BGP Processes
Understanding BGP Processes
A Cisco IOS process, in general, consists of the individual threads and associated data that perform tasks, such as system maintenance, switching packets, and implementing routing protocols. Several Cisco IOS processes executed on the router enable BGP to run. Use the show process cpu | include BGP command to see the amount of CPU utilization due to BGP processes. This table lists the function of the BGP processes and shows that each process runs at different times, depending on the tasks that it handles. Because the BGP scanner and BGP router processes are responsible for a large amount of calculations, you may see high CPU due to either one of these processes. The following sections discuss these processes in greater detail.
| Process Name | Description | Interval |
|---|---|---|
| BGP Open | Performs BGP peer establishment. | At initialization, when establishing a TCP connection with a BGP peer. |
| BGP I/O | Handles queueing and processing of BGP packets, such as UPDATES and KEEPALIVES. | As BGP control packets are received. |
| BGP Scanner | Walks the BGP table and confirms reachability of the next hops. BGP scanner also checks conditional-advertisement to determine whether or not BGP should advertise condition prefixes, performs route dampening. In an MPLS VPN environment, BGP scanner imports and exports routes into a particular VPN routing and forwarding instance (VRF). | Once a minute. |
| BGP Router | Calculates the best BGP path and processes any route "churn". It also sends and receives routes, establishes peers, and interacts with the routing information base (RIB). | Once per second and when adding, removing, or soft-reconfiguring a BGP peer. |