Single-active multi-homing service model

The following example shows a PE1 configuration that provides single-active multi-homing to CE2, as shown in Figure: Backup PE.

*A:PE1>config>service>system>bgp-evpn# info 
----------------------------------------------
  route-distinguisher 10.1.1.1:0
  ethernet-segment "ESI2" create
    esi 01:12:12:12:12:12:12:12:12:12
    multi-homing single-active
    service-carving
      mode auto 
    lag 1
    no shutdown

*A:PE1>config>redundancy>evpn-multi-homing# info 
----------------------------------------------
    boot-timer 120
    es-activation-timer 10

*A:PE1>config>service>vpls# info 
----------------------------------------------
  description "evpn-mpls-service with single-active multihoming"
  bgp
  bgp-evpn
    evi 10
    mpls
      no shutdown
      auto-bind-tunnel resolution any
  lag 1:1 create 
  exit

The PE2 example configuration for this scenario is as follows.

*A:PE1>config>service>system>bgp-evpn# info 
----------------------------------------------
  route-distinguisher 10.1.1.1:0
  ethernet-segment "ESI2" create
    esi 01:12:12:12:12:12:12:12:12:12
    multi-homing single-active
    service-carving
    lag 2 
    no shutdown

*A:PE1>config>redundancy>evpn-multi-homing# info 
----------------------------------------------
    boot-timer 120
    es-activation-timer 10

*A:PE1>config>service>vpls# info 
----------------------------------------------
  description "evpn-mpls-service with single-active multihoming"
  bgp
  bgp-evpn
    evi 10
    mpls
      no shutdown
      auto-bind-tunnel resolution any
  lag 2:1 create 
  exit

In single-active multi-homing, the non-DF PEs for a specified ESI block unicast and BUM traffic in both directions (upstream and downstream) on the object associated with the ESI. Otherwise, single-active multi-homing is similar to all-active multi-homing with the following differences:

• The ethernet-segment is configured for single-active: service>system>bgp-evpn>eth-seg>multi-homing single-active.

• The advertisement of the ESI-label in an AD per-ESI is optional for single-active ESs. Use the service system bgp-evpn eth-seg multi-homing single-active no-esi-label command to control the ESI label advertisement. By default, the ESI label is also used for single-active ESs.

• For single-active multi-homing, the ES can be associated with a port or lag-id, as shown in Figure: Backup PE, where:

  • port is used for single-active SAP redundancy without the need for LAG

  • lag is used for single-active LAG redundancy

    Note:

    For a LAG configured with single-active homing, the LAG parameters key, system-id, and system-priority must be different on the PEs that are part of the ES.

• For single-active multi-homing, when the PE is non-DF for the service, the SAPs on the ethernet-segment are down and show StandByForMHProtocol as the reason.

• From a service perspective, single-active multi-homing can provide redundancy to CEs (MHD, Multi-Homed Devices) with the following setup:

  • LAG with or without LACP

    In this case, the multi-homed ports on the CE are part of the different LAGs (a LAG per multi-homed PE is used in the CE).

  • regular Ethernet 802.1q/ad ports

    In this case, the multi-homed ports on the CE/network are not part of any LAG.