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can be received by the ASBR-PEs (or PEs). Route targets configured on the PEs in different ASs do not have
such requirements.
Configuring inter-AS option B
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 must configure MPLS LDP
between ASBRs.
•
Change the next hop on an ASBR. With this method, MPLS LDP is not required between ASBRs.
The device supports only the second method. Therefore, MP-EBGP routes 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 hop to a local address, use the
peer
{
ip-address
|
group-name
}
next-hop-local
command. For more information about the command, see
Layer 3—IP Routing Configuration Guide
.
To configure inter-AS option B on ASBR PEs:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view for the
interface connecting to the
remote ASBR-PE.
interface
interface-type
interface-number
N/A
3.
Configure the IP address of
the interface.
ip address
ip-address
{
mask
|
mask-length
}
N/A
4.
Return to system view.
quit
N/A
5.
Enter BGP view.
bgp
as-number
N/A
6.
Enter BGP-VPNv4 subaddress
family view.
ipv4-family vpnv4
N/A
7.
Disable route target based
filtering of VPNv4 routes.
undo policy vpn-target
By default, PE filters received
VPNv4 routes by route targets.
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 need to 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 route target-based filtering.
In the inter-AS option B solution, for the same VPN, the route targets for the VPN instances on the PEs in
different ASs must match.
Configuring inter-AS option C
To configure inter-AS option C, perform proper configurations on PEs and ASBR PEs, and configure
routing policies on the ASBR PEs.
Configuring the PEs
You must establish ordinary IBGP peer relationship between PEs and ASBR PEs in an AS and MP-EBGP
peer relationship between PEs of different ASs.
