Path Engineering for Bit Index Explicit Replication (BIER-TE)
draft-ietf-bier-te-arch-06
Network Working Group T. Eckert, Ed.
Internet-Draft Futurewei
Intended status: Standards Track G. Cauchie
Expires: August 22, 2020 Bouygues Telecom
M. Menth
University of Tuebingen
February 19, 2020
Path Engineering for Bit Index Explicit Replication (BIER-TE)
draft-ietf-bier-te-arch-06
Abstract
This memo introduces per-packet stateless strict and loose path
engineered replication and forwarding for Bit Index Explicit
Replication packets (RFC8279). This is called BIER-TE.
BIER-TE leverages RFC8279 and extends it with a new semantic for bits
in the bitstring. BIER-TE can leverage BIER forwarding engines with
little or no changes.
In BIER, the BitPositions (BP) of the packets bitstring indicate BIER
Forwarding Egress Routers (BFER), and hop-by-hop forwarding uses a
Routing Underlay such as an IGP.
In BIER-TE, BitPositions indicate adjacencies. The BIFT of each BFR
are only populated with BPs that are adjacent to the BFR in the BIER-
TE topology. The BIER-TE topology can consist of layer 2 or remote
(route) adjacencies. The BFR then replicates and forwards BIER
packets to those adjacencies. This results in the aforementioned
strict and loose path forwarding.
BIER-TE can co-exist with BIER forwarding in the same domain, for
example by using separate sub-domains. In the absence of routed
adjacencies, BIER-TE does not require a BIER routing underlay, and
can then be operated without requiring an IGP routing protocol.
BIER-TE operates without explicit in-network tree-building and
carries the multicast distribution tree in the packet header. It can
therefore be a good fit to support multicast path steering in Segment
Routing (SR) networks.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Eckert, et al. Expires August 22, 2020 [Page 1]
Internet-Draft BIER-TE ARCH February 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. BIER-TE and Traffic Engineering . . . . . . . . . . . . . 4
1.2. Basic Examples . . . . . . . . . . . . . . . . . . . . . 5
1.3. BIER-TE Topology and adjacencies . . . . . . . . . . . . 8
1.4. Comparison with BIER . . . . . . . . . . . . . . . . . . 9
1.5. Requirements Language . . . . . . . . . . . . . . . . . . 9
2. Components . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1. The Multicast Flow Overlay . . . . . . . . . . . . . . . 10
2.2. The BIER-TE Controller . . . . . . . . . . . . . . . . . 10
2.2.1. Assignment of BitPositions to adjacencies of the
network topology . . . . . . . . . . . . . . . . . . 11
2.2.2. Changes in the network topology . . . . . . . . . . . 11
2.2.3. Set up per-multicast flow BIER-TE state . . . . . . . 11
2.2.4. Link/Node Failures and Recovery . . . . . . . . . . . 12
2.3. The BIER-TE Forwarding Layer . . . . . . . . . . . . . . 12
2.4. The Routing Underlay . . . . . . . . . . . . . . . . . . 12
3. BIER-TE Forwarding . . . . . . . . . . . . . . . . . . . . . 12
3.1. The Bit Index Forwarding Table (BIFT) . . . . . . . . . . 12
3.2. Adjacency Types . . . . . . . . . . . . . . . . . . . . . 14
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