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In other words, configure VPN instances on PEs and ASBR PEs respectively. The VPN instances on
PEs are used to allow CEs to access the network, and those on ASBR PEs are used to access the
peer ASBR PEs. For more information, see "
In the inter-AS option A solution, for the same VPN, the route targets configured on the PEs must
match those configured on the ASBR-PEs in the same AS to make sure VPN routes sent by the PEs
(or ASBR-PEs) can be received by the ASBR-PEs (or PEs). Route targets configured for VPN
instances on the PEs in different ASs do not have such requirements.
Configuring inter-AS option B
For inter-AS option B, two 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
are 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 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.