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Minimal Configuration
Using the * means that you wish to clear the entire BGP routing table. You
can use the soft syntax so that the router advertises all its routing updates
again and the configuration is not cleared. Using the address syntax instead
of the asterisk, only the network address identified is removed from the BGP
table. The in and out syntaxes are used with the soft syntax to identify that
the triggered updates are to occur either on triggered inbound updates or
outbound updates.
Disabling BGP Synchronization
If all of the routers in your AS are running BGP, then there is no need to have
synchronization turned on between BGP and your IGPs that are running.
When BGP Synchronization is turned on, the router will wait to learn about
internal routes from an IGP instead of advertising routes learned by BGP.
With BGP Synchronization turned off, you can carry fewer IGP learned
routes in the topology table and BGP can converge much more quickly. To
turn off BGP Synchronization, use the following command in BGP Config-
uration mode:
Router1(config-router)# no synchronization
Troubleshooting BGP
The most important part of troubleshooting is verifying the status of the
peering router. When you issue the show ip bgp neighbors command, the
basic troubleshooting information is displayed on the screen. Let's first take
a look at the command syntaxes and then view a problem configuration
where the BGP peers have not synchronized.
2514#show ip bgp ?
A.B.C.D IP prefix <network>/<length>, e.g.,
A.B.C.D Network in the BGP routing table to
cidr-only Display only routes with non-natural
community Display routes matching the communities
community-list Display routes matching the community-
dampened-paths Display paths suppressed due to
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