Flapping BGP

chenhui · Created Jul 20, 2021 07:33:51

Hi,
BGP establishes neighbors through the TCP protocol. After the neighbor establishment is completed, keepalive packets are periodically sent to maintain the session status.
When BGP flaps occur, it is usually caused by the loss of the source and destination IP addresses for establishing BGP neighbors.
For example, Router A and Router B establish neighbors through the loopback interface, and at the same time advertise the loopback interface address to the peer through BGP after the neighbor is established. In this case, the basis for BGP to establish neighbors disappears from the routing table. , Causing the BGP neighbor to go down, and then the route appears in the routing table, again and again, causing BGP to flip

jason_hu · Created Jul 19, 2021 01:12:56

Hello friend！
Route flapping is caused by pathological conditions (hardware errors, software errors, configuration errors, intermittent errors in communications links, unreliable connections, etc.) within the network which cause certain reachability information to be repeatedly advertised and withdrawn.
But in most cases, when the BGP route disappears and reappears in the routing table, BGP Flapping will appear.
Hope to help you!

chenhui · Created Jul 20, 2021 07:33:51

Hi,
BGP establishes neighbors through the TCP protocol. After the neighbor establishment is completed, keepalive packets are periodically sent to maintain the session status.
When BGP flaps occur, it is usually caused by the loss of the source and destination IP addresses for establishing BGP neighbors.
For example, Router A and Router B establish neighbors through the loopback interface, and at the same time advertise the loopback interface address to the peer through BGP after the neighbor is established. In this case, the basis for BGP to establish neighbors disappears from the routing table. , Causing the BGP neighbor to go down, and then the route appears in the routing table, again and again, causing BGP to flip

Unicef · Created Jul 21, 2021 15:41:03

Good answer

vagkaefer · Created Jul 21, 2021 17:51:25

Hello Friend,

The NE40 is the NE40E-M2x? If so, I've already had a problem with this model. Same situation, everything was correct and the peer crashed and came back.

It was a software problem, after updating the firmware and patch to the stable and officially recommended version, the problem never happened again.

Flapping BGP

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