Cisco: BGP Multipath Loadbalancing maximum-paths

sumber: https://learningnetwork.cisco.com/thread/42531

have read that BGP does not really support load balancing, but now I have discovered the BGP maximum-paths command.

maximum-paths (BGP)

To control the maximum number of parallel routes that the Border Gateway Protocol (BGP) can support, use the maximum-paths command. To restore the default number of parallel routes, use the no form of this command.

maximum-paths [ ibgp ] number-paths
no maximum-paths [ ibgp ] number-paths

For instance, consider the following single multihomed design:

As an example, a default route can be received from ISP1 and ISP2 with the same AS_Path, origin code and metric. Thus, both default routes tie by step 8 (according Odom's CCNP Route book) and configuring 'maximum-paths 2' under the bgp process I think I can load balance traffic between ISP1 and ISP2.

So, in the end, does BGP support load balancing considering this command?

router bgp 100
no synchronization
bgp log-neighbor-changes
network 192.168.0.0
network 192.168.1.0
neighbor 10.0.0.1 remote-as 200
neighbor 172.16.0.1 remote-as 300
maximum-paths 2
no auto-summary

From Odom's CCNP Route book:

If the BGP best path algorithm does not choose a best path by Step 8 (per the numbering in this book), the routes which still tie for being best path through Step 8 will be allowed into the IP routing table, up to the number defined by the BGP maximum-paths number-of-paths router subcommand.

Alternatif Lain

Perintah

bgp bestpath as-path multipath-relax

This will allow the router to load-share across multiple BGP paths even if the as-path is different.

Referensi

• https://learningnetwork.cisco.com/thread/42531

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