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Carrier Grade Minimalist Multicast (CGM2) using Bit Index Explicit Replication (BIER) with Recursive BitString Structure (RBS) Addresses

Document Type Replaced Internet-Draft (individual)
Expired & archived
Authors Toerless Eckert , Bing Xu
Last updated 2022-08-13 (Latest revision 2022-02-09)
Replaced by draft-eckert-bier-rbs
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Replaced by draft-eckert-bier-rbs
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


This memo introduces the architecture of a multicast architecture derived from BIER-TE, which this memo calls Carrier Grade Minimalist Multicast (CGM2). It reduces limitations and complexities of BIER-TE by replacing the representation of the in-packet-header delivery tree of packets through a "flat" BitString of adjacencies with a hierarchical structure of BFR-local BitStrings called the Recursive BitString Structure (RBS) Address. Benefits of CGM2 with RBS addresses include smaller/fewer BIFT in BFR, less complexity for the network architect and in the CGM2 controller (compared to a BIER-TE controller) and fewer packet copies to reach a larger set of BFER. The additional cost of forwarding with RBS addresses is a slightly more complex processing of the RBS address in BFR compared to a flat BitString and the novel per-hop rewrite of the RBS address as opposed to bit-reset rewrite in BIER/BIER-TE. CGM2 can support the traditional deployment model of BIER/BIER-TE with the BIER/BIER-TE domain terminating at service provider PE routers as BFIR/BFER, but it is also the intention of this document to expand CGM2 domains all the way into hosts, and therefore eliminating the need for an IP Multicast flow overlay, further reducing the complexity of Multicast services using CGM2. Note that this is not fully detailed in this version of the document. This document does not specify an encapsulation for CGM2/RBS addresses. It could use existing encapsulations such as [RFC8296], but also other encapsulations such as IPv6 extension headers.


Toerless Eckert
Bing Xu

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)