 6 • Locally  significant  to  node  allocating  it • Node  processes  SID  and  switches  packet   towards  adjacency • Advertised  as  an  absolute  value   • Globally  significant  within  SR  domain • All  nodes  switch  packet  towards  prefix/node   via  shortest  path • Advertised  as  a  relative  (index)  value • Make  use  of  a  per-­node  reserved  block  (SR   Global  Block  or  SRGB) B C N O Z D P A 9101 9105 9107 9103 9105 B C N O Z D P A 65 65 65 65 Prefix/Node  SID Adjacency  SID
  7. 7. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 7 D (php) 7 A B C D E 103 103 Payload Payload 201 202 Payload 202 201 202 Payload 202 Payload Payload C D A B E 202 202 201 102 202 Payload A B 102 C D E 202 Payload 202 Payload C E C D EB C D (php) EB Node  Path Adjacency  Path Combined  Path
  8. 8. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 8 • Efficient  packet  networks  leverage  ecmp-­aware   shortest-­path! node  segment! • Simplicity one  less  protocol  to  operate No  complex  LDP/ISIS  synchronization  to  troubleshoot 8 A B M N PE2PE1 All  VPN  services  ride  on  the  node  segment   to  PE2
  9. 9. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 9
  10. 10. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 10 • 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 Tokyo  to  Brussels:  via  US 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   10 Node  segment  to  Brussels Node  segment  to  Russia
  11. 11. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 11 • For  Traffic  Engineering • or  for  OAM   11 B C N O Z D P A 9101 9105 9107 9103 9105 9101 9101 9105 9107 9103 9105 9101
  12. 12. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 12 12 Path  ABCOPZ  is  ok.  I  account  the  BW.   Then  I  steer  the  traffic  on  this  path FULL 66 65 68 Tunnel  AZ  onto     {66,  68,  65}   The  network   is  simple,   highly   programmable   and   responsive   to  rapid   changes 2G from A to Z please
  13. 13. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 13 Definition Applications  express   requirements   – bandwidth,  latency,   SLAs SDN  controllers  are  capable  of   collecting  data  from   the  network   – topology,  link  states,   link   utilization,  … Applications  are  mapped  to  a  path   defined  by  a  list  of  segments The  network  only  maintains   segments No  application   state Segment   Routing SDN Controller Applications 1 2 3
  14. 14. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 14 • Applications  program   the  network  on  a  per-­ flow  basis • End-­to-­End policy DC,  WAN,  AGG,  PEER • Millions  of  flows No  per-­flow  midpoint  state No  reclassification  at boundaries • Simple BGP  and  ISIS/OSPF DC (or AGG) 10 11 12 13 14 2 4 6 5 7 Default ISIS cost metric: 10 Default Latency metric: 10 50 WAN 3 1 PEER Low Lat, Low BW High-BW to 7 for application … Push {16001, 16005} High Lat, High BW
  15. 15. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 15 • Automated   50msec  FRR DC (or AGG) 10 11 12 13 14 2 4 6 5 7 Default ISIS cost metric: 10 Default Latency metric: 10 50 WAN 3 1 PEER Low Lat, Low BW High-BW to 7 for application … Push {16001, 16005} High Lat, High BW
  16. 16. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 16 • Any  policy  can  be   programmed   by  the   application • The  network  scaling  and   simplicity  is  preserved DC (or AGG) 10 11 12 13 14 2 4 6 5 7 Default ISIS cost metric: 10 Default Latency metric: 10 50 WAN 8 8 PEER Low Lat, Low BW High-BW to 7 Load-share across DC edges for application … Push {16008, 16005} High Lat, High BW
  17. 17. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 17 • Any  policy  can  be   programmed   by  the   application • The  network  scaling  and   simplicity  is  preserved DC (or AGG) 10 11 12 13 14 2 4 6 5 7 Default ISIS cost metric: 10 Default Latency metric: 10 50 WAN 3 1 PEER Low Lat, Low BW Low-Latency to 7, DC Plane 0 only for application … Push {16010, 16001, 200, 147} High Lat, High BW
  18. 18. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 18 • Any  policy  can  be   programmed   by  the   application • The  network  scaling  and   simplicity  is  preserved DC (or AGG) 10 11 12 13 14 2 4 6 5 7 Default ISIS cost metric: 10 Default Latency metric: 10 50 WAN 3 1 PEER Low Lat, Low BW High-BW to 7, 1st VNF at 14 2nd VNF at 6 for application … Push {16014, 301, 16003, 16006, 302, 16005} High Lat, High BW
  19. 19. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 19 Adding  value  at  your  own  pace Enable  Segment  Routing  on  the  network  (Software  only) Insert  Orchestration,  SDN  controller Connect  with  Cisco’s   and  third  party  VNFs Network  Simplification Network  Resiliency End-­User  Experience Network  Optimization Service  Velocity E2E  Application   Control Benefits
  20. 20. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 20Cisco  Confidential 20©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved.
  21. 21. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 21 • Control  plane  scale  and  complexity • Many  protocols • Many  encapsulations • Many  bugs • Forwarding  plane  capacity • Lots  of  growth  ==  lots  of  stress  
  22. 22. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 22 • Peering  -­-­-­ want  programmatic  control  over  policy • Massively  Scaled  Datacenters  (even  more  protocols,   high  device  and  link  counts,  commodity  hardware,   greater  vendor  diversity,  legacy  applications) • Inter-­DC  vs  External  workloads Latency-­sensitive  vs  bulk Scheduled  vs  unscheduled
  23. 23. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 23 • Reduced  complexity Protocol   counts Fewer  protocols  ==  less  code  ==  fewer  bugs Amount   of  distributed   control  plane   state Unified   forwarding   plane   (analog   of  BGP  is  the  Better  IGP ) • Maintain  healthy  vendor  diversity • Want  to  (eventually  and  incrementally)  enable  software  control Leverage   our  in-­house   software   (and  networking)   expertise Re-­use  ongoing   controller   and  TE  work Don’t  want  another  new  parallel  network
  24. 24. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 24 • Well-­understood  forwarding  plane  (MPLS) • Encourages  sensible  engineering  tradeoffs • Possibility  of  removing  some  distributed  signaling  protocols • Removes  per-­tunnel  state  from  the  core • Gets  us  closer  to  a  static  core,  significantly  quieter  control  plane • Good  interop  with  existing  protocols Safe  incremental   deployment • SDN  with  standards-­based  interfaces Segments   are  defined   at  a  useful   level  of  abstraction   for  composition Anycast is  also  useful
  25. 25. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 25 • Autopilot  for  orchestration   • SWAN  for  TE • BGP-­LS  for  topology  and  SR  label  discovery • BGP-­LU  for  creating  tunnels Widely  supported,  so  we  can  impose  on  the  non-­SR  edge Single  label  (but  can  hack  w/Route  Resolution) Label  stacks  would  be  nicer Can  scale  with  indirection  and  vanilla  BGP Non-­standard  use  of  RFC  3107,  maybe  we  can  do  better • BGP  prefix  SID’s  for  the  MSDC • EPE  scenario  for  peering BMP  for  route  collection
  26. 26. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 26 • Built  out  a  full  emulation  of  core  network  using  VM’s  running  early   vendor(s)  code Fantastic   tool,   please   more  fidelity. • Modeled  the  entire  control  plane  w/MPLS  forwarding Obviously  slower  in  the  forwarding  plane • Very  basic  controller  driving  BGP-­LU  via  REST
  27. 27. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 27 • Investigated  several  use  cases: Basic  forwarding   over  an  SR  routed   network Traffic   steering EPE Vendor   interop Server-­to-­server • Found  a  few  bugs  and  interop  issues Mostly  design/use   cases. • Management  is  on  the  thin  side Still  awkward   to  see  some  SR  state Not  quite   fully  integrated
  28. 28. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 28
  29. 29. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 29 • IETF  standardization  in  SPRING  working   group • Protocol  extensions  progressing  in  multiple   groups IS-­IS OSPF PCE IDR 6MAN • Broad  vendor  and  customer  support Sample  IETF  Documents Segment  Routing  Architecture (draft-­ietf-­spring-­segment-­routing) Problem  Statement  and  Requirements (draft-­ietf-­spring-­problem-­statement) IPv6  SPRING  Use  Cases   (draft-­ietf-­spring-­ipv6-­use-­cases) Segment  Routing  Use  Cases   (draft-­filsfils-­spring-­segment-­routing-­use-­cases) Topology  Independent  Fast  Reroute  using  Segment  Routing (draft-­francois-­spring-­segment-­routing-­ti-­lfa) IS-­IS  Extensions  for  Segment  Routing (draft-­ietf-­isis-­segment-­routing-­extensions) OSPF  Extensions  for  Segment  Routing (draft-­ietf-­ospf-­segment-­routing-­extensions) PCEP  Extensions  for  Segment  Routing (draft-­ietf-­pce-­segment-­routing) Close  to  30  IETF  drafts   in  progress
  30. 30. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 30 • Strong  commitment  for  standardization  and multi-­vendor  support • SPRING  Working-­Group • All  key  documents  are  WG-­status • Over  25  drafts  maintained  by  SR  team Over  50%  are  WG  status Over  75%  have  a  Cisco  implementation • Several  interop  reports  are  available www.segment-routing.net tools.ietf.org/wg/spring/
  31. 31. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 31 • Fundamental  to  the  velocity  and  success • Over  30  operators  involved • Technology  tailored  to  solve  real   requirements Tactical:  solve  long-­reported  issues Strategic:  key  architecture  for  long-­term  evolution  
  32. 32. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 32 • Platforms:  ASR9000,  CRS-­1/CRS-­3,  WAE  (shipping) • IS-­IS  IPv4  (shipping) Node/Adjacency   SID  advertisement LDP  interworking   (mapping   server/client) Traffic   protection   (topology   independent   LFA  link  protection) • OSPFv2  (shipping) Node  SID  advertisement Traffic   protection   (LFA) • Upcoming IS-­IS  /  OSPFv2  parity SR  Traffic  Engineering   (manual   provisioning   and  PCEP) OAM  (Ping/Trace)
  33. 33. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 33
  34. 34. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 34 • Simple  routing  extensions  to  implement  source  routing • Packet  path  determined  by  prepended   segment  identifiers  (one  or  more) • Data  plane  agnostic  (MPLS,  IPv6) • Network  scalability  and  agility  by  reducing  network  state  and  simplifying  control  plane • Traffic  protection  with  100%  coverage  with  more  optimal  routing • Interworking  capabilities  with  LDP-­only  devices 34
  35. 35. ©  2013    Cisco  and/or  its  affiliates.   All  rights  reserved. Cisco  Confidential 35 Thank  you. http://tools.ietf.org/wg/spring/ http://www.segment-­routing.net/

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