Administrator Guide

The neighbor information that this command displays does not include counts corresponding to ignored prefixes
and updates. However, the martian case is an exception where neighbor information corresponding to ignored
updates is displayed.
BGP shows the exact information that is exchanged between the BGP peers. It also indicates whether or not this
information is received by the BGP peer.
The following describes the show ip bgp neighbors command shown in the following examples.
The Lines
Beginning
with:
Description
BGP neighbor Displays the BGP neighbor address and its AS number. The last phrase in the line indicates
whether the link between the BGP router and its neighbor is an external or internal one. If
they are located in the same AS, the link is internal; otherwise the link is external.
BGP version Displays the BGP version (always version 4) and the remote router ID.
BGP state Displays the neighbor’s BGP state and the amount of time in hours:minutes:seconds it has
been in that state.
Last read This line displays the following information:
• last read is the time (hours:minutes:seconds) the router read a message from its
neighbor
• hold time is the number of seconds configured between messages from its neighbor
• keepalive interval is the number of seconds between keepalive messages to help
ensure that the TCP session is still alive.
Received
messages
This line displays the number of BGP messages received, the number of notifications
(error messages), and the number of messages waiting in a queue for processing.
Sent messages The line displays the number of BGP messages sent, the number of notifications (error
messages), and the number of messages waiting in a queue for processing.
Received updates This line displays the number of BGP updates received and sent.
Soft
reconfiguration
This line indicates that soft reconfiguration inbound is configured.
Minimum time Displays the minimum time, in seconds, between advertisements.
(list of inbound
and outbound
policies)
Displays the policy commands configured and the names of the Route map, AS-PATH
ACL, or Prefix list configured for the policy.
For address
family:
Displays the IPv4 Unicast as the address family.
BGP table version Displays which version of the primary BGP routing table the router and the neighbor are
using.
accepted prefixes Displays the number of network prefixes the router accepts and the amount of memory
used to process those prefixes.
Prefix advertised Displays the number of network prefixes advertised, the number rejected, and the number
withdrawn from the BGP routing table.
Connections
established
Displays the number of TCP connections established and dropped between the two peers
to exchange BGP information.
Last reset Displays the amount of time since the peering session was last reset. Also states if the
peer resets the peering session. If the peering session was never reset, the word never is
displayed.
Local host: Displays the peering address of the local router and the TCP port number.
Foreign host: Displays the peering address of the neighbor and the TCP port number.
390 Border Gateway Protocol