Overview
Describes the BGP route types supported for multihoming.
BGP EVPN multihoming supports multiple route types that collectively provide control plane intelligence for both traditional non-fabric and fabric networks. The BGP control plane between targeted ES systems enables scalable, loop-free, all-active Layer 2 redundancy across multiple provider edge devices. BGP EVPN multihoming also supports fast convergence during unplanned link or node failures, delivering deterministic non-stop business communication within the enterprise campus networks.
| Route type |
Description |
|---|---|
| 1 |
Used for network-wide messaging, primarily in multihoming scenarios. It advertises the Ethernet Segment Identifier (ESI) to enable functions like split-horizon filtering, aliasing (load balancing), and fast convergence/mass MAC withdrawal in case of a link failure. Used for network-wide messaging, primarily in multihoming scenarios. It advertises the Ethernet Segment Identifier (ESI) to enable functions like split-horizon filtering, aliasing (load balancing), and fast convergence/mass MAC withdrawal in case of a link failure.
|
| 2 |
MAC-only: can be suppressed through the configuration to reduce route scale. |
| MAC-IPv4: Advertises endpoint reachability information, including both the MAC and IPv4 addresses of hosts connected to the network. It provides MAC/IP address bindings which allow for ARP suppression, reducing broadcast traffic in the network. |
|
| MAC-IPv6: Same for IPv6 hosts reachability. |
|
| 3 |
IMET: Used to set up the flooding tree for Broadcast, Unknown Unicast, and Multicast (BUM) traffic for a specific virtual network interface (VNI). It announces the source's capability and intention to use ingress replication for BUM traffic. |
| 4 |
ES: Advertises the ESI and the originating router's IP address. This route is critical for the auto-discovery of multihomed Ethernet segments and the Designated Forwarder (DF) election process, which prevents duplicate BUM traffic from being sent to multihomed devices. |
| 5 |
IP-Prefix: Advertises internal IP subnets and externally learned routes, typically for inter-subnet forwarding (Layer 3 routing). These routes are essential for efficient routing between different VLANs/subnets within the VXLAN fabric. |
| 6 |
SMET/IGMP-MLD Proxy: Used to distribute the explicit interest of a host or virtual machine in receiving traffic for a specific multicast group (either [*,G] or [S,G]). This allows Ethernet segment switches to build a more selective forwarding list for multicast flows, avoiding unnecessary flooding. |
| 7 |
IGMP/MLD Join Sync: Used in multihoming scenarios to synchronize the Internet Group Management Protocol (IGMP) or Multicast Listener Discovery (MLD) join states between a pair of Ethernet segment switches connected to the same Ethernet Segment Identifier (ESI). This ensures that if the designated forwarder fails, the backup ES switch has the correct multicast state to take over seamlessly. |
| 8 |
IGMP/MLD Leave Sync: Functions similar to Type 7, but for synchronizing IGMP or MLD leave messages. This ensures that a pair of multihomed Ethernet segment switches are aware when a receiver is no longer interested in a multicast stream, allowing for efficient pruning of the multicast forwarding tree. |