Introduction to Segment Routing

Transcription

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2 BRKRST-2124 Introduction to Segment Routing Alberto Donzelli, Solution Architect Service Provider

3 Cisco Spark How Questions? Use Cisco Spark to communicate 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 cs.co/ciscolivebot#brkrst Cisco and/or its affiliates. All rights reserved. Cisco Public

4 Introduction to Segment Routing 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public

5 Agenda Technology Overview Traffic Protection Use Cases A Closer Look at the Control and Data Planes Traffic Engineering Conclusion

6 Value SP Disruption: Complexity vs. Value OSI Reference Model Application Presentation Session Transport Network Data-Link Physical Traditional SP Complexity Complex Network The complexity should be where the ROI is best Application / Service / Customization Revenues, Stickiness Cloud Scale SP Complexity BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 6

7 Infrastructure Simplification and Convergence Areas Delayering Unified Infrastructure Horizontal Integration IP Data Access ATM/Ethernet SDH replacement Aggregation SDH/OTN Video Edge WDM Fixed Mobile Core and DC Transformation IP WDM SDN Driven Automation and Virtualization Fixed Mobile Data Video Circuit End to End IP Segment Routing BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 7

8 Challenges of Todays Service Creation Limited Cross-domain Automation Legacy Central Office Metro Network Domain Core Network Domain Data Center Domain L2VPN L3VPN VXLAN VNF VNF Aggregation Access HW Appliances Ethernet MPLS IP Centralized Delivery of Services E2E service provisioning is lengthy and complex: Multiple network domains under different management teams Manual operations Heterogeneous Underlay and Overlay networks BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 8

9 Unified Stateless Fabric for Service Creation Cloud Scale Networking Central Office Controller Access Metro Network Core and Peering Network Network Data Center EVPN VNF VNF VNF VNF Segment Routing Compute Leaf Spine Simplify Unified underlay and overlay networks with segment routing and EVPN Automate E2E Cross-domain automation with model-driven programmability and streaming telemetry Virtualize Transform the CO into a data center to enable distributed service delivery and speed up service creation BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 9

10 Network Transport Evolution Simplify - Optimize - Enable Service Protocol s Transpor t Protocol s Unified MPLS SR Enabled Transport BGP-EVPN IGP/SR IP Do more with less!! BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 10

11 Segment Routing Standardization IETF standardization in SPRING working group First RFC document - RFC 7855 (May 2016) Protocol extensions progressing in multiple groups IS-IS OSPF PCE IDR 6MAN BESS Broad vendor support Strong customer adoption and support WEB, SP, Enterprise 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 Cisco and/or its affiliates. All rights reserved. Cisco Public 11

12 Wide adoption of Segment Routing Availability Now IOS XR IOS XE NexOS Deployments SP Core/Edge SP Metro/Aggregation WEB Large Enterprises Multi-vendor Consensus Interop testing First at MPLS WC 2015 Next round MPLS WC 2018 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 12

13 Technology Overview

14 Segment Routing An IP and MPLS source-routing architecture that seeks the right balance between distributed intelligence and centralized optimization Path expressed in the packet Data Dynamic path Paths options Dynamic (Headend computation) Explicit (Operator / Controller) Control Plane Explicit path Routing protocols with extensions (IS-IS,OSPF, BGP) MPLS (segment labels) Data Plane SDN controller IPv6 (+SR header) BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 14

15 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 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 15

16 Segment Routing Evolve MPLS with Segment Routing Mission Route the luggage to Berlin via Mexico and Madrid Segment Routing Seattle Toronto New-York London Madrid Berlin 1. A unique and global luggage tag is attached to the luggage with the list of stops to the final destination Mexico MEX MAD BER 2. At each stop, the luggage is simply routed to the next hop listed on the luggage tag MAD BER BER RESULT: Path can be controlled Simple and scalable BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 16

17 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 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 17

18 Segment Routing Segment: an identifier for specific forwarding instruction forwarding or service Source Routing the source chooses a path and encodes it on top of the packet as an ordered list of segments the rest of the network executes the encoded instructions Packet to Packet to 5 5 Packet to Packet to 5 4 Packet to 5 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 18

19 Global and Local Segments Global Segment Any node in SR domain can execute the associated instruction Each node in SR domain installs the associated instruction in its forwarding table MPLS label pool: Value in Segment Routing Global Block (SRGB) Local Segment Only originating node can execute the associated instruction MPLS label pool: locally allocated label BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 19

20 IGP segments Two basic building blocks distributed by IGP Prefix Segments Adjacency Segments BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 20

21 IGP Prefix Segment Shortest-path to the IGP prefix Equal Cost MultiPath (ECMP)-aware Global Segment Label = Index Advertised as index Distributed by ISIS/OSPF / All nodes use default SRGB 16,000 23,999 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 21

22 IGP Prefix Segment Shortest-path to the IGP prefix Equal Cost MultiPath (ECMP)-aware Global Segment Label = Index Advertised as index Distributed by ISIS/OSPF All nodes use default SRGB 16,000 23, / BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 22

23 IGP Adjacency Segment Forward on the IGP adjacency Local Segment Advertised as label value Distributed by ISIS/OSPF 1 2 Adj to Adj to Adj to 3 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 23

24 Combining IGP Segments Steer traffic on any path through the network Path is specified by a stack of labels No path is signaled Packet to All nodes use default SRGB 16,000 23,999 No per-flow state is created Single protocol: IS-IS or OSPF Packet to BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 24

25 Traffic Protection

26 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 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 26

27 TI-LFA Zero-Segment Example TI-LFA for link R1R2 on R1 Calculate post-convergence SPT SPT with link R1R2 removed from topology prefix-sid(z) Packet to Z A Z 1 2 Derive SID-list to steer traffic on post-convergence path prefix-sid(z) Packet to Z R1 will steer the traffic towards LFA R5 Packet to Z 4 3 Default metric: 10 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 27

28 TI-LFA Single-Segment Example TI-LFA for link R1R2 on R1 prefix-sid(z) A Z Calculate post-convergence SPT Packet to Z 1 2 Packet to Z 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 prefix-sid(r4) prefix-sid(z) Packet to Z prefix-sid(z) Packet to Z Default metric:10 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 28

29 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 A Z prefix-sid(z) Packet to Z Packet to Z 1 2 prefix-sid(r4) adj-sid(r4-r3) 5 prefix-sid(z) prefix-sid(z) Packet to Z Packet to Z R4 4 R adj-sid(r4-r3) Default metric: 10 prefix-sid(z) Packet to Z BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 29

30 Use Cases

31 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 Packet to 8 CE PE vpn Packet to 8 MP-BGP vpn Packet to 8 PE CE /32 Prefix-SID / ::a00:0/126 vrf RED SR Domain vpn Packet to 8 vrf RED BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 31

32 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 vpn Packet LDP(7) vpn 2 3 Packet vpn Packet Packet Packet 6 5 Site 1 Site vpn Mapping-servers /32 SID /32 SID Packet BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 32

33 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 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 33

34 A Closer Look at the Control and Data Planes

35 MPLS Control and Forwarding Operation with Segment Routing Services PE1 MP-BGP PE2 IPv4 IPv6 IPv4 VPN IPv6 VPN VPWS VPLS No changes to control or forwarding plane Packet Transport PE1 IGP PE2 LDP RSVP Static BGP IS-IS OSPF MPLS Forwarding IGP or BGP label distribution for IPv4 and IPv6. Forwarding plane remains the same BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 35

36 SID Encoding SR enabled node Prefix SID Label form SR Global Block (SRGB) SRGB advertised within IGP via 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 1 st index E.g. index 1 SID is 16, = 16,001 Adjacency SID Locally significant Automatically allocated by the IGP for each adjacency Always encoded as an absolute (i.e. not indexed) value 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 = Advertised as Adjacency SID = BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 36

37 SR IS-IS Control Plane Summary 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 Cisco and/or its affiliates. All rights reserved. Cisco Public 37

38 SID index IS-IS Configuration Example 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!! 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 Ipv4 Prefix-SID value for loopback0 Ipv6 Prefix-SID value for loopback DIS BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 38

39 SR OSPF Control Plane Summary 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 Cisco and/or its affiliates. All rights reserved. Cisco Public 39

40 SID index OSPF Configuration Example router ospf 1 router-id segment-routing mpls area 0 interface Loopback0 passive enable prefix-sid absolute 16001!!! Enable SR on all areas Prefix-SID for loopback DR BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 40

41 MPLS Data Plane Operation (labeled) Prefix SID SRGB [16,000 23,999 ] Adjacency SID SRGB [16,000 23,999 ] Swap Pop Adjacency SID = X X X X Y Y Payload Payload Payload Payload 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 Packet forwarded along IGP adjacency Pop operation performed on input label Top labels will likely differ Penultimate hop always pops last adjacency SID BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 41

42 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 ] A B C D Loopback X.X.X.X Prefix SID Index = 41 Push Push Swap Pop Pop VPN Label VPN Label VPN Label Payload Payload Payload Payload Payload BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 42

43 MPLS Data Plane Operation (Adjacency SIDs) SRGB [16,000 23,999 ] SRGB [16,000 23,999 ] SRGB [16,000 23,999 ] SRGB [16,000 23,999 ] A B X D Loopback X.X.X.X Adjacency Prefix SID Index = 41 SID = Push Push Push VPN Label Pop VPN Label Pop VPN Label Pop Payload Payload Payload Payload Payload BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 43

44 Traffic Engineering (SR-TE)

45 Traffic Engineering with Segment Routing Source-Based routing State only at ingress PE 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 Segment Routing TE LSP BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 45

46 MPLS LFIB with Segment Routing LFIB populated by IGP (ISIS / OSPF) PE PE PE PE Forwarding table remains constant (Nodes + Adjacencies) regardless of number of paths PE PE P PE PE Network Node Segment Ids Node Adjacency Segment Ids In Label Out Label Out Interface L1 L1 Intf1 L2 L2 Intf1 L8 L8 Intf4 L9 L9 Intf2 L10 Pop Intf2 Ln Pop Intf5 Forwarding table remains constant BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 46

47 Circuit Optimization vs SR Optimization pkt pkt pkt Classic Algo is not efficient!! Need to specify all hops: {4, 5, 7, 3} No ECMP, Old algorithm and technology, ATM optimized With SR we can do much better 8 9 SR-native algo is needed!no more circuit! Recognized Innovation - Sigcomm 2015 SID List: {7, 3} ECMP, minimized SID list, IP-optimized BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 47

48 SR-TE: Binding SID

49 Binding SID Binding Segment is a fundamental building block of SRTE pkt 1 3 The Binding Segment is a local segment Has local significance A Binding-Segment ID identifies a SRTE Policy Each SRTE Policy is associated 1-for-1 with a Binding-SID Packet received with Binding-SID as top label is steered into the SRTE Policy associated with the Binding-SID Binding-SID label is popped, SRTE Policy s SID list is pushed Binding SID can be automatically assigned or statically configured as part of the SRTE policy BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 49

50 Binding SID 2 Binding Segment is a fundamental building block of SRTE pkt pkt pkt 3 pkt The Binding Segment is a local segment Has local significance A Binding-Segment ID identifies a SRTE Policy Each SRTE Policy is associated 1-for-1 with a Binding-SID Packets received with Binding-SID as top label are steered into the SRTE Policy associated with the Binding-SID Binding-SID label is popped, SRTE Policy s SID list is pushed Binding SID can be automatically assigned or statically configured as part of the SRTE policy BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 50

51 SR-TE Use Cases

52 Node1 Low- Delay path Use-Case SID-list: <16005, 16004, 16003> D:800 I:10 1 D:1500 I:10 5 D:2000 I: D:800 I:10 D:1500 I: D:800 I:10 D:2200 I:10 segment-routing traffic-eng policy POLICY1 color 20 end-point ipv candidate-paths preference 100 dynamic mpls metric type delay Head-end computes a SID-list that expresses the shortest-path according to the selected metric delay BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 52

53 Link Delay Measurement Protocol PTP Accurate time-stamp TX Timestamp T1 (phase1) One Way Delay = (T2 T1) (future) Two-Way Delay RX Timestamp T2 MPLS PM using GAL/Gach defined in RFC 6374 IGP and BGP support: Local-end PM Query Packet Remote-end Extended TE Link Delay Metrics will be supported in ISIS (RFC 7810) and OSPF (RFC 7471) BGP-LS (draft-ietf-idr-te-pm-bgp) Extended TE Link Delay Metrics No additional configuration in ISIS/OSPF/BGP- IS : Latency automatically flooded PM Response Packet Link[0]: local address , remote address Local node: ISIS system ID: level-2 ASN: Remote node: TE router ID: Host name: Napoli-5 ISIS system ID: level-2 ASN: Metric: IGP 1, TE 1,Delay 6000 Bandwidth: Total , Reservable 0 Adj SID: (protected) (unprotected) Excluded from CSPF: no Reverse link exists: yes XTC (PCE) view BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 53

54 Different VPNs need different underlay SLA 2 6 I: 50 1 CE D: 15 IGP cost 30 Default IGP cost: I:10 Default Delay cost: D:10 TE cost I: 50 1 CE D: Basic VPN should use lowest cost underlay path Premium VPN should use lowest delay path Objective: operationalize this service for simplicity, scale and performance Default IGP cost: I:10 Default Delay cost: D:10 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 54

55 ➎ On-Demand SR Policy work-flow Automatic LSP setup and steering router bgp 1 neighbor address-family vpnv4 unicast! segment-routing traffic-eng on-demand color 20 preference 100 metric type delay SR Policy template Low-Delay (color 20) ➌ BGP: 20/8 via PE4 VPN-LABEL: Low-Delay (color 20) ➍ PE4 with Low- Delay (color 20)? ➎ use template color 20 ➏ SID-list <16002, 30204> RR 2 1 CE 6 I: 50 D: ➋ BGP: 20/8 via PE4 VPN-LABEL: Low-Delay (color 20) ➊ BGP: 20/8 via CE 20/8 Default IGP cost: I:10 Default Delay cost: D:10 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 55

56 Automated performant steering ➐ ➑ FIB table at PE1 BGP: 20/8 via 4001 SRTE: 4001: Push <16002, 30204> ➌ BGP: 20/8 via PE4 VPN-LABEL: Low-latency (color 20) RR ➋ BGP: 20/8 via PE4 VPN-LABEL: Low-latency (color 20) Automatically, the service route resolves on the Binding SID (4001) of the SR Policy it requires Simplicity and Performance No route-policy required. No complex PBR to configure, no PBR performance tax ➍ PE4 with Lowlatency (color 20)? ➎ use template color 20 ➏ SID-list <16002, 30204> ➐ instantiate SR Policy BSID 4001 ➑ Install in FIB 20/8 via BSID label 4001 ➐ Low Latency to PE4 2 1 CE 6 I: 50 L: Default IGP cost: I:10 Default Latency cost: L:10 ➊ BGP: 20/8 via CE 20/8 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 56

57 SR-TE Use Cases Inter domain connectivity with SLA

58 Crossing the AS border: BGP Peering Segment AS AS pkt pkt /32 6 pkt pkt Pop and Forward to the BGP peer Local Segment like an adjacency SID external to the IGP Dynamically allocated but persistent What is missing? How do I get topology info of external domains? BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 58

59 Inter Area Path Computation with SLA Ask: Provide latency optimized path across multiple AS s from a source to a destination Service Y w/ SLA Latency Service Configuration Request PCE to compute path to A9 with SLA X Get back SID-list Configuration of SR Policy to Node 1 with SLA Latency PCE Delegation to the PCE for reopt. Real Time Topology feed via BGP-LS segment-routing traffic-eng policy POL1 end-point color 20 path preference 100 dynamic mpls pce metric type latency T Region1 CORE Region2 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 59

60 Peering links XR Transport Controller XTC is an IOS XR multi-domain stateful SR Path Computation Element (PCE) Fundamentally Distributed (RR-like Deployment) Supports RSVP-TE XTC On XTC: pce address ipv ! Domain1 Domain2 BGP-LS Domain3 On PE: A BR1 BR3 BR5 pcc pce address ipv ! BR2 BR4 BR6 Z BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 60

61 Peering links XTC Receives & Consolidates Multiple Topologies Each domain feeds its topology to XTC via BGP-LS A Domain1 BR1 BR1 Domain2 BR3 BR3 BR5 BR5 Domain3 XTC combines the different topologies to compute paths across entire topology XTC BR2 BR2 BR4 BR4 BR6 BR6 Z Domain1 Domain2 Domain3 A BR1 BR3 BR5 BR2 BR4 BR6 Z BGP-LS BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 61

62 Node6 Node1 Service Disjointness Intra and inter domain XTC XTC 1 2 SID-list: I:100 {30102, 30203} I: SID-list: I:100 I:100 {16007, 16008} Default IGP link metric: I: segment-routing traffic-eng policy POLICY1 color 20 end-point ipv candidate-paths preference 100 dynamic mpls pce metric type igp association group 1 type node segment-routing traffic-eng policy POLICY2 color 20 end-point ipv candidate-paths preference 100 dynamic mpls pce metric type igp association group 1 type node Two dynamic paths between two different pairs of (head-end, end-point) must be disjoint from each other BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 62

63 Path Computation Distributed or Centralized? Policy Single-Domain Multi-Domain Reachability IGP s Centralized Low Latency Distributed or Centralized Centralized Disjoint from same node Distributed or Centralized Centralized Disjoint from different node Centralized Centralized Avoiding resources Distributed or Centralized Centralized Capacity optimization Centralized Centralized Multi Layer Centralized Centralized BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 63

64 SR-TE Simple, Automated and Scalable No state in the network: 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 Lots of Functionality and flexibility Designed with lead operators along their use-cases BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 64

65 Stay Up-To-Date amzn.com/b01i58lsuo segment-routing.net linkedin.com/groups/ twitter.com/segmentrouting facebook.com/segmentrouting/ BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 65

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68 Continue Your Education Segment Routing: Technology deep-dive [BRKRST-3122] Clarence Filsfils, Fellow, Cisco Multicast and Segment Routing [BRKIPM-2239] IJsbrand Wijnands, Distinguished Engineer, Cisco SP SDN - Segment Routing in Action [LTRMPL-2201] Vinit Jain, Technical Leader, Cisco Jose Liste, Technical Marketing Engineer, Cisco Derek Tay, Technical Marketing Engineer, Cisco Service Provider Programmable SDN solution for the Metro Fabric, powered by Segment Routing and EVPN [BRKSPG-2518] Jiri Chaloupka, Technical Marketing Engineer, Cisco Segment Routing in action at World of Solution: 6 demo available BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 68

69 Thank you

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72 Extra Slides

73 IGP Prefix Segment Shortest-path to the IGP prefix Equal Cost Multipath (ECMP)-aware Global Segment Label = Index Index of NodeX = X is used for illustrative purposes Distributed by ISIS/OSPF DC (BGP-SR) WAN (IGP-SR) PEER BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 73

74 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 DC (BGP-SR) WAN (IGP-SR) 7 PEER BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 74

75 BGP Prefix Segment Shortest-path to the BGP prefix Global Segment Index Index of NodeX = X is used for illustrative purposes Signaled by BGP DC (BGP-SR) WAN (IGP-SR) PEER BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 75

76 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 Low Lat, Low BW High Lat, High BW 7 14 DC (BGP-SR) WAN (IGP-SR) PEER BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 76

77 Multi-Domain Topology SR Path Computation Element (PCE) PCE collects via BGP- LS IGP segments BGP segments Topology BGP-LS 10 SR PCE 1 BGP-LS BGP-LS 2 4 Low Lat, Low BW DC (BGP-SR) WAN (IGP-SR) PEER BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 77

78 End-to-End Policy, Unified Data Plane Construct a path by combining segments to form an end-to-end path: (Prefix-SID) (Prefix-SID) (Adj-SID) (Peer-SID) Per-application flow engineering Millions of flows No signaling No midpoint state No reclassification at boundaries Low-Latency to 7 for application {16001, 16002, 30204, } PCEP, Netconf, BGP DC (BGP-SR) SR PCE Default ISIS cost metric: 10 WAN (IGP-SR) Low Lat Low BW 7 PEER BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 78

79 IETF Strong commitment for standardization and multi-vendor support SPRING Working-Group (started Nov 2013) All key documents are WG-status Over 40 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) BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 79

80 Segment Routing Product Support Platforms: IOS-XR (ASR9000, CRS-1/CRS-3, NCS5000, NCS5500, NCS6000) IOS-XE (ASR1000, CSR1000v, ASR903, ASR907, ASR920, ISR4400) NX-OS (N3K, N9K) Open Source (FD.io/VPP, Linux Kernel, ODL, ONOS, OpenWRT) PCE (WAN Automation Engine, XTC) BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 80

81 Next Generation SP Spend and Complexity Traditional Model Application Presentation Session Transport Network Data-Link Physical New Model Services Tie Services to Network Lean Agile Automated Physical BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 86

82 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 AS7 5 AS5 7 6 AS6 Also applicable for engineering egress traffic from DC to peer BGP Prefix and Peering Segments Packet AS1 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 87

83 Traditional Traffic Engineering Algorithms 1 Constraint: Avoid link Shortest path Avoid link 2-3 RSVP-TE creates a tunnel: all states are programmed hop by hop in all the intermediate nodes {4, 5, 7, 3} The tunnel will select only one of the available paths Traffic is not balanced Resources unequally used 8 9 With SR we can do much better BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 88

84 Node1 Service Disjointness Use-Case POLICY1 SID-list: <16002, 30203, 16007> 1 POLICY2 SID-list: <16005, 16006, 16007> 2 3 I: I:100 Default IGP link metric: I:10 The head-end computes two, disjoint paths segment-routing traffic-eng policy POLICY1 color 20 end-point ipv candidate-paths preference 100 dynamic mpls metric type igp association group 1 type node! policy POLICY2 color 30 end-point ipv candidate-paths preference 100 dynamic mpls metric type igp association group 1 type node BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 89

85 Automated performant steering ➐ ➑ FIB table at PE1 BGP: 20/8 via 4001 SRTE: 4001: Push <16002, 30204> ➌ BGP: 20/8 via PE4 VPN-LABEL: Low-latency (color 20) RR ➋ BGP: 20/8 via PE4 VPN-LABEL: Low-latency (color 20) Forwarding table on Node1 In Out Out_intf Fraction 4001 <16002, 30204> To Node 2 100% ➍ PE4 with Lowlatency (color 20)? ➎ use template color 20 ➏ SID-list <16002, 30204> ➐ Low Latency to PE4 2 1 CE 6 I: 50 D: ➊ BGP: 20/8 via CE 20/8 ➐ instantiate SR Policy BSID 4001 ➑ forward 20/8 via BSID 4001 Default IGP cost: I:10 Default Latency cost: D:10 BRKRST Cisco and/or its affiliates. All rights reserved. Cisco Public 90

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