IP Multicast Forwarding (PIM-DM)

IP Multicast traffic within the BGP auto-peering network is forwarded using PIM-Dense Mode (PIM-DM) configured on ExtremeXOS devices. BGP auto-peering automatically enables PIM-DM globally for IPv4 and IPv6, as well as on each VLAN interface. Access VLANS must be configured and IPMC forwarding should be enabled to enable PIM-DM.

IPv4 Multicast sources and receivers from the access side are switched in the cloud. AutoBGP VLANs have only v6 interfaces, so PIM-DM is enabled in v6 mode on the network side. IPv6 network interfaces are added to the egress list of IPv4 cache entries so that IPv4 traffic reaches auto-peering devices. PIM-DM works on flood and prune mechanism so interfaces that have v6 and v4 neighbors or IGMP group joins receive the multicast traffic. IPv6 PIM-enabled interfaces process the IPv4 Multicast traffic and replicate it to the Multicast-enabled outgoing interfaces.

All the PIM-DM functionalities are supported in the auto-peering cloud:

Auto-peering Connection with PIM-Spare Mode (SM) Domain

PIM-DM is able to connect with PIM-SM domains present outside of the auto-peering network. ExtremeXOS creates (*,*,RP) cache entries to pull the traffic from the SM domain to the auto-peering domain. The auto-peering network then applies dense behavior to the incoming Multicast traffic. Traffic originating from Dense Mode is carried until it meets a Multicast border router (MBR) node where both auto-peering and PIM-SM interfaces are present. PIM-SM becomes the first-hop router (FHR) for the incoming stream and generates a register message to RP.

Auto-peering Connection with PIM-DM Domain

PIM-DM interfaces switch and receive Multicast streams with non-auto-peering DM interfaces.

Existing PIM-SM Domains within the Auto-peering Network

SM and DM domains cannot overlap within the auto-peering network. Since auto-peering interfaces are configured with DM, existing SM configuration may not function as expected.