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NOTE:
In the inter-AS option A solution, for the same VPN, the VPN targets configured on the PEs must match
those configured on the ASBR-PEs in the same AS to make sure that VPN routes sent by the PEs (or
ASBR-PEs) can be received by the ASBR-PEs (or PEs). VPN targets configured on the PEs in different ASs
do not have such requirements.
Configuring inter-AS option B
To configure inter-AS option B on ASBR PEs:
To do…
Use the command…
Remarks
Enter system view
system-view
—
Enter interface view for the
interface connecting to the remote
ASBR-PE
interface
interface-type
interface-number
—
Configure the IP address of the
interface
ip address
ip-address
{
mask
|
mask-length
}
Required
Return to system view
quit
—
Enter BGP view
bgp
as-number
—
Enter BGP-VPNv4 subaddress
family view
ipv4-family vpnv4
—
Disable VPN target filtering for
VPNv4 routes
undo policy vpn-target
Required
By default, PE performs VPN target
filtering of the received VPNv4
routes.
The routes surviving the filtering
will be added to the routing table,
and the others are discarded.
In the inter-AS option B solution, the ASBR PEs must maintain all VPNv4 routing information and advertise
the information to peer ASBR PEs. In this case, the ASBR PEs must receive all VPNv4 routing information
without performing VPN target based filtering.
NOTE:
In the inter-AS option B solution, for the same VPN, the VPN targets for the VPN instances on the PEs in
different ASs must match.
CAUTION:
For inter-AS option B, the following configuration methods are available:
•
Do not change the next hop on an ASBR. With this method, you still need to configure MPLS LDP
between ASBRs.
•
Change the next hop on an ASBR. With this method, MPLS LDP is not required between ASBRs.
The switch supports only the second method. Therefore, MP-eBGP routes will get their next hops changed
by default before being redistributed to MP-iBGP. However, normal eBGP routes to be advertised to iBGP
do not have their next hops changed by default. To change the next hops to local addresses, use the
peer
{
ip-address | group-name }
next-hop-local
command. For information about the command, see
Layer
3—IP Routing Configuration Guide.
