1. Redundancy, Symmetry and Load Balancing Presented by Sagi Shporer

2. Terminology Redundancy Symmetry Load Balancing

3. Terminology – Cont. Outbound decision Which way should the traffic be sent to NetA ? AS2AS1 NetA

4. Terminology – Cont. Inbound decision I want to receive inbound traffic for NetB via SA1 link only AS2AS1 NetB NetC

5. Terminology – Cont. Load Balancing – choosing ISP ISP2 Customer ISP1

6. Setting Default Routers Gateway of last resort Dynamic Learned Defaults Statically Set Defaults

7. Setting Default Routers – Cont. AS1 AS2 Primary Backup 2.2.2.2Set local pref = 50 1.1.1.1 Set local pref = 100 Gateway of last resort is 1.1.1.1

8. Setting Default Routers – Cont. AS1 AS2 Primary Backup 2.2.2.2 Set local pref = 50 1.1.1.1 Set local pref = 100 Gateway of last resort is 1.1.1.1

9. Setting Default Routers – Cont. Statically Set Defaults –IP of next-hop gateway Example : IP 201.1.2.3 –A network number Example : The route to that network number is learned dynamically –A specific router interface Example : Ethernet interface 0

10. Routing Tables No Routes Partial Routes Full Routes

11. Specific Scenarios Single-Homing Multihoming to a Single Provider Multihoming to Different Providers Customers of the Same Provider with Backup Link Customers of Different Providers with a Backup Link

12. Scenario 1 : Single-Homing Customer Default ISP Static Incoming traffic Outgoing traffic

13. Scenario 2 : Multihoming to a Single Provider Default only, one Primary, one Backup Provider Customer Default-2 Backup Metric : 100 Default-1 Primary Mertic : 50

14. Scenario 2 – Cont. Default, Primary and Backup plus partial routing

15. C2C2 C3C5C4 NAP (X,Y)(Z,W) W: 200 Z: 200 Rest : 250 Y: 200 X: 200 Rest : 300 C5: 300 C4: 300 Rest : 250 C3: 300 C2: 300 Rest : 200 Metrics Preference Default-1 Primary Default-2 Backup Customer ISP

16. Scenario 2 – Cont. Default, Primary and Backup plus full and partial routing –Full route on one link, and no route or partial route on the other links

17. Scenario 2 – Cont. Automatic load balancing 192.213.10.6 192.213.10.5 192.213.10.4 192.213.10.3 192.213.10.2 192.213.10.1 135135 246246 ISP Customer

18. Scenario 2 – Cont. Balancing between two routers sharing multiple paths 11.11.11.111.11.11.2 10.10.10.110.10.10.2 RTA NetX RTB BGP Session Link2 Link1

19. DestinationNext Hop NetX10.10.10.2 (best) NetX11.11.11.2 RTA’s BGP Table 11.11.11.111.11.11.2 10.10.10.110.10.10.2 RTA NetX RTB BGP Session Link2 Link1

20. DestinationNext Hop NetX10.10.10.2 10.10.10.0/24Link1 RTA’s Routing Table 11.11.11.111.11.11.2 10.10.10.110.10.10.2 RTA NetX RTB BGP Session Link2 Link1

21. DestinationNext Hop NetX12.12.12.12 RTA’s BGP Table BGP Session 11.11.11.111.11.11.2 10.10.10.110.10.10.2 RTA NetX RTB Link2 Link1 9.9.9.912.12.12.12

22. DestinationNext Hop NetX12.12.12.12 12.12.12.0/24Link1 12.12.12.0/24Link2 RTA’s Routing Table BGP Session 11.11.11.111.11.11.2 10.10.10.110.10.10.2 RTA NetX RTB Link2 Link1 9.9.9.912.12.12.12

23. Scenario 3 : Multihoming to Different Providers Default only, Primary and Backup NAP 192.213.0.0/16 Pref=200 192.213.0.0/16 Pref=100 192.213.0.0/16

24. Scenario 3 – Cont. Default, Primary and Backup plus partial routing

25. NAP Customer IBGP Default-1 primary Default-2 backup Partial Routes

26. Scenario 3 – Cont. Default, Primary and Backup plus full and partial routing

27. NAP Customer IBGP Primary Backup Partial Routes

28. Scenario 3 – Cont. Customer Inbound Traffic

29. NAP 192.213.1.0/24 – 200 100 192.213.1.0/24 – 300 100 100 192.213.1.0/24 – 100 192.213.1.0/24 – 100 100 192.213.1.0/24 Customer IBGP AS100 AS200 AS300

30. Scenario 4 : Customers of the Same Provider with Private Link Private link used as pure backup NAPAS1AS3AS2 Pref=200 Pref=100 Backup

31. Scenario 4 – Cont. Private link used as primary link NAP AS1 AS3 AS2 Pref=300 Pref=200 AS3 Routes Updates that do not contain AS3 Pref=100

32. Scenario 5 : Customers of Different Providers with a Private Link NAP ISP1 ISP2 AS2AS1

33. Community Approach ISP routes - 60 Customer transit routes - 40 Customer local routes - 100 ISP1 ISP2 AS1 AS2 AS400 40100 60

34. PatternCommunityLocal Pref. Customer local routesNone100 Customer transit routes400:4040 ISP routes400:6060 ISP routes - 60 Customer transit routes - 40 Customer local routes - 100 AS1 AS2 AS400 40100 60 ISP2ISP1

35. AS Path Manipulation AS2’s routes via ISP2 AS_Path: 500 1 AS2’s routes via AS1 AS_Path: 1 1 2 ISP1ISP2 AS1 AS2 AS400