Path Maximum Transmission Unit Discovery (PMTUD) for Bit Index Explicit Replication (BIER) Layer
draft-ietf-bier-path-mtu-discovery-08
BIER Working Group G. Mirsky
Internet-Draft ZTE Corp.
Intended status: Standards Track T. Przygienda
Expires: November 22, 2020 Juniper Networks
A. Dolganow
Individual contributor
May 21, 2020
Path Maximum Transmission Unit Discovery (PMTUD) for Bit Index Explicit
Replication (BIER) Layer
draft-ietf-bier-path-mtu-discovery-08
Abstract
This document describes Path Maximum Transmission Unit Discovery
(PMTUD) in Bit Indexed Explicit Replication (BIER) layer.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. PMTUD Mechanism for BIER . . . . . . . . . . . . . . . . . . 4
3.1. Data TLV for BIER Ping . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
In packet switched networks, when a host seeks to transmit data to a
target destination, the data is transmitted as a set of packets. In
many cases, it is more efficient to use the largest size packets that
are less than or equal to the least Maximum Transmission Unit (MTU)
for any forwarding device along the routed path to the IP destination
for these packets. Such "least MTU" is known as Path MTU (PMTU).
Fragmentation or packet drop, silent or not, may occur on hops along
the route where an MTU is smaller than the size of the datagram. To
avoid any of the listed above behaviors, the packet source must find
the value of the least MTU, i.e. PMTU, that will be encountered along
the route that a set of packets will follow to reach the given set of
destinations. Such MTU determination along a specific path is
referred to as path MTU discovery (PMTUD).
[RFC8279] introduces and explains Bit Index Explicit Replication
(BIER) architecture and how it supports forwarding of multicast data
packets. A BIER domain consists of Bit-Forwarding Routers (BFRs)
that are uniquely identified by their respective BFR-ids. An ingress
border router (acting as a Bit Forwarding Ingress Router (BFIR))
inserts a Forwarding Bit Mask (F-BM) into a packet. Each targeted
egress node (referred to as a Bit Forwarding Egress Router (BFER)) is
represented by Bit Mask Position (BMP) in the BMS. A transit or
intermediate BIER node, referred to as BFR, forwards BIER
encapsulated packets to BFERs, identified by respective BMPs,
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