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SDN Controllers in the WAN

SDN Controllers in the WAN. Julian Lucek jlucek@juniper.net @ julianlucek. Agenda. Introduction to SDN Controller for WAN Towards Self-Driving with Closed Loop Automation Automated Congestion Avoidance Dynamic Minimum Latency Path Self-Driving Egress Peering Engineering

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SDN Controllers in the WAN

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  1. SDN Controllers in the WAN Julian Lucek jlucek@juniper.net @julianlucek

  2. Agenda • Introduction to SDN Controller for WAN • Towards Self-Driving with Closed Loop Automation • Automated Congestion Avoidance • Dynamic Minimum Latency Path • Self-Driving Egress Peering Engineering • Automated Network Self-Healing • P2MP Traffic Engineering

  3. WAN Controller Concept Requests via Northbound REST API • Creation of LSPs according to service requirements. • Placement of LSP paths according to traffic demands. • Automation of network operations. Requests via GUI Controller TE LSP creation/modification (PCEP, BGP SR-TE) Real-time topology (BGP-LS) Streaming Telemetry LSP status (PCEP) MPLS Network

  4. Topology discovery using BGP-LS F B D H Adj-SID = 78 BW=100 Admin-group: green K A E SRLG 200 G J C Red-dashed zones denote IGP areas At least one BGP-LS session into each IGP area In practice, 2+ RR’s for resilience RR BGP-LS session Controller

  5. Path computation element protocol (PCEP) • PCE: Path Computation Element Computes the path • PCC: Path Computation Client Receives the path. Sets up LSP using RSVP or Segment Routing. • PCEP: PCE Protocol (RFC 5440) For PCE/PCC communication PCE PCEP PCEP PCC PCEP PCC PCC

  6. CLOSED-LOOP Automation Disturbances (Outages, Congestion etc) The Network WAN Controller + X Network state User intent - Measured output Streaming Telemetry Traffic on each link Traffic on each LSP Link latency data Packet loss stats Streaming Telemetry allows much more frequent updates than SNMP. Push paradigm, rather than request/response. Stats collected on linecard are sent directly from there without passing through control processor.

  7. Automated actions, based on link utilisation (1) Controller knows via Streaming Telemetry that red link is currently experiencing high utilization

  8. Automated actions, based on link utilisation (2) Controller also knows via Streaming Telemetry how much traffic is travelling on each LSP So it automatically moves away some LSPs from the congested link

  9. Programmablecost function 15 15 15 15 10 X 10 Y 10 Lowest IGP metric path Blue numbers show IGP metric Cost function = lowest IGP metric path that meets the required path constraints (BW etc) Node is tagged as available again after maintenance window finishes. Optimum LSP paths are restored again through PCEP update and LSP re-signaling

  10. Minimum latency path 10 10 10 10 11 X 11 Y 10 Lowest latency path Red numbers show latency of each link Node is tagged as available again after maintenance window finishes. Optimum LSP paths are restored again through PCEP update and LSP re-signaling

  11. Minimum latency path Latency has increased Controller automatically moves minimum-latency LSP onto the lowest latency path 15 10 10 10 11 X 11 Y 10 Lowest latency path Red numbers show latency of each link Node is tagged as available again after maintenance window finishes. Optimum LSP paths are restored again through PCEP update and LSP re-signaling

  12. Automated self-healing 3. REST API call: Maintenance interval on Link L1 NorthStar WAN Controller 4. WAN Controller recomputes paths of all TE LSPs that pass through Link L1, and sends PCEP messages to corresponding ingress routers to change the paths accordingly AppFormix 2. AppFormix determines that Link L1 is unhealthy 1. Streaming Telemetry from all network nodes L1

  13. Automated self-healing 3. REST API call: Maintenance interval on Link L1 NorthStar WAN Controller 4. WAN Controller recomputes paths of all TE LSPs that pass through Link L1, and sends PCEP messages to corresponding ingress routers to change the paths accordingly AppFormix 2. AppFormix determines that Link L1 is unhealthy 1. Streaming Telemetry from all network nodes L1 https://forums.juniper.net/t5/Industry-Solutions-and-Trends/Enabling-rapid-remediation-in-the-Self-Driving-Network/ba-p/321375

  14. Self-Driving Egress Peering Engineering

  15. Self-Driving egress peering engineering (EPE) prefix X • Each PE sends flow stats to Controller - how much traffic the PE is sending to each destination prefix. • Controller decides which {egress link, egress ASBR} each PE should use to send traffic to prefix X. • Cost function based on: • cost to reach ASBR • cost of using each peering link • current utilisation of each peering link • user-defined preferences ASBR G ASBR F ASBR E ASBR1 ASBR2 PE1 PE4 PE2 PE3

  16. Self-driving egress peering engineering (EPE) prefix X • Peering link on ASBR1 is approaching congestion outbound. • Controller moves traffic from PE2 to prefix X onto one of the peering links on ASBR2. ASBR G ASBR F ASBR E ASBR1 ASBR2 PE1 PE4 PE2 PE3

  17. EPE ingredients: PEER-SID • SID values manually configured on ASBR A • Advertised via BGP-LS to NorthStar • SID label steers packet towards desired peering link • ASBR A pops label, so plain IP packet is sent on the peering link ASBR B PeerNode SID = 100 IP 200 IP ASBR C PeerNode SID = 200 ASBR A PeerAdj SID = 300 PeerAdj SID = 400 ASBR D

  18. Self-Driving egress peering engineering (EPE) prefix X ASBR G ASBR F • Traffic to Prefix X from PE2 uses the SR-TE tunnel shown in red, which has been computed and instantiated by the Controller. • This tunnel steers the traffic across the core to ASBR2, and then onto the peering link to ASBR F ASBR E 300 ASBR1 ASBR2 26 58 17 PE1 PE4 PE2 PE3 SR-TE tunnel: Push 300, Push 26, Push 58, Push 17 (top), NH=ASBR2

  19. P2MP LSPs with WAN Controller

  20. P2MP LSP Path Diversity • Controller performs diverse path computation and then instantiates the P2MP LSPs using PCEP • Applications: • Broadcast TV • Financial Market Data • Air Traffic Radar Multicast Source Diversely routed P2MP LSPs Receiver at Site A Receiver at Site B

  21. P2MP LSP: Physical layout

  22. P2MP LSP: LOGICAL layout

  23. NorthStar P2MP LSP deployment in SKY Source: IBC 2019 Showcase Theatre, http://vsf.tv/events_archive/2019-09_IBC2019/Tuesday/Massimo%20Magnani%20-%20IBC%202019%20-%20JNPR%20SKYTV%20NS%20Controller%20in%20M&B%20Networks%20IBC2019%20v9.pdf

  24. NorthStar P2MP LSP deployment in SKY Source: IBC 2019 Showcase Theatre, http://vsf.tv/events_archive/2019-09_IBC2019/Tuesday/Massimo%20Magnani%20-%20IBC%202019%20-%20JNPR%20SKYTV%20NS%20Controller%20in%20M&B%20Networks%20IBC2019%20v9.pdf

  25. NorthStar P2MP LSP deployment in SKY Source: IBC 2019 Showcase Theatre, http://vsf.tv/events_archive/2019-09_IBC2019/Tuesday/Massimo%20Magnani%20-%20IBC%202019%20-%20JNPR%20SKYTV%20NS%20Controller%20in%20M&B%20Networks%20IBC2019%20v9.pdf

  26. Useful References • NorthStar Controller documentation • https://www.juniper.net/documentation/product/en_US/northstar-controller • Blogs at https://forums.juniper.net/t5/user/viewprofilepage/user-id/24095 • Nanog presentation • https://www.youtube.com/watch?v=vzF6T5Jl3Qg • PCEP and BGP-LS deep-dive webinar • https://www.ipspace.net/PCEP_and_BGP-LS_Deep_Dive

  27. ThaNK YOU!

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