• Disable BGP synchronization, clear the BGP sessions, and re-examine the IP routing table after the BGP table becomes stable.
In old BGP designs, redistribution between BGP and an IGP was common practice, and these protocols had to be synchronized to ensure proper packet forwarding. In modern designs, redistribution is no longer used and synchronization has to be turned off. However, the default value is to have synchronization enabled.
Routers with BGP synchronization enabled will not be able to install IBGP routes in the routing table or propagate them to other EBGP neighbors.
You can fix this problem by configuring no synchronization in the router BGP configuration.
© 2005, Cisco Systems, Inc. BGP Transit Autonomous Systems 2-65
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