The num parameter species a local AS number in the range 1 through 4294967295. It has no default. AS numbers 64512 - 65535
are the well-known private BGP4 AS numbers and are not advertised to the Internet community.
Setting the local AS number for VRF instances
The local autonomous system (AS) number identies the AS in which the BGP4 device resides.
You can assign dierent BGP AS numbers for each VRF instance. If you do not assign an AS number, the BGP VRF instances use the
default BGP AS number, as in previous releases.
The local-as command is available under the "global BGP" CLI level and "address- family ipv4 unicast vrf" CLI level.
To set the local as number for a VRF, enter commands such as the following.
device(config-bgp)# address-family ipv4 unicast vrf vrf-name
device(config-bgp)# local-as num
Syntax: [no] local-as num
The num parameter
species a local AS number in the range 1 - 4294967295. It has no default. AS numbers 64512 - 65535 are the
well-known private BGP4 AS numbers and are not advertised to the Internet community.
The conguration takes eect immediately and the BGP VRF instance is reset. All BGP peering within the VRF is reset, and take the new
AS number.
The local AS number for the VRF instance, if congured, is displayed in the show running-cong and show ip bgp cong command
output.
Enter the show ip bgp cong command:
device# show ip bgp config
Current BGP configuration:
router bgp
local-as 100
neighbor 10.10.10.10 remote-as 200
address-family ipv4 unicast
exit-address-family
address-family ipv6 unicast
exit-address-family
address-family ipv4 unicast vrf vrf_a
local-as 300
neighbor 10.111.111.111 remote-as 400
exit-address-family
Adding a loopback interface
You can
congure the device to use a loopback interface instead of a specic port or virtual routing interface to communicate with a
BGP4 neighbor. A loopback interface adds stability to the network by working around route ap problems that can occur due to unstable
links between the device and neighbors.
Loopback interfaces are always up, regardless of the states of physical interfaces. Loopback interfaces are especially useful for IBGP
neighbors (neighbors in the same AS) that are multiple hops away from the device. When you congure a BGP4 neighbor on the device,
you can specify whether the device uses the loopback interface to communicate with the neighbor. As long as a path exists between the
device and the neighbor, BGP4 information can be exchanged. The BGP4 session is not associated with a specic link, but is instead
associated with the virtual interfaces.
Basic conguration tasks required for BGP4
FastIron Ethernet Switch Layer 3 Routing
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