Support for EVPN Single-active Multihoming

[UchihaItachiSama]

Enhancement summary

Add support to allow configuring EVPN single-active multihoming.

• Template enhancement
• Role enhancement
• Documentation enhancement (avd.sh)

CLI

interface Port-Channel1
   switchport mode trunk
   switchport trunk allowed vlan 100-200
   evpn ethernet-segment
      identifier 0123:0123:0123:0123:0123
      route-target import 12:34:12:34:12:34
      redundancy single-active

Which component of AVD is impacted

eos_designs, eos_cli_config_gen

Use case example

Allow user to configure Single-Active multihoming, instead of the default Active-Active multihoming.

Describe the solution you would like

In connected endpoints we already have short_esi key, in addition to that we can have a redundancy_mode key to facilitate configuring active-active or single-active multihoming.

servers:
  server01:
    rack: RackB
    adapters:
      - endpoint_ports: [ E0, E1 ]
        switch_ports: [ Ethernet10, Ethernet10 ]
        switches: [ DC1-SVC3A, DC1-SVC4A ]
        profile: VM_Servers
        port_channel:
          description: PortChanne1
          mode: active
          short_esi: 0303:0202:0101
          redundancy_mode: <single-active | active-active> # default active-active

The same can be used for port_channel_interfaces

port_channel_interfaces:
   < Port-Channel_interface_1 >:
            esi: < EVPN Ethernet Segment Identifier (Type 1 format) >
            rt: < EVPN Route Target for ESI with format xx:xx:xx:xx:xx:xx >
            lacp_id: < LACP ID with format xxxx.xxxx.xxxx >
            redundancy_mode: <single-active | active-active> # default active-active

Describe alternatives you have considered

For eos_cli_config_gen we can use eos_cli under port_channel_interfaces to currently configure single-active mode.

Additional context

https://eos.arista.com/eos-4-26-0f/evpn-single-active-multihoming-preference-based-df-election/

Contributing Guide

• I agree to follow this project's Code of Conduct

[ClausHolbechArista]

We would need two PRs here. One for eos_cli_config_gen and one for eos_designs.
The key in eos_cli_config_gen should be redundancy to match the EOS CLI.

[UchihaItachiSama]

Sure, i'll start working on the eos_cli_config_gen PR first. And keep the key as redundancy to match the EOS CLI.

[UchihaItachiSama]

Created a PR for this. Ready for review.

Have also added designated-forwarder election algorithm but let me know if the DF election change is required to be done via a different issue and PR.