BIER

Overview

Bit Indexed Explicit Replication (BIER) offers an architecture for forwarding multicast data packets without the need for multicast trees or for intermediate routers to maintain a per-multicast flow state. BIER information is distributed in the network using the underlay IGP.

A BIER domain is a connected set of bit forwarding routers, each with a unique ID. A BIER domain can be divided into sub-domains for scalability without a linear increase in size of the BIER header. For example, in IS-IS, a BIER sub-domain is an IS-IS multi topology, where ipv4-unicast is a single sub-domain and ipv4-multicast is another sub-domain.

BIER is supported on FP4 network interfaces. BIER is not supported on FP3 or earlier cards, or on access interfaces.

If a chassis has a mix of FP3 and FP4 network ports, BIER is signaled on all FP3 and FP4 interfaces which are part of the IS-IS. 

BIER templates

BIER is configured by creating a BIER template. The BIER template contains the sub-domain to multi-topology mapping and other BIER configurations, such as the bit forwarding router ID and BIER prefix.