Subject: [Bier] WELCOME!

From: Greg Shepherd <[email-masked]>
Date: Thu, 18 Sep 2014 22:26:31 -0700

Description
There is a need to simplify network operations for multicast services.
Current solutions require a tree-building control plane, which maintains
end-to-end tree state per flow, impacting router state capacity and network
convergence times. Multi-point tree building protocols are often considered
complex to deploy and debug and include mechanics from legacy use-cases
and/or assumptions which may no longer apply to the current deployments.
When multicast services are transiting a provider network through an
overlay, the core network has a choice to either aggregate customer state
into a minimum set of core states resulting in flooding traffic to unwanted
network end-points, or to map per-customer, per-flow tree state directly
into the provider core state amplifying the network-wide state problem.

This BOF intends to discuss a new architecture for the forwarding of
multicast data packets.  The goal is to provide optimal forwarding of
multicast packets through a "multicast domain" without requiring an
explicit tree-building protocol, nor requiring intermediate nodes to
maintain any per-flow state.  This architecture is known as "Bit Index
Explicit Replication" (BIER).  When a multicast data packet enters the
domain, the ingress router determines the set of egress routers to which
the packet needs to be sent.  The ingress router then encapsulates the
packet in a BIER header.  The BIER header contains a bit-string in which
each bit represents exactly one egress router in the domain; to forward the
packet to a given set of egress routers, the bits corresponding to those
routers are set in the BIER header. Elimination of the per-flow state and
the explicit tree-building protocols results in a considerable
simplification.

First IDs will be published over the next few days.

Cheers,
Greg