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Cisco Live! :: Introduction to Segment Routing :: BRKRST-2124 | Las Vegas 2017

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This session provides an overview of the segment routing technology and its use cases. This new routing paradigm provides high operational simplicity and maximum network scalability and flexibility. You will get an understanding of the basic concepts behind the technology and its wide applicability ranging from simple transport for MPLS services, disjoint routing, traffic engineering and its benefits in the context of software defined networking. Previous knowledge of IP routing and MPLS is required.

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Cisco Live! :: Introduction to Segment Routing :: BRKRST-2124 | Las Vegas 2017

  1. 1. Introduction to Segment Routing Michael Kowal, Vertical Solutions Architect @ciscomk BRKRST-2124
  2. 2. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Cisco Spark Questions? Use Cisco Spark to chat with the speaker after the session 1. Find this session in the Cisco Live Mobile App 2. Click “Join the Discussion” 3. Install Spark or go directly to the space 4. Enter messages/questions in the space How cs.co/ciscolivebot#BRKRST-2124Cisco Spark spaces will be available until July 3, 2017.
  3. 3. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 4BRKRST-2124 Abstract This session provides an overview of the segment routing technology and its use cases. This new routing paradigm provides high operational simplicity and maximum network scalability and flexibility. You will get an understanding of the basic concepts behind the technology and its wide applicability ranging from simple transport for MPLS services, disjoint routing, traffic engineering and its benefits in the context of software defined networking. Previous knowledge of IP routing and MPLS is required. Introduction to Segment Routing
  4. 4. • Technology Overview • Use Cases • A Closer Look at the Control and Data Planes • Traffic Protection • Traffic Engineering • Conclusion Agenda
  5. 5. Technology Overview
  6. 6. © 2017 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 • This presentation: IGP-based forwarding construct 7BRKRST-2124
  7. 7. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Segment Routing – 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 • This presentation: MPLS data plane • Segment → Label • Basic building blocks distributed by the IGP or BGP 8BRKRST-2124
  8. 8. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public IGP Prefix Segment • Shortest-path to the IGP prefix • Equal Cost Multipath (ECMP)-aware • Global Segment • Label = 16000 + Index • Index of NodeX = X is used for illustrative purposes • Distributed by ISIS/OSPF 9BRKRST-2124 DC (BGP-SR) 10 11 12 13 14 2 4 6 5 7 WAN (IGP-SR) 3 1 PEER 16005
  9. 9. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public IGP Adjacency Segment • “Pop and Forward on the IGP adjacency” • Local Segment • Dynamically allocated • Value “30X0Y” used for illustration • X is the “from” • Y is the “to” • Advertised as a label value • Distributed by ISIS/OSPF 10BRKRST-2124 DC (BGP-SR) 10 11 12 13 14 2 4 6 5 7 WAN (IGP-SR) 3 1 PEER 30204
  10. 10. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public BGP Prefix Segment • Shortest-path to the BGP prefix • Global Segment • 16000 + Index • Index of NodeX = X is used for illustrative purposes • Signaled by BGP 11 DC (BGP-SR) 10 11 12 13 14 2 4 6 5 7 WAN (IGP-SR) 3 1 PEER 16001 BRKRST-2124
  11. 11. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public BGP Peering Segment • “Pop and Forward to the BGP peer” • Local Segment • Dynamically allocated • Value 40X0Y (for illustration) • X is the “from” • Y is the “to” • Signaled by BGP-LS (topology information) to the controller 12 DC (BGP-SR) 10 11 12 13 14 2 6 7 WAN (IGP-SR) 3 1 PEER Low Lat, Low BW 4 5 High Lat, High BW 40407 BRKRST-2124
  12. 12. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Multi-Domain Topology • SR Path Computation Element (PCE) • PCE collects via BGP- LS • IGP segments • BGP segments • Topology 13 DC (BGP-SR) 10 11 12 13 14 2 4 6 5 7 WAN (IGP-SR) 3 1 PEER Low Lat, Low BW BGP-LS BGP-LS BGP-LS BRKRST-2124 SR PCE
  13. 13. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public End-to-End Policy, Unified Data Plane • Construct a path by combining segments to form an end-to-end path: • 16001 (Prefix-SID) • 16002 (Prefix-SID) • 30204 (Adj-SID) • 40407 (Peer-SID) • Per-application flow engineering • Millions of flows • No signaling • No midpoint state • No reclassification at boundaries 14 PCEP, Netconf, BGP BRKRST-2124 SR PCE Low-Latency to 7 for application … DC (BGP-SR) 10 11 12 13 14 2 4 6 5 7 WAN (IGP-SR) 3 1 PEER Low Lat Low BW 50 Default ISIS cost metric: 10 16001 16001 16002 30204 40407 {16001, 16002, 30204, 40407 }
  14. 14. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Segment Routing Standardization • IETF standardization in SPRING working group • Protocol extensions progressing in multiple groups • IS-IS • OSPF • PCE • IDR • 6MAN • BESS • Broad vendor support • Strong customer adoption • WEB, SP, Enterprise 15 Sample IETF Documents Problem Statement and Requirements (RFC 7855) Segment Routing Architecture (draft-ietf-spring-segment-routing) IPv6 SPRING Use Cases (draft-ietf-spring-ipv6-use-cases) Segment Routing with MPLS data plane (draft-ietf-spring-segment-routing-mpls) Topology Independent Fast Reroute using Segment Routing (draft-bashandy-rtgwg-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 40 IETF drafts in progress BRKRST-2124
  15. 15. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Segment Routing Product Support • Platforms: • IOS-XR (ASR9000, CRS-1/CRS-3, NCS5000, NCS5500, NCS6000) • IOS-XE (ASR1000, CSR1000v, ASR902, ASR903, ASR920, ISR4400) • NX-OS (N3K, N9K) • Open Source (FD.io/VPP, Linux Kernel, ODL, ONOS, OpenWRT) • PCE (WAN Automation Engine, XTC) 16BRKRST-2124
  16. 16. Use Cases
  17. 17. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Simple and Efficient Transport of MPLS services • No change to service configuration • MPLS services ride on the prefix segments • Simple: IGP-only • One less protocol to operate • No LDP, no RSVP-TE SR Domain vrf REDvrf RED 7 1 3 4 2 8 5 6 MP-BGP 1.1.1.2/32 Prefix-SID 16002 10.0.0.0/30 2001::a00:0/126 CE CEPE PE Packet to 8 vpn 16002 Packet to 8 vpn Packet to 8 Packet to 8 vpn 16002 BRKRST-2124 18
  18. 18. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Interworking with LDP • SR to LDP Interworking requires Mapping Server functionality • E.g. Nodes 6 & 8 can advertise prefix-SIDs in IGP, on behalf of non-SR nodes. • SR nodes install these prefix- SIDs in their forwarding table. • Mapping server is a control plane mechanism and doesn’t have to be in the data path • LDP to SR Interworking is Automatic and Seamless. 19 1 2 3 4 6 5 7 Site 1 Site 2 BRKRST-2124 Mapping-servers 1.1.1.4/32  SID 16004 1.1.1.7/32  SID 16007 8 Packet vpn 16007 Packet vpn 16007 Packet vpn LDP(7) Packet vpn Packet Packet
  19. 19. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Topology-Independent LFA (TI-LFA FRR) • 50msec FRR in any topology • Link, Node, or SRLG • IGP Automated • No LDP, no RSVP-TE • Optimum • Post-convergence path • No midpoint backup state • Detailed operator report • S. Litkowski, B. Decraene, Orange • WAN Automation Engine Design • How many backup segments? • Perform capacity analysis 20 1 2 3 4 6 5 7 BRKRST-2124 Packet 16007 Packet 16007 Packet 16007 16005
  20. 20. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Automated Traffic Matrix Collection • Traffic Matrix is fundamental for • capacity planning • centralized traffic engineering • IP/Optical optimization • Most operators do not have an accurate traffic matrix • With SR, the traffic matrix collection is automated 21BRKRST-2124 1 2 3 4 1 2 3 4 1 2 4 3
  21. 21. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Optimized Content Delivery • On a per-content, per-user basis, the content delivery application can engineer • the path within the AS • the selected border router • the selected peer • Also applicable for engineering egress traffic from DC to peer • BGP Prefix and Peering Segments 22 1 2 6 4 3 AS1 5 7 AS6AS5 AS7 BRKRST-2124 Packet 16002 16003 40206
  22. 22. A Closer Look at the Control and Data Planes
  23. 23. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 24 MPLS Control and Forwarding Operation with Segment Routing PE1 PE2 IGPPE1 PE2 Services IPv4 IPv6 IPv4 VPN IPv6 VPN VPWS VPLS Packet Transport LDP MPLS Forwarding RSVP BGPStatic IS-IS OSPF No changes to control or forwarding plane IGP or BGP label distribution for IPv4 and IPv6. Forwarding plane remains the same MP-BGP BRKRST-2124
  24. 24. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public • Prefix SID • Uses SR Global Block (SRGB) • SRGB advertised with router capabilities TLV • In the configuration, Prefix-SID can be configured as an absolute value or an index • In the protocol advertisement, Prefix-SID is always encoded as a globally unique index Index represents an offset from SRGB base, zero-based numbering, i.e. 0 is 1st index E.g. index 1  SID is 16,000 + 1 = 16,001 • Adjacency SID • Locally significant • Automatically allocated for each adjacency • Always encoded as an absolute (i.e. not indexed) value SID Encoding SRGB = [ 16,000 – 23,999 ] – Advertised as base = 16,000, range = 8,000 Prefix SID = 16,001 – Advertised as Prefix SID Index = 1 Adjacency SID = 24000 – Advertised as Adjacency SID = 24000 SR enabled node BRKRST-2124 25
  25. 25. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public SR IS-IS Control Plane Overview • IS-IS Segment Routing functionality • IPv4 and IPv6 control plane • Level 1, level 2 and multi-level routing • Prefix Segment ID (Prefix-SID) for host prefixes on loopback interfaces • Adjacency Segment IDs (Adj-SIDs) for adjacencies • Prefix-to-SID mapping advertisements (mapping server) • MPLS penultimate hop popping (PHP) and explicit-null signaling BRKRST-2124 26
  26. 26. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public router isis 1 address-family ipv4 unicast metric-style wide segment-routing mpls ! address-family ipv6 unicast metric-style wide segment-routing mpls ! interface Loopback0 passive address-family ipv4 unicast prefix-sid absolute 16001 ! address-family ipv6 unicast prefix-sid absolute 20001 ! ! IS-IS Configuration – Example Ipv4 Prefix-SID value for loopback0 Wide metrics enable SR IPv4 control plane and SR MPLS data plane on all ipv4 interfaces in this IS-IS instance Wide metrics enable SR IPv6 control plane and SR MPLS data plane on all ipv6 interfaces in this IS-IS instance Ipv6 Prefix-SID value for loopback0 SID index 1 1.1.1.11.1.1.2 1.1.1.4 1.1.1.6 DIS BRKRST-2124 27
  27. 27. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public SR OSPF Control Plane Overview • OSPF Segment Routing functionality • OSPFv2 control plane • Multi-area • IPv4 Prefix Segment ID (Prefix-SID) for host prefixes on loopback interfaces • Adjacency Segment ID (Adj-SIDs) for adjacencies • Prefix-to-SID mapping advertisements (mapping server) • MPLS penultimate hop popping (PHP) and explicit-null signaling BRKRST-2124 28
  28. 28. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public router ospf 1 router-id 1.1.1.1 segment-routing mpls area 0 interface Loopback0 passive enable prefix-sid absolute 16001 ! ! ! OSPF Configuration Example Prefix-SID for loopback0 Enable SR on all areas SID index 1 1.1.1.11.1.1.2 1.1.1.5 1.1.1.3 DR 1.1.1.4 BRKRST-2124 29
  29. 29. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 30 MPLS Data Plane Operation • Packet forwarded along IGP shortest path (ECMP) • Swap operation performed on input label • Same top label if same/similar SRGB • PHP if signaled by egress LSR Payload SRGB [16,000 – 23,999 ] X Payload Swap X Payload SRGB [16,000 – 23,999 ] Y Payload Pop Y Adjacency SID = X X Prefix SID Adjacency SID  Packet forwarded along IGP adjacency  Pop operation performed on input label  Top labels will likely differ  Penultimate hop always pops last adjacency SID BRKRST-2124
  30. 30. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Payload VPN Label 31 MPLS Data Plane Operation (Prefix SID) SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] Loopback X.X.X.X Prefix SID Index = 41 A B C D Payload 16041 Payload Push Push Swap Pop Payload Payload VPN Label 16041 VPN Label Pop BRKRST-2124
  31. 31. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Payload VPN Label 32 MPLS Data Plane Operation (Adjacency SIDs) Payload 16041 Payload Push Push Push Pop Pop Payload Payload VPN Label 16041 VPN Label Pop Adjacency SID = 30206 30206 A B X D BRKRST-2124 Loopback X.X.X.X Prefix SID Index = 41 SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ]
  32. 32. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public MPLS LFIB with Segment Routing • LFIB populated by IGP (ISIS / OSPF) • Other protocols (LDP, RSVP, BGP) can still program LFIB • Forwarding table remains constant (Nodes + Adjacencies) regardless of number of paths 33 PE PE PE PE PE PE PE PE P In Label Out Label Out Interface L1 L1 Intf1 L2 L2 Intf1 … … … L8 L8 Intf4 L9 L9 Intf2 L10 Pop Intf2 … … … Ln Pop Intf5 Network Node Segment Ids Node Adjacency Segment Ids Forwarding table remains constant BRKRST-2124
  33. 33. Traffic Protection
  34. 34. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Topology Independent LFA (TI-LFA) – Benefits • 100%-coverage 50-msec link, node, and SRLG protection • Simple to operate and understand • automatically computed by the IGP • Prevents transient congestion and suboptimal routing • leverages the post-convergence path, planned to carry the traffic • Incremental deployment • also protects LDP and unlabeled traffic 35BRKRST-2124
  35. 35. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public TI-LFA – Zero-Segment Example • TI-LFA for link R1R2 on R1 • Calculate post-convergence SPT • SPT with link R1R2 removed from topology • Derive SID-list to steer traffic on post-convergence path  empty SID-list • R1 will steer the traffic towards LFA R5 36BRKRST-2124 1000 Default metric: 10 A 55 4 Packet to Z Packet to Z prefix-SID(Z) 1 2 Z 3 Packet to Z prefix-SID(Z)
  36. 36. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public TI-LFA – Single-Segment Example • TI-LFA for link R1R2 on R1 • Calculate post-convergence SPT • Derive SID-list to steer traffic on post-convergence path  <Prefix-SID(R4)> • Also known as “PQ-node” • R1 will push the prefix-SID of R4 on the backup path 37BRKRST-2124 Packet to Z prefix-SID(Z) prefix-SID(R4) Default metric:10 5 21 A Z 3 Packet to Z prefix-SID(Z) Packet to Z 4 Packet to Z prefix-SID(Z) 4
  37. 37. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 38BRKRST-2124 TI-LFA – Double-Segment Example • TI-LFA for link R1R2 on R1 • Calculate post-convergence SPT • Derive SID-list to steer traffic on post-convergence path  <Prefix- SID(R4), Adj-SID(R4-R3) • Also known as “P- and Q-node” • R1 will push the prefix-SID of R4 and the adj-SID of R4-R3 link on the backup path Default metric: 10 5 21 A Z R3R4 34 Packet to Z prefix-SID(Z) Packet to Z Packet to Z prefix-SID(Z) adj-SID(R4-R3) prefix-SID(R4) Packet to Z prefix-SID(Z) adj-SID(R4-R3) 1000 Packet to Z prefix-SID(Z)
  38. 38. Traffic Engineering (SR-TE)
  39. 39. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Traffic Engineering with Segment Routing • Provides explicit routing • Supports constraint-based routing • Supports centralized admission control • Uses existing ISIS / OSPF extensions to advertise link attributes • No RSVP-TE to establish LSPs • Supports ECMP 40 TE LSP Segment Routing BRKRST-2124
  40. 40. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 2 3 4 1 Default IGP link metric: I:10 Default TE link metric: T:10 5 SID-list: <16005, 16004, 16003> 6 Low-Latency Use-Case • Head-end computes a SID-list that expresses the shortest-path according to the selected metric segment-routing traffic-eng policy POLICY1 color 20 end-point ipv4 1.1.1.3 candidate-paths preference 100 dynamic mpls metric type te Node1 T:15 I:10 T:15 I:10 T:10 I:30 T:8 I:10 BRKRST-2124 41
  41. 41. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public segment-routing traffic-eng policy POLICY1 color 20 end-point ipv4 1.1.1.7 candidate-paths preference 100 dynamic mpls metric type igp association group 1 type node ! policy POLICY2 color 30 end-point ipv4 1.1.1.7 candidate-paths preference 100 dynamic mpls metric type igp association group 1 type node 2 3 5 6 4 71 I:100 Default IGP link metric: I:10 I:100 POLICY1 SID-list: <16002, 30203, 16007> POLICY2 SID-list: <16005, 16006, 16007> Service Disjointness from the same head-end Use-Case • The head-end computes two, disjoint paths Node1 BRKRST-2124 42
  42. 42. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Different VPNs need different underlay SLA Single Domain Topology 2 6 1 CE 5 4 I: 50 Default IGP cost: I:10 Default TE cost: T:10 IGP cost 30 T: 15 2 6 1 CE 5 4 TE cost 20 Basic VPN should use lowest cost underlay path Premium VPN should use lowest latency path Objective: operationalize this service for simplicity, scale and performanceI: 50 T: 15 Default IGP cost: I:10 Default TE cost: T:10 BRKRST-2124 44
  43. 43. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 2 6 1 CE 5 4 I: 50 T: 15 On-Demand SR Policy work-flow ➊ BGP: 20/8 via CE 20/8 RR ➋ BGP: 20/8 via PE4 VPN-LABEL: 99999 Low-latency (color 20) ➌ BGP: 20/8 via PE4 VPN-LABEL: 99999 Low-latency (color 20) router bgp 1 neighbor 1.1.1.10 address-family vpnv4 unicast ! segment-routing traffic-eng on-demand color 20 preference 100 metric type te ➍ PE4 with Low- latency (color 20)? ➎ use template color 20 ➏  SID-list <16002, 30204> ➎ Default IGP cost: I:10 Default TE cost: T:10 SR Policy template Low-latency (color 20) BRKRST-2124 45
  44. 44. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 2 6 1 CE 5 4 I: 50 T: 15 Automated performant steering ➊ BGP: 20/8 via CE 20/8 RR ➋ BGP: 20/8 via PE4 VPN-LABEL: 99999 Low-latency (color 20) ➌ BGP: 20/8 via PE4 VPN-LABEL: 99999 Low-latency (color 20) ➍ PE4 with Low- latency (color 20)? ➎ use template color 20 ➏  SID-list <16002, 30204> FIB table at PE1 SRTE: 4001: Push <16002, 30204> ➐ instantiate SR Policy BSID 4001 Low Latency to PE4 ➐ ➑ forward 20/8 via BSID 4001 ➑➐ BGP: 20/8 via 4001 Default IGP cost: I:10 Default TE cost: T:10 In Out Out_intf Fraction 4001 <16002, 30204> To Node 2 100% Forwarding table on Node1 BRKRST-2124 47
  45. 45. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public SR-TE • Simple, Automated and Scalable • No core state: state in the packet header • No tunnel interface: “SR Policy” • No head-end a-priori configuration: on-demand policy instantiation • No head-end a-priori steering: automated steering • Multi-Domain • XR Traffic Controller (XTC) for compute • Binding-SID (BSID) for scale • Lots of Functionality • Designed with lead operators along their use-cases BRKRST-2124 55
  46. 46. Conclusion
  47. 47. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Conclusion • Simple routing extensions to implement source routing • Packet path determined by prepended segment identifiers (one or more) • Data plane agnostic (MPLS, IPv6) • Increase network scalability and agility by reducing network state and simplifying control plane • Traffic protection with 100% coverage with more optimal routing Recommended Follow-up Session: Segment Routing: Technology deep-dive and advanced use cases (BRKRST-3122) 57BRKRST-2124
  48. 48. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 58BRKRST-2124 Segment Routing Sessions Breakout Sessions Labs Introduction to Segment Routing (BRKRST-2124) ←you are here SP SDN - Segment Routing in Action (LTRMPL-2201) Segment Routing: Technology Deep-Dive and Advanced Use Cases (BRKRST-3122) MPLS Segment Routing Introduction (LABSPG-1020) Troubleshooting Segment Routing (BRKRST-3009) Segment Routing for Policy Aware Network (LABRST-1015) Application Engineered Routing: Allowing Applications to Program the Network (BRKSPG-2066) Next Generation Service Provider Network using Segment Routing & BIER (LABSPG-2012) Automated Networks with Segment Routing in the Datacenter (BRKDCN-2050) Segment Routing in Datacenter using Nexus 9000/3000 (LABDCN-2020) Multicast and Segment Routing (BRKIPM-2249) DevNet Workshop – Application Engineered Egress Routing (DEVNET-2062) Evolving Network Application Use-Cases Using Segment Routing In the Enterprise (BRKMPL-2118) DevNet Workshop-WAN Automation Engine API (DEVNET-2035) Cisco Live 2017
  49. 49. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Stay Up-To-Date http://www.segment-routing.net/ https://www.linkedin.com/groups/8266623 https://twitter.com/SegmentRouting https://www.facebook.com/SegmentRouting/ amzn.com/B01I58LSUO BRKRST-2124 59
  50. 50. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 60 Participate in the “My Favorite Speaker” Contest • Promote your favorite speaker through Twitter and you could win $200 of Cisco Press products (@CiscoPress) • Send a tweet and include • Your favorite speaker’s Twitter handle @ciscomk • Two hashtags: #CLUS #MyFavoriteSpeaker • You can submit an entry for more than one of your “favorite” speakers • Don’t forget to follow @CiscoLive and @CiscoPress • View the official rules at http://bit.ly/CLUSwin Promote Your Favorite Speaker and You Could Be a Winner BRKRST-2124
  51. 51. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public • Give us your feedback to be entered into a Daily Survey Drawing. A daily winner will receive a $750 gift card. • Complete your session surveys through the Cisco Live mobile app or on www.CiscoLive.com/us. Complete Your Online Session Evaluation Don’t forget: Cisco Live sessions will be available for viewing on demand after the event at www.CiscoLive.com/Online.
  52. 52. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Continue Your Education • Demos in the Cisco campus • Walk-in Self-Paced Labs • Table Topics • Meet the Engineer 1:1 meetings • Related sessions 62BRKRST-2124
  53. 53. Thank you
  54. 54. Backup Slides
  55. 55. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Migration Scenario: LDP to SR • Initial state: All nodes run LDP, not SR 66BRKRST-2124 1 LDP 3 4 2 5 6 LDP Domain LDP LDP LDP LDP LDP LDP
  56. 56. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Migration Scenario: LDP to SR • Initial state: All nodes run LDP, not SR • Step1: All nodes are upgraded to SR • In no particular order • Default label imposition preference = LDP 67BRKRST-2124 1 LDP 3 4 2 5 6 SR+LDP Domain SR+LDP SR+LDP SR+LDP SR+LDP SR+LDP SR+LDP
  57. 57. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Migration Scenario: LDP to SR • Initial state: All nodes run LDP, not SR • Step1: All nodes are upgraded to SR • In no particular order • leave default LDP label imposition preference • Step2: All PEs are configured to prefer SR label imposition • In no particular order 68BRKRST-2124 SR+LDP Domain 1 SR 3 4 2 5 6 SR+LDP SR+LDP SR+LDP SR+LDP SR+LDP segment-routing mpls sr-prefer
  58. 58. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Migration Scenario: LDP to SR • Initial state: All nodes run LDP, not SR • Step1: All nodes are upgraded to SR • In no particular order • leave default LDP label imposition preference • Step2: All PEs are configured to prefer SR label imposition • In no particular order • Step3: LDP is removed from the nodes in the network • In no particular order • Final state: All nodes run SR, not LDP 69BRKRST-2124 SR Domain 1 SR 3 4 2 5 6 SR SR SR SR SR SR
  59. 59. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public How Traffic Engineering Works • Link information Distribution • ISIS-TE • OSPF-TE • Path Calculation • Path Setup • Forwarding Traffic down path • Auto-route (announce / destinations) • Static route • PBR • PBTS / CBTS • Forwarding Adjacency • Pseudowire Tunnel select 70 IP/MPLS Head end Mid-point Tail end TE LSP BRKRST-2124
  60. 60. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Stateful PCE • PCE maintains topology and path database (established paths) • More optimal centralized path computation • Enables centralized path initiation and update control • Well suited for SDN deployments 71 PCEP Stateful PCE TED LSP DB PCC BRKRST-2124
  61. 61. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Topology Acquisition • An external PCE requires some form of topology acquisition • A PCE may learn topology using BGP- LS, IGP, SNMP, etc. • BGP-LS characteristics • aggregates topology across one or more domains • provides familiar operational model • New BGP-LS attribute TLVs for SR • IGP: links, nodes, prefixes • BGP: peer node, peer adjacency, peer set 72 Domain 1 Domain 2 Domain 0 BGP-LS TED BGP-LS BGP-LS RR PCE BRKRST-2124
  62. 62. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Active Stateful PCE • PCC or PCE may initiate path setup • PCC may delegate update control to PCE • PCC may revoke delegation • PCE may return delegation 73 PCEP Active Stateful PCE TED LSP DB Stateful PCC PCE has update control over delegated paths BRKRST-2124
  63. 63. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 74 Active Stateful PCE PCE-Initiated and PCC-Initiated LSPs • PCE part of controller architecture managing full path life cycle • Tighter integration with application demands PCEP PCC-Initiated (Active Stateful PCE) TED LSP DB Stateful PCC PCEP PCE-Initiated (Active Stateful PCE) TED LSP DB Stateful PCC PCC initiates LSP and delegates update control PCE initiates LSP and maintains update control  PCC may initiate path setup based on distributed network state  Can be used in conjunction with PCE- initiated paths BRKRST-2124
  64. 64. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public PCE Extensions for Segment Routing (SR) • Segment routing enables source routing based on segment ids distributed by IGP • PCE specifies path as list of segment ids • PCC forwards traffic by pushing segment id list on packets • No path signaling required • Minimal forwarding state • Maximum network forwarding virtualization • The state is no longer in the network but in the packet • Paths may be PCE- or PCC-initiated 75 PCEP Segment List:: 10,20,30,40 Stateful PCE TED LSP DB Stateful PCC Node SID Adjacency SID Forwarding table remains constant In Out Int L1 L1 Intf1 … … … L7 L7 Int3 L8 Pop Intf3 … … … L9 Pop Intf5 Application Path Request BRKRST-2124
  65. 65. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public router isis DEFAULT net 49.0001.1720.1625.5001.00 address-family ipv4 unicast metric-style wide segment-routing mpls ! interface Loopback0 passive address-family ipv4 unicast prefix-sid absolute 16041 ! ! interface GigabitEthernet0/0/0/0 address-family ipv4 unicast fast-reroute per-prefix fast-reroute per-prefix ti-lfa ! ! ! 76 Configuring Topology Independent Fast Reroute for IPv4 using Segment Routing and IS-IS (Cisco IOS XR) Enable TI-LFA for IPv4 prefixes on interface GigabitEthernet0/0/0/0 BRKRST-2124
  66. 66. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public router isis DEFAULT net 49.0001.1720.1625.5001.00 address-family ipv6 unicast metric-style wide segment-routing mpls ! interface Loopback0 passive address-family ipv6 unicast prefix-sid absolute 16061 ! ! interface GigabitEthernet0/0/0/0 address-family ipv6 unicast fast-reroute per-prefix fast-reroute per-prefix ti-lfa ! ! ! 77 Configuring Topology Independent Fast Reroute for IPv6 using Segment Routing and IS-IS (Cisco IOS XR) Enable TI-LFA for IPv6 prefixes on interface GigabitEthernet0/0/0/0 BRKRST-2124
  67. 67. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public router isis DEFAULT net 49.0001.1720.1625.5001.00 address-family ipv4 unicast metric-style wide segment-routing mpls segment-routing prefix-sid-map receive segment-routing prefix-sid-map advertise-local ! ... ! segment-routing address-family ipv4 prefix-sid-map 172.16.255.1/32 4041 range 8 ! ! ! 78 Configuring a Mapping Server for SR and LDP Interworking for IPv4 Using IS-IS (Cisco IOS XR) Local prefix-to-SID mapping policy 172.16.255.1/32 – 4041 : 172.16.255.8/32 - 4048 Construct active mapping policy using remotely learned and locally configured mappings (mapping client) Advertise local mapping policy (mapping server) BRKRST-2124
  68. 68. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public router isis DEFAULT net 49.0001.1720.1625.5001.00 address-family ipv4 unicast metric-style wide segment-routing mpls segment-routing prefix-sid-map receive ! interface Loopback0 passive address-family ipv4 unicast prefix-sid absolute 16041 ! ! interface GigabitEthernet0/0/0/0 point-to-point address-family ipv4 unicast ! ! ! 79 Configuring a Mapping Client for SR and LDP Interworking for IPv4 Using IS-IS (Cisco IOS XR) Construct active mapping policy using remotely learned and locally configured mappings (mapping client) BRKRST-2124
  69. 69. © 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public Enabling Segment Routing Feature NXOS feature bgp install feature-set mpls feature-set mpls feature mpls l3vpn feature mpls segment-routing Under Interface configuration: mpls ip forwarding Commands: BRKRST-2124 80

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