Configuring Ospf Sham Link; Configuration Prerequisites; Configuring A Loopback Interface - 3Com MSR 50 Series Configuration Manual

1496 C 79: MPLS L3VPN C
HAPTER
Configuring OSPF
Sham Link
Configuration
Prerequisites
Configuring a Loopback
Interface
ONFIGURATION
To do...
Enter system view
Enter BGP view
Enter BGP-VPNv4 subaddress
family view
Enable the exchange of
BGP-VPNv4 routing
information with a peer
Specify a BGP peer or peer
group as the UPE
Specify to advertise default
routes of a VPN instance to a
UPE
With the peer default-route-advertise vpn-instance command configured, the
SPE always advertises a default route using the local address as the next hop
address to the UPE, regardless of whether the default route is present in the local
routing table or not.
n
The default routes of a VPN instance can be advertised to only a BGP peer or
■
peer group that is UPE.
It is not recommended for an SPE to be connected to a CE directly. If an SPE
■
must be directly connected with a CE, the VPN instance on the SPE and that on
the UPE must be configured with different RDs.
The sham link is considered an OSPF intra-area route. It is used to ensure that the
VPN traffic is transmitted over the backbone instead of the backdoor link between
two CEs.
The source and destination addresses of the sham link must be loopback interface
addresses with 32-bit masks. Besides, the loopback interfaces must be bound to
the VPN instances and be advertised through BGP.
Before configuring OSPF sham link, be sure to complete these tasks:
Configuring basic MPLS L3VPN (OSPF is used between PE and CE)
■
Configuring OSPF in the LAN where CEs reside
■
Follow these steps to configure a loopback interface:
To do...
Enter system view
Create a loopback interface
and enter loopback interface
view
Bind the loopback interface to
VPN instance
Use the command...
system-view
bgp as-number
ipv4-family vpnv4
peer { group-name |
ip-address } enable
peer { group-name |
ip-address } upe
peer { group-name |
ip-address }
default-route-advertise
vpn-instance
vpn-instance-name
Use the command...
system-view
interface loopback
interface-number
ip binding vpn-instance
vpn-instance-name
Remarks
-
-
Required
Required
Required
Optional
By default, BGP does not
advertise default routes to a
VPNv4 peer.
Remarks
-
Required
Required
By default, an interface is
associated with no VPN
instance.