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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RFC 4379

Network Working Group                         Kireeti Kompella (Juniper)
Internet Draft                                        Ping Pan (Juniper)
Expiration Date: September 2002                  Nischal Sheth (Juniper)
Network Working Group                      Dave Cooper (Global Crossing)
                                                  George Swallow (Cisco)
                                               Sanjay Wadhwa (Unisphere)
                                                   Ron Bonica (Worldcom)


                Detecting Data Plane Liveliness in MPLS

                    draft-ietf-mpls-lsp-ping-00.txt

Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.

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 describes a simple and efficient mechanism that can be
used to detect data plane failures in MPLS LSPs.  There are two parts to
this document: information carried in an MPLS "echo request" and "echo
reply" for the purposes of fault detection and isolation; and mechanisms
for transporting the echo reply.

Sub-IP ID Summary

(See Abstract above.)

RELATED DOCUMENTS

May be found in the "references" section.



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WHERE DOES IT FIT IN THE PICTURE OF THE SUB-IP WORK

Fits in the MPLS box.

WHY IS IT TARGETED AT THIS WG

MPLS WG is currently looking at MPLS-specific error detection and
recovery mechanisms.  The mechanisms proposed here are for packet-based
MPLS LSPs, which is why the MPLS WG is targeted.

JUSTIFICATION

The WG should consider this document, as it allows network operators to
detect MPLS LSP data plane failures in the network.  This type of
failures have occurred, and are a source of concern to operators
implementing MPLS networks.


1. Introduction

   This document describes a simple and efficient mechanism that can be
   used to detect data plane failures in MPLS LSPs.  There are two parts
   to this document: information carried in an MPLS "echo request" and
   "echo reply"; and mechanisms for transporting the echo reply.  The
   first part aims at providing enough information to check correct
   operation of the data plane, as well as a mechanism to verify the
   data plane against the control plane, and thereby localize faults.
   The second part suggests two methods of reliable reply channels for
   the echo request message, for more robust fault isolation.

   An important consideration in this design is that MPLS echo requests
   follow the same data path that normal MPLS packets would traverse.
   MPLS echo requests are meant primarily to validate the data plane,
   and secondarily to verify the data plane against the control plane.
   Mechanisms to check the control plane are valuable, but are not
   covered in this document.

   To avoid potential Denial of Service attacks, it is recommended to
   regulate the MPLS ping traffic going to the control plane.  A rate
   limiter should be applied to the well-known UDP port defined below.











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2. Motivation

   When an LSP fails to deliver user traffic, the failure cannot always
   be detected by the MPLS control plane.  There is a need to provide a
   tool that would enable users to detect such traffic "black holes" or
   misrouting within a reasonable period of time; and a mechanism to
   isolate faults.

   In this document, we describe a mechanism, termed "MPLS ping", that
   accomplishes these goals.  This mechanism is modeled after the ICMP
   echo request/reply, used by ping and traceroute to detect and
   localize faults in IP networks.  This document also offers some
   alternative methods for replying to MPLS echo requests.

   The basic idea is to test that packets that belong to a particular
   Forwarding Equivalence Class (FEC) actually end their MPLS path on an
   LSR that is an egress for that FEC.  Therefore, an MPLS echo request
   carries information about the FEC whose MPLS path is being verified.
   This echo request is forwarded just like any other packet belonging
   to that FEC.  In "ping" mode (basic connectivity check), the packet
   should reach the end of the path, at which point it is sent to the
   control plane of the egress LSR, which then verifies that it is
   indeed an egress for the FEC.  In "traceroute" mode (fault
   isolation), the packet is sent to the control plane of each transit
   LSR, which performs various checks that it is indeed a transit LSR
   for this path; this LSR also returns further information that helps
   check the control plane against the data plane, i.e., that forwarding
   matches what the routing protocols determined as the path.

   One way these tools can be used is to periodically ping a FEC to
   ensure connectivity.  If the ping fails, one can then initiate a
   traceroute to determine where the fault lies.  One can also
   periodically traceroute FECs to verify that forwarding matches the
   control plane; however, this places a greater burden on transit LSRs
   and thus should be used with caution.
















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3. Packet Format

   An MPLS ping packet is a (possibly labelled) UDP packet with the
   following payload format:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Sequence Number                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      TimeStamp (seconds)                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    TimeStamp (microseconds)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Reply mode  |  Reply flags  |  Return Code  |  Must be zero |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            TLVs ...                           |
      .                                                               .
      .                                                               .
      .                                                               .
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Sequence Number is assigned by the sender of the MPLS echo
   request, and can be used to detect missed replies (for example).

   The TimeStamp is set to the time of day (in seconds and microseconds)
   when the MPLS echo request or reply is sent, and may be used to
   compute delay or round trip time (for example).

   The Reply Mode can take one of the following values:

       Value    Meaning
       -----    -------
           1    Reply via an IPv4 UDP packet
           2    Reply via an IPv4 UDP packet with Router Alert
           3    Reply via the control plane

   Reply Flags are a bit vector with bit 0x1 being the Least Significant
   Bit and bit 0x80 being the Most Significant Bit; the following bits
   are defined:

         Bit    Meaning when set
         ---    ----------------
         0x1    Downstream Mappings desired
         0x2    Upstream direction pinged

   Bit 0x2 is set when the reverse (upstream) direction of a bidirection



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   LSP is being tested.  The details of the procedures in this case will
   be given in a later version.

   The rest of the bits are reserved and must be zero.

   The Return code can take one of the following values:

       Value    Meaning
       -----    -------
           1    Replying router is an egress for the FEC
           2    Replying router has no mapping for the FEC
           3    Replying router is not one of the "Downstream Routers".
           4    Replying router is one of the "Downstream Routers",
                and its mapping for this FEC on the received interface
                is the given label
           5    Replying router is one of the "Downstream Routers",
                but its mapping for this FEC is not the given label

   TLVs (Type-Length-Value tuples) have the following format:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Value                             |
      .                                                               .
      .                                                               .
      .                                                               .
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Types are defined below; Length is the length of the Value field in
   octets.  The Value field depends on the Type; it is zero padded to
   align to a four-octet boundary.

         Type #                           Value Field
         ------                           -----------
              1                      Target FEC Stack
              2                    Downstream Mapping


3.1. Target FEC Stack

   A Target FEC Stack is a list of sub-TLVs.  The number of elements is
   determined by the looking at the sub-TLV length fields.

         Type #       Length              Value Field



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         ------       ------              -----------
              1            5              IPv4 prefix
              2           17              IPv6 prefix
              3           16        RSVP IPv4 Session
              4           52        RSVP IPv6 Session
              5            6            CR-LDP LSP ID
              6           13          VPN IPv4 prefix
              7           25          VPN IPv4 prefix
              8           ??          L2 VPN "prefix"

   Other FEC Stack Types will be defined as needed.

   Note that this TLV defines a stack of FECs, the first FEC element
   corresponding to the top of the label stack, etc.  However, we will
   assume for now that the stack consists of just one element.  Also,
   only the formats for FEC Types 1-5 will be described in this version.


3.1.1. IPv4 Prefix

   The value consists of four octets of an IPv4 prefix followed by one
   octet of prefix length in bits.  The IPv4 prefix is in network byte
   order.


3.1.2. IPv6 Prefix

   The value consists of sixteen octets of an IPv6 prefix followed by
   one octet of prefix length in bits.  The IPv6 prefix is in network
   byte order.


3.1.3. RSVP IPv4 Session

   The value has the format below.  The value fields are taken from
   [RFC3209, sections 4.6.1.1 and 4.6.2.1]

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 IPv4 tunnel end point address                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  LSP ID       |     Tunnel ID                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Extended Tunnel ID                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   IPv4 tunnel sender address                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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3.1.4. RSVP IPv6 Session

   The value has the format below.  The value fields are taken from
   [RFC3209, sections 4.6.1.2 and 4.6.2.2]

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 IPv6 tunnel end point address                 |
      |                                                               |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  LSP ID       |     Tunnel ID                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Extended Tunnel ID                      |
      |                                                               |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   IPv6 tunnel sender address                  |
      |                                                               |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


3.1.5. CR-LDP LSP ID

   The value consists of the LSPID of the LSP being pinged.  An LSPID is
   a four octet IPv4 address (a local address on the head end LSR) plus
   a two octet identifier that is unique for each LSP that starts on an
   LSR.


3.2. Downstream Mapping

   The Downstream Mapping is an optional TLV in an echo request.  The
   Length is 4 + 4*N, where N is the number of Downstream Labels.  The
   Value of a Downstream Mapping has the following format:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Downstream IPv4 Router ID                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Downstream Label                |    Protocol   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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      .                                                               .
      .                                                               .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Downstream Label                |    Protocol   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   'Protocol' is taken from the following table:

         Protocol #        Signaling Protocol
         ----------        ------------------
                  0        Unknown
                  1        Static
                  2        BGP
                  3        LDP
                  4        RSVP-TE
                  5        CR-LDP

   The notion of "downstream router" should be explained.  Consider an
   LSR X.  If a packet with outermost label L and TTL n>1 arrived at X
   on interface I, X must be able to compute which LSRs could receive
   the packet with TTL=n, and what label they would see.  (It is outside
   the scope of this document to specify how this computation may be
   done.)  The set of these LSRs are the downstream routers (and their
   corresponding labels) for X with respect to L.

   The case where X is the LSR originating the echo request is a special
   case.  X needs to figure out what LSRs would receive a labelled
   packet with TTL=1 when X tries to send a packet to the FEC Stack that
   is being pinged.


4. Theory of Operation

4.1. MPLS Echo Request

   An MPLS echo request is a labeled UDP packet sent to the well-known
   port for MPLS ping [UDP port # 3503 assigned by IANA], with
   destination IP address set to the ALL-ROUTERS multicast address
   (224.0.0.2).  The source IP address is set to a routable address of
   the sender; the source port identifies the sending process.  The IP
   TTL in the UDP packet is set to 1.

   An MPLS echo request MUST have a FEC Stack TLV.  Also, the Reply Mode
   must be set to the desired reply mode; the Return Code is set to zero
   and ignored on receipt.

   In "ping" mode (end-to-end connectivity check), the TTL in the



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   outermost label is set to 255.

   In "traceroute" mode (fault isolation mode), the TTL is set
   successively to 1, 2, ....

   In the "traceroute" mode, the echo request SHOULD contain one or more
   Downstream Mapping TLVs.  For TTL=1, all the downstream routers (and
   corresponding labels) for the sender with respect to the FEC Stack
   being pinged SHOULD be sent in the echo request.  For n>1, the
   Downstream Mapping TLVs from the echo reply for TTL=(n-1) are copied
   to the echo request with TTL=n.


4.2. MPLS Echo Reply

   An MPLS echo reply is a UDP packet.  It MUST ONLY be sent in response
   to an MPLS echo request.  The source IP address is the Router ID of
   the replier; the source port is the well-known UDP port for MPLS
   ping.  The destination IP address and UDP port are copied from the
   source IP address and UDP port of the echo request.  The IP TTL is
   set to 255.  If the Reply Mode in the echo request is "Reply via an
   IPv4 UDP packet with Router Alert", then the IP header MUST contain
   the Router Alert IP option.

   The format of the echo reply is the same as the echo request.  The
   Sequence Number is copied from the echo request; the TimeStamp is set
   to the time-of-day that the echo request is received (note that this
   information is most useful if the time-of-day clocks on the requestor
   and the replier are synchronized).  The FEC Stack TLV from the echo
   request is copied to the reply.

   The replier MUST fill in the Return Code.  This is set based on
   whether the replier has a mapping for the FEC, and whether it is an
   egress for that FEC.  Note that 'having a mapping' for an RSVP FEC
   means that the replier is a transit LSR for the RSVP LSP defined by
   the FEC.

   If the echo request contains a Downstream Mapping TLV, the replier
   MUST further check whether its Router ID matches one of the
   Downstream IPv4 Router IDs; and if so, whether the given Downstream
   Label is in fact the label that the replier sent as its mapping for
   the FEC.  For an RSVP FEC, the downstream label is the label that the
   replier sent in its Resv message.  The result of these checks are
   captured in the Return Code.

   If the flag requesting Downstream Mapping TLVs is set in the Reply
   Flags, the replier SHOULD compute its downstream routers and
   corresponding labels for the incoming label, and add Downstream



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   Mapping TLVs for each one to the echo reply it sends back.


4.3. Non-compliant Routers

   If the egress for the FEC Stack being pinged does not support MPLS
   ping, then no reply will be sent, resulting in possible "false
   negatives".  If in "traceroute" mode, a transit LSR does not support
   MPLS ping, then no reply will be forthcoming from that LSR for some
   TTL, say n.  The LSR originating the echo request SHOULD try sending
   the echo request with TTL=n+1, n+2, ..., n+k in the hope that some
   transit LSR further downstream may support MPLS echo requests and
   reply.  In such a case, the echo request for TTL>n MUST NOT have
   Downstream Mapping TLVs, until a reply is received with a Downstream
   Mapping.


5. Reliable Reply Path

   One of the issues that are faced with MPLS ping is to distinguish
   between a failure in the forward path (the MPLS path being 'pinged')
   and a failure in the return path.  Note that this problem exists with
   vanilla IP ping as well.  In the case of MPLS ping, it is assumed
   that the IP control and data planes are reliable.  However, it could
   be that the forwarding in the return path is via an MPLS LSP.

   In this specification, we give two solutions for this problem.  One
   is to set the Router Alert option in the MPLS echo reply.  When a
   router sees this option, it MUST forward the packet as an IP packet.
   Note that this may not work if some transit LSR does not support MPLS
   ping.

   Another option is to send the echo reply via the control plane.  At
   present, this is defined only for RSVP-TE LSPs, and described below.

   These options are controlled by the ingress LSR, using the Reply Mode
   in the MPLS echo request packet.


5.1. RSVP-TE Extension

   To test an LSP's liveliness, an ingress LSR sends MPLS echo requests
   over the LSP being tested.  When an egress LSR receives the message,
   it needs to acknowledge the ingress LSR by sending an LSP_ECHO object
   in a RSVP Resv message. The object has the following format:

         Class = LSP_ECHO  (use form 11bbbbbb for compatibility)




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         C-Type = 1

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Sequence Number                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      TimeStamp (seconds)                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    TimeStamp (microseconds)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        UDP Source Port        |  Return Code  | Must be zero  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Sequence Number is copied from the Sequence Number of the echo
   request.  The TimeStamp is set to the time the echo request is
   received.  The UDP Source Port is copied from the UDP source port of
   the MPLS echo request.  The FEC is implied by the Session and the
   Sender Template Objects.


5.2. Operation

   For the sake of brevity in the context of this document by "the
   control plane" we mean "the RSVP-TE component of the control plane".

   Consider an LSP between an ingress LSR and an egress LSR spanning
   multiple LSR hops.


5.3. Procedures at the ingress LSR

   One must ensure before setting the Reply Mode to "reply via the
   control plane" that the egress LSR supports this feature.

   The ingress LSR, say X, selects a unique UDP source port for its MPLS
   ping.  X also sets the FEC Stack TLV Type to RSVP IPv4 (IPv6), and
   copies the SESSION and SENDER_TEMPLATE into the appropriate fields of
   the value field.  Finally, X sets the Reply Mode to "reply via the
   control plane".

   If X does not receive an Resv message from the egress LSR that
   contains an LSP_ECHO object within some period of time, it declares
   the LSP as "down".  At this point, the ingress LSR may apply the
   necessary procedures to fix the LSP.  These may include generating a
   message to network management, tearing-down and re-building the LSP,
   and/or rerouting user traffic to a backup LSP.




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   To test an LSP that carries non-IP traffic, before injecting ICMP and
   MPLS ping messages into the LSP, the IPv4 Explicit NULL label should
   be prepended to such messages. The ingress and egress LSR's must
   follow the procedures defined in [LABEL-STACKING].


5.4. Procedures at the egress LSR

   When the egress LSR receives an MPLS ping message, it follows the
   procedures given above.  If the Reply Mode is set to "Reply via the
   control plane", the LSR can, based on the RSVP SESSION and
   SENDER_TEMPLATE objects carried in the MPLS ping message, find the
   corresponding LSP in its RSVP-TE database.  The LSR then checks to
   see if the Resv message for this LSP contains an LSP_ECHO object with
   the same source UDP port value.  If not, the LSR adds or updates the
   LSP_ECHO object and refreshes the Resv message.


5.5. Procedures for the intermediate LSR's

   At intermediate LSRs, normal RSVP processing procedures will cause
   the LSP_ECHO object to be forwarded as RSVP messages are refreshed.

   At the LSR's that support MPLS ping the Resv messages that carry the
   LSP_ECHO object MUST be delivered upstream immediately.

   Note that an intermediate LSR using RSVP refresh reduction [RSVP-
   REFRESH], the new or changed LSP_ECHO object will cause the LSR to
   classify the RSVP message as a trigger message.


6. Security Considerations

   The security  considerations pertaining to the original RSVP protocol
   remain relevant.
















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7. Intellectual Property Considerations

   Juniper Networks, Inc. is seeking patent protection on technology
   described in this Internet-Draft. If technology in this Internet-
   Draft is adopted as a standard, Juniper Networks agrees to license,
   on reasonable and non-discriminatory terms, any patent rights it
   obtains covering such technology to the extent necessary to comply
   with the standard.


8. Acknowledgments

   This is the outcome of many discussions among many people, that also
   include Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa Gan,
   Brook Bailey and Eric Rosen.


9. References

   [ICMP] J. Postel, "Internet Control Message Protocol", RFC792.

   [RSVP] R. Braden, Ed., et al, "Resource ReSerVation protocol (RSVP)
   -- version 1 functional specification," RFC2205.

   [RSVP-TE] D. Awduche, et al, "RSVP-TE: Extensions to RSVP for LSP
   tunnels" Internet Draft.

   [LABEL-STACKING] E. Rosen, et al, "MPLS Label Stack Encoding",
   RFC3032.

   [RSVP-REFRESH] L. Berger, et al, "RSVP Refresh Overhead Reduction
   Extensions", RFC2961.

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
















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10. Author Information


Kireeti Kompella
Ping Pan
Nischal Sheth
Juniper Networks
1194 N.Mathilda Ave
Sunnyvale, CA 94089
e-mail: kireeti@juniper.net
e-mail: pingpan@juniper.net
e-mail: nsheth@juniper.net
phone: 408.745.2000

Dave Cooper
Global Crossing
960 Hamlin Court
Sunnyvale, CA 94089
email: dcooper@gblx.net
phone: 916.415.0437

George Swallow
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA 01824
e-mail:  swallow@cisco.com
phone: 978.244.8143

Sanjay Wadhwa
Unisphere Networks, Inc.
10 Technology Park Drive
Westford, MA 01886-3146
email: swadhwa@unispherenetworks.com
phone: 978.589.0697

Ronald P. Bonica
WorldCom
22001 Loudoun County Pkwy
Ashburn, Virginia, 20147
email: ronald.p.bonica@wcom.com
phone: 703.886.1681










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