3com S7906E Instruccion De Instalación

 

1-38 

In the inter-provider VPN option C solution, an inter-provider VPN 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. 

Follow these steps to configure an ASBR PE for inter-provider VPN option C: 

Enter system view 

— 

Enter BGP view 

bgp as-number 

— 

Configure each PE in the same 
AS as the IBGP peer 

peer { group-name | 
ip-address } as-number 
as-number 

Required 

Enable the ASBR PE to 
exchange labeled IPv4 routes 
with the PEs in the same AS 

peer { group-name | 
ip-address } 
label-route-capability 

Required 

By default, the device does not 
advertise labeled routes to the 
IPv4 peer/peer group. 

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 

Required 

By default, a BGP speaker 
does not use its address as the 
next hop when advertising a 
route to its IBGP peer/peer 
group. 

Configure the remote ASBR PE 
as the EBGP peer 

peer { group-name | 
ip-address } as-number 
as-number 

Required 

Enable the ASBR PE to 
exchange labeled IPv4 routes 
with the peer ASBR PE 

peer { group-name | 
ip-address } 
label-route-capability 

Required 

By default, the device does not 
advertise labeled routes to the 
IPv4 peer. 

Apply a routing policy to the 
routes advertised by peer 
ASBR PE 

peer { group-name | 
ip-address } route-policy 
route-policy-name export 

Required 

By default, no routing policy is 
applied to a peer or peer group.

 

After you configure and apply a routing policy on an ASBR PE, it: 

z 

Assigns MPLS labels to the routes received from the PEs in the same AS before advertising them 

to the peer ASBR PE. 

z 

Assigns new MPLS labels to the labeled IPv4 routes to be advertised to the PEs in the same AS. 

Which IPv4 routes are to be assigned with MPLS labels depends on the routing policy. Only routes that 

satisfy the criteria are assigned with labels. All the other routes are still common IPv4 routes.