Internet Draft R. Bonica Expiration Date: October 2003 WorldCom K. Kompella Juniper Networks D. Meyer Sprint April 2003 Tracing Requirements for Generic Tunnels draft-ietf-ccamp-tracereq-01 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. Abstract This document specifies requirements for a generic route-tracing application. It also specifies requirements for a protocol that will support the generic route-tracing application. Network operators will use the generic route-tracing application to verify proper operation of the IP forwarding plane. They also use the generic route-tracing application to discover details regarding tunnels that support IP forwarding. 1. Introduction Currently, the IETF supports several tunneling technologies. 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 the generic route-tracing application. Network operators will use the generic route-tracing application to verify proper operation of the IP forwarding plane. They also use the generic route-tracing application to discover details regarding tunnels that support IP forwarding. 2. 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 deploy 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 deploy MPLS in 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. 3. 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), (9), (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. Unlike existing solutions [RFC-2151] [RFC-2925], the application will not rely upon IP options or require access to the SNMP agent in order to support third-party traces. 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, GMPLS, 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 through the forwarding plane, the control plane or both. 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. 4. 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. 4.1. Information Requirements The protocol consists of probes and probe responses. Each probe elicits exactly one response. Each response 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. 4.2. Transport Layer Requirements UDP carries all protocol messages to their destinations. 4.3. 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 tunnel ingress. 4.4. Stateless Protocol The protocol must be stateless. That is, no node should have to maintain state between successive traceroute messages. 5. 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 or replaying messages. 6. Informative References [RFC-2151], Kessler, G., Shepard, S., A Primer On Internet and TCP/IP Tools and Ut ilities, RFC 2151, Hill Associates, Inc., June 1997 [RFC-2925], White, K., "Definitions of Managed Objects for Remote Ping, Traceroute, and Lookup Operations", RFC 2925, September, 2000. 7. Acknowledgements Thanks to Randy Bush and Steve Bellovin for their comments. 8. Author's Addresses Ronald P. Bonica WorldCom 22001 Loudoun County Pkwy Ashburn, Virginia, 20147 Phone: 703 886 1681 Email: email@example.com Kireeti Kompella Juniper Networks, Inc. 1194 N. Mathilda Ave. Sunnyvale, California 94089 Email: firstname.lastname@example.org Dave Myers Email: email@example.com 9. 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. 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