How do I show timers in BGP?
To verify currently configured advertisement timer, you can look on show ip bgp neighbors to see it. The same output for iBGP session would show you advertisement timer set to 0 second by default as inside one AS, the updates should be propagated immediately.
What is BGP scan timer?
BGP uses a scanner that checks all routes in the BGP table every 60 seconds. The BGP scanner does best path calculation, checks the next hop addresses, and if the next hops are reachable. 60 seconds is a long time.
What is BGP keepalive timer?
The keepalive timer is the KEEPALIVE_INTERVAL between periodic BGP messages exchanged between a Cloud Router and its corresponding on-premises peer router. You can configure this value as described in Update the BGP keepalive interval. The default value is 20 seconds.
How can I speed up BGP convergence?
Optimizing BGP and IGP interaction requires the following:
- Tuning the underlying IGP for fast convergence.
- Enabling BGP Next-Hop Tracking process for all BGP speakers and tuning the BGP NHT delay in accordance with IGP response time.
- Applying IGP summarization carefully to avoid hiding BGP NHT information.
What is marker in BGP?
The Marker field is filled with a recognizable pattern that clearly marks the start of each message, to keep BGP peers synchronized. Before a BGP connection is established, the Marker field is just filled with all ones. Thus, this is the pattern used for Open messages.
How long does BGP take to converge?
This takes up to 60 seconds depending on the when the BGP Scanner process last ran. So even with a super optimized IGP, BGP will be very slow to converge.
How long is BGP convergence?
What is EoR in BGP?
BGP End-of-RIB marker (EoR) is a BGP extension used to improve initial routing convergence between two BGP neighbors. It has application in initial convergence and BGP Graceful Restart.
What is graceful shutdown in BGP?
The BGP Graceful Shutdown feature reduces or eliminates the loss of inbound or outbound traffic flows that were initially forwarded along the peering link that is being shut down for maintenance. This feature is primarily for PE-CE, PE-RR and PE-PE links.
How many BGP neighbors are there?
Create a global limit of BGP dynamic subnet range neighbors. The value ranges from 1 to 5000.
How long does BGP take to propagate?
The propagation of BGP routing changes between neighboring ASes can sometimes take more than 30 minutes. The longest propagation times from Abilene to GEANT are due to route-flap damping.
How do you test BGP graceful restart?
To verify proper operation of graceful restart, use the following commands:
- show bgp neighbor (for BGP graceful restart)
- show log (for IS-IS and OSPF/OSPFv3 graceful restart)
- show (ospf | ospfv3) overview (for OSPF/OSPFv3 graceful restart)
- show rsvp neighbor detail (for RSVP graceful restart—helper router)