During the last Cisco Live in Milan, I met a couple of engineers that are developing a very interesting stateless multicast solution, which should be available in the upcoming IOS releases.
So what is this all about?
As the draft reads, Bit Index Explicit Replication, is an “architecture that provides optimal multicast forwarding through a BIER domain without requiring intermediate routers to maintain any multicast related flow state.”
The major advantage of this solution, is that there is no control-plane that need to keep track of the state of each multicast tree.
In addition, once a user has joined a group via regular IGMP, the join is encoded via a special MPLS label, which is signaled via BGP across the entire BIER domain, in a similar way to how MPLS-VPN labels are exchanged.
While mVPNs will obvious benefit from this, regular IPTV services will still take advantage of the faster joining mechanism provided by the PIM-free core.
> "With BIER, there is no need of tree building from egress to ingress. Further, any addition of new channel or new egress routers can be directly controlled from ingress router. When a new channel is included, the multicast group is mapped to Bit string that includes all egress routers. Ingress router would start sending the new channel and deliver it to all egress routers. As it can be observed, there is no need for static IGMP provisioning in each egress routers whenever a new channel/stream isadded. Instead, it can be controlled from ingress router itself by configuring the new group to Bit Mask mapping on ingress" [router.draft-kumar-bier-use-cases-00]