Bridge Virtual Interface (BVI) Over L3VPN
Overview
A Bridge Virtual Interface (BVI) is a virtual interface on a router that acts like a routed interface and is associated with a single bridge domain.
BVI Interface acts as L3 routed interface gateway between bridge domain and L3VPN for traffic exchange. The incoming tagged packet from the L2 sub-interface consolidated itself into a bridge domain. The bridge domain in turn uses the BVI interface to forward the IP traffic to the L3VPN tunnel.
For details on BVI Over 6vPE, see Bridge Virtual Interface (BVI) Over 6vPE. For QoS and ACL configuration for BVIs, see the QoS and ACL over Bridge Virtual Interface (BVI) chapter in Layer 3 guide.
Characteristics of BVI Over L3VPN
| • | The BVI functions as an L3 routed interface for a bridge domain, allowing IP traffic from L2 subinterfaces within the domain to be routed to L3VPN tunnels. |
| • | L2 subinterfaces can be grouped into a bridge domain under the BVI. The BVI aggregates traffic from multiple subinterfaces within the same domain and routes it as required. |
| • | The BVI remains operationally “up” as long as at least one of the subinterfaces in the bridge domain is active. |
| • | BVI supports unicast forwarding of IPv4 traffic between other L3 interfaces and L3VPNs. The BVI can function as a DHCP server or relay for IP address allocation within the network. |
Benefits
| • | The BVI enables seamless communication between L2 bridge domains and L3 networks (e.g., L3VPN), allowing for flexible traffic forwarding between the two layers. |
| • | The BVI serves as an L3 gateway for M-plane traffic, routing it efficiently to L3VPN tunnels for further processing or external routing. |
| • | The BVI remains operational even if only one subinterface is active, ensuring high availability and fault tolerance. |
Limitations
| • | Only Q1 and Q2-based platforms are supported. |
| • | Everything related to ipv6 is not supported. |
| • | L2 sub interfaces support only pop and pop2-tag vlan rewrite translations and for the purpose of bridge-domain support, all member L2 sub interfaces should have relevant rewrite configurations to make sure that all traffic for bridge-domain has uniform encapsulation. |
| • | The dot1q and dot1ad encapsulations with range are not supported for the BVI. |
| • | BVI is a generic L3 interface and allows users to configure any / all existing OcNOS features. However, only a few of these are supported in release 6.6.0 and those are IP address related, VRF, any routing protocol specific commands (OSPF/IS-IS/BGP related), MTU, DHCP server/relay, Ingress/Egress ACL and QoS commands related to marking. |
| • | L3 ACL applied at BVI is only relevant for routed traffic. Bridged traffic between L2 sub-interfaces will not be subjected to L3 ACL configured at BVI. |
| • | No Interface counters are supported for BVI Interface. |
| • | BVI can’t be used as a network interface for all transports in MPLS core network. |
| • | For QoS, only marking related CLIs are supported. Policing, rate limiting, shaping and other queuing features are not supported at BVI level. However, existing QoS scheduling and queuing features on other interfaces can be used in conjunction with the BVI interface. |
| • | QoS features like shaping, queueing, policing, re-marking are not supported on the BVI interface associated to VPLS. |
| • | BUM traffic is not supported. |