Layer Two Tunneling Protocol "L2TP" - [RFC2661]

(last updated 2006-09-01)

List of registries included on this page:
  Control Message Attribute Value Pairs
  Message Type AVP (Attribute Type 0) Values
  Result Code AVP (Attribute Type 1) Values
  Proxy Authen Type AVP (Attribute Type 29) Values
  Service Category AVP (Attribute Type 42) Flag Field
  PPP Disconnect Cause Code (Attribute Type 46) Values
  ATM Alarm Status AVP (Attribute Type 88) Values
  Bearer Field definition
  Framing Field definition
  Leading Bits of the L2TP AVP Header
  Leading Bits of the L2TP Message Header
  L2TPv3 Pseudowire Types
  Circuit Status Bits
  Default L2-Specific Sublayer bits
  L2-Specific Sublayer Type
  Data Sequencing Level
  ATM-Specific Sublayer bits

Control Message Attribute Value Pairs
For registration procedures, please see [RFC3438].

To maximize extensibility while still permitting interoperability, a
uniform method for encoding message types and bodies is used
throughout L2TP.  This encoding will be termed AVP (Attribute-Value
Pair).

The following sections contain a list of all L2TP AVPs defined in RFC
2661.

Attribute
Type        Description                                     Reference
---------   ------------------                              ---------
        0   Message Type AVP                                [RFC2661]
            Also, see Message Type AVP values below
        1   Result Code AVP                                 [RFC2661]
            Also, see Result Code AVP values below
        2   Protocol Version AVP                            [RFC2661]
        3   Framing Capabilities AVP                        [RFC2661]
            Also, see Framing Field definition below
        4   Bearer Capabilities AVP                         [RFC2661] 
            Also, see Bearer Field definition below
        5   Tie Breaker AVP                                 [RFC2661] 
        6   Firmware Revision AVP                           [RFC2661]
        7   Host Name AVP                                   [RFC2661]
        8   Vendor Name AVP                                 [RFC2661]
        9   Assigned Tunnel ID AVP                          [RFC2661]
       10   Receive Window Size AVP                         [RFC2661]
       11   Challenge AVP                                   [RFC2661]
       12   Q.931 Cause Code AVP                            [RFC2661]
       13   Response AVP                                    [RFC2661]
       14   Assigned Session ID AVP                         [RFC2661]
       15   Call Serial Number AVP                          [RFC2661]
       16   Minimum BPS AVP                                 [RFC2661]
       17   Maximum BPS AVP                                 [RFC2661]
       18   Bearer Type AVP                                 [RFC2661]
            Also, see Bearer Field definition below
       19   Framing Type AVP                                [RFC2661]
            Also, see Framing Field definition below
       20   Reserved                                        [RFC2661]
       21   Called Number AVP                               [RFC2661]
       22   Calling Number AVP                              [RFC2661]
       23   Sub-Address AVP                                 [RFC2661]
       24  (Tx) Connect Speed BPS AVP                       [RFC2661]
       25   Physical Channel ID AVP                         [RFC2661]
       26   Initial Received LCP CONFREQ AVP                [RFC2661]
       27   Last Sent LCP CONFREQ AVP                       [RFC2661]
       28   Last Received LCP CONFREQ AVP                   [RFC2661]
       29   Proxy Authen Type AVP                           [RFC2661]
            Also, see Proxy Authen Type AVP Values below
       30   Proxy Authen Name AVP                           [RFC2661]
       31   Proxy Authen Challenge AVP                      [RFC2661]
       32   Proxy Authen ID AVP                             [RFC2661]
       33   Proxy Authen Response AVP                       [RFC2661]
       34   Call Errors AVP                                 [RFC2661]
       35   ACCM AVP                                        [RFC2661]
       36   Random Vector AVP                               [RFC2661]
       37   Private Group ID AVP                            [RFC2661]
       38   Rx Connect Speed AVP                            [RFC2661]
       39   Sequencing Required AVP                         [RFC2661]
       40   Rx Minimum BPS                                  [RFC3301]
       41   Rx Maximum BPS                                  [RFC3301]
       42   Service Category                                [RFC3301]
            Also, see Service Category AVP Flag Fields
            below
       43   Service Name                                    [RFC3301]
       44   Calling Sub-Address                             [RFC3301]
       45   VPI/VCI Identifier                              [RFC3301]
       46   PPP Disconnect Cause Code                       [RFC3145]
            Also, see PPP Disconnect Cause Code Values 
            below
       47   CCDS AVP                                        [RFC3308]
       48   SDS AVP                                         [RFC3308]
       49   LCP Want Options                                [RFC3437] 
       50   LCP Allow Options                               [RFC3437]   
       51   LNS Last Sent LCP Confreq                       [RFC3437]
       52   LNS Last Received LCP Confreq                   [RFC3437]
       53   Modem On-Hold Capable AVP                       [RFC3573]
       54   Modem On-Hold Status AVP                        [RFC3573]
       55   PPPoE Relay AVP                                 [RFC3817]
       56   PPPoE Relay Response Capability AVP             [RFC3817]
       57   PPPoE Relay Forward Capability AVP              [RFC3817]
       58   Extended Vendor ID AVP                          [RFC3931]
       59   Message Digest                                  [RFC3931]
       60   Router ID                                       [RFC3931]
       61   Assigned Control Connection ID                  [RFC3931]
       62   Pseudowire Capabilities List                    [RFC3931]
       63   Local Session ID                                [RFC3931]
       64   Remote Session ID                               [RFC3931]
       65   Assigned Cookie                                 [RFC3931]
       66   Remote End ID                                   [RFC3931]
       67   Application Code                                [RFC3931]
       68   Pseudowire Type                                 [RFC3931]
       69   L2-Specific Sublayer                            [RFC3931]
       70   Data Sequencing                                 [RFC3931]
       71   Circuit Status                                  [RFC3931]
       72   Preferred Language                              [RFC3931]
       73   Control Message Authentication Nonce            [RFC3931]
       74   Tx Connect Speed                                [RFC3931]
       75   Rx Connect Speed                                [RFC3931]
       76   Failover Capability                             [draft-ietf-l2tpext-failover-04.txt]
       77   Tunnel Recovery                                 [draft-ietf-l2tpext-failover-04.txt]
       78   Suggested Control Sequence                      [draft-ietf-l2tpext-failover-04.txt]
       79   Failover Session State                          [draft-ietf-l2tpext-failover-04.txt]
       80   Multicast Capability                            [RFC4045]
       81   New Outgoing Sessions                           [RFC4045] 
       82   New Outgoing Sessions Acknowledgement           [RFC4045]
       83   Withdraw Outgoing Sessions                      [RFC4045]
       84   Multicast Packets Priority                      [RFC4045]
       85   Frame-Relay Header Length                       [RFC4591]
       86   ATM Maximum Concatenated Cells AVP              [RFC4454]
       87   OAM Emulation Required AVP                      [RFC4454]
       88   ATM Alarm Status AVP                            [RFC4454]
            Also, see ATM Alarm Status AVP Values below
       89   Attachment Group Identifier                     [draft-ietf-l2tpext-l2vpn-07.txt]
       90   Local End Identifier                            [draft-ietf-l2tpext-l2vpn-07.txt]
       91   Interface Maximum Transmission Unit             [draft-ietf-l2tpext-l2vpn-07.txt]
       92   FCS Retention                                   [RFC-ietf-pwe3-fcs-retention-04.txt]
       93   Tunnel Switching Aggregator ID AVP              [draft-ietf-l2tpext-tunnel-switching-06.txt]
       94    Maximum Receive Unit (MRU) AVP                 [RFC4623]
       95    Maximum Reassembled Receive Unit (MRRU) AVP    [RFC4623]


Message Type AVP (Attribute Type 0) Values
------------------------------------------

  Control Connection Management

      0  (reserved)

      1  (SCCRQ)    Start-Control-Connection-Request
      2  (SCCRP)    Start-Control-Connection-Reply
      3  (SCCCN)    Start-Control-Connection-Connected
      4  (StopCCN)  Stop-Control-Connection-Notification
      5  (reserved)
      6  (HELLO)    Hello
     20  (ACK)      Explicit Acknowledgement        [RFC3931]
  
  Call Management

      7  (OCRQ)     Outgoing-Call-Request
      8  (OCRP)     Outgoing-Call-Reply
      9  (OCCN)     Outgoing-Call-Connected
      10 (ICRQ)     Incoming-Call-Request
      11 (ICRP)     Incoming-Call-Reply
      12 (ICCN)     Incoming-Call-Connected
      13 (reserved)
      14 (CDN)      Call-Disconnect-Notify
      21 (FSQ)      Failover Session Query Message      [draft-ietf-l2tpext-failover-04.txt]
      22 (FSR)      Failover Session Response Message   [draft-ietf-l2tpext-failover-04.txt]

  Link Status

      15 (WEN)      WAN-Error-Notify             
      16 (SLI)      Set-Link-Info
      17 (MDMST)    Modem Status                        [RFC3573]

  PPPoE Relay

      18 (SRRQ)     Service Relay Request Message       [RFC3817]
      19 (SRRP)     Service Relay Reply Message         [RFC3817]

  Multicast Management

      23 (MSRQ)     Multicast-Session-Request       [RFC4045]
      24 (MSRP)     Multicast-Session-Response      [RFC4045]
      25 (MSE)      Multicast-Session-Establishment [RFC4045]
      26 (MSI)      Multicast-Session-Information   [RFC4045]
      27 (MSEN)     Multicast-Session-End-Notify    [RFC4045]

Result Code AVP (Attribute Type 1) Values
-----------------------------------------

  Defined Result Code values for the StopCCN message are:

         0 - Reserved
         1 - General request to clear control connection
         2 - General error--Error Code indicates the problem
         3 - Control channel already exists
         4 - Requester is not authorized to establish a control
             channel
         5 - The protocol version of the requester is not
             supported
             Error Code indicates highest version supported
         6 - Requester is being shut down
         7 - Finite State Machine error
         8 - Control connection due to mismatching CCDS value     [RFC3308] 

  Defined Result Code values for the CDN message are:

         0 - Reserved
         1 - Call/Session disconnected due to loss of carrier
         2 - Call/Session disconnected for the reason indicated
             in error code
         3 - Call/Session disconnected for administrative reasons
         4 - Call/Session failed due to lack of appropriate facilities
             being available (temporary condition)
         5 - Call/Session failed due to lack of appropriate facilities being
             available (permanent condition)
         6 - Invalid destination
         7 - Call failed due to no carrier detected
         8 - Call failed due to detection of a busy signal
         9 - Call failed due to lack of a dial tone
         10 - Call was not established within time allotted by LAC
         11 - Call was connected but no appropriate framing was
              detected
         12 - Disconnecting call due to mismatching SDS value              [RFC3308]
         13 - Session not established due to losing tie breaker (L2TPv3).  [RFC3931]
         14 - Session not established due to unsupported PW type (L2TPv3). [RFC3931]
         15 - Session not established, sequencing required without valid   [RFC3931]
              L2-Specific Sublayer (L2TPv3).
         16 - Finite state machine error or timeout.                       [RFC3931]
         17 - FR PVC was deleted permanently (no longer provisioned)       [RFC4591]
         18 - FR PVC has been INACTIVE for an extended period of time      [RFC4591]
         19 - Mismatched FR Header Length                                  [RFC4591]
         20 - HDLC Link was deleted permanently (no longer provisioned)    [RFC4349]
         21 - HDLC Link has been INACTIVE for an extended period of time   [RFC4349]
         22 - Session not established due to other LCCE can not support    [RFC4454]
              the OAM Cell Emulation
         23 - Mismatching interface MTU                                    [draft-ietf-l2tpext-l2vpn-07.txt]
         24 - Attempt to connect to non-existent forwarder                 [draft-ietf-l2tpext-l2vpn-07.txt]
         25 - Attempt to connect to unauthorized forwarder                 [draft-ietf-l2tpext-l2vpn-07.txt]
         26 - Loop Detected                                                [draft-ietf-l2tpext-tunnel-switching-06.txt]


  Defined Result Code values for the MSEN message are:

         0 - Reserved
         1 - No multicast traffic for the group                            [RFC4045]
         2 - Session terminated for the reason indicated in the error code [RFC4045]
         3 - No more receivers                                             [RFC4045]
         4 - No more receivers (filter-mode change)                        [RFC4045]

  General Error Codes

         0 - No general error
         1 - No control connection exists yet for this LAC-LNS pair
         2 - Length is wrong
         3 - One of the field values was out of range or
             reserved field was non-zero
         4 - Insufficient resources to handle this operation now
         5 - The Session ID is invalid in this context
         6 - A generic vendor-specific error occurred in the LAC
         7 - Try another.  If LAC is aware of other possible LNS
             destinations, it should try one of them.  This can be
             used to guide an LAC based on LNS policy, for instance,
             the existence of multilink PPP bundles.
         8 - Session or tunnel was shutdown due to receipt of an
             unknown AVP with the M-bit set (see section 4.2). The Error
             Message SHOULD contain the attribute of the offending AVP in
             (human readable) text form.
         9 - Try another directed.  If an LAC or LNS is aware of other
             possible destinations, it should inform the initiator of the
             control connection or session.  The Error Message MUST contain
             a comma-separated list of addresses from which the initiator
             may choose.  If the L2TP data channel runs over IPv4, then
             this would be a comma-separated list of IP addresses in the
             canonical dotted-decimal format (e.g., "192.0.2.1, 192.0.2.2,
             192.0.2.3") in the UTF-8 charset [RFC3629] using the Default
             Language [RFC2277].  If there are no servers for the LAC or
             LNS to suggest, then Error Code 7 should be used.  For IPv4,
             the delimiter between addresses MUST be precisely a single
             comma and a single space.  For IPv6, each literal address MUST
             be enclosed in "[" and "]" characters, following the encoding
             described in [RFC2732].
        10 - Next hop unreachable.  This identifies an error condition     [draft-ietf-l2tpext-tunnel-switching-06.txt]
             explicitly in the multi-TSA environment.
        11 - Next hop busy.  This identifies an error condition            [draft-ietf-l2tpext-tunnel-switching-06.txt]
             explicitly in the multi-TSA environment.
        12 - TSA busy.  This identifies an error condition                 [draft-ietf-l2tpext-tunnel-switching-06.txt]
             explicitly in the multi-TSA environment.


Proxy Authen Type AVP (Attribute Type 29) Values
------------------------------------------------

         0 - Reserved
         1 - Textual username/password exchange
         2 - PPP CHAP
         3 - PPP PAP
         4 - No Authentication
         5 - Microsoft CHAP Version 1 (MSCHAPv1)
         6 - Reserved
         7 - EAP                                                       [draft-ietf-l2tpext-proxy-authen-ext-eap-00.txt]


Service Category AVP (Attribute Type 42) Flag Field
----------------------------------------------------

The Attribute Value field is a 16-bit field, with current
defined bits:

Value	 Description                            Reference
------   ------------------------------------	---------
0x0001	 S-bit (real-time)                      [RFC3301]


PPP Disconnect Cause Code (Attribute Type 46) Values
----------------------------------------------------

  Global Errors  

  0    No information available

  1    Administrative disconnect.

  2    Link Control Protocol (LCP) renegotiation at 
       LNS disabled; LNS expects proxy LCP information, 
       LAC did not send it.

  3    Normal Disconnection, LCP Terminate-Request sent.
        Valid Direction values are:
          1: LCP Terminate-Request sent by peer
          2: LCP Terminate-Request sent by local

  4    Compulsory encryption required by a PPP peer was 
       refused by the other.
        Valid Direction values are:
          1: Required by local; refused by peer
          2: Required by peer; refused by local

  LCP Errors

  5    FSM (Finite State Machine) Timeout error.  
       (PPP event "TO-".)

  6    No recognizable LCP packets were received.

  7    LCP failure: Magic Number error; link possibly 
       looped back.

  8    LCP link failure: Echo Request timeout.

  9    Peer has unexpected Endpoint-Discriminator for 
       existing Multilink PPP (MP) bundle.

  10   Peer has unexpected MRRU for existing MP bundle.

  11   Peer has unexpected Short-Sequence-Number option 
       for existing MP bundle.

  12   Compulsory call-back required by a PPP peer was 
       refused by the  other.
        Valid Direction values are:
          1: Required by local; refused by peer
          2: Required by peer; refused by local

  Authentication Errors

  13   FSM Timeout error.

  14   Peer has unexpected authenticated name for 
       existing MP bundle.

  15   PPP authentication failure: Authentication protocol
       unacceptable.
        Valid Direction values are:
          1: All local authentication protocols were 
             rejected by the peer.
          2: All authentication protocols requested by peer 
             were unacceptable or unimplemented locally.

  16   PPP authentication failure: Authentication failed 
       (bad name, password, or secret).
        Valid Direction values are:
          1: Authentication of peer identity by local system.
          2: Authentication of local identity by peer system.

  Network Control Protocol (NCP) Errors

  17   FSM Timeout error.

  18   No NCPs available (all disabled or rejected); no NCPs 
       went to Opened state.  (Control Protocol Number may be 
       zero only if neither peer has enabled NCPs.)

  19   NCP failure: failed to converge on acceptable addresses.
        Valid Direction values are:
          1: Too many Configure-Naks received from peer.
          2: Too many Configure-Naks sent to peer.

  20   NCP failure: user not permitted to use any addresses.
        Valid Direction values are:
          1: Local link address not acceptable to peer.
          2: Remote link address not acceptable to local system.

  21-32767 Unassigned (by IESG Approval)

  32768-65279 Unassigned (by the IANA)

  65280-65535 Private or Experimental Use


ATM Alarm Status AVP (Attribute Type 88) Values - per [RFC4454]
-----------------------------------------------
Registration Procedures: Expert Review

   Circuit Status Reason values for the SLI message are as follows:
        Value  Description                                               Reference
        -----  --------------------------------------------------------  ---------
           0 - Reserved                                                  [RFC4454]
           1 - No alarm or alarm cleared (default for Active Status)     [RFC4454]
           2 - Unspecified or unknown Alarm Received (default for        [RFC4454]  
               Inactive Status)
           3 - ATM Circuit received F1 Alarm on ingress LCCE             [RFC4454]
           4 - ATM Circuit received F2 Alarm on ingress LCCE             [RFC4454]
           5 - ATM Circuit received F3 Alarm on ingress LCCE             [RFC4454]
           6 - ATM Circuit received F4 Alarm on ingress LCCE             [RFC4454]
           7 - ATM Circuit received F5 Alarm on ingress LCCE             [RFC4454] 
           8 - ATM Circuit down due to ATM Port shutdown on Peer LCCE    [RFC4454]
           9 - ATM Circuit down due to loop-back timeout on ingress LCCE [RFC4454]

   The general ATM Alarm failures are encoded as below:
        Value  Description                                               Reference
        -----  --------------------------------------------------------  ---------
           0 - Reserved                                                  [RFC4454]
           1 - No Alarm type specified (default)                         [RFC4454]
           2 - Alarm Indication Signal (AIS)                             [RFC4454]
           3 - Remote Defect Indicator (RDI)                             [RFC4454]
           4 - Loss of Signal (LOS)                                      [RFC4454]
           5 - Loss of pointer (LOP)                                     [RFC4454]
           6 - Loss of framer (LOF)                                      [RFC4454]
           7 - loopback cells (LB)                                       [RFC4454]
           8 - Continuity Check (CC)                                     [RFC4454]



Bearer Field definition:
-----------------------
The Bearer field is used by the Bearer Capabilities and Bearer Type
AVPs. It is a 32-bit bit field, with current defined bit values of:

Value       Meaning                             Reference
0x00000001	D-bit (Digital access requested)    [RFC2661]
0x00000002	A-bit (Analogue access requested)   [RFC2661]
0x00000004	B-bit (ATM Bearer support)          [RFCXXXX]


Framing Field definition:
------------------------
The Framing field is used by the Framing Capabilities and Framing Type
AVPs. It is a 32-bit bit field, with current defined bit values of:

Value       Meaning                         Reference
0x00000001	S-bit (synchronous framing)     [RFC2661]
0x00000002	A-bit (asyncronous framing)     [RFC2661]


Leading Bits of the L2TP AVP Header - per [RFC2661, RFC3931]
-----------------------------------
There are six bits at the beginning of the L2TP AVP header. 
L2TPv2 and L2TPv3 share a common registry for the definitions 
of the six leading bits.  New bits are assigned via Standards 
Action [RFC2434].

Bit 0 - Mandatory Bit, "M-bit"               [RFC2661, RFC3931]
Bit 1 - Hidden Bit, "H-bit"                  [RFC2661, RFC3931]
Bit 2 - Reserved                             [RFC2661, RFC3931]
Bit 3 - Reserved                             [RFC2661, RFC3931]
Bit 4 - Reserved                             [RFC2661, RFC3931]
Bit 5 - Reserved                             [RFC2661, RFC3931]


Leading Bits of the L2TP Message Header - per [RFC2661, RFC3931]
---------------------------------------
There are 12 bits at the beginning of the L2TP Message Header.  
L2TPv2 and L2TPv3 share a common registry for the definitions 
of the 12 leading bits.  Reserved bits should only be defined 
by Standard Action [RFC2434].

Bit  0 - Message Type, "T-bit"               [RFC2661, RFC3931]  
Bit  1 - Length Field is Present, "L-bit"    [RFC2661, RFC3931]
Bit  2 - Reserved                            [RFC2661, RFC3931] 
Bit  3 - Reserved                            [RFC2661, RFC3931] 
Bit  4 - Sequence Numbers Present, "S-bit"   [RFC2661, RFC3931]
Bit  5 - Reserved                            [RFC2661, RFC3931] 
Bit  6 - Offset Field is Present             [RFC2661]
Bit  7 - Priority Bit, "P-bit"               [RFC2661]
Bit  8 - B (Fragmentation) bit               [RFC4623]
Bit  9 - E (Fragmentation) bit               [RFC4623]
Bit 10 - Reserved                            [RFC2661, RFC3931] 
Bit 11 - Reserved                            [RFC2661, RFC3931] 


L2TPv3 Pseudowire Types - per [RFC3931]
-----------------------
The Pseudowire Type (PW Type, Section 5.4) is a two-octet value used
in the Pseudowire Type AVP and Pseudowire Capabilities List AVP
defined in Section 5.4.3.  0 to 32767 are assignable by Expert Review
[RFC2434], 32768 to 65535 by a First Come First Served policy
[RFC2434]. There are no specific pseudowire types assigned within
this document. Each pseudowire-specific document must allocate its
own PW types from IANA as necessary.

0x0001 - Frame Relay DLCI Pseudowire Type   [RFC4591]
0x0002 - ATM AAL5 SDU VCC transport         [RFC4454]
0x0003 - ATM Cell transparent Port Mode     [RFC4454]
0x0004 - Ethernet VLAN Pseudowire Type      [draft-ietf-l2tpext-pwe3-ethernet-03.txt]
0x0005 - Ethernet Pseudowire Type           [draft-ietf-l2tpext-pwe3-ethernet-03.txt]
0x0006 - HDLC Pseudowire Type               [RFC4349]
0x0009 - ATM Cell transport VCC Mode        [RFC4454]
0x000A - ATM Cell transport VPC Mode        [RFC4454]
0x000B - Unassigned
0x000C - MPEG-TS Payload Type (MPTPW)       [DOCSIS CM-SP-DEPI]  30 January 2006
0x000D - Packet Streaming Protocol (PSPPW)  [DOCSIS CM-SP-DEPI]  30 January 2006

Circuit Status Bits - per [RFC3931] 
-------------------
The Circuit Status field is a 16 bit mask, with the two high order
bits assigned. Additional bits may be assigned by IETF Consensus
[RFC2434].

Bit 14 - N (New) bit                           [RFC3931] 
Bit 15 - A (Active) bit                        [RFC3931] 

Default L2-Specific Sublayer bits - per [RFC3931] 
---------------------------------
The Default L2 Specific Sublayer contains 8 bits in the low-order
portion of the header. Reserved bits may be assigned by IETF
Consensus [RFC2434].

Bit 0 - Reserved                               [RFC3931] 
Bit 1 - S (Sequence) bit                       [RFC3931] 
Bit 2 - B (Fragmentation) bit                  [RFC4623] 
Bit 3 - E (Fragmentation) bit                  [RFC4623] 
Bit 4 - Reserved                               [RFC3931] 
Bit 5 - Reserved                               [RFC3931]  
Bit 6 - Reserved                               [RFC3931] 
Bit 7 - Reserved                               [RFC3931] 

L2-Specific Sublayer Type - per [RFC3931] 
-------------------------
The L2-Specific Sublayer Type is a 2 octet unsigned integer.
Additional values may be assigned by Expert Review [RFC2434].

0 - No L2-Specific Sublayer                     [RFC3931] 
1 - Default L2-Specific Sublayer present        [RFC3931] 
2 - ATM-Specific Sublayer present               [RFC4454]
3 - MPT-Specific Sublayer                       [DOCSIS CM-SP-DEPI]  30 January 2006
4 - PSP-Specific Sublayer                       [DOCSIS CM-SP-DEPI]  30 January 2006

Data Sequencing Level - per [RFC3931] 
---------------------
The Data Sequencing Level is a 2 octet unsigned integer
Additional values may be assigned by Expert Review [RFC2434].

0 - No incoming data packets require sequencing.   [RFC3931] 
1 - Only non-IP data packets require sequencing.   [RFC3931] 
2 - All incoming data packets require sequencing.  [RFC3931]  

ATM-Specific Sublayer bits - per [RFC4454]
--------------------------
Registration Procedures: IETF Consensus

     Bit    Description                  Reference
   -------  ---------------------------  ---------
    Bit 0 - Reserved                     [RFC4454]
    Bit 1 - S (Sequence) bit             [RFC4454]
    Bit 2 - B (Fragmentation) bit        [RFC4454]
    Bit 3 - E (Fragmentation) bit        [RFC4454]
    Bit 4 - T (Transport type) bit       [RFC4454]
    Bit 5 - G (EFCI) bit                 [RFC4454]
    Bit 6 - C (CLP) bit                  [RFC4454]
    Bit 7 - U (Command/Response) bit     [RFC4454]


References
----------
[RFC2661]  Townsley, W., et al., "Layer Two Tunneling Protocol "L2TP"",
           RFC 2661, August 1999.
	
[RFC3145]  R. Verma, M. Verma, and J. Carlson, "L2TP Disconnect 
           Cause Information", RFC 3145, July 2001. 

[RFC3301]  Y. T'Joens, P. Crivellari, and B. Sales, "Layer Two 
           Tunnelling Protocol : ATM access network extensions", 
           RFC 3301, June 2002.

[RFC3308]  P. Calhoun, W. Luo, D. McPherson, and K. Peirce, "L2TP 
           Differentiated Services Extension", RFC 3308, November 2002.

[RFC3437]  W. Palter and W. M. Townsley, "Layer-Two Tunneling Protocol 
           (L2TP) Extensions for PPP Link Control Protocol (LCP) 
           Negotiation, RFC 3437, November 2002.

[RFC3438]  W. M. Townsley, "Layer Two Tunneling Protocol (L2TP) Internet
[BCP68]    Assigned Numbers Authority (IANA) Considerations Update",
           RFC 3438, BCP 68, November 2002.

[RFC3573]  I. Goyret, "Signalling of Modem-On-Hold status in Layer 2 
           Tunneling Protocol (L2TP)", RFC 3573, July 2003.

[RFC3817]  W. M. Townsley and R. da Silva, "Layer 2 Tunneling Protocol 
           (L2TP) Active Discovery Relay for PPP over Ethernet (PPPoE)",
           RFC 3817, June 2004. 

[RFC3931]  J. Lau, M. Townsley, and I. Goyret, Eds., "Layer Two Tunneling 
           Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.
 
[RFC4045]  G. Bourdon, "Extensions to support efficient carrying of multicast 
           traffic in Layer-2 Tunneling Protocol (L2TP)", RFC 4045, April 2005.

[RFC4349]  C. Pignataro and W. M. Townsley, "HDLC Frames over L2TPv3", 
           RFC 4349, February 2006.

[RFC4454]  S. Singh, W. M. Townsley and C. Pignataro, "ATM over L2TPv3", 
           RFC 4454, May 2006.

[RFC4591]  W. M. Townsley, G. Wilkie, S. Booth, S. Bryant, and J. Lau, 
           "Frame-Relay over L2TPv3", RFC 4591, July 2006.

[draft-ietf-l2tpext-failover-04.txt]       Work in progress.  Added via Expert Review.
[draft-ietf-l2tpext-pwe3-ethernet-03.txt]  Work in progress.  Added via Expert Review.
[draft-ietf-l2tpext-tunnel-switching-06.txt]
           Work in progress.  Added via Expert Review.
[draft-ietf-l2tpext-proxy-authen-ext-eap-00.txt]
           Work in progress.  Added via Expert Review.


[DOCSIS CM-SP-DEPI]
"Data-Over-Cable Service Interface Specifications: Downstream External PHY Interface 
Specification CM-SP-DEPI-I01-050805", DOCSIS, August 2005, available at:
http://www.cablemodem.com/specifications/
http://www.cablelabs.com/specifications/archives/
 
[RFC-ietf-pwe3-fcs-retention-04.txt]
       A. Malis, D. Allan and N. Del Regno, "PWE3 Frame Check Sequence Retention",
       RFC XXXX, Month Year.

[RFC-ietf-l2tpext-l2vpn-07.txt]
       W. Luo, "L2VPN Extensions for L2TP", RFC XXXX, Month Year.

[RFC4623]  Andrew G. Malis, W. Mark Townsley, "PWE3 Fragmentation and Reassembly",
           RFC 4623, August 2006.

PWE3 Fragmentation and Reassembly
 
(created March 2003) 

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