draft-ietf-ccamp-tracereq-02.txt   draft-ietf-ccamp-tracereq-03.txt 
Internet Draft R. Bonica Internet Draft R. Bonica
Expiration Date: October 2003 MCI Category: Informational MCI
K. Kompella Expiration Date: November 2003 K. Kompella
Juniper Networks Juniper Networks
D. Meyer D. Meyer
Sprint Sprint
April 2003 May 2003
Tracing Requirements for Generic Tunnels Tracing Requirements for Generic Tunnels
draft-ietf-ccamp-tracereq-02 draft-ietf-ccamp-tracereq-03
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC-2026. all provisions of Section 10 of RFC-2026.
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Abstract Abstract
This document specifies requirements for a generic route-tracing This document specifies requirements for a generic route-tracing
application. It also specifies requirements for a protocol that will application. It also specifies requirements for a protocol that will
support the generic route-tracing application. Network operators will support that application. Network operators will use the generic
use the generic route-tracing application to verify proper operation route-tracing application to verify proper operation of the IP
of the IP forwarding plane. They also use the application to discover forwarding plane. They will also use the application to discover
details regarding tunnels that support IP forwarding. details regarding tunnels that support IP forwarding.
The generic route-tracing application, specified herein, supports a
superset of the functionality that "traceroute" currently offers.
Like traceroute, the generic route-tracing application can discover
the forwarding path between two interfaces that are contained by an
IP network. Unlike traceroute, this application can reveal details
regarding tunnels that support the IP forwarding path.
Bonica, Kompella, Meyer [Page 1]
1. Introduction 1. Introduction
IP networks utilize several tunneling technologies. Although these IP networks utilize several tunneling technologies. Although these
tunneling technologies provide operators with many useful features, tunneling technologies provide operators with many useful features,
they also present management challenges. Network operators require a they also present management challenges. Network operators require a
generic route-tracing application that they can use to verify the generic route-tracing application that they can use to verify the
correct operation of the IP forwarding plane. As multiple tunneling correct operation of the IP forwarding plane. The generic route-
technologies support the IP forwarding plane, the generic route-
tracing application must be capable of detecting tunnels and tracing application must be capable of detecting tunnels and
revealing tunnel details. The application also must be useful in revealing tunnel details. The application also must be useful in
diagnosing tunnel faults. diagnosing tunnel faults.
Implementors also require a new protocol that will support the Implementors also require a new protocol that will support the
generic-route tracing application. This document specifies generic-route tracing application. This document specifies
requirements for that protocol. It specifies requirements, primarily, requirements for that protocol. It specifies requirements, primarily,
by detailing the desired capabilities of the generic route-tracing by detailing the desired capabilities of the generic route-tracing
application. A particular version of generic route-tracing application. A particular version of generic route-tracing
application may implement some subset of the desired capabilities. It application may implement some subset of the desired capabilities. It
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capabilities when designing the new protocol. capabilities when designing the new protocol.
This document also specifies a few protocol requirements, stated as This document also specifies a few protocol requirements, stated as
such. These requirements are driven by desired characteristics of the such. These requirements are driven by desired characteristics of the
generic route-tracing application. Whenever a protocol requirement is generic route-tracing application. Whenever a protocol requirement is
stated, it is mapped to desired characteristic of the route-tracing stated, it is mapped to desired characteristic of the route-tracing
application. application.
2. Review of Existing Functionality 2. Review of Existing Functionality
Currently, network operators use "traceroute" to identify the path Currently, network operators use "traceroute" to trace through the
toward any destination in an IP network. Section 3.4 of [RFC-2151] forwarding path of an IP network. Section 3.4 of [RFC-2151] provides
provides a thorough description of traceroute. Although traceroute a thorough description of traceroute. Although traceroute is very
is very reliable and very widely deployed, it is deficient with reliable and very widely deployed, it is deficient with regard to
regard to tunnel tracing. tunnel tracing.
Depending upon tunnel type, traceroute may display an entire tunnel 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 as a single IP hop, or it may display the tunnel as a collection of
hops, without indicating that they are part of a tunnel. IP hops, without indicating that they are part of a tunnel.
For example, assume that engineers deploy IP tunnels in an IP For example, assume that engineers deploy an IP tunnel in an IP
network. Assume also that they configure a tunnel so that the head- network. Assume also that they configure the tunnel so that the
end router does not copy the TTL value from the inner IP header to ingress router does not copy the TTL value from the inner IP header
outer IP header. Instead, the head-end router always sets the outer to outer IP header. Instead, the ingress router always sets the
TTL value to its maximum permitted value. When engineers trace outer TTL value to its maximum permitted value. When engineers trace
routes through the network, traceroute will always display the tunnel through the network, traceroute will always display the tunnel as a
as a single IP hop, hiding all components except the tail-end single IP hop, hiding all components except the egress interface.
interface.
Now assume that engineers deploy MPLS in an IP network. Assume also Bonica, Kompella, Meyer [Page 2]
that engineers configure an MPLS LSP so that the ingress router Now assume that engineers deploy an MPLS LSP in an IP network.
propagates the TTL value from the IP header to the MPLS header. When Assume also that engineers configure the MPLS LSP so that the ingress
engineers trace routes through the network, traceroute will display router propagates the TTL value from the IP header to the MPLS
the LSP as a series of IP hops, without indicating that they are part header. When engineers trace through the network, traceroute will
of a tunnel. display the LSP as a series of IP hops, without indicating that they
are part of a tunnel.
3. Application Requirements 3. Application Requirements
Network operators require a new route-tracing application. The new Network operators require a new route-tracing application. The new
application must provide all functionality that traceroute currently application must support all functionality that traceroute currently
provides. It also must provide enhanced tunnel tracing capabilities. offers. It also must provide enhanced tunnel tracing capabilities.
The following list provides specific requirements for the new route- The following list provides specific requirements for the new route-
tracing application: tracing application:
1) Support the notion of a security token as part of the tunnel 1) Support the notion of a security token as part of the tunnel
trace request. The security token identifies the tracer's trace request. The security token identifies the tracer's
privileges in tracing tunnels. Network elements will use this privileges in tracing tunnels. Network elements will use this
security token to determine whether or not to return the requested security token to determine whether or not to return the requested
information to the tracer. In particular, appropriate privileges information to the tracer. In particular, appropriate privileges
are required for items (2), (3), (6), (8), (10), (13), and (14). are required for items (2), (3), (6), (8), (10), (13), and (14).
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Justification: Operators may need to discover network forwarding Justification: Operators may need to discover network forwarding
details, while concealing those details from unauthorized parties. details, while concealing those details from unauthorized parties.
2) Support in-line traces. An in-line trace reveals the path 2) Support in-line traces. An in-line trace reveals the path
between the host upon which the route-tracing application executes between the host upon which the route-tracing application executes
and any interface in an IP network. and any interface in an IP network.
Justification: Operators need to discover how the network would Justification: Operators need to discover how the network would
forward a datagram between any two IP interfaces. forward a datagram between any two IP interfaces.
3) Support third party traces. A third party trace reveals the 3) Support third-party traces. A third-party trace reveals the
path between any two points in an IP network. The application path between any two points in an IP network. The application
that initiates a third party trace need not execute upon a host or that initiates a third-party trace need not execute upon a host or
router that is part of the traced path. Unlike existing solutions router that is part of the traced path. Unlike existing solutions
[RFC-2151] [RFC-2925], the application will not rely upon IP [RFC-2151] [RFC-2925], the application will not rely upon IP
options or require access to the SNMP agent in order to support options or require access to the SNMP agent in order to support
third-party traces. third-party traces.
Justification: Operators need to discover how the network would Justification: Operators need to discover how the network would
forward a datagram between any two IP interfaces. forward a datagram between any two IP interfaces.
4) Support partial traces through broken paths or tunnels. 4) Support partial traces through broken paths or tunnels.
Bonica, Kompella, Meyer [Page 3]
Justification: Operators need to identify the root cause of Justification: Operators need to identify the root cause of
forwarding plane failures. forwarding plane failures.
5) When tracing through a tunnel, either as part of an in-line 5) When tracing through a tunnel, either as part of an in-line
trace or a third party trace, display the tunnel either as a 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 single IP hop or in detail. The user's request determines how the
application displays tunnels, subject to the user having application displays tunnels, subject to the user having
permission to do this. permission to do this.
Justification: As they discover IP forwarding details, operators Justification: As they discover IP forwarding details, operators
may need to reveal or mask tunneling details. may need to reveal or mask tunneling details.
6) When displaying a tunnel in detail, include the tunnel type 6) When displaying a tunnel in detail, include the tunnel type
(e.g., GRE, MPLS), the tunnel name (if applicable), the tunnel (e.g., GRE, MPLS), the tunnel name (if applicable), the tunnel
identifier (if applicable) and tunnel endpoint addresses. Also, identifier (if applicable) and tunnel endpoint addresses. Also,
include tunnel components and round trip delay across each include tunnel components and round trip delay across each
component. component.
Justification: As they discover IP forwarding details, operators Justification: As they discover IP forwarding details, operators
may need to reveal tunneling details. may need to reveal tunneling details.
7) Support the following tunneling technologies: GRE, MPLS, IPSEC, 7) Support the following tunneling technologies: GRE, MPLS, IPSEC,
GMPLS, IP-in-IP, L2TP. Be easily extensible to suppport new tunnel GMPLS, IP-in-IP, L2TP. Be easily extensible to support new tunnel
technologies. technologies.
Justification: Operators will use the generic route-tracing Justification: Operators will use the generic route-tracing
application to discover how an IP network forwards datagrams. As application to discover how an IP network forwards datagrams. As
many tunnel types may support the IP network, the generic route- many tunnel types may support the IP network, the generic route-
tracing application must detect and reveal details concerning tracing application must detect and reveal details concerning
multiple tunnel types. multiple tunnel types.
8) Trace through nested, heterogeneous tunnels (e.g., IP-in-IP 8) Trace through nested, heterogeneous tunnels (e.g., IP-in-IP
over MPLS). over MPLS).
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concerning nested, heterogeneous tunnels. concerning nested, heterogeneous tunnels.
9) At the users request, trace through the forwarding plane, the 9) At the users request, trace through the forwarding plane, the
control plane or both. control plane or both.
Justification: Operators need to identify the root cause of Justification: Operators need to identify the root cause of
forwarding plane failu res. Control plane information is sometimes forwarding plane failu res. Control plane information is sometimes
useful in determining the cause of forwarding plane failure. useful in determining the cause of forwarding plane failure.
10) Support control plane tracing for all tunnel types. When 10) 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. Bonica, Kompella, Meyer [Page 4]
tracing through the control plane, the hop ingress device reports
hop details. The hop ingress device is the device that originates
the hop.
Justification: Control plane information is available regarding Justification: Control plane information is available regarding
all tunnel types. all tunnel types.
11) Support tracing through forwarding plane for all tunnel types 11) Support tracing through forwarding plane for all tunnel types
that implement TTL decrement (or some similar mechanism). When that implement TTL decrement (or some similar mechanism). When
tracing through the forwarding plane, the device at the tail-end tracing through the forwarding plane, the hop egress device
of a hop reports hop details. reports hop details. The hop egress devices is the device that
terminates the hop.
Justification: Forwarding plane information may not be available Justification: Forwarding plane information may not be available
regarding tunnels that do not support TTL decrement. regarding tunnels that do not support TTL decrement.
12) Support tracing through the forwarding plane for all tunnel 12) Support tracing through the forwarding plane for all tunnel
types that implement TTL decrement, regardless of whether the types that implement TTL decrement, regardless of whether the
tunnel engages in TTL propagation. (That is, support tunnel tunnel engages in TTL propagation. (That is, support tunnel
tracing regardless of whether the TTL value is copied from an tracing regardless of whether the TTL value is copied from an
inner header to an outer header at tunnel ingress). inner header to an outer header at tunnel ingress).
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Justification: MTU information is sometimes useful in identifying Justification: MTU information is sometimes useful in identifying
the root cause of forwarding plane failures. the root cause of forwarding plane failures.
14) When tracing through the forwarding plane, display the MTU 14) When tracing through the forwarding plane, display the MTU
associated with each hop in the reverse direction. associated with each hop in the reverse direction.
Justification: MTU information is sometimes useful in identifying Justification: MTU information is sometimes useful in identifying
the root cause of forwarding plane failures. the root cause of forwarding plane failures.
15) Support partial traces through paths containing devices that
do not provide protocol support for generic route tracing. When
the application encounters such a device, it should inform the
user and attempt to descover details regarding the next interface
downstream.
Justification: The application must provide useful information
even if the supporting protocol is not universally deployed.
Bonica, Kompella, Meyer [Page 5]
4. Protocol Requirements 4. Protocol Requirements
Implementors require a new protocol that supports the generic route- Implementors require a new protocol that supports the generic route-
tracing application. This protocol reveals the path between two tracing application. This protocol reveals the path between two
points in an IP network. When access policy permits, the protocol points in an IP network. When access policy permits, the protocol
also reveals tunnel details. also reveals tunnel details.
4.1. Information Requirements 4.1. Information Requirements
The protocol consists of probes and probe responses. Each probe The protocol consists of probes and probe responses. Each probe
elicits exactly one response. Each response represents a hop that elicits exactly one response. Each response represents a hop that
connects the head-end of the traced path to the tail-end of the that contributes to the path between two interfaces. A hop can be
traced path. A hop can be either a top-level IP hop or lower-level either a top-level IP hop or lower-level hop that is contained by a
hop that is contained by a tunnel. tunnel.
Justification: Because the generic route-tracing application must Justification: Because the generic route-tracing application must
trace through broken paths, the required protocol must use a separate trace through broken paths, the required protocol must use a separate
response message to deliver details regarding each hop. The protocol response message to deliver details regarding each hop. The protocol
must use a separate probe to elicit each response because the must use a separate probe to elicit each response because the
alternative approach, using the single probe with the IP Router Alert alternative approach, using the single probe with the IP Router Alert
Option, is unacceptable. Many network forward datagrams that specify Option, is unacceptable. Many network forward datagrams that specify
IP options differently than they would forward datagrams that do not IP options differently than they would forward datagrams that do not
specify IP options. specify IP options.
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Justification: Because the probe/response scheme described above is Justification: Because the probe/response scheme described above is
stateless, a stateless transport is required. Candidate transports stateless, a stateless transport is required. Candidate transports
included UDP over IP, IP and ICMP. ICMP was disqualified because included UDP over IP, IP and ICMP. ICMP was disqualified because
carrying MPLS information in an ICMP datagram would constitute a carrying MPLS information in an ICMP datagram would constitute a
layer violation. IP was disqualified in order to conserve protocol layer violation. IP was disqualified in order to conserve protocol
identifiers. identifiers.
4.3. Stateless Protocol 4.3. Stateless Protocol
The protocol must be stateless. That is, no node should have to The protocol must be stateless. That is, nodes should not have to
maintain state between successive traceroute messages. maintain state between successive traceroute messages.
Justification: Statelessness is required to support scaling and to Justification: Statelessness is required to support scaling and to
prevent denial of service attacks. prevent denial of service attacks.
Bonica, Kompella, Meyer [Page 6]
4.4. Routing Requirements 4.4. Routing Requirements
The device that hosts the route-tracing application must maintain an 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 ingress of the traced path. It must also maintain an
IP route to the head-end of each tunnel for which it is requesting IP route to the ingress of each tunnel for which it is requesting
tunnel details. The device that hosts the tunnel tracing application tunnel details. The device that hosts the tunnel tracing application
need not maintain a route to any other device that supports the need not maintain a route to any other device that supports the
traced path. traced path.
All of the devices to which the route-tracing application must All of the devices to which the route-tracing application must
maintain a route must maintain a route back to the route-tracing maintain a route must maintain a route back to the route-tracing
application. application.
In order for the protocol to provide tunnel details, all devices In order for the protocol to provide tunnel details, all devices
contained by a tunnel must maintain an IP route to the tunnel contained by a tunnel must maintain an IP route to the tunnel
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Justification: The protocol must be sufficiently robust to operate Justification: The protocol must be sufficiently robust to operate
when tunnel interior devices do not maintain a route back to the when tunnel interior devices do not maintain a route back to the
device that hosts the route tracing application. device that hosts the route tracing application.
5. Security Considerations 5. Security Considerations
A configurable access control policy determines the degree to which A configurable access control policy determines the degree to which
features described herein are delivered. The access control policy features described herein are delivered. The access control policy
requires user identification and authorization. requires user identification and authorization.
As stated above, the new protocol must not introduce security holes The new protocol must not introduce security holes nor consume
nor consume excessive resources (e.g., CPU, bandwidth). It also must excessive resources (e.g., CPU, bandwidth). It also must not be
not be exploitable by those launching DoS attacks or replaying exploitable by those launching DoS attacks or replaying messages.
messages.
6. Informative References 6. Informative References
[RFC-2151], Kessler, G., Shepard, S., A Primer On Internet and TCP/IP [RFC-2151], Kessler, G., Shepard, S., A Primer On Internet and TCP/IP
Tools and Ut ilities, RFC 2151, Hill Associates, Inc., June 1997 Tools and Ut ilities, RFC 2151, Hill Associates, Inc., June 1997
[RFC-2925], White, K., "Definitions of Managed Objects for Remote [RFC-2925], White, K., "Definitions of Managed Objects for Remote
Ping, Traceroute, and Lookup Operations", RFC 2925, September, 2000. Ping, Traceroute, and Lookup Operations", RFC 2925, September, 2000.
Bonica, Kompella, Meyer [Page 7]
7. Acknowledgements 7. Acknowledgements
Thanks to Randy Bush and Steve Bellovin for their comments. Thanks to Randy Bush and Steve Bellovin for their comments.
8. Author's Addresses 8. Authors' Addresses
Ronald P. Bonica Ronald P. Bonica
MCI MCI
22001 Loudoun County Pkwy 22001 Loudoun County Pkwy
Ashburn, Virginia, 20147 Ashburn, Virginia, 20147
Phone: 703 886 1681 Email: ronald.p.bonica@mci.com
Email: rbonica@mci.net
Kireeti Kompella Kireeti Kompella
Juniper Networks, Inc. Juniper Networks, Inc.
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, California 94089 Sunnyvale, California 94089
Email: kireeti@juniper.net Email: kireeti@juniper.net
Dave Myers David Meyer
Email: dmm@sprint.net Email: dmm@maoz.com
9. Full Copyright Statement 9. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
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copyrights defined in the Internet Standards process must be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than followed, or as required to translate it into languages other than
English. English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
Bonica, Kompella, Meyer [Page 8]
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Bonica, Kompella, Meyer [Page 9]
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