Configuring EVPN E-LAN over mLDP P2MP Tunnels

An EVPN can carry multicast services. To reduce redundant traffic and conserve bandwidth resources, you can configure EVPN to use an mLDP P2MP tunnel for service transmission.

Usage Scenario

Multicast services, such as IPTV, multimedia conferencing, and Massive Multiplayer Online Role Playing Game (MMORPG) services, are becoming more and more common. As a result, the number of multicast services carried over EVPNs is growing. On the network shown in Figure 1, PE1 is the root node, and PE2 and PE3 are leaf nodes. The access side is the multicast source and the receiver. By default, an EVPN sends multicast service traffic from PE1 to PE2 and PE3 by means of ingress replication. Specifically, PE1 replicates a multicast packet into two copies and sends them to the P. The P then sends one copy to PE2 and the other copy to PE3. For each additional receiver, an additional copy of the multicast packet is sent. This increases the volume of traffic on the link between PE1 and the P, consuming bandwidth resources. To conserve bandwidth resources, you can configure EVPN to use an mLDP P2MP tunnel to transmit multicast services. After the configuration is complete, PE1 sends only one copy of multicast traffic to the P. The P replicates the multicast traffic into copies and sends them to the leaf nodes, reducing the volume of traffic between PE1 and P.

Figure 1 Carrying multicast services over an EVPN

Pre-configuration Tasks

Before configuring EVPN E-LAN over mLDP P2MP tunnels, complete the following tasks:

Configure BD-based EVPN functions over the EVPN.

Procedure

Perform the following steps on the root node:
1. Run system-view
  The system view is displayed.
2. Run evpn vpn-instance vpn-instance-name bd-mode
  The view of a BD-EVPN instance is displayed.
3. Run inclusive-provider-tunnel
  The EVI I-PMSI view is created and displayed.
4. Run root
  The current device is specified as the root node for the multicast EVPN, and the EVI I-PMSI root view is displayed.
5. Run mldp p2mp
  An mLDP P2MP tunnel is specified for the BD-EVPN instance to carry multicast services, and the EVI I-PMSI root mLDP view is displayed.
6. Run root-ip ip-address
  An IP address is specified for the root node of the mLDP P2MP tunnel.
7. Run quit
  Return to the EVI I-PMSI root view.
8. (Optional) Run data-delay-time delay-time
  A hold-off time for the mLDP P2MP tunnel to go Up is set. If you want the mLDP P2MP tunnel to go Up after all leaf nodes are configured, run this command to set a hold-off time for the mLDP P2MP tunnel to go Up.
9. (Optional) Run data-switch disable
  Multicast traffic is disabled from being forwarded through a P2P tunnel if the mLDP P2MP tunnel goes Down.
  
  Before an mLDP P2MP tunnel carries multicast services, you can establish a bypass tunnel to provide mLDP P2MP FRR protection for the primary mLDP P2MP tunnel. The bypass tunnel is a P2P tunnel. If both the primary P2MP tunnel and bypass P2P tunnel go Down, the backup mLDP P2MP tunnel carries multicast services. After the bypass P2P tunnel for the primary mLDP P2MP tunnel goes Up, the P2P tunnel carries multicast services. Because the primary mLDP P2MP tunnel remains Down, a leaf node also receives multicast traffic from the backup mLDP P2MP tunnel. As a result, the leaf node receives and forwards duplicate copies of traffic. To prevent this issue, run this command to disable multicast traffic from being forwarded through a P2P tunnel when the mLDP P2MP tunnel goes Down.
10. Run commit
  The configuration is committed.
Perform the following steps on each leaf node:
1. Run system-view
  The system view is displayed.
2. Run evpn vpn-instance vpn-instance-name bd-mode
  The view of a BD-EVPN instance is displayed.
3. Run inclusive-provider-tunnel
  The EVI I-PMSI view is created and displayed.
4. Run leaf
  The current device is specified as a leaf node for the multicast EVPN.
5. (Optional) Run root-ip root-ip use-next-hop
  In a cross-IGP-area EVPN E-LAN scenario, you must run this command on a leaf node to configure the next hop of a BGP EVPN route as the root node IP address, which is used as the IP address of the ABR on the area border. Without this configuration, EVPN cannot use an mLDP P2MP tunnel for service transmission.
6. Run commit
  The configuration is committed.

Verifying the Configuration of EVPN to Use an mLDP P2MP Tunnel for Service Transmission

Run the display evpn vpn-instance name vpn-instance-name inclusive-provider-tunnel verbose command to check information about EVPN using an mLDP P2MP tunnel for service transmission.