Introduction and terminology

EVPN OISM is similar to Multicast VPNs (MVPN) in some aspects, because it does IP multicast routing in VPNs, uses MP-BGP to signal the interest of a PE in a secified multicast group and uses Provider Multicast Service Interface (PMSI) trees among the PEs to send and receive the IP multicast traffic.

However, OISM is simpler than MVPN and allows efficient multicast in networks that integrate Layer 2 and Layer 3; that is, networks where PEs may be attached to different subnets, but could also be attached to the same subnet.

OISM is simpler than MVPN since:

• it does not need to setup shared trees (that need to switchover to shortest path trees)

• it does not require of the MVPN Any Source Multicast (ASM) complex procedures or the Rendezvous Point (RP) function

• it does not require Upstream Multicast Hop (UMH) selection and therefore does not have the UMH potential issues and limitations described in RFC6513 and RFC6514

• multiple PEs can be attached to the same Receiver subnet or Source subnet, which provides full flexibility when designing the multicast network

EVPN OISM is defined by draft-ietf-bess-evpn-irb-mcast and uses the following terminology that is also used in the rest of this section:

BD with IRB

Broadcast Domain with an Integrated Routing and Bridging interface. It is an R-VPLS service in SR OS.

Ordinary BD

refers to an R-VPLS where sources and, or receivers are connected

SBD

Supplementary Broadcast Domain. It is a backhaul R-VPLS that connects the PEs' VPRN services and is configured as an evpn-tunnel interface in the VPRN services. The SBD is mandatory in OISM and is needed to receive multicast traffic on the PEs that are not attached to the source ordinary BD.

EVPN Tenant Domain

refers to the group of BDs and IP-VRFs (VPRNs) of the same tenant

SMET route or EVPN route type 6

the EVPN route that the PEs use to signal interest for a specific multicast group (S ,G) or (*,G)

IIF and OIF

refers to Incoming Interface and Outgoing Interface. A multicast enabled VPRN has Layer 3 IIF and OIFs. A multicast enabled R-VPLS have Layer 2 OIFs.

Upstream and Downstream PEs

refers to the PEs that are connected to sources and receivers respectively