BGP

The "neighbor 127.0.0.1 shutdown" command is used to administratively shut down a BGP neighbor.

The "no neighbor 127.0.0.1 shutdown" command is used to administratively bring the BGP neighbor back up.

The "neighbor next-hop-self" command forces BGP to use its own IP address as the next-hop address for each network that it advertises to its IBGP neighbor, rather than letting the protocol choose the next-hop address to use.

The neighbor update-source option in the neighbor command overrides the default source IP address used for BGP packets. It is necessary to tell the router which IP address to use as the source address for all BGP packets if a loopback interface is to be used instead of the physical interface.