260
Step Command
Remarks
8.
Configure the PE not to
change the next hop of a
route when advertising it to
the EBGP peer.
peer
{
group-name
|
ip-address
}
next-hop-invariable
Optional.
Required only when RRs are used
to advertise VPNv4 routes, where
the next hop of a route advertised
between RRs cannot be changed.
Configuring the ASBR PEs
In the inter-AS option C solution, an inter-AS LSP is required, and the routes advertised between the
relevant PEs and ASBRs must carry MPLS label information.
An ASBR-PE establishes common IBGP peer relationship with PEs in the same AS, and common EBGP
peer relationship with the peer ASBR PE. All of them exchange labeled IPv4 routes.
The public routes carrying MPLS labels are advertised through MP-BGP. According to RFC 3107
“Carrying Label Information in BGP-4”, the label mapping information for a particular route is
piggybacked in the same BGP update message that is used to distribute the route itself. This capability
is implemented through BGP extended attributes and requires that the BGP peers can handle labeled
IPv4 routes.
To configure an ASBR PE for inter-AS option C:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp
as-number
N/A
3.
Configure each PE in the
same AS as the IBGP peer.
peer
{
group-name
|
ip-address
}
as-number
as-number
N/A
4.
Enable the ASBR PE to
exchange labeled IPv4 routes
with the PEs in the same AS.
peer
{
group-name
|
ip-address
}
label-route-capability
By default, the device does not
advertise labeled routes to the IPv4
peer/peer group.
5.
Configure the ASBR PE to
change the next hop to itself
when advertising routes to PEs
in the same AS.
peer
{
group-name
|
ip-address
}
next-hop-local
By default, a BGP speaker does not
use its address as the next hop
when advertising a route to its
IBGP peer/peer group.
6.
Configure the remote ASBR PE
as the EBGP peer.
peer
{
group-name
|
ip-address
}
as-number
as-number
N/A
7.
Enable the ASBR PE to
exchange labeled IPv4 routes
with the peer ASBR PE.
peer
{
group-name
|
ip-address
}
label-route-capability
By default, the device does not
advertise labeled routes to the IPv4
peer.
8.
Apply a routing policy to the
routes advertised by peer
ASBR PE.
peer
{
group-name
|
ip-address
}
route-policy
route-policy-name
export
By default, no routing policy is
applied to a peer or peer group.
Configuring the routing policy
After you configure and apply a routing policy on an ASBR PE, it:
•
Assigns MPLS labels to the routes received from the PEs in the same AS before advertising them to
the peer ASBR PE.
•
Assigns new MPLS labels to the labeled IPv4 routes to be advertised to the PEs in the same AS.
