draft-shore-icmp-aup-01.txt

Network Working Group                                           M. Shore
Internet-Draft                                      No Mountain Software
Expires: January 14, 2013                                   C. Pignataro
                                                     Cisco Systems, Inc.
                                                           July 13, 2012


         An Acceptable Use Policy for New ICMP Types and Codes
                        draft-shore-icmp-aup-01

Abstract

   Some recent proposals to add new Internet Control Message Protocol
   (ICMP) types and/or codes have highlighted a need to describe
   policies for when adding new features to ICMP is desirable and when
   it is not.  In this document we provide a basic description of ICMP's
   role in the IP stack and some guidelines for the future.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on January 14, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Acceptable use policy  . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Classification of existing message types . . . . . . . . .  4
   3.  ICMP's role in the internet  . . . . . . . . . . . . . . . . .  8
   4.  Management vs control  . . . . . . . . . . . . . . . . . . . .  9
   5.  Security considerations  . . . . . . . . . . . . . . . . . . . 11
   6.  IANA considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
   8.  Informative references . . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15




































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1.  Introduction

   There have been some recent proposals to add new message types and
   codes to ICMP [RFC792].  Not all of these proposal are consistent
   with the design and intent of ICMP, and so we attempt to lay out a
   description of when (and when not) to move functionality into ICMP.

   This document is the result of discussions within the IETF Operations
   area "ICMP Society," and concerns expressed by the OPS area
   leadership.









































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2.  Acceptable use policy

   In this document we describe a proposed acceptable use policy for new
   ICMP message types and codes, and provide some background behind the
   proposed policy.

   In summary, we propose that any future message types added to ICMP
   should be limited to two broad categories:

   1.  to inform a datagram's originator that a forwarding plane anomaly
       has been encountered downstream.  The datagram originator must be
       able to determine whether or not the datagram was discarded by
       examining the ICMP message

   2.  to discover on-link routers and hosts

2.1.  Classification of existing message types

   This section provides a rough breakdown of existing message types
   according to the taxonomy described in Section 2.

      IPV4 forwarding plane anomaly reporting



      3:   Destination unreachable

      4:   Source quench (deprecated)

      5:   Redirect

      6:   Alternate host address

      11   Time exceeded

      12   Parameter problem

      31:   Datagram converson error

      32:   Mobile host redirect

      41:   ICMP messages utilized by experimental mobility protocols,
         such as Seamoby

      IPv4 router or host discovery






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      0:   Echo reply

      8:   Echo

      9:   Router advertisement

      10:   Router solicitation

      13:   Timestamp

      14:   Timestamp reply

      15:   Information request

      16:   Information reply

      17:   Address mask request

      18:   Address mask reply

      30:   Traceroute

      33:   IPv6 Where-Are-You

      34:   IPv6 I-Am-Here

      35:   Mobile registration request

      36:   Mobile registration reply

      37:   Domain name request

      38:   Domain name reply

      39:   SKIP

      40:   Photuris

      41:   ICMP messages utilized by experimental mobility protocols,
         such as Seamoby

      IPv6 forwarding plane anomaly reporting









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      1:   Destination unreachable

      2:   Packet too big

      3:   Time exceeded

      4:   Parameter problem

      137:   Redirect message

      150:   ICMP messages utilized by experimental mobility protocols,
         such as Seamoby

      IPv6 router or host discovery



      128:   Echo request

      129:   Echo reply

      130:   Multicast listener query

      131:   Multicast listener report

      132:   Multicast listener done

      133:   Router solicitation

      134:   Router advertisement

      135:   Neighbor solicitation

      136:   Neighbor advertisement

      138:   Router renumbering

      139:   ICMP node information query

      140:   ICMP node information response

      141:   Inverse neighbor discovery solicitation message

      142:   Inverse neighbor discovery advertisement message







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      143:   Version 2 multicast listener report

      144:   Home agent address discovery request message

      145:   Home agent address discovery reply message

      146:   Mobile prefix solicitation

      147:   Mobile prefix advertisement

      148:   Certification path solicitation message

      149:   Certification path advertisement message

      150:   ICMP messages utilized by experimental mobility protocols,
         such as Seamoby

      151:   Multicast router advertisement

      152:   Multicast router solicitation

      153:   Multicast router termination

      154:   FMIPv6 messages

      155:   RPL control message

























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3.  ICMP's role in the internet

   ICMP was originally intended to be a mechanism for routers to report
   error conditions back to hosts [RFC792].  The word "control" in the
   protocol name did not describe ICMP's function (i.e. it did not
   "control" the internet), but rather that it was used to communicate
   about the control functions in the internet.  For example, even
   though ICMP included a redirect message type, it was and is not used
   as a routing protocol.

   Most likely because of the presence of the word "control" in the
   protocol name, ICMP is often understood to be a control protocol,
   borrowing some terminology from circuit networks and the PSTN.  That
   is probably not correct - it might be more correct to describe it as
   being closer to a management plane protocol, given the data plane/
   control plane/ management plane taxonomy often used in describing
   telephony protocols.  However, layering in IP networks is not very
   clean and there's often some intermingling of function that can tend
   to lead to confusion about where to place new functions.

   In following sections we provide some background on the differences
   between control and management traffic.





























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4.  Management vs control

   In this section we attempt to draw a distinction between management
   and control planes, acknowledging in advance that this may serve to
   muddle the differences even further.  Ultimately the difference may
   not matter that much for the purpose of creating a policy for adding
   new types to ICMP, but because that terminology has become
   ubiquitous, even in IETF discussions, and because it has come up in
   prior discussions of ICMP policies, it seems worthwhile to take a few
   paragraph to describe what they are and what they are not.

   The terms "management plane" and "control plane" came into use to
   describe one aspect of layering in telecommunications networks.  It
   is particularly important, in the context of this discussion, to
   understand that "control plane" in telecomm networks almost always
   refers to 'signaling,' or call control and network control
   information.  This includes "call" establishment and teardown, route
   establishment and teardown, requesting QoS or other parameters, and
   so on.

   "Management," on the other hand, tends to fall under the rubric
   "OAM," or "Operations, Administration, and Management." typical
   functions include fault management and performance monitoring
   (Service Level Agreement [SLA] compliance), discovery, etc.

   The correct answer to the question of where ICMP fits into the
   management/control/data taxonomy is that it doesn't, at least not
   neatly.  While some of the message types are unambiguously management
   message (ICMP type 3, or "unreachable" messages), others are less
   clearly identifiable.  For example, the "redirect" (ICMP type 5)
   message can be construed to contain control (in this case, routing)
   information, even though it is in some very real sense an error
   message.

   At this time,

   o  there are many, many other protocols that can be (and are) used
      for control traffic, whether they're routing protocols, telephony
      signaling protocols, QoS protocols, middlebox protocols, AAA
      protocols, etc.

   o  the transport characteristics needed by control traffic can be
      incompatible with the ICMP protocol standard -- for example, they
      may require reliable delivery, very large payloads, or have
      security requirements that cannot be met.

   and because of this we propose that any future message types added to
   ICMP must conform to the policy proposed in Section 2.  ICMP should



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   not be used as a routing or network management protocol.


















































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5.  Security considerations

   This document attempts to describe a high-level policy for adding
   ICMP types and codes.  While special attention must be paid to the
   security implications of any particular new ICMP type or code,
   specific security considerations are outside the scope of this paper.













































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6.  IANA considerations

   There are no actions required by IANA.
















































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7.  Acknowledgments

   This document was originally proposed by, and received substantial
   review and suggestions from, Ron Bonica.















































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8.  Informative references

   [RFC792]  Postel, J., "INTERNET CONTROL MESSAGE PROTOCOL", RFC 792,
             September 1981.















































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Authors' Addresses

   Melinda Shore
   No Mountain Software
   PO Box 16271
   Two Rivers, AK  99716
   US

   Phone: +1 907 322 9522
   Email: melinda.shore@nomountain.net


   Carlos Pignataro
   Cisco Systems, Inc.
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   Email: cpignata@cisc.com
































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