266Step Command Remarks1. Enter system view. system-view N/A2. Enter BGP view. bgp as-number N/A3. Enter BGP-VPNv4 subaddressfamily view. ipv4-family vpnv4 N/A4. Enable the exchange ofBGP-VPNv4 routinginformation with a peer.peer { group-name | ip-address }enable N/A5. Specify a BGP peer or peergroup as the UPE.peer { group-name | ip-address }upeThe default route of a VPN instancecan be advertised to only a BGPpeer or peer group that is UPE.6. Advertise routes to the UPE.• (Approach 1) Advertise adefault VPN route:peer { group-name |ip-address }default-route-advertisevpn-instancevpn-instance-name• (Approach 2) Advertise routespermitted by a routing policy:peer { group-name |ip-address } upe route-policyroute-policy-name exportUse either approach.By default, BGP does not advertiseroutes to a VPNv4 peer.With the peerdefault-route-advertisevpn-instance commandconfigured, the SPE alwaysadvertises a default route using thelocal address as the next hopaddress to the UPE, regardless ofwhether the default route is presentin the local routing table or not.Configuring an OSPF sham linkThe sham link is considered an OSPF intra-area route. It is used to make sure that the VPN traffic istransmitted 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-bitmasks. Besides, the loopback interfaces must be bound to the VPN instances and be advertised throughBGP.Before you configure an OSPF sham link, complete the following tasks:• Configure basic MPLS L3VPN (OSPF is used between PEs and CEs)• Configure OSPF in the LAN where CEs resideConfiguring a loopback interfaceStep Command Remarks1. Enter system view. system-view N/A2. Create a loopback interfaceand enter loopback interfaceview.interface loopbackinterface-number N/A3. Bind the loopback interface toa VPN instance.ip binding vpn-instancevpn-instance-nameBy default, an interface isassociated with no VPN instance.
