[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03

Internet Draft                                                R. Bonica
Expiration Date: May 2002                                      WorldCom
                                                            K. Kompella
                                                       Juniper Networks
                                                               D. Meyer
                                                          Cisco Systems
                                                          November 2001

                Tracing Requirements for Generic Tunnels
                    draft-bonica-tunneltrace-02.txt


1. Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of [RFC-2026].

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.  Internet-Drafts are draft documents valid for a maximum of
   six months and may be updated, replaced, or obsoleted by other
   documents at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


2. Abstract

   This document specifies requirements for a generic route tracing
   application.  The application must provide all functionality that
   "traceroute" [RFC 2151] currently provides.  It also must provide
   enhanced capabilities with regard to tunnel tracing (e.g., tracing
   through IP-in-IP tunnels, tracing through MPLS LSPs).


3. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC-2119].


4. Introduction

   Currently, the IETF supports the following tunneling technologies:

           Generic Routing Encapsulation (GRE)
           Multiprotocol Label Switching (MPLS)
           IP over Optical (IPO)
           IP Security Protocol (IPSEC)
           IP in IP
           Layer 2 Tunneling Protocol (L2TP)

   Although these tunneling technologies provide operators with many
   useful features, they also present management challenges.  Operators
   require a generic route tracing application that they can use to
   verify tunnel paths and diagnose tunnel faults.

   This document specifies requirements for that generic route tracing
   application.  It also specifies requirements for a protocol that will
   support that application.


5. Review of Existing Functionality

   Currently, network operators use "traceroute" to identify the path
   toward any destination in an IP network.  Section 3.4 of [RFC-2151]
   provides a thorough description of traceroute.  Although traceroute
   is very reliable and very widely deployed, it is deficient with
   regard to tunnel tracing.

   Depending upon tunnel type, traceroute may display an entire tunnel
   as a single IP hop, or it may display a tunnel as a collection of IP
   hops, without indicating that they are part of a tunnel.

   For example, assume that engineers are using IP tunnels in an IP
   network.  Assume also that they configure a tunnel so that the head-
   end router does not copy the TTL value from the inner IP header to
   outer IP header.  Instead, the head-end router always sets the outer
   TTL value to its maximum permitted value.  When engineers trace
   routes through the network, traceroute will always display the tunnel
   as a single IP hop, hiding all components except the tail-end
   interface.

   Now assume that engineers are using MPLS to support an IP network.
   Assume also that engineers configure an MPLS LSP so that the ingress
   router propagates the TTL value from the IP header to the MPLS
   header.  When engineers trace routes through the network, traceroute
   will display the LSP as a series of IP hops, without indicating that
   they are part of a tunnel.



6. Application Requirements

   Network operators require a new route-tracing application.  The new
   application must provide all functionality that traceroute currently
   provides. It also must provide enhanced tunnel tracing capabilities.

   The following list provides specific requirements for the new route-
   tracing application:

      1) Support the notion of a security token as part of the tunnel
      trace request.  The security token identifies the tracer's
      privileges in tracing tunnels.  Network elements will use this
      security token to determine whether or not to return the requested
      information to the tracer.  In particular, appropriate privileges
      are required for items (2), (3), (5), (8), (12), and (13).

      2) Support in-line traces.  An in-line trace reveals the path
      between the host upon which the route-tracing application executes
      and any interface in an IP network.

      3) Support third party traces.  A third party trace reveals the
      path between any two points in an IP network.  The application that
      initiates a third party trace need not execute upon a host or
      router that is part of the traced path.

      4) When tracing through a tunnel, either as part of an in-line
      trace or a third party trace, display the tunnel either as a single
      IP hop or in detail. The user's request determines how the application
      displays tunnels, subject to the user having permission to do this.

      5) When displaying a tunnel in detail, include the tunnel type
      (e.g., GRE, MPLS), the tunnel name (if applicable) and the tunnel
      identifier (if applicable).  Also, include tunnel components and
      round trip delay across each component.

      6) Support the following tunneling technologies: GRE, MPLS, IPSEC,
      IP/O, IP-in-IP, L2TP. Be easily extensible to suppport new tunnel
      technologies.

      7) Trace through nested, heterogeneous tunnels (e.g., IP-in-IP
      over MPLS).

      8) At the users request, trace either through the forwarding
      plane or the control plane.

      9) Support control plane tracing for all tunnel types. When
      tracing through the control plane, the device at the head-end
      of a hop reports hop details.

      10) Support tracing through forwarding plane for all tunnel types
      that implement TTL decrement (or some similar mechanism). When tracing
      through the forwarding plane, the device at the tail-end of a hop
      reports hop details.

      11) Support tracing through the forwarding plane for all tunnel types
      that implement TTL decrement, regardless of whether the tunnel engages
      in TTL propagation. (That is, support tunnel tracing regardless of
      whether the TTL value is copied from an inner header to an outer
      header at tunnel ingress).

      12) When tracing through the control plane, display the MTU
      associated with each hop.

      13) When tracing through the forwarding plane, display the
      MTU associated with each hop in the reverse direction.




7. Protocol Requirements

   Implementers require a new protocol that supports the application
   described above.  This protocol reveals the path between two points
   in an IP network.  When access policy permits, the protocol also
   reveals tunnel details.






7.1. Information Requirements

   The protocol elicits a series of traceResponse messages.  Each
   traceResponse message represents a hop that connects the head-end of
   the traced path to the tail-end of the traced path.  A hop can be
   either a top-level IP hop or lower-level hop that is contained by a
   tunnel.

   The protocol also supports a traceProbe message. Each traceProbe
   message elicits exactly one traceResponse message.


7.2. Transport Layer Requirements

   UDP carries traceProbe and traceResponse messages to their
   destinations.


7.3. Routing Requirements

   The device that hosts the route tracing application must maintain an
   IP route to the head end of the traced path. It must also maintain an
   IP route to the head end of each tunnel for which it is requesting
   tunnel details. The device that hosts the tunnel tracing application
   need not maintain a route to any other device that supports the
   traced path.

   All of the devices mentioned above must maintain an IP route back to
   the device that hosts the route tracing application.

   In order for the protocol to provide tunnel details, all devices
   contained by a tunnel must maintain an IP route to the device that
   hosts the tunnel ingress.


7.4. Maintaining State

   The protocol must be stateless.


8. Security Considerations

   A configurable access control policy determines the degree to which
   features described herein are delivered.  The access control policy
   requires user identification and authorization.

   As stated above, the new protocol must not introduce security holes
   nor consume excessive resources (e.g., CPU, bandwidth).  It also must
   not be exploitable by those launching DoS attacks.











9. References

   [RFC-2026], Bradner, S., "Internet Standards Process Revision 3", RFC
   2026, Harvard University, October 1996.

   [RFC-2119], Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", RFC 2119, Harvard University, March 1997

   [RFC-2151], Kessler, G., Shepard, S., A Primer On Internet and TCP/IP
   Tools and Utilities, RFC 2151, Hill Associates, Inc., June 1997

   [RFC-2434] T. Narten and H. Alvestrand, "Guidelines for Writing an
   IANA Considerations Section in RFCs", RFC 2434, October, 1998.

   [RFC-2637] Hamzeh, K. et. al., "Point-to-Point Tunneling Protocol
   (PPTP)", RFC 2637, July, 1999.


10. Acknowledgements

   Thanks to Randy Bush and Steve Bellovin for their comments.


11. Author's Addresses

      Ronald P. Bonica
      WorldCom
      22001 Loudoun County Pkwy
      Ashburn, Virginia, 20147
      Phone: 703 886 1681
      Email: rbonica@mci.net

      Kireeti Kompella
      Juniper Networks, Inc.
      1194 N. Mathilda Ave.
      Sunnyvale, California 94089
      Email: kireeti@juniper.net

      Dave Myers
      Cisco Systems
      170 Tasman Drive
      San Jose, California 94025
      Email: dmm@cisco.com


12. Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Html markup produced by rfcmarkup 1.129b, available from https://tools.ietf.org/tools/rfcmarkup/