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Segment Routing: Technology
Update and Advanced Use-Cases
Steve Braaten, Solutions Architect
BRKRST-3122
• Segment Routing Executive Summary
• Reminders
• Incremental Deployment Use-Cases
• Inter-Domain Policy at Scale
• Topolo...
Segment Routing
Executive Summary
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Segment Routing
• Source Routing
• the source choose...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Deployed !
• First deployments in 2015 – just 15 mon...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
IETF
• Strong commitment for standardization and
mul...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Foundation for modern IP/MPLS networking
• Simplicit...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Session Assumptions
• Thorough understanding of SR t...
Reminders
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Prefix segment
• Shortest-path to the prefix
• Equal...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Adjacency segment
• Forward on the IGP adjacency
• L...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR operations illustration
• Steer traffic on any pa...
Incremental Deployment
Use-Cases
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR Innovation VPN /
Service
Transport
Topology
Indep...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR Innovation Topology
Independent
IP FRR
Traffic
En...
Inter-Domain Policy at Scale
draft-filsfils-spring-large-scale-interconnect
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Use-Case Description
• Segment Routing use-case aimi...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SRGB and SID allocation
• Homogenous end-to-end SRGB...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
IGP/SR within WAN and Metro Domains
• Each domain ru...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Segment Routing in the Datacenter
• Datacenter fabri...
Inter-Domain Policy at Scale
SR connectivity across domains
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Intra-Domain Routing – DC A1 and DC B2
• BGP SR in t...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Intra-Domain Routing – Metro A and Metro B
• In a me...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Intra-Domain Routing – WAN
• ISIS / OSPF SR in WAN
•...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Inter-Domain Routing
• WAN aggs are re-distributed d...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Inter-Domain Routing
• Redistribution: from center t...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Inter-Domain Routing (Cont’d)
vPE1
20001
ToR
20002
S...
Inter-Domain Policy at Scale
SR PCE
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR PCE
• Multi-Domain topology
• Real-time reactive ...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Circuit Optimization vs SR Optimization
2
4
1
5
3
6
...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Four SR-native TE algorithms developed
• Metric opti...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR PCE - Fundamentally Distributed
• SR PCE not to b...
Inter-Domain Policy at Scale
On-Demand SR Next Hop (ODN)
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Service Provisioning
• vPE1 learns about a service r...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
On-Demand SR Next-Hop
Overview
• When the vPE’s does...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
On-Demand SR Next-Hop
Reachability
• vPE1’s ODN func...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
On-Demand SR Next-Hop
SLA enabled
• Inter-domain SLA...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Anycast SID’s for pairs of border nodes
• Anycast SI...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
On-Demand SR Next-Hop
Reachability with Anycast SID
...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Binding SID to stitch Policies
• End-to-end policies...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Seamless Transition
• Best-effort reachability could...
Inter-Domain Policy at Scale
Inter-Domain Disjoint Services
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Example: Two Disjoint Inter-domain PW’s
• ODN/SR-PCE...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Example: Inter-Domain PW - Disjoint Primary / Backup...
Topology Independent LFA (TI-LFA)
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
TI-LFA - Benefits
• 50msec Protection upon local lin...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Automated Per-Destination optimization
• 2’s compute...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Flexible Link vs Node vs SRLG protection
• 2 checks ...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Automated and Optimum
• 2 computes the post-converge...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Do we need many SID’s? No!
BRKRST-3122 51
Microloop Avoidance
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Microloops are a day-1 IP drawback
• IP hop-by-hop r...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR Microloop Avoidance
• Prevent any microloop upon ...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Illustration – Link Down
• No microloop can occur th...
Conclusion
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Conclusion
• Functionality never seen before
• SR is...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Resources
• Stay Informed - Tutorials, Conferences, ...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Complete Your Online Session Evaluation
Don’t forget...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Continue Your Education
• Demos in the Cisco campus
...
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Segment Routing opportunities at CiscoLive!
• BRKRST...
Thank you
Segment Routing Advanced Use Cases - Cisco Live 2016 USA
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Segment Routing Advanced Use Cases - Cisco Live 2016 USA

  1. 1. Segment Routing: Technology Update and Advanced Use-Cases Steve Braaten, Solutions Architect BRKRST-3122
  2. 2. • Segment Routing Executive Summary • Reminders • Incremental Deployment Use-Cases • Inter-Domain Policy at Scale • Topology Independent LFA (TI-LFA) • Microloop Avoidance • Conclusion Agenda
  3. 3. Segment Routing Executive Summary
  4. 4. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Segment Routing • Source Routing • the source chooses a path and encodes it in the packet header as an ordered list of segments • the rest of the network executes the encoded instructions • Segment: an identifier for any type of instruction • forwarding or service • Forwarding Plane: • MPLS: an ordered list of segments is represented as a stack of labels • IPv6: an ordered list of segments is encoded in a routing extension header • Multi-Vendor solution BRKRST-3122 5
  5. 5. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Deployed ! • First deployments in 2015 – just 15 months after FCS !!! • Strong start in 2016 with many new deployments BRKRST-3122 6
  6. 6. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public IETF • Strong commitment for standardization and multi-vendor support • SPRING Working-Group (started Nov 2013) • 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 • First RFC document - RFC 7855 (May 2016) www.segment-routing.net tools.ietf.org/wg/spring/ BRKRST-3122 7
  7. 7. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Foundation for modern IP/MPLS networking • Simplicity • Set of few, well-chosen building blocks • Solution to unsolved problems • End-to-end policy, local and/or centralized PCE, 50msec protection, microloop avoidance, and more… • Scale • Granular traffic engineering with minimal network state • Seamless Deployment • SR/LDP interworking, SR/RSVP-TE interworking, ship-in-the-night co-existence • Decoupled data and control planes • Low-cost 1 BRKRST-3122 8
  8. 8. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Session Assumptions • Thorough understanding of SR tutorial • http://www.segment-routing.net/home/tutorial • You should know • SRGB • IGP Prefix and Adj SID’s • Anycast SID • SR/LDP interworking • BGP Prefix SID and the MSDC use-case • Use-Cases in this presentation described for SR/MPLS • Same concept applies to SRv6 (native IPv6 SR extension header, no MPLS) BRKRST-3122 9
  9. 9. Reminders
  10. 10. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Prefix segment • Shortest-path to the prefix • Equal Cost MultiPath (ECMP)-aware • Global Segment • Label = 16000 + Index • Advertised as index • Distributed by ISIS/OSPF/BGP 1 2 3 4 5 16004 16004 16004 16004 16004 16004 16004 1.1.1.4/32 All nodes use default SRGB 16,000 – 23,999 BRKRST-3122 11
  11. 11. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Adjacency segment • Forward on the IGP adjacency • Local Segment • Advertised as label value • Distributed by ISIS/OSPF • But only local adjacency SID’s are installed in FIB! 1 2 3 4 5 24024 24025 Adj to 5 Adj to 4 All nodes use default SRGB 16,000 – 23,999 BRKRST-3122 12
  12. 12. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SR operations illustration • Steer traffic on any path through the network • Path is specified by list of segments in packet header, a stack of labels • No path is signaled • No per-flow state is created • IS-IS, OSPF, BGP all supported Node Z 56056 1 3 5 7 2 4 6 8 101 Payload to Z 16101 56056 16005 Payload to Z 16101 56056 16005 Payload to Z 16101 56056 Payload to Z 16101 Payload to Z 16101 Payload to Z Goal: Go to Z but avoid node 7 BRKRST-3122 13
  13. 13. Incremental Deployment Use-Cases
  14. 14. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SR Innovation VPN / Service Transport Topology Independent IP FRR Traffic Engineering Egress Peering Engineering Data Center Fabric Microloop Avoidance Demand Matrix Application Engineered Routing Inter-Domain Policy at ScaleIncremental Use Case Deployment http://blogs.cisco.com/sp/supercharge-your-network-with-segment-routing-innovations BRKRST-3122 15
  15. 15. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SR Innovation Topology Independent IP FRR Traffic Engineering Egress Peering Engineering Data Center Fabric Microloop Avoidance Demand Matrix Application Engineered Routing Inter-Domain Policy at ScaleIncremental Use Case Deployment VPN / Service Transport http://blogs.cisco.com/sp/supercharge-your-network-with-segment-routing-innovations BRKRST-3122 16
  16. 16. Inter-Domain Policy at Scale draft-filsfils-spring-large-scale-interconnect
  17. 17. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Use-Case Description • Segment Routing use-case aiming to scale the network to support hundreds of thousands of network nodes, and tens of millions of physical underlay endpoints • Applicable to the interconnection of massive-scale DC's and/or large aggregation networks • Principles are equally applicable to a network of any size vPE1 ToR Spine LSR LSR vPE2ToRSpineLSR DC A1 METRO A METRO BWAN DC B2 Datacenter Datacenter Metro Metro Core BRKRST-3122 18
  18. 18. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SRGB and SID allocation • Homogenous end-to-end SRGB for simplicity • Globally Unique Prefix SIDs for devices WAN and Metro domains • Locally Unique Prefix SIDs for Datacenters vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 20k-24k 20k-24k 17k-18k 18k-19k 16k-17k 16k-24k BRKRST-3122 19
  19. 19. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public IGP/SR within WAN and Metro Domains • Each domain runs ISIS/OSPF SR • Incremental deployment and seamless interworking with LDP DCI1 17001 LSR 17002 LSR 16003 DCI2 18001 LSR 18002 METRO A METRO BWAN IGP / SR 2 IGP / SR 3IGP / SR 1 BRKRST-3122 20
  20. 20. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Segment Routing in the Datacenter • Datacenter fabric runs BGP SR • Example: 20006 is the BGP Prefix SID to DCI6 • ECMP-aware • Simple (no LDP/RSVP) • Policy-driven vPE1 20001 ToR2 20002 Spine4 20004 Leaf3 20003 DCI6 20006 vPE11 20011 ToR12 20012 Spine14 20014 Leaf13 20013 Leaf15 20015 DCI16 20016 AS2 AS11 AS3 AS4 AS5 AS6AS1 Leaf5 20005 BRKRST-3122 21
  21. 21. Inter-Domain Policy at Scale SR connectivity across domains
  22. 22. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Intra-Domain Routing – DC A1 and DC B2 • BGP SR in the DC • Often eBGP would be used but iBGP can also be used (see tutorial) • Smart AS (ClusterID) allocation in eBGP (iBGP) provides automated path filtering (see tutorial) vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 vPE1/32 NH: vPE1 BGP-LU LABEL: POP PREFIX-SID: 20001 (relative 4001) vPE1/32 NH: TOR BGP-LU LABEL: 20001 PREFIX-SID: 20001 (relative 4001) vPE1/32 NH: SPINE BGP-LU LABEL: 20001 PREFIX-SID: 20001 (relative 4001) DCI2/32 NH: DCI2 BGP-LU LABEL: POP PREFIX-SID: 18001 (relative 2001) DCI2/32 NH: SPINE BGP-LU LABEL: 18001 PREFIX-SID: 18001 (relative 2001) DCI2/32 NH: TOR BGP-LU LABEL: 18001 PREFIX-SID: 18001 (relative 2001) BRKRST-3122 23
  23. 23. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Intra-Domain Routing – Metro A and Metro B • In a metro, BGP/SR or ISIS-OSPF/SR are likely, both illustrated here • Example: Metro A: BGP/SR • Example: Metro B: ISIS/SR vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 DCI1/32 NH: DCI1 BGP-LU LABEL: POP PREFIX-SID: 17001 (relative 1001) DCI1/32 NH: LSR BGP-LU LABEL: 17001 PREFIX-SID: 17001 (relative 1001) ISIS LSP of AGG2 Leaf: Agg2 PREFIX-SID: 16002 (relative 2) BRKRST-3122 24
  24. 24. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Intra-Domain Routing – WAN • ISIS / OSPF SR in WAN • During a migration, benefit from SR seamless interworking with LDP and ship-in- the-night with RSVP vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 ISIS LSP of AGG1 Leaf: Agg1 PREFIX-SID: 16001 (relative 1) BRKRST-3122 25
  25. 25. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Inter-Domain Routing • WAN aggs are re-distributed down to Metro and DC • Nothing is redistributed up !!! • How does vPE1 reaches vPE2? vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 WAN Aggs WAN AggsWAN AggsWAN Aggs BRKRST-3122 26
  26. 26. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Inter-Domain Routing • Redistribution: from center to leaves • WAN redistributes (only) its AGG’s into metro’s • Metro redistributes (only) the WAN AGG’s into DC’s • Redistribution: from leaves to center • Nothing vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 ISIS LSP of AGG2 Leaf: AGG1 PREFIX-SID: 16001 (relative 1) AGG1 NH: DCI2 BGP-LU LABEL: 16001 PREFIX-SID: 16001 (relative 1) AGG1 NH: SPINE BGP-LU LABEL: 16001 PREFIX-SID: 16001 (relative 1) AGG1 NH: ToR BGP-LU LABEL: 16001 PREFIX-SID: 16001 (relative 1) BRKRST-3122 27
  27. 27. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Inter-Domain Routing (Cont’d) vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 ISIS LSP of AGG1 Leaf: AGG2 PREFIX-SID: 16002 (relative 2) AGG2 NH: DCI1 BGP-LU LABEL: 16002 PREFIX-SID: 16002 (relative 2) AGG2 NH: SPINE BGP-LU LABEL: 16002 PREFIX-SID: 16002 (relative 2) AGG2 NH: TOR BGP-LU LABEL: 16002 PREFIX-SID: 16002 (relative 2) BRKRST-3122 28
  28. 28. Inter-Domain Policy at Scale SR PCE
  29. 29. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SR PCE • Multi-Domain topology • Real-time reactive feed via BGP-LS/ISIS/OSPF from multiple domains • Including ip address and SID • Compute: stateful with native SRTE algorithms vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 Multi-Domain Topology SR PCE Compute Demo BRKRST-3122 30
  30. 30. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Circuit Optimization vs SR Optimization 2 4 1 5 3 6 7 8 9 Classic TE is circuit-based CSPF => non-ECMP path SID List: {4, 5, 7, 3} Poor ECMP, big SR list, ATM optimized 2 4 1 5 3 6 7 8 9 SR-native TE algorithms needed Recognized Innovation - Sigcomm 2015 SID List: {7, 3} ECMP, Small SR list, IP-optimized BRKRST-3122 31
  31. 31. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Four SR-native TE algorithms developed • Metric optimization with inclusion/exclusion constraint and bound • Metric: IGP metric, TE metric, extended TE-latency metric • Inclusion/exclusion: IP address, SRLG, TE affinity, Link Loss • Margin: any solution within the margin of the optimum is accepted • Favor more ECMP or shorter SID list instead of insignificant optimization increment • Also available on the router-based SRTE functionality • Disjointness • (A to Z) or ((A, B) to (Y, Z)) • With minimized latency diff, ECMP and shorter SID list • (A to Z) also available on the router-based SRTE functionality • Tactical BW optimization • Multi-Constrained • Sigcomm 2015 [url] • Furthermore … TI-LFA and Microloop avoidance algorithms BRKRST-3122 32
  32. 32. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SR PCE - Fundamentally Distributed • SR PCE not to be considered as a single “God” box • SR PCE deployment model more like BGP Route Reflectors • Different vPE’s can use different pairs of SR PCE’s • SR PCE preference can either be based on proximity or service vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE SR PCE SR PCE SR PCESR PCE SR PCE SR PCE SR PCE BRKRST-3122 33
  33. 33. Inter-Domain Policy at Scale On-Demand SR Next Hop (ODN)
  34. 34. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Service Provisioning • vPE1 learns about a service route with nhop vPE2 • RR shown could be any flavor of overlay controller • How does vPE1 reach the nhop? • vPE1 only has routes within DC A1 and to the AGG’s of the WAN domain • Solution: On-Demand SR Next Hop (ODN) vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 BGP RR 2: V via vPE2 VPN-LABEL: 99999 1: V via vPE2 VPN-LABEL: 99999 BRKRST-3122 35
  35. 35. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public On-Demand SR Next-Hop Overview • When the vPE’s does not have any RIB entry for the (locator, policy), the On-Demand SR Next-Hop automatically sends a stateful PCEP request to the SR PCE • Key benefit: provide the glue between the overlay and underlay controllers while decoupling them • E.g. overlay controller does not need to react to multi-domain underlay topology change, nor compute TE policies • E.g. underlay controller does not need to be involved in service orchestration, does not store any a priori TE policy • E.g. no direct API or coupled workflow between the controllers vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE 3: vPE2 ? 4: {SID List} Demo BGP RR 2: V via vPE2 VPN-LABEL: 99999 1: V via vPE2 VPN-LABEL: 99999 BRKRST-3122 36
  36. 36. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public On-Demand SR Next-Hop Reachability • vPE1’s ODN functionality automatically request a solution from SR PCE • Scalable: vPE1 only gets the inter-domain paths that it needs • Simple: no BGP3107 pushing all routes everywhere vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 16002 vPE2 20001 ToR 20002 Spine 20003 18001LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE 3: vPE2 ? 4: {16002, 18001, 20001} 2: V via vPE2 VPN-LABEL: 99999 1: V via vPE2 VPN-LABEL: 99999 Demo BGP RR BRKRST-3122 37
  37. 37. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public On-Demand SR Next-Hop SLA enabled • Inter-domain SLA with scale and simplicity • No RSVP, no midpoint state, no tunnel to configure !! vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE 3: vPE2 with Low- Latency? 4: {16001, 16003, 16002, 18001, 20001} 2: V via vPE2 VPN-LABEL: 99999 EXT-COM: LATENCY 1: V via vPE2 VPN-LABEL: 99999 EXT-COM: LATENCY Demo BGP RR BRKRST-3122 38
  38. 38. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Anycast SID’s for pairs of border nodes • Anycast SID’s provide for better ECMP and High Availability vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 17901 16901 16902 18901 16902 1890117901 16901 16902 1890117901 16901 BRKRST-3122 39
  39. 39. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public On-Demand SR Next-Hop Reachability with Anycast SID • Better load-balancing: ECMP across border routers • Better availability: sub-50msec upon remote aggregation router failure • Better control plane scalability: no PCE re-computation, no PCEP update, no FIB update vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE 3: vPE2 ? 4: {16902, 18901, 20001} 16902 18901 vPE2 20001 2: V via vPE2 VPN-LABEL: 99999 1: V via vPE2 VPN-LABEL: 99999 16902 1890117901 16901 16902 1890117901 16901 BGP RR BRKRST-3122 40
  40. 40. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Binding SID to stitch Policies • End-to-end policies can be composed from more basic ones • An SRTE policy is bound by default to a Binding SID • RSVP-TE tunnels can also be bound to a Binding SID and hence RSVP-TE tunnels can be used within an end-to-end SR policy • Shorter SID list and churn isolation between domains • Even if the WAN-MetroA sub-path changes, the related Binding SID 4001 is constant vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE 2: vPE2 with Min LAT? 1: REPORT {16003, 16002, 18002, 18001}, UP, BindingSID 4001 3: REPLY {16001, 4001, 20001} instead of {16001, 16003, 16002, 18002, 18001, 20001} BRKRST-3122 41
  41. 41. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Seamless Transition • Best-effort reachability could be provided by BGP3107 • ODN and SRTE / PCE provides interdomain reachability with SLA requirements • Eventually, migration of more/all services over SR PCE vPE1 20001 ToR 20002 Spine 20003 LSR 17002 LSR 16003 vPE2 20001 ToR 20002 Spine 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 SR PCE 3: vPE2 with Low Latency? 4: {16001, 16002, 18001, 20001} BGP RR vPE2/32 via DCI2 PREFIX-SID: 20001 DCI2/32 via AGG2 PREFIX-SID: 18001 2: vPE2/32 via DCI2 PREFIX-SID: 20001DCI2/32 via AGG2 PREFIX-SID: 18001 1: BRKRST-3122 42
  42. 42. Inter-Domain Policy at Scale Inter-Domain Disjoint Services
  43. 43. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Example: Two Disjoint Inter-domain PW’s • ODN/SR-PCE automated compute disjoint paths for PW1 and PW2 • PW1 and PW2 do not share the same headend, neither the same tailend • Inter-domain SLA with scale and simplicity • No RSVP, no midpoint state, no tunnel to configure !! SR PCE vPE2 disjoint group 7 {20003, 16001, 16002, 18001, 20001} vPE22 disjoint group 7 vPE1 20001 ToR2 20002 Spine3 20003 LSR 17002 LSR 16003 vPE2 20001 ToR3 20002 Spine4 20003 LSR 18002 DC A1 METRO A METRO BWAN DC B2 vPE11 20011 ToR12 20012 Spine13 20013 vPE22 20021 ToR23 20022 Spine24 20023 {20013, 16011, 16012, 18011, 20021} PW1 PW2 BRKRST-3122 44
  44. 44. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Example: Inter-Domain PW - Disjoint Primary / Backup paths • ODN/SR-PCE automatically computes disjoint primary/sec paths for the PW • sBFD runs at 3x50msec on each SRTE path • Upon failure detection of the primary, the secondary SRTE Path is used • Inter-domain SLA with scale and simplicity • No RSVP, no midpoint state, no tunnel to configure !! vPE1 20001 ToR 20002 Spine1 20003 DCI1 17001 17901 LSR 17002 AGG1 16001 16901 LSR 16003 AGG2 16002 16902 vPE2 20001 ToR 20002 Spine 20003 DCI2 18001 18901 LSR 18002 DC A1 METRO A METRO BWAN DC B2 DCI11 17011 17901 AGG11 16011 16901 AGG12 16012 16902 DCI11 18011 18901 Spine2 20004 Spine2 20004 SR PCE1 Primary 1: Two disjoint paths to vPE2 2: PRIMARY: {17001, 16001, 16003, 18001, 20001} SECONDARY: {17011, 16011, 16013, 18011, 20001} Pri Sec BRKRST-3122 45
  45. 45. Topology Independent LFA (TI-LFA)
  46. 46. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public TI-LFA - Benefits • 50msec Protection upon local link, node or SRLG failure • Simple to operate and understand • automatically computed by the router’s IGP process (ISIS and OSPF) • 100% coverage across any topology • predictable (backup = post convergence) • Optimum backup path • leverages the post-convergence path, planned to carry the traffic • avoid any intermediate flap via alternate path • Incremental deployment • also protects LDP and IP traffic BRKRST-3122 47
  47. 47. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Automated Per-Destination optimization • 2’s computes a primary path to 5 100 100 PE4 5 2 31 6 7 8 Source Dest2 Default metric: 10 FIB of 2 for destination 5 Incoming Label: 16005 Primary: SWAP 16005 for 16005, oif: 3 Demo BRKRST-3122 48
  48. 48. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Flexible Link vs Node vs SRLG protection • 2 checks the protection preference for the primary interface of the destination • Link protection (illustration assumption) • Node protection • SRLG protection 100 100 PE4 5 2 31 6 7 8 Source Dest2 Default metric: 10 Demo BRKRST-3122 49
  49. 49. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Automated and Optimum • 2 computes the post-convergence path if the preferred failure would occur • Optimality: the operator planned and dimensioned the post-convergence path to carry the traffic in the failure case • 2 uses SR to encode the post- convergence path in a loop-free manner • 2 updates the FIB with the backup path to 5 100 100 PE4 5 2 31 6 7 8 Source Dest2 Default metric: 10 FIB of 2 for destination 5 Incoming Label: 16005 Primary: SWAP 16005 for 16005, oif: 3 Backup: SWAP 16005 for 16005, PUSH 16007, oif: 6 Demo BRKRST-3122 50
  50. 50. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Do we need many SID’s? No! BRKRST-3122 51
  51. 51. Microloop Avoidance
  52. 52. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Microloops are a day-1 IP drawback • IP hop-by-hop routing may induce microloop at any topology transition • Link up/down, metric up/down Upon link down convergence Illustration for the post-convergence microloop impacting traffic from 1 to 9 after link45 going down. Default link metric 10 2 3 4 5 8 7 6 1 1000 9 Pre-convergence Path Post-convergence Path BRKRST-3122 53
  53. 53. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public SR Microloop Avoidance • Prevent any microloop upon isolated convergence due to • link up/down event & metric increase/decrease event • 2-stage convergence • Stage 1: non-looping SID lists to implement the post-convergence path • Stage 2: post-convergence path • If multiple back-to-back convergences, fall back to native IP convergence FIB @ 1 for Destination 9 Initially: {16009} OIF 2 Stage1: {16006, 24065, 16009} Stage2: {16009} OIF 8 2 3 4 5 8 7 6 1 1000 9 Pre-convergence Path Post-convergence Path Explicit Post-convergence Path microloop avoidance segment-routing Demo BRKRST-3122 54
  54. 54. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Illustration – Link Down • No microloop can occur thanks to the 2-stage convergence and the use of non- looping SID lists to implement the post-convergence path in stage1 2 3 4 5 8 7 6 1 Default link metric 10 1000 Pre-convergence Path Post-convergence Path FIB @ 1 for Destination 9 Initially: OIF to 2 Stage1: {16006, 24065, 16009} Finally (stage2): OIF 8 9 FIB @ 8 for Destination 9 Initially: OIF to 1 Stage1: {16006, 24065, 16009} Finally (stage2): OIF 7 FIB @ 7 for Destination 9 Initially: OIF to 8 Stage1: {16006, 24065, 16009} Finally (stage2): OIF 6 FIB @ 6 for Destination 9 Initially: OIF to 7 Stage1: {24065, 16009} Finally (stage2): OIF 5 Illustration for the post-convergence microloop impacting traffic from 1 to 9 after link45 going down Demo BRKRST-3122 55
  55. 55. Conclusion
  56. 56. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Conclusion • Functionality never seen before • SR is fundamental architecture for modern IP network • Unified Fabric with Policy through DC, Metro and WAN • Simplification through Automation and protocol removal • Strong operator endorsement • Multi vendor consensus • Impressive deployment and velocity BRKRST-3122 57
  57. 57. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Resources • Stay Informed - Tutorials, Conferences, IETF, Open-source SW • http://www.segment-routing.net/ • Join us – Segment Routing @ LinkedIN • Get in Touch • ask-segment-routing@cisco.com • “Latest” SR Demonstrations • On-demand Next-Hop and SR PCE • TI-LFA Node protection • Microloop Avoidance • SRv6 “Spray” use-case • Segment Routing book • Pre-order available now! BRKRST-3122 58
  58. 58. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Complete Your Online Session Evaluation Don’t forget: Cisco Live sessions will be available for viewing on-demand after the event at CiscoLive.com/Online • Give us your feedback to be entered into a Daily Survey Drawing. A daily winner will receive a $750 Amazon gift card. • Complete your session surveys through the Cisco Live mobile app or from the Session Catalog on CiscoLive.com/us. BRKRST-3122 59
  59. 59. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Continue Your Education • Demos in the Cisco campus • Walk-in Self-Paced Labs • Lunch & Learn • Meet the Engineer 1:1 meetings • Related sessions… BRKRST-3122 60
  60. 60. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public Segment Routing opportunities at CiscoLive! • BRKRST-2124: Introduction to Segment Routing • Presented Monday – view session materials on CiscoLive.com • LABSPG-2012: Next Generation Service Provider Network using Segment Routing & BIER • In the Walk-in Self-Paced (WISP) lab area of the hub until 5pm today! • BRKDCN-2050: Segment Routing in Datacenter using Nexus 9000 and 3000 • At 1pm today! South Pacific B, Lower Level • LTRMPL-2104: Cisco WAN Automation Engine (WAE) Network Programmability with Segment Routing BRKRST-3122 61
  61. 61. Thank you
  • UgurErsoy1

    Aug. 7, 2019
  • zak379

    Feb. 5, 2018
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    Mar. 6, 2017
  • FedorRodjukov

    Oct. 25, 2016

Segment Routing Advanced Use Cases delivered at Cisco Live USA by Steve Braaten (BRKRST-3122)

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