BIER is Bit Indexed Explicit Replication which is a newest proposal for IP Multicast.
Although I say IP Multicast, of course it works on MPLS networks as well.
BIER works by assigning every edge device a Bit Mask position. Then, instead of sending Multicast packet to each destination IP address (Receiver IP address), basically it sets the Bit positions and save the amount of data plane state.
It uses Unicast transport as underlay reachability, and Bit Mask is advertised through IGP control plane.
So, OSPF and IS-IS newly assigned TLVs handle the BitMask to Edge device (BFER – Bit Forwarding Edge Router in BIER terminology) assignment and distribution.
It is in theory can be used not only for multicast but also for Unicast traffic as well.
When we use it, we don’t need to have mLDP, RSVP P2MP LSPs, or PIM in the Core Network (Of course at the Edge, you can still have towards the customer in mVPN scenarios).
So basically, by removing those protocols from the network, in theory, simpler network design you should have. I am saying in theory, because having less protocol doesn’t always mean, having simpler design.
Because we would be throwing the complexity to Continue reading