Cisco Systems 3750E manual Type of Reset Advantages Disadvantages, Show ip bgp neighbors, 38-51

Chapter 38 Configuring IP Unicast Routing

Configuring BGP

establish a TCP session. A soft reset allows the dynamic exchange of route refresh requests and routing information between BGP routers and the subsequent re-advertisement of the respective outbound routing table.

•When soft reset generates inbound updates from a neighbor, it is called dynamic inbound soft reset.

•When soft reset sends a set of updates to a neighbor, it is called outbound soft reset.

A soft inbound reset causes the new inbound policy to take effect. A soft outbound reset causes the new local outbound policy to take effect without resetting the BGP session. As a new set of updates is sent during outbound policy reset, a new inbound policy can also take effect.

Table 38-10lists the advantages and disadvantages hard reset and soft reset.

Table 38-10	Advantages and Disadvantages of Hard and Soft Resets
Type of Reset		Advantages	Disadvantages
Hard reset		No memory overhead	The prefixes in the BGP, IP, and FIB tables
			provided by the neighbor are lost. Not
			recommended.
Outbound soft reset		No configuration, no storing of routing table	Does not reset inbound routing table updates.
		updates
Dynamic inbound soft reset		Does not clear the BGP session and cache	Both BGP routers must support the route
		Does not require storing of routing table updates	refresh capability (in Cisco IOS Release 12.1
		and has no memory overhead	and later).

Beginning in privileged EXEC mode, follow these steps to learn if a BGP peer supports the route refresh capability and to reset the BGP session:

	Command	Purpose
Step 1
	show ip bgp neighbors	Display whether a neighbor supports the route refresh capability. When supported,
		this message appears for the router:
		Received route refresh capability from peer.
Step 2
	clear ip bgp {* address	Reset the routing table on the specified connection.
	peer-group-name}	• Enter an asterisk (*) to specify that all connections be reset.
		• Enter an IP address to specify the connection to be reset.
		• Enter a peer group name to reset the peer group.
Step 3
	clear ip bgp {* address	(Optional) Perform an outbound soft reset to reset the inbound routing table on the
	peer-group-name}soft out	specified connection. Use this command if route refresh is supported.
		• Enter an asterisk (*) to specify that all connections be reset.
		• Enter an IP address to specify the connection to be reset.
		• Enter a peer group name to reset the peer group.
Step 4
	show ip bgp	Verify the reset by checking information about the routing table and about BGP
	show ip bgp neighbors	neighbors.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		38-51