Configuring BGP Restrictions for BGP, on page 1 Information About BGP, on page 1 How to Configure BGP, on page 13 Configuration Examples for BGP, on page 54 Monitoring and Maintaining BGP, on page 56 Feature History for Border Gateway Protocol, on page 57 Restrictions for BGP • When you configure the bgp graceful-restart command , ensure that the BGP hold time is higher than the minimum graceful restart time for the Extended Fast Software Upgrade (xFSU) capable devices. The minimum graceful restart time is specific to a device. A lower hold time value is configurable, however BGP is not supported in an xFSU event.
If a BGP peer sends an unsupported hold timer in the BGP open message, the proposed hold timer is accepted, but BGP is not supported on an xFSU event. • Layer 3 forwarding is delayed until routing tables are populated on a device when you switch on the device or execute the clear ip bgp command. Note The routing tables require around 80 seconds for population. You can use the show ip bgp ip-address command, in privileged EXEC mode, to check whether the routing tables are populated or not.
Information About BGP The Border Gateway Protocol (BGP) is an exterior gateway protocol that is used to set up an interdomain routing system that guarantees the loop-free exchange of routing information between autonomous systems. Autonomous systems are made up of routers that operate under the same administration and that run Interior Gateway Protocols (IGPs), such as RIP or OSPF, within their boundaries and that interconnect by using an Exterior Gateway Protocol (EGP). BGP Version 4 is the standard EGP for interdomain routing in the Internet. The protocol is defined in RFCs 1163, 1267, and 1771. Configuring BGP 1