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05 - IDNOG04 - Bambang Gunawan (Juniper) - Segment Routing

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05 - IDNOG04 - Bambang Gunawan (Juniper) - Segment Routing

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05 - IDNOG04 - Bambang Gunawan (Juniper) - Segment Routing

  1. 1. Segment Routing Bambang Gunawan. System Engineer bgunawan@juniper.net
  2. 2. Agenda • Segment Routing Basic • Segment Routing Use Case • Segment Routing Deployment
  3. 3. Introduction E V O L U T I O N LDP RSVP-TE • Source Routing • Uses existing MPLS Data Plane (Packet format) • Same MPLS label operation (Push, Swap & Pop) • SR currently only for Transport label SDN ReadyAddress existing protocols weaknesses • LDP is simple but has no TE capability • RSVP provide TE capability without a good scaling (midpoint state problem) • Segment Routing was built for SDN
  4. 4. How can SR get rid of LDP & RSVP-TE? • LDP – By using OSPF/IS-IS extensions to distribute label – OSPF Opaque LSA & IS-IS new TLV • RSVP – By using global index/SID (SRGB + index) – Thus source router can steer the path by stacking the desired segments
  5. 5. Global and Local Segments • Global Segment – The related instruction is supported by all the SR- capable nodes in the domain. In the MPLS architecture, a Global Segment has a globally-unique index (SRGB + Index) • Local Segment – The related instruction is supported only by the node originating it
  6. 6. Segment Types • IGP Segments – Prefix Segments • Node Segment • Anycast Segment – Adjacency Segments • IGP segment attached to an unidirectional adjacency or set of adjacencies • BGP Segments – Peer Node Segments • BGP prefix segment which identifies a specific router (e.g. a loopback) – Peer Adjacency Segments • BGP segment attached to an unidirectional adjacency – Peer Set Segments • BGP segment attached to a set of adjacencies
  7. 7. IGP Segment Types 2 3 1 CE2 5 4 24024 CE1 16001 16002 16003 16004 16005 24035 24013 24012 24045 16024 16035 Node SID Anycast SID Adjacency SID
  8. 8. Use Case of Segment Routing • Disjointness • BGP On-Demand Next-hop • BGP Egress Peer Engineering (EPE) • Integration with PCE Controller
  9. 9. Disjointness B Z 11 13 12 14 21 23 22 24 A SID: 16111 SID: 16111 SID: 16111 SID: 16111 SID: 16222 SID: 16222 SID: 16222 SID: 16222 SID: 16065 MP-BGP 16111 16065 IP packet
  10. 10. BGP On-Demand Next-hop 2 3 1 CE2 5 4 50 15 CE1 B: 20/8 NH: CE2 20/8 must receive low-latency service PE4 tags 20/8 with community “Low-Lat” B: 20/8 NH: PE4 Comm: Low-Lat 20.0.0.1/24 Default IGP cost: 10 Default TE cost: 10
  11. 11. BGP On-Demand Next-hop 2 3 1 CE2 5 4 50 15 CE1 MAP: Low-Lat means “minimize TE metric” COMPUTE: minimize TE metric to node 4 RESULT: SR-TE: push [16002, 24024] Lowest TE metric path TE cost 20 BGP: 20/8 NH PE4 (path-type TE-LL) (best) FIB: BGP: 20/8 via 30001 FIB: SRTE: (PE4 –TE-LL) Binding SID: 30001: Push [16002, 24024] 20.0.0.1/24 Default IGP cost: 10 Default TE cost: 10 SRTE policy’s Binding SID
  12. 12. BGP EPE 3 16001 16002 AS 100 4 5 AS 200 AS 300 21 Flowspec BGP LS 16003 16004 16005 24023 24024 24052 24025 24234 24225 100 24225 IP packet Peer Node Peer Adj Peer Set Northstar Controller
  13. 13. Integration with PCE Controller A1 B1 A3 B3 A4 B4 A6 B6 C2 C5 A2 A5 B2 B5 AS X AS Y (Backbone) Northstar Controller v v
  14. 14. SR Deployment Scenario • Green-field deployment • Always consider to run SR only for green-field deployment • Integration with existing MPLS Core • All nodes currently running support SR • Upgrade OS to enable SR Support • Configure SR on OSPF/IS-IS • Monitor label allocation has been fully populated • Switch label preference to SR • Some nodes doesn’t support SR • Do as above for SR ready island • For non SR island: • Have one (preferably more node) running as mapping server to map LDP to SR label
  15. 15. Mapping Server A1 B1 A3 B3 A4 B4 A6 B6 C2 C5 A2 A5 B2 B5 SR only LDP only Northstar Controller v v Mapping Server to map A5, A6, C5, B4, B5, B6 SID to SR only island
  16. 16. Thank You

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