IP Fragmentation Considered Fragile
draft-ietf-intarea-frag-fragile-05

Document Type Active Internet-Draft (intarea WG)
Last updated 2019-01-11
Replaces draft-bonica-intarea-frag-fragile
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Internet Area WG                                               R. Bonica
Internet-Draft                                          Juniper Networks
Intended status: Best Current Practice                          F. Baker
Expires: July 15, 2019                                      Unaffiliated
                                                               G. Huston
                                                                   APNIC
                                                               R. Hinden
                                                    Check Point Software
                                                                O. Troan
                                                                   Cisco
                                                                 F. Gont
                                                            SI6 Networks
                                                        January 11, 2019

                  IP Fragmentation Considered Fragile
                   draft-ietf-intarea-frag-fragile-05

Abstract

   This document describes IP fragmentation and explains how it reduces
   the reliability of Internet communication.

   This document also proposes alternatives to IP fragmentation and
   provides recommendations for developers and network operators.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   This Internet-Draft will expire on July 15, 2019.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Bonica, et al.            Expires July 15, 2019                 [Page 1]
Internet-Draft          IP Fragmentation Fragile            January 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  IP Fragmentation  . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Links, Paths, MTU and PMTU  . . . . . . . . . . . . . . .   3
     2.2.  Fragmentation Procedures  . . . . . . . . . . . . . . . .   5
     2.3.  Upper-Layer Reliance on IP Fragmentation  . . . . . . . .   6
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   7
   4.  Reduced Reliability . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Policy-Based Routing  . . . . . . . . . . . . . . . . . .   7
     4.2.  Network Address Translation (NAT) . . . . . . . . . . . .   8
     4.3.  Stateless Firewalls . . . . . . . . . . . . . . . . . . .   8
     4.4.  Stateless Load Balancers  . . . . . . . . . . . . . . . .   9
     4.5.  IPv4 Reassembly Errors at High Data Rates . . . . . . . .  10
     4.6.  Security Vulnerabilities  . . . . . . . . . . . . . . . .  10
     4.7.  Blackholing Due to ICMP Loss  . . . . . . . . . . . . . .  11
       4.7.1.  Transient Loss  . . . . . . . . . . . . . . . . . . .  12
       4.7.2.  Incorrect Implementation of Security Policy . . . . .  12
       4.7.3.  Persistent Loss Caused By Anycast . . . . . . . . . .  13
     4.8.  Blackholing Due To Filtering  . . . . . . . . . . . . . .  13
   5.  Alternatives to IP Fragmentation  . . . . . . . . . . . . . .  14
     5.1.  Transport Layer Solutions . . . . . . . . . . . . . . . .  14
     5.2.  Application Layer Solutions . . . . . . . . . . . . . . .  15
   6.  Applications That Rely on IPv6 Fragmentation  . . . . . . . .  16
     6.1.  DNS . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
     6.2.  OSPF  . . . . . . . . . . . . . . . . . . . . . . . . . .  17
     6.3.  Packet-in-Packet Encapsulations . . . . . . . . . . . . .  17
     6.4.  Licklider Transmission Protocol (LTP) . . . . . . . . . .  17
   7.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .  18
     7.1.  For Application and Protocol Developers . . . . . . . . .  18
     7.2.  For System Developers . . . . . . . . . . . . . . . . . .  18
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