User's Manual

34-8
If the path 2 is wished, which is through EBGP path, we can add two extra AS path numbers into the AS-PATH
messages from SwitchA to SwitchD so as to change the determination SwitchC take to 192.68.11.0/24.
Figure 34-1 Policy routing Configuration
Configuration procedure: (only SwitchA is listed, configurations for other switches are omitted.)
The configuration of Layer 3 switchA:
SwitchA#config
SwitchA(config) #router bgp 1
SwitchA(config-router)#network 192.68.11.0 mask 255.255.255.0
SwitchA(config-router)#neighbor 172.16.20.2 remote-as 3
SwitchA(config-router)#neighbor 172.16.20.2 route-map AddAsNumbers out
SwitchA(config-router)#neighbor 192.68.6.1 remote-as 2
SwitchA(config-router)#exit
SwitchA(config)#route-map AddAsNumbers permit 10
SwitchA(config-route-map)#set as-path prepend 1 1
34.2.4 Troubleshooting
Faq: The routing protocol could not achieve the routing messages study under normal protocol running state
Troubleshooting: check the following errors:
 Each node of route-map should at least has one node set to permit match mode. When the route map
is used in routing messages filtering, the routing messages will be considered not passing the routing
messages filtering if certain routing messages does not pass the filtering of any nodes. When all nodes
are set to deny mode, all routing messages will not pass the filtering in this route-map.
 Items in address prefix list should at least have one item set to permit mode. The deny mode items can
be defined first to quickly remove the unmatched routing messages, however, if all the items are set to
deny mode, any route will not be able to pass the filtering of this address prefix list. We can define a
permit 0.0.0.0/0 le 32 item after several deny mode items are defined so as to permit all other routing
messages to pass through. Only default route will be matched in less-equal 32 not specified.
AS1
VLAN1
192.68.11.1
AS3
AS2
VLAN2
192.68.6.2
VLAN3
172.16.20.1
VLAN2
192.68.6.1
VLAN3
172.16.20.2
VLAN2
1721611
VLAN3
192.68.10.1
VLAN1
192.68.5.2
VLAN1
192.68.5.1
VLAN2
172.16.1.2
SwitchA
SwitchB
SwitchC
SwitchD