Show ip bgp x.x.x.x/y output

R1#show ip bgp
BGP routing table entry for, version 4
Paths: (2 available, best #2, table default)
Advertised to update-groups:
Refresh Epoch 1
2, (received & used) from (
Origin IGP, metric 0, localpref 100, valid, external
Refresh Epoch 1
2, (received & used) from (
Origin IGP, metric 0, localpref 100, valid, external, best

what is the meaning of "Refresh Epoch 1 " ? what problems does it solves?
and what is the meanig of (received & used) ? what problems does it solves?


Hey Major,

The only documentation I could find on the refresh epoch has to do with the NSF feature.

For a VERY high level overview, SSO (Stateful Switch Over) is a feature where a device, let’s say a router, has multiple processors in it that can handle the control plane. If a processor were to fail, the other processor has been mirroring configuration information and can take over rapidly, providing a degree of high availability within a single chassis.

A VERY high level overview of NSF (Non-Stop forwarding) allows the line card with CEF to continue forwarding packets while the processors fail over.

A BGP advanced feature is to configure it to be NSF-compatible. This means once it fails over, BGP will actively verify the routes from the connected neighbors, and update the routing table all over again. As it updates, it also pushes that information to CEF, which then adds it to the FIB etc. The Epoch 1 is used to keep track of the version in the CEF. So, BGP after the failover will update the CEF and it will receive a new Epoch number to indicate that it has been refreshed.

1 Like