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
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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 no-esi-label
service-carving
mode auto
lag 1
no shutdown
*A:PE1>config>redundancy>evpn-multi-homing# info
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boot-timer 120
es-activation-timer 10
*A:PE1>config>service>vpls# info
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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
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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 no-esi-label
service-carving
lag 2
no shutdown
*A:PE1>config>redundancy>evpn-multi-homing# info
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boot-timer 120
es-activation-timer 10
*A:PE1>config>service>vpls# info
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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 in standards 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 on the 7210 SAS, the ESI label is not used for single-active ESs, and there is no option available to enable the use of the ESI label.
The 7210 SAS ignores the ESI label received from an EVPN peer, which means that BUM traffic sent by the 7210 SAS to a peer DF node is always sent without the ESI label advertised by the DF. On the 7210 SAS-Mxp and 7210 SAS-Sx/S 1/10GE, only multi-homing single-active no-esi-label can be configured.
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
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.