Setting Timers

BGP uses a keepalive timer to control the interval at which keepalive messages are sent. A hold-time timer controls how long BGP waits for a keepalive message before declaring a peer not available.

BGP negotiates the hold time with each neighbor when establishing the BGP connection. The peers use the lower of the two configured hold times. BGP sets the keepalive timer based on this negotiated hold time and the configured keepalive time.

neighbor timers

• Use to set the keepalive and hold-time timers for the specified neighbor or peer group.
• Overrides timer values set with the timers bgp command.
• If you specify a BGP peer group by using the peerGroupName argument, all the members of the peer group inherit the characteristic configured with this command unless it is overridden for a specific peer.
• If you set the keepalive timer to 0, BGP does not send any keepalive messages.
• If you do not expect the peer to send any keepalives, set the hold-time timer to 0.
• This command takes effect immediately and automatically bounces the session to force BGP to send a new open message to renegotiate the new timer values.
• Example

  host1(config-router)#neighbor 192.168.21.5 timers 90 240

• Use the no version to restore the default values on the specified neighbor or peer group—30 seconds for the keepalive timer and 90 seconds for the hold-time timer.
• See neighbor timers.

timers bgp

• Use to set the keepalive and hold-time timers for all neighbors.
• If you set the keepalive timer to 0, BGP does not send any keepalive messages.
• If you do not expect the peer to send any keepalives, set the hold-time timer to 0.
• Example

  host1(config-router)#timers bgp 75 300

• The new timer values are used by every session that comes up after you issue the command; timers configured specifically for the sessions take precedence over these values.

  To force sessions that are already established to use the new timer values, you must use the clear ip bgp command to perform a hard clear.

• Use the no version to restore the default values on all neighbors—30 seconds for the keepalive timer and 90 seconds for the hold-time timer.
• See timers bgp.

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