Added OpenConfig Support for Static Multicast RPF Routes

[arun-arista]

• (M) release/models/multicast/openconfig-mrib.yang
• (M) release/models/network-instance/openconfig-network-instance.yang
• (M) release/models/policy/openconfig-policy-types.yang

Change Scope

• In the multicast forwarding table (MFIB), each (*,G) and (S, G) route has an expected incoming interface for traffic. This interface is determined through a RPF lookup. To influence this lookup, static RPF routes can be manually configured. These static routes are stored in the MRIB and are used during the RPF check to ensure multicast traffic is forwarded correctly.

• Today it is not possible to set a static RPF route for multicast via OpenConfig. The proposal is to have a container named static-mrib for supporting rpf routes. There exists a static-routes container under protocol. Hence, we would like to have the static-mrib container at the same level, under protocol. At the same time, we had to consider adding another top level container that allows for config/state to globally configure all MRIB routes. Hence we propose another container named routes that goes under static-mrib. This way we will be able to create /network-instances/network-instance/protocols/protocol/static-mrib/{config|state} if needed, in future.

• The pyang output is given below.

module: openconfig-network-instance
  +--rw network-instances
     +--rw network-instance* [name]
        +--rw protocols
           +--rw protocol* [identifier name]
              +--rw static-mrib
                 +--rw routes
                    +--rw route* [prefix]
                       +--rw prefix       -> ../config/prefix
                       +--rw config
                       |  +--rw prefix?   openconfig-inet-types:ip-prefix
                       +--ro state
                       |  +--ro prefix?   openconfig-inet-types:ip-prefix
                       +--rw next-hops
                          +--rw next-hop* [index]
                             +--rw index            -> ../config/index
                             +--rw config
                             |  +--rw index?           string
                             |  +--rw next-hop-addr?   openconfig-inet-types:ip-address
                             |  +--rw preference?      uint8
                             +--ro state
                             |  +--ro index?           string
                             |  +--ro next-hop-addr?   openconfig-inet-types:ip-address
                             |  +--ro preference?      uint8
                             +--rw interface-ref
                                +--rw config
                                |  +--rw interface?      -> /oc-if:interfaces/interface/name
                                |  +--rw subinterface?   -> /oc-if:interfaces/interface[oc-if:name=current()/../interface]/subinterfaces/subinterface/index
                                +--ro state
                                   +--ro interface?      -> /oc-if:interfaces/interface/name
                                   +--ro subinterface?   -> /oc-if:interfaces/interface[oc-if:name=current()/../interface]/subinterfaces/subinterface/index

Platform Implementations

• Arista: https://www.arista.com/en/um-eos/eos-multicast-architecture

• CLI Configuration:

switch(config)# router multicast
switch(config-router-multicast)# ipv4
switch(config-router-multicast-ipv4)# rpf route {source_prefix | source_address | mask}{rpf_interface | rpf_neighbor>} [admin_distance]

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[ghananigans]

Hi! Thank you for submitting this pull request.

For openconfig model changes, we generally ask for at least two vendors' public-facing documentation showing support for this feature. Can we please update this PR with this information?

Also, please review the CLA requirements.

[dplore]

/gcbrun