Managing Routing Policy Changes - Cisco 3845 - Security Bundle Router Software Manual
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Chapter 29
Configuring IP Unicast Routing
Switch(config-router)# neighbor 129.213.1.2 remote-as 100
Switch(config-router)# neighbor 175.220.1.2 remote-as 200
Router C:
Switch(config)# router bgp 200
Switch(config-router)# neighbor 175.220.212.1 remote-as 200
Switch(config-router)# neighbor 192.208.10.1 remote-as 300
Router D:
Switch(config)# router bgp 300
Switch(config-router)# neighbor 192.208.10.2 remote-as 200
To verify that BGP peers are running, use the show ip bgp neighbors privileged EXEC command. This
is the output of this command on Router A:
Switch# show ip bgp neighbors
BGP neighbor is 129.213.1.1, remote AS 200, external link
BGP version 4, remote router ID 175.220.212.1
BGP state = established, table version = 3, up for 0:10:59
Last read 0:00:29, hold time is 180, keepalive interval is 60 seconds
Minimum time between advertisement runs is 30 seconds
Received 2828 messages, 0 notifications, 0 in queue
Sent 2826 messages, 0 notifications, 0 in queue
Connections established 11; dropped 10
Anything other than state = established means that the peers are not running. The remote router ID is
the highest IP address on that router (or the highest loopback interface). Each time the table is updated
with new information, the table version number increments. A table version number that continually
increments means that a route is flapping, causing continual routing updates.
For exterior protocols, a reference to an IP network from the network router configuration command
controls only which networks are advertised. This is in contrast to Interior Gateway Protocols (IGPs),
such as EIGRP, which also use the network command to specify where to send updates.
For detailed descriptions of BGP configuration, see the "IP Routing Protocols" part of the Cisco IOS IP
Configuration Guide, Release 12.2. For details about specific commands, see the Cisco IOS IP
Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2. See
Commands in Cisco IOS Release 12.2(52)EY,"
supported by the switch.
Managing Routing Policy Changes
Routing policies for a peer include all the configurations that might affect inbound or outbound routing
table updates. When you have defined two routers as BGP neighbors, they form a BGP connection and
exchange routing information. If you later change a BGP filter, weight, distance, version, or timer, or
make a similar configuration change, you must reset the BGP sessions so that the configuration changes
take effect.
There are two types of reset, hard reset and soft reset. The switch supports a soft reset without any prior
configuration when both BGP peers support the soft route refresh capability, which is advertised in the
OPEN message sent when the peers 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.
•
•
OL-23400-01
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.
for a list of BGP commands that are visible but not
Cisco ME 3800X and 3600X Switch Software Configuration Guide
Configuring BGP
Appendix C, "Unsupported
29-47
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