Segment Routing. Clarence Filsfils Distinguished Engineer

Transcription

1 Segment Routing Clarence Filsfils Distinguished Engineer

2 Segment Routing Unified DC + WAN + Aggregation from server in the DC, through WAN and to the service edge Policy-aware DC: disjoint planes, flow-based congestion avoidance WAN: disjoint services, latency-sensitive traffic, scheduled bulk transfer Application programs the end-to-end policy The end-to-end policy is encoded by the application as an SR segment list in the packet header Balance between distributed and centralized intelligence Distributed: automated sub-30msec FRR link/node in any topology with optimum backup path Centralized: traffic optimization for better use of the installed capacity Applicable to MPLS and IPv6 dataplanes Much simpler to operate than MPLS Classic Cisco Confidential 2

3 Key Concepts

4 Segment Routing Source Routing: the source chooses a path and encodes it in the packet header as an ordered list of segments. Segment: an identifier for any type of instruction Service Context Locator IGP-based forwarding construct BGP-based forwarding construct Local value or Global Index Segment = Instructions such as "go to node N using the shortest path" Cisco Confidential 4

5 Segment Routing MPLS: an ordered list of segments is represented as a stack of labels SR re-uses MPLS dataplane without any change IPv6: an ordered list of segments is represented as a routing extension header, see 4.4 of RFC2460 IGP-based segments require minor extension to the existing linkstate routing protocols (OSPF and IS-IS). The remainder of this session focuses on SR on MPLS dataplane Cisco Confidential 5

6 IGP Segments Node segment to C A B C D Node segment to C Adj Segment Z M N O P Simple extension to let IGP install segments in the MPLS dataplane Excellent Scale: a node installs N+A FIB entries N node segments and A adjacency segments Node segment to Z Cisco Confidential 6

7 Node Segment Packet to Z FEC Z push A B C Packet to Z swap to Packet to Z swap to Packet to Z D pop Z Packet to Z A packet injected anywhere with top segment will reach Z via shortest-path Z advertises a global node segment with its loopback simple ISIS sub-tlv extension > default SRGB [16000, 23999] at all nodes is a request from all lead operators for operational simplicity. The protocol and implementation allows for different SRGB at every node All remote nodes install in their FIB the node segment to Z Cisco Confidential 7

8 Node Segment A B C D Z M N O P ECMP A node segment to distributes traffic across all ECMP paths to O Cisco Confidential 8

9 Adjacency Segment A B C M N O Pop D P Z A packet injected at node C with segment is forced through datalink CO C allocates a local segment and maps it to the instruction complete the segment and forward along the interface CO C advertises the adjacency segment in ISIS simple sub-tlv extension C is the only node to install the adjacency segment in FIB Cisco Confidential 9

10 Explicit path as Segment List ECMP Node segment Per-flow state only at head-end not at midpoints Source Routing the path state is in the packet header Packet to Z Packet to Z Packet to Z A B C M N O Packet to Z D P Packet to Z Z Packet to Z Cisco Confidential 10

11 Automated 50-msec Protection for IGP Segments Guaranteed Link/Node FRR in any topology 50msec protection Simplicity Entirely automated No directed LDP session No RSVP-TE tunnels Incremental deployment Applicable to LDP primary traffic Optimal backup path along postconvergence path Prevents transient congestion and suboptimal routing Cisco Confidential 11

12 What is Segment Routing? IP/MPLS architecture that seeks the right balance between distributed intelligence and centralized optimization and programming. simplifies operation (lower opex) enables application-based service creation (new revenue) allows for better utilization of the installed infrastructure (lower capex) An IP/MPLS architecture with wide application (SP, OTT/Web, GET) across (WAN, Metro/Agg, DC) MPLS and IPv6 dataplanes SDN controller An architecture designed with SDN in mind Cisco Confidential 12

13 Industry Acceptance & Standardization

14 Strong Operator Partnership Fundamental to the velocity and success Significant commitment technical transparency multi-vendor commitment beta and poc Many more operators now involved Deployments in a few months Cisco Confidential 14

15 IETF Working-Group is created Use-Case is WG status Architecture is WG status Protocol Extension is WG status ~ 25 drafts maintained by SR team Over 50% are WG status Over 75% have a Cisco implementation Cisco Confidential 15

16 SR ToolBox

17 SR ToolBox Impressive in < 24months ISIS Prefix and Adjacency Segment with 50msec link-frr IOS-XR SR/LDP seamless interworking for ISIS IOS-XR OSPF Prefix and Adjacency Segment with 50msec link-frr IOS-XR SRTE Head-end on ASR9k SRTE head-end on VPEF BGP Peering Segment BGP Prefix Segment Beta Beta Beta Beta SR Planning and Design Mate Design 6.0 Get involved and provide ideas and requirements Leverage dcloud.cisco.com virtual labs Cisco Confidential 17

18 SR Traffic Engineering

19 SRTE Headend Classify packets and push the matching segment-list All the TE functionality is leveraged (counters, autoroute, PBTS...) Network Design Virtual PE facing Application VM s: VPP beta available DCI, PE or Aggregation: IOS-XR/ASR9k beta available Cisco Confidential 19

20 SRTE midpoint Does not exist No state overhead No signalling overhead Cisco Confidential 20

21 SR Policy Computation Router (headend) WAE Mate Design Latency V V V Avoid a topological resource V V V Disjoint from another service V (if both originate on the same headend) BW - V V Inter-Area/Inter-Domain - V V Integration with IP/Optical - V V V V Cisco Confidential 21

22 The benefits of centralized TE Cisco Confidential 22

23 The benefits of centralized TE Centralized Traffic Engineering Better optimum Better predictability Faster convergence Better suited for Application Programmability (Nbound-API) Network Programmability (Sbound-API, PCEP) Centralized TE with Segment Routing Controller expresses path as segment list Network maintains segments and provide FRR for them ECMP-awareness No signalling and per-flow state at midpoint Cisco Confidential 23

24 Centralized Traffic Engineering 2G from A to Z please FULL Link CD is full, I cannot use the shortest-path 65 straight to Z Cisco Confidential 24

25 Centralized Traffic Engineering Tunnel AZ onto {16066, 16068, 16065} FULL Path ABCOPZ is ok. I account the BW. Then I steer the traffic on this path Highly programmable and responsive to rapid changes perfect support for centralized optimization efficiency, if required Cisco Confidential 25

26 Real Data-Set times less tunnels SR-TE and Centralized Controller: 50% capex gain with better predictibility and optimality than RSVP-TE and with 1000 times less tunnels Cisco Confidential 26

27 SRTE Optimization Real Data Sets

28 BGP Peering Segment

29 Automated BGP Peering SID allocation BGP Peering SID s in C s MPLS Dataplane PeerNode SID s: 16012: pop and fwd to / : pop and fwd to / : pop and fwd to /32 (ecmp!) PeerAdj SID s: 16032: pop and fwd to / : pop and fwd to /32 Cisco Confidential 29

30 BGP-LS extensions to signal Peering SID to controller The controller learns the BGP Peering SID s and the external topology of the egress border router via BGP-LS EPE routes BGP EPE Signalling from egress PE to Controller Cisco Confidential 30

31 BGP Prefix Segment

32 MSDC Massive Scale DC Built on BGP3107 BGP Prefix Segment Straightforward BGP3107 extension BGP equivalent to IGP Prefix SID Any node within the topology allocates the same BGP Segment for the same switch ebgp ipv4 labeled-unicast ebgp ipv4 unicast Cisco Confidential 32

33 BGP Prefix SID Same benefits as IGP Prefix SID ECMP Automated FRR (BGP PIC) Building block for Traffic Engineering Cisco Confidential 33

34 Use-Cases and Benefits

35 TI-LFA: Automated 50-msec Protection for IGP Segments Guaranteed Link/Node FRR in any topology 50msec protection Simplicity Entirely automated No directed LDP session No RSVP-TE tunnels Incremental deployment Applicable to LDP primary traffic Optimal backup path along postconvergence path Prevents transient congestion and suboptimal routing Cisco Confidential 35

36 Mate Design TILFA Simulation How many segments in backup chain Capacity analysis during FRR transient state Cisco Confidential 36

37 IPv4 MPLS Transport with FRR A B PE1 PE2 M N All VPN services ride on the prefix segment to PE2 Any service resolving on IGP IPv4 Prefix SID Internet VPNv4 6PE PW IPv4 over MPLS: the obvious way it should have been done Just the IGP to operate Sub50msec FRR integrated and automated Seamless migration SR/LDP interworking Cisco Confidential 37

38 IPv6 MPLS Transport with FRR PE1 A M B N PE2 Any service resolving on IGP IPv6 Prefix SID Internet v6 VPNv6 Internet/v6 rides on the Prefix segment to PE2 IPv6: the opportunity to do it right from the start Just the IGP to operate Sub50msec FRR integrated and automated Cisco Confidential 38

39 MPLS dataplane monitoring B 9105 C A OAM 9102 N O 9104 draft-geib-spring-oam-usecase-02 Nanog57, Feb 2013 Cisco Confidential 39

40 Disjoint TE Service Beta Available A to Z any plane IGP shortest-path PrefixSID of Z (65) A to Z via blue plane SRTE policy pushes one additional segment Blue Anycast (111) Benefits ECMP No hop-by-hop signalling load and delay No midpoint state pkt pkt Cisco Confidential 40

41 Latency TE Service Data from Tokyo to Brussels IGP shortest-path via US, higher and cheaper capacity PrefixSID of Brussels Voice from Tokyo to Brussels SRTE policy pushes one additional segment Russia Anycast Low-latency path Benefits ECMP Availability of the anycast segment against node failure No hop-by-hop signalling load and delay No midpoint state Node segment to Brussels Node segment to Russia Russia Brussels Brussels pkt pkt Data Voice Cisco Confidential 41

42 Content producer engineers its WAN traffic to egress peers AS1 Best BGP and IGP Path PrefixSID(B) Payload ISIS/SR-based WAN B Payload AS2 D AS4 A TE Policy installed by Controller PrefixSID (C) PeeringSID(E) Payload Engineered Path PeeringSID(E) Payload C Payload AS3 E /32 Engineered Path Cisco Confidential 42

43 SR-based MSDC MPLS dataplane BGP control-plane No LDP, No RSVP-TE Integrated/Automated FRR > no hop-by-hop manual configuration of static routes and their FRR behaviors Global label for easier operation Same SRGB at each switch SRTE WAN Optimization Controller applicable to DC fabric Cisco Confidential 43

44 Distributed DC for Content Engineering to local Peers AS1 Best BGP Path PrefixSID(B) Payload BGP/SR-based DC Fabric B Payload AS2 D AS4 TE Policy installed by Controller PrefixSID (C) PeeringSID(E) Payload Engineered Path PeeringSID(E) Payload C Payload AS3 E /32 Engineered Path Cisco Confidential 44

45 End-to-end policy from DC, through WAN to peer App SR DC SR WAN BR vpef ToR Leaf Spine DCE LSR BR App BR Classify flow and push SR segment list Top Segment provides ECMP-path to selected DCI Next segments implement WAN Policy: Cost vs Latency Disjointness Select egress BR Last segment selects egress peer Cisco Confidential 45

46 End-to-end policy from DC, through WAN to peer SR DC SR WAN BR ToR Leaf Spine DCE LSR BR BR Illustrated end-to-end policy implemented by the application: Two service hops in the DC Low-latency path in the WAN Engineered peering exit to Internet consumer Cisco Confidential 46

47 Large-Scale Aggregation ASBR SID s are anycast ASBR SID s are unique across the entire domain A 70 Acces1 B 72 ASBR1A 1001 ASBR1B 1001 Core ASBR2A 1002 ASBR2B 1002 Acces2 C 72 ASBR anycast prefixes and SID are redistributed within each access region Access Nodes are provided a SID which is unique with respect to its attached ASBR s but not necessarily unique across the whole domain Only IGP/SR (no BGP) Automated FRR including ASBR failure SRGB (k) << # access nodes (100k) {72} leads to B within Access1 {72} leads to C within Access2 {1001, 72} leads to B from anywhere {1002, 72} leads to C from anywhere SDN Controller programs the segment list together with service creation Cisco Confidential 47

48 Conclusion

49 Segment Routing Unified DC + WAN + Aggregation from server in the DC, through WAN and to the service edge Policy-aware DC: disjoint planes, flow-based congestion avoidance WAN: disjoint services, latency-sensitive traffic, scheduled bulk transfer Application programs the end-to-end policy The end-to-end policy is encoded by the application as an SR segment list in the packet header Balance between distributed and centralized intelligence Distributed: automated sub-30msec FRR link/node in any topology with optimum backup path Centralized: traffic optimization for better use of the installed capacity Applicable to MPLS and IPv6 dataplanes Much simpler to operate than MPLS Classic Cisco Confidential 49

50 Get involved All of these use-cases are either FCS or beta available Leverage dcloud.cisco.com virtual labs Get involved and provide ideas and requirements SR is operator driven Visit the lab/demo offered by Kris Michielsen Your help is key Cisco Confidential 50

51 Thank you.

52 Complete Your Online Session Evaluation Please complete your online session evaluations after each session. Complete 4 session evaluations & the Overall Conference Evaluation (available from Thursday) to receive your Cisco Live T-shirt. All surveys can be completed via the Cisco Live Mobile App or the Communication Stations Cisco Confidential 52

53 Segment Routing Leverage MPLS dataplane and services Drastically improve MPLS control-plane while enabling new services Simplicity, Scale, Functionality, Centralized Optimization and Programmability Strong operator adoption and tight involvement Innovation and Standardization Aggressive productization by Cisco PoC and Beta code available Cisco Confidential 53

54 Stay Informed Cisco Confidential 54

55 End-to-end policy from DC, through WAN to peer App SR DC SR WAN BR vpef ToR Leaf Spine DCE LSR BR App BR Cisco Confidential 55