Troubleshooting guide

Additional BGP Configuration

Hold Timer

Use the hold-timer command to set the default hold time for BGP neighbors. The command can be issued

in BGP configuration mode to set the default hold time for all neighbors in that BGP process, or the

command can be issued in BGP Neighbor Configuration mode to set the hold time for only that neighbor.

(config-bgp)#hold-timer <value>

(config-bgp-neighbor)#hold-timer <value>

<value> Specifies a time interval (in seconds) within which a keepalive must be received from a peer

before it is declared a dead peer. Range is 0 to 65535 seconds.

The peers will negotiate and use the lowest configured setting. The keepalive interval will be set to

one-third of the negotiated hold time.

Local AS

Some multihoming network designs require a customer to appear as a different AS number to individual

service providers. Also, service providers sometimes assign the same AS to multiple sites, which can cause

problems due to BGP’s loop avoidance check mechanism (refer to

Example 2 on page 37). The local-as

command rectifies both situations by substituting an AS number that is different from the one specified in

the command router bgp <AS number>.

Use the local-as command to specify an AS number for the unit to use when communicating with this BGP

neighbor.

(config-bgp-neighbor)#local-as <value>

<value> Specifies the AS number to use when communicating with this neighbor. The value must be

different than the AS number for this router and the peer router. It is only valid for eBGP connections.

Range is 0 to 4294967295. When 0 is used, it indicates that the BGP process local AS is used, because 0 is

not a valid AS number.

The default hold time is 180 seconds.

Network advertisements from routers using the local-as command contain only the AS

specified within that command. When the local-as command is used, the AS specified using

the router bgp command is not advertised.

By default, the local-as value is set to match the configured router BGP value.