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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 4905

Network Working Group                                       Luca Martini
Internet Draft                                           Nasser El-Aawar
Expiration Date: November 2001              Level 3 Communications, LLC.

Steve Vogelsang                                            Daniel Tappan
John Shirron                                               Eric C. Rosen
Toby Smith                                                 Alex Hamilton
Laurel Networks, Inc.                                Jayakumar Jayakumar
                                                     Cisco Systems, Inc.

Vasile Radoaca                                  Dimitri Stratton Vlachos
Nortel Networks                                      Mazu Networks, Inc.

Andrew G. Malis                                       Chris Liljenstolpe
Vinai Sirkay                                            Cable & Wireless
Vivace Networks, Inc.
                                                             Giles Heron
                                                              Gone2 Ltd.

                                                                May 2001


    Encapsulation Methods for Transport of Layer 2 Frames Over MPLS


               draft-martini-l2circuit-encap-mpls-02.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.





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Abstract

   This document describes methods for encapsulating the Protocol Data
   Units (PDUs) of layer 2 protocols such as Frame Relay, ATM AAL5, or
   Ethernet for transport across an MPLS network.


Table of Contents

    1      Specification of Requirements  ..........................   2
    2      Introduction  ...........................................   3
    3      General encapsulation method  ...........................   3
    3.1    The Control Word  .......................................   3
    3.1.1  Setting the sequence number  ............................   4
    3.1.2  Processing the sequence number  .........................   5
    3.2    MTU Requirements  .......................................   5
    3.3    MPLS Shim EXP Bit Values  ...............................   6
    3.4    MPLS Shim S Bit Value  ..................................   6
    3.5    MPLS Shim TTL Values  ...................................   6
    4      Protocol-Specific Details  ..............................   6
    4.1    Frame Relay  ............................................   6
    4.2    ATM  ....................................................   8
    4.2.1  ATM AAL5 CPCS-PDU Mode  .................................   8
    4.2.2  ATM Cell Mode  ..........................................   9
    4.2.3  OAM Cell Support  .......................................  11
    4.2.4  CLP bit to MPLS label stack EXP bit mapping  ............  11
    4.3    Ethernet VLAN  ..........................................  11
    4.4    Ethernet  ...............................................  12
    4.5    HDLC ( Cisco )  .........................................  12
    4.6    PPP  ....................................................  12
    5      Security Considerations  ................................  13
    6      Intellectual Property Disclaimer  .......................  13
    7      References  .............................................  13
    8      Author Information  .....................................  13





1. Specification of Requirements

   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







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2. Introduction

   In an MPLS network, it is possible to carry the Protocol Data Units
   (PDUs) of layer 2 protocols by prepending an MPLS label stack to
   these PDUs. This document specifies the necessary encapsulation
   procedures for accomplishing this. One possible control protocol
   method is described in [1]. QoS related issues are not discussed in
   this draft. For the purpose of this document R1 will be defined as
   the ingress LSR, and R2 as the egress LSR. A layer 2 PDU will be
   received at R1, encapsulated at R1, transported, decapsulated at R2,
   and transmitted out of R2. In a similar way, the "VC label" is
   defined as the label at the bottom of the label stack used to
   transmit the layer 2 PDU.


3. General encapsulation method

   When transporting layer 2 protocols over MPLS it is, in most cases,
   not necessary to transport the layer 2 encapsulation across the MPLS
   network. In most cases the layer 2 header can be stripped at R1, and
   reproduced at R2 with the help of some extra encapsulation
   information, some of which is a priori signaled, and some of which
   may be carried in the control word described below.


3.1. The Control Word

   There are three requirements that may need to be satisfied when
   transporting layer 2 protocols over MPLS:
        -i. Sequentiality may need to be preserved.
       -ii. Small packets may need to be padded in order to be
            transmitted on a medium where the minimum transport unit is
            larger than the actual packet size.
      -iii. Control bits carried in the header of the layer 2 frame may
            need to be transported.

   The control word defined here addresses all three of these
   requirements. For some protocols this word is REQUIRED, and for
   others OPTIONAL.

   In all cases the the egress LSR must be aware of whether the ingress
   LSR will send a control word over a specific virtual circuit.  This
   may be achived by configuration of the LSRs, or by signaling, for
   example as defined in [1].

   The control word is defined as follows:





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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Rsvd  | Flags |    Length     |        Sequence Number        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   In the above diagram the first 4 bits are reserved for future use.
   They MUST be set to 0 when transmitting, and MUST be ignored upon
   receipt.

   The next 4 bits provide space for carrying protocol specific flags.
   These are defined in the protocol-specific details below.

   The next 8 bits provide a length field, which is used as follows:  If
   the packet's length (defined as the length of the layer 2 payload
   plus the length of the control word) is less than 256 bytes, the
   length field MUST be set to the packet's length. Otherwise the length
   field MUST be set to zero. The value of the length field, if non-
   zero, can be used to remove any padding. When the packet reaches the
   service provider's egress LSR, it may be desirable to remove the
   padding before forwarding the packet.

   The next 16 bits provide a sequence number that can be used to
   guarantee ordered packet delivery. The processing of the sequence
   number field is OPTIONAL.

   The sequence number space is a 16 bit, unsigned circular space. The
   sequence number value 0 is used to indicate an unsequenced packet.


3.1.1. Setting the sequence number

   Given a VC label V and a pair of LSRs R1 and R2, where R2 has
   distributed V to R1. If R1 supports packet sequencing then the
   following procedures should be used:

     - the initial packet transmitted to label V MUST use sequence
       number 1
     - subsequent packets MUST increment the sequence number by one for
       each packet
     - when the transmit sequence number reaches the maximum 16 bit
       value (65535) the sequence number MUST wrap to 1

   If the transmitting LSR R1 does not support sequence number
   processing, then the sequence number field in the control word MUST
   be set to 0.





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3.1.2. Processing the sequence number

   If an LSR R2 supports receive sequence number processing, then the
   following procedures should be used:

   When a VC label V is first distributed, the "expected sequence
   number" associated with V MUST be initialized to 1

   When a packet is received with label V the sequence number should be
   processed as follows:
     - if the sequence number on the packet is 0, then the packet passes
       the sequence number check
     - otherwise if the packet sequence number >= the expected sequence
       number and the packet sequence number - the expected sequence
       number < 32768, then the packet is in order.
     - otherwise if the packet sequence number < the expected sequence
       number and the expected sequence number - the packet sequence
       number >= 32768, then the packet is in order.
     - otherwise the packet is out of order.

   If a packet passes the sequence number check, or is in order then, it
   can be delivered immediately. If the packet is in order, then the
   expected sequence number should be set using the algorithm:

   expected_sequence_number := packet_sequence_number + 1 mod 2**16
   if (expected_sequence_number = 0) then expected_sequence_number := 1;

   Packets which are received out of order MAY be dropped or reordered
   at the discretion of the receiver.

   If an LSR R2 does not support receive sequence number processing,
   then the sequence number field MAY be ignored.


3.2. MTU Requirements

   The MPLS network MUST be configured with an MTU that is sufficient to
   transport the largest frame size that will be transported in the
   LSPs.  Note that this is likely to be 12 or more bytes greater than
   the largest frame size.  If a packet length, once it has been
   encapsulated on the ingress LSR, exceeds the LSP MTU, it MUST be
   dropped. If an egress LSR receives a packet on a VC LSP with a
   length, once the label stack and control word have been popped, that
   exceeds the MTU of the destination layer 2 interface, it MUST be
   dropped.






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3.3. MPLS Shim EXP Bit Values

   The ingress LSR, R1, SHOULD set the EXP field of the VC label to the
   same value as the EXP field of the previous label in the stack (if in
   fact a stack of more than one label is imposed at the ingress.)  This
   will ensure that the EXP field will be visible to the egress LSR, R2,
   in the event of the packet having been penultimate hop popped.


3.4. MPLS Shim S Bit Value

   The ingress LSR, R1, MUST set the S bit of the VC label to a value of
   1 to denote that the VC label is at the bottom of the stack.


3.5. MPLS Shim TTL Values

   The ingress LSR, R1, MAY set the TTL field of the VC label to a value
   of 2.


4. Protocol-Specific Details

4.1. Frame Relay

   A Frame Relay PDU is transported without the Frame Relay header or
   the FCS.  The control word is REQUIRED.

   The BECN, FECN, DE and C/R bits are carried across the network in the
   control word. The edge LSRs that implement this document MAY, when
   either adding or removing the encapsulation described herein, change
   the BECN and/or FECN bits from zero to one in order to reflect
   congestion in the MPLS network that is known to the edge LSRs, and
   the D/E bit from zero to one to reflect marking from edge policing of
   the Frame Relay Committed Information Rate. The BECN, FECN, and D/E
   bits MUST NOT be changed from one to zero.

   The following is an example of a Frame Relay packet:













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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               VC Label                | EXP |S|     TTL       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Rsvd  |B|F|D|C|    Length     |        Sequence Number        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Frame Relay PDU                          |
   |                             "                                 |
   |                             "                                 |
   |                             "                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     * B ( BECN ) Bit

       The ingress LSR, R1, MUST copy the BECN field from the incoming
       Frame Relay header into this field. The egress LSR, R2, MUST
       generate a new BECN field based on the value of the B bit.

     * F ( FECN ) Bit

       The ingress LSR, R1, MUST copy the FECN field from the incoming
       Frame Relay header into this field. The egress LSR, R2, MUST
       generate a new FECN field based on the value of the F bit.

     * D ( DE ) Bit

       The ingress LSR, R1, MUST copy the DE field from the incoming
       Frame Relay header into this field. The egress LSR, R2, MUST
       generate a new DE field based on the value of the D bit.

       The ingress LSR, R1, MAY consider the DE bit of the Frame Relay
       header when determining the value to be placed in the EXP field
       of the MPLS label stack.  In a similar way, the egress LSR, R2,
       MAY consider the EXP field of the VC label when queuing the
       packet for egress. Note however that frames from the same VC MUST
       NOT be reordered by the MPLS network.

     * C ( C/R ) Bit

       The ingress LSR, R1, MUST copy the C/R bit from the received
       Frame Relay PDU to the C bit of the control word.  The egress
       LSR, R2, MUST copy the C bit into the output frame.

   The Label, EXP, S, and TTL fields are described in [2].






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4.2. ATM

   Two encapsulations are supported for ATM transport: one for ATM AAL5
   and another for ATM cells.

   The AAL5 CPCS-PDU encapsulation consists of the MPLS label stack, a
   REQUIRED control word, and the AAL5 CPCS-PDU.

   The ATM cell encapsulation consists of an MPLS label stack, an
   OPTIONAL control word, a 4 byte ATM cell header, and the ATM cell
   payload.


4.2.1. ATM AAL5 CPCS-PDU Mode

   In ATM AAL5 mode the ingress LSR is required to reassemble AAL5
   CPCS-PDUs from the incoming VC and transport each CPCS-PDU as a
   single packet. No AAL5 trailer is transported. The control word is
   REQUIRED.

   The EFCI and CLP bits are carried across the network in the control
   word. The edge LSRs that implement this document MAY, when either
   adding or removing the encapsulation described herein, change the
   EFCI bit from zero to one in order to reflect congestion in the MPLS
   network that is known to the edge LSRs, and the CLP bit from zero to
   one to reflect marking from edge policing of the ATM Sustained Cell
   Rate. The EFCI and CLP bits MUST NOT be changed from one to zero.

   The AAL5 CPCS-PDU is prepended by the following header:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               VC Label                | EXP |S|     TTL       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Rsvd  |T|E|L|C|    Length     |        Sequence Number        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     ATM  AAL5 CPCS-PDU                        |
   |                             "                                 |
   |                             "                                 |
   |                             "                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     * T (transport type) bit

       Bit (T) of the control word indicates whether the MPLS packet
       contains an ATM cell or an AAL5 CPCS-PDU. If set the packet
       contains an ATM cell, encapsulated according to the ATM cell mode



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       section below, otherwise it contains an AAL5 CPCS-PDU. The
       ability to transport an ATM cell in the AAL5 mode is intended to
       provide a means of enabling OAM functionality over the AAL5 VC.


     * E ( EFCI ) Bit

       The ingress LSR, R1, SHOULD set this bit to 1 if the EFCI bit of
       the final cell of those that transported the AAL5 CPCS-PDU is set
       to 1, or if the EFCI bit of the single ATM cell to be transported
       in the MPLS packet is set to 1.  Otherwise this bit SHOULD be set
       to 0. The egress LSR, R2, SHOULD set the EFCI bit of all cells
       that transport the AAL5 CPCS-PDU to the value contained in this
       field.

     * L ( CLP ) Bit

       The ingress LSR, R1, SHOULD set this bit to 1 if the CLP bit of
       any of the ATM cells that transported the AAL5 CPCS-PDU is set to
       1, or if the CLP bit of the single ATM cell to be transported in
       the MPLS packet is set to 1.  Otherwise this bit SHOULD be set to
       0. The egress LSR, R2, SHOULD set the CLP bit of all cells that
       transport the AAL5 CPCS-PDU to the value contained in this field.

     * C ( Command / Response Field ) Bit

       When FRF.8.1 Frame Relay / ATM PVC Service Interworking [3]
       traffic is being transported, the CPCS-UU Least Significant Bit
       (LSB) of the AAL5 CPCS-PDU may contain the Frame Relay C/R bit.
       The ingress LSR, R1, SHOULD copy this bit to the C bit of the
       control word. The egress LSR, R2, SHOULD copy the C bit to the
       CPCS-UU Least Significant Bit (LSB) of the AAL5 CPCS PDU.

   The Label, EXP, S, and TTL fields are described in [2].


4.2.2. ATM Cell Mode

   In this encapsulation mode ATM cells are transported individually
   without a SAR process. The ATM cell encapsulation consists of an MPLS
   label stack, an OPTIONAL control word, and one or more ATM cells -
   each consisting of a 4 byte ATM cell header and the 48 byte ATM cell
   payload. This ATM cell header is defined as in the FAST encapsulation
   [4] section 3.1.1, but without the trailer byte. The length of each
   frame, without the MPLS header and the control word, is a multiple of
   52 bytes long. The maximum number of ATM cells that can be fitted in
   an MPLS frame, in this fashion, is limited only by the MPLS network
   MTU and by the ability of the egress LSR to process them. The ingress



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   LSR MUST NOT send more cells than the egress LSR is willing to
   receive. The number of cells that the egress LSR is willing to
   receive may either be configured in the ingress LSR or may be
   signaled, for example using the methods described in [1]. The number
   of cells encapsulated in a particular frame can be inferred by the
   frame length. The control word is OPTIONAL. If the control word is
   used then the flag bits in the control word are not used, and MUST be
   set to 0 when transmitting, and MUST be ignored upon receipt.

   The EFCI and CLP bits are carried across the network in the ATM cell
   header.  The edge LSRs that implement this document MAY, when either
   adding or removing the encapsulation described herein, change the
   EFCI bit from zero to one in order to reflect congestion in the MPLS
   network that is known to the edge LSRs, and the CLP bit from zero to
   one to reflect marking from edge policing of the ATM Sustained Cell
   Rate. The EFCI and CLP bits MUST NOT be changed from one to zero.

   This diagram illustrates an encapsulation of two ATM cells:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               VC Label                | EXP |S|     TTL       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Control word ( Optional )                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          VPI          |              VCI              | PTI |C|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  ATM Payload ( 48 bytes )                     |
   |                          "                                    |
   |                          "                                    |
   |                          "                                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          VPI          |              VCI              | PTI |C|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  ATM Payload ( 48 bytes )                     |
   |                          "                                    |
   |                          "                                    |
   |                          "                                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     * VPI

       The ingress router MUST copy the VPI field from the incoming cell
       into this field. The egress router MAY generate a new VPI based
       on the value of the VC label and ignore the VPI contained in this
       field.



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     * VCI

       The ingress router MUST copy the VCI field from the incoming ATM
       cell header into this field.  The egress router MAY generate a
       new VCI based on the value of the VC label.

     * PTI & CLP ( C bit )

       The PTI and CLP fields are the PTI and CLP fields of the incoming
       ATM cells.  The cell headers of the cells within the packet are
       the ATM headers (without HEC) of the incoming cell.


4.2.3. OAM Cell Support

   OAM cells MAY be transported on the VC LSP. A router that does not
   support transport of OAM cells MUST discard incoming MPLS frames on
   an ATM VC LSP that contain an ATM cell with the high-order bit of the
   PTI field set to 1. A router that supports transport of OAM cells
   MUST follow the procedures outlined in [4] section 8 for mode 0 only,
   in addition to the applicable procedures specified in [1].


4.2.4. CLP bit to MPLS label stack EXP bit mapping

   The ingress LSR MAY consider the CLP bit when determining the value
   to be placed in the EXP fields of the MPLS label stack. This will
   give the MPLS network visibility of the CLP bit.  Note however that
   cells from the same VC MUST NOT be reordered by the MPLS network.


4.3. Ethernet VLAN

   For an Ethernet 802.1q VLAN the entire Ethernet frame without the
   preamble or FCS is transported as a single packet. The control word
   is OPTIONAL. If the control word is used then the flag bits in the
   control word are not used, and MUST be set to 0 when transmitting,
   and MUST be ignored upon receipt. The 4 byte VLAN tag is transported
   as is, and MAY be overwritten by the egress LSR.

   The ingress LSR MAY consider the user priority field [5] of the VLAN
   tag header when determining the value to be placed in the EXP fields
   of the MPLS label stack. In a similar way, the egress LSR MAY
   consider the EXP field of the VC label when queuing the packet for
   egress. Ethernet packets containing hardware level CRC errors,
   framing errors, or runt packets MUST be discarded on input.





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4.4. Ethernet

   For simple Ethernet port to port transport, the entire Ethernet frame
   without the preamble or FCS is transported as a single packet. The
   control word is OPTIONAL. If the control word is used then the flag
   bits in the control word are not used, and MUST be set to 0 when
   transmitting, and MUST be ignored upon receipt. As in the Ethernet
   VLAN case, Ethernet packets with hardware level CRC errors, framing
   errors, and runt packets MUST be discarded on input.


4.5. HDLC ( Cisco )

   HDLC (Cisco) mode provides port to port transport of Cisco HDLC
   encapsulated traffic. The HDLC PDU is transported in its entirety,
   including the HDLC address, control and protocol fields, but
   excluding HDLC flags and the FCS.  Bit stuffing is undone. The
   control word is OPTIONAL. If the control word is used then the flag
   bits in the control word are not used, and MUST be set to 0 when
   transmitting, and MUST be ignored upon receipt.


4.6. PPP

   PPP mode provides point to point transport of PPP encapsulated
   traffic, as specified in [6]. The PPP PDU is transported in its
   entirety, including the protocol field (whether compressed using PFC
   or not), but excluding any media-specific framing information, such
   as HDLC address and control fields or FCS.  Since media-specific
   framing is not carried the following options will not operate
   correctly if the PPP peers attempt to negotiate them:

   Frame Check Sequence (FCS) Alternatives Address-and-Control-Field-
   Compression (ACFC) Asynchronous-Control-Character-Map (ACCM)

   Note also that VC LSP Interface MTU negotiation as specified in [1]
   is not affected by PPP MRU advertisement.  Thus if a PPP peer sends a
   PDU with a length in excess of that negotiated for the VC LSP that
   PDU will be discarded by the ingress LSR.

   The control word is OPTIONAL. If the control word is used then the
   flag bits in the control word are not used, and MUST be set to 0 when
   transmitting, and MUST be ignored upon receipt.








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5. Security Considerations

   This document does not affect the underlying security issues of MPLS.


6. Intellectual Property Disclaimer

   This document is being submitted for use in IETF standards
   discussions.


7. References

   [1] "Transport of Layer 2 Frames Over MPLS", draft-martini-
   l2circuit-trans-mpls-06.txt. ( work in progress )

   [2] "MPLS Label Stack Encoding", E. Rosen, Y. Rekhter, D. Tappan, G.
        Fedorkow, D. Farinacci, T. Li, A. Conta. RFC3032

   [3] "Frame Relay / ATM PVC Service Interworking Implementation
   Agreement", Frame Relay Forum 2000.

   [4] "Frame Based ATM over SONET/SDH Transport (FAST)," 2000.

   [5] "IEEE 802.3ac-1998" IEEE standard specification.

   [6] "The Point-to-Point Protocol (PPP)", RFC 1661.


8. Author Information


   Luca Martini
   Level 3 Communications, LLC.
   1025 Eldorado Blvd.
   Broomfield, CO, 80021
   e-mail: luca@level3.net


   Nasser El-Aawar
   Level 3 Communications, LLC.
   1025 Eldorado Blvd.
   Broomfield, CO, 80021
   e-mail: nna@level3.net







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   Giles Heron
   Gone2 Ltd.
   c/o MDP
   One Curzon Street
   London
   W1J 5HD
   United Kingdom
   e-mail: giles@goneto.net


   Dimitri Stratton Vlachos
   Mazu Networks, Inc.
   125 Cambridgepark Drive
   Cambridge, MA 02140
   e-mail: d@mazunetworks.com


   Dan Tappan
   Cisco Systems, Inc.
   250 Apollo Drive
   Chelmsford, MA, 01824
   e-mail: tappan@cisco.com


   Jayakumar Jayakumar,
   Cisco Systems Inc.
   225, E.Tasman, MS-SJ3/3,
   San Jose , CA, 95134
   e-mail: jjayakum@cisco.com


   Alex Hamilton,
   Cisco Systems Inc.
   285 W. Tasman , MS-SJCI/3/4,
   San Jose, CA, 95134
   e-mail: tahamilt@cisco.com


   Eric Rosen
   Cisco Systems, Inc.
   250 Apollo Drive
   Chelmsford, MA, 01824
   e-mail: erosen@cisco.com







Martini, et al.                                                [Page 14]

Internet Draft draft-martini-l2circuit-encap-mpls-02.txt        May 2001



   Steve Vogelsang
   Laurel Networks, Inc.
   2607 Nicholson Rd.
   Sewickley, PA 15143
   e-mail: sjv@laurelnetworks.com


   John Shirron
   Laurel Networks, Inc.
   2607 Nicholson Rd.
   Sewickley, PA 15143
   e-mail: jshirron@laurelnetworks.com


   Toby Smith
   Laurel Networks, Inc.
   2607 Nicholson Rd.
   Sewickley, PA 15143
   e-mail: tob@laurelnetworks.com


   Andrew G. Malis
   Vivace Networks, Inc.
   2730 Orchard Parkway
   San Jose, CA 95134
   e-mail: Andy.Malis@vivacenetworks.com


   Vinai Sirkay
   Vivace Networks, Inc.
   2730 Orchard Parkway
   San Jose, CA 95134
   e-mail: vinai.sirkay@vivacenetworks.com


   Vasile Radoaca
   Nortel Networks
   600  Technology Park
   Billerica MA 01821
   e-mail: vasile@nortelnetworks.com


   Chris Liljenstolpe
   Cable & Wireless
   11700 Plaza America Drive
   Reston, VA 20190
   chris@cw.net



Martini, et al.                                                [Page 15]

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Martini, et al.                                                [Page 16]


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