How to solve BGP Route jitter in the IGP route table

Source: Internet
Author: User

Basic Configuration:


Router bgp 9806

Nei too many connections 20 remote-as 4808

Bgp router-id


Router bgp 4808

Nei remote-as 9806

Nei update-source lo0

Bgp router-id

Network bandwidth limit 21 mask limit 255

Only the bgp neighbor relationship between r1 and r2 cannot be established. Remember to configure it on r1.

Nei route 0000000020 ebgp-multihop

At this time, r1 still needs to be able to reach limit 20, so it is configured in r1

Ip route // because as9806 is the last node, only the default route is configured. This is also the cause of the following problems:

After the preceding command is configured, the bgp neighbor relationship is successfully established. r2 sends the update of zookeeper 21/32 (next-hop: zookeeper Protocol 20) to r1, when r1 receives an update, it puts route 0000000021/32 into the bgp and igp route tables. Then, r1 queries whether route 00000000000020 is reachable in the next hop of Route route segment 255.000021, and finds that route 0000000020 can be reached through the default route, finally, route Route 21/32 (next-hop: Route route 000020) will be retained in the igp route table.

Problem !!!

In this case, the Administrator publishes the loopback0 of R2.

Network bandwidth limit 20 mask limit 255

R2 releases a new update to r1, namely, (next-hop: After r1 receives the update, it mounts the route to the bgp and igp route tables. At this time, the next hop of r1 in the igp route table that queries route 0000000020/32 is still the longest matching of Route 000020, so it will not continue to query the default route), which obviously does not conform to the logic itself and cannot trust itself ), therefore, all the routes with the next hop of Route 0000000020 are deleted from the igp route table, that is, route 0000000020/32 and route 0000000021/32. After a while, r2 will still send new updates, and r1 will repeat the previous actions, which eventually leads to the constant oscillation of learned routes in the igp routing table through bgp.


Configure on r1

Ip route 0000000020

When r1 receives an update of ipv000020/32, it loads the bgp and igp route tables and queries the next hop of ipv0000000020 through the static route configured above. r1 keeps the route in the igp route table, therefore, the result of the above bgp Route Oscillating in the igp route table will not appear.


1. When the interface used by the peer party to establish a bgp neighbor relationship with itself is not directly connected to itself, you must configure a static route pointing to the peer's bgp neighbor address.

2. When the peer uses loopback to establish a bgp neighbor relationship, you must configure an ebgp-multihop.


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