Multicast Path MTU
draft-nandy-utkarsh-pim-mcast-path-mtu-00

Document Type Active Internet-Draft (individual)
Authors tathagata nandy  , Utkarsh Srivastava 
Last updated 2021-01-17
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INTERNET-DRAFT                                      Tathagata Nandy
Intended Status: Proposed Standard                  HPE 
                                                    Utkarsh Srivastava
                                                    HPE
Expires: 18 July 2021                               January 18, 2021

                          Multicast Path MTU
        draft-nandy-utkarsh-pim-mcast-path-mtu-00
                
Abstract
   Path MTU discovery (rfc1191) is a standard technique to determine
   the supported MTU between two Internet Protocol (IP) hosts to avoid
   any fragmentation. In a multicast distribution tree, source will
   not know where the receivers are located. So the technique used to
   compute the path MTU for a unicast stream does not work in a
   multicast network.  This document describes a method to discover
   multicast path MTU with the goal to avoid traffic loss. This
   solution also aims to solve the problem of traffic loss in for
   multicast streams because of incorrect MTU setting and no path MTU
   support for multicast networks. 
  
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Tathagata, et al.        Expires 12 June 2021                [Page 1]
Internet-Draft          PIM Multicast Path MTU            December 2020


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document . . . . . . . . . . . . .  3
   3.  Problem Statement . . . . . . . . . . . . . . . . . . . . .  4
   4.  Multicast Path MTU  . . . . . . . . . . . . . . . . . . . .  5
   5.  Security Considerations . . . . . . . . . . . . . . . . . .  6
   6. IANA considerations . . . . . . . . . . . . . . . . . . . .   6
   7. References  . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References . . . . . . . . . . . . . . . .   7
   8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8    
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . .  8

Tathagata, et al.        Expires 12 June 2021                [Page 2]
Internet-Draft          PIM Multicast Path MTU            December 2020


1.  Introduction
   When one IP host has a large amount of data to send to another
   host, the data is transmitted as a series of IP datagrams. It is
   usually preferable that these datagrams be of the largest size that
   does not require fragmentation anywhere along the path from the
   source to the destination.  (For the case against fragmentation,
   see [5].) This datagram size is referred to as the Path MTU (PMTU),
   and it is equal to the minimum of the MTUs of each hop in the path.
   A shortcoming of the current Internet protocol suite is the lack of
   a standard mechanism for a host to discover the PMTU of an
   arbitrary path.  Note: The Path MTU is what in [1] is called the
   "Effective MTU for sending" (EMTU_S). A PMTU is associated with a
   path, which is a particular combination of IP source and
   destination address and perhaps a Type-of-service (TOS).  The
   current practice [1] is to use the lesser of 576 and the first-hop
   MTU as the PMTU for any destination that is not connected to the
   same network or subnet as the source.  In computer networking,
   multicast is group communication where data transmission is
   addressed to a group of destination computers simultaneously.
   Multicast can be one-to-many or many-to-many distribution.
   Multicast should not be confused with physical layer
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