One document matched: draft-ietf-l2tpext-ppp-discinfo-01.txt
Differences from draft-ietf-l2tpext-ppp-discinfo-00.txt
Network Working Group Rohit Verma
INTERNET-DRAFT Deloitte Consulting
Expires July 2001 Madhvi Verma
3Com Corporation
James Carlson
Sun Microsystems
January 2001
L2TP Disconnect Cause Information
<draft-ietf-l2tpext-ppp-discinfo-01.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
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Abstract
The Layer 2 Tunneling Protocol (``L2TP'') defines a mechanism for
tunneling PPP sessions. This protocol lacks a mechanism for the LNS
to provide PPP related disconnect cause information to the LAC. This
information, provided by the extension described in this document,
can be useful for accounting and debugging purposes.
1. Introduction
L2TP [1] defines a general-purpose mechanism for tunneling PPP over
various media. By design, it insulates L2TP operation from the
details of the PPP session that is being encapsulated by L2TP. There
are, however, cases where it may be desirable for PPP-specific
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disconnect information to be provided to an L2TP host (LAC or LNS) in
a descriptive format. The lack of this information is especially a
problem when the LAC and LNS are not owned or managed by the same
entities.
The Result and Error Codes defined for L2TP specify only L2TP-
specific disconnect information. This document provides an addi-
tional AVP that MAY be used by an L2TP host to provide PPP-specific
disconnect information to its peer for accounting and debugging pur-
poses. This AVP should be used in conjunction with, and not as a
replacement for, the Result and Error Code AVPs.
The PPP Disconnect Cause Code AVP can also be used to provide a
human-readable disconnect reason to the user. The following AVP
should not have any effect on either the functioning of the tunnel or
the functioning of the PPP session; it is for informational and log-
ging purposes only.
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 BCP 14 [2].
2. PPP Disconnect Cause Code AVP
The AVP is valid in the L2TP Call-Disconnect-Notify (CDN) message
only, and it MUST NOT be marked Mandatory.
The PPP Disconnect Cause Code AVP is encoded with Vendor ID 0 and an
Attribute Type of PPP Disconnect Cause Code (TBD). The length of the
Value field MUST be at least 11 octets. If the length is more than
11 octets, the additional octets SHOULD contain a descriptive text in
UTF-8 [3] format that can be displayed to the user or in a log file.
The format of the AVP is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|H| rsvd | Length | Vendor ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Type | Disconnect Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control Protocol Number | Direction | Message...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 1: PPP Disconnect Cause Code AVP
Mandatory (M) bit: MUST be 0.
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Hidden (H) bit: MAY be 1 if the attribute is hidden.
Length: The length of the entire attribute in octets, expressed as a
single octet. The length MUST be at least 11.
Vendor ID: A two octet value in network byte order; set to 0 to indi-
cate that this is an IETF-assigned attribute.
Attribute Type: A two octet value in network byte order; set to TBD
(PPP Disconnect Cause Code).
Disconnect Code: A two octet value in network byte order. (Described
in this document.)
Control Protocol Number: The PPP Control Protocol number of the pri-
mary protocol known to have caused the error, if any. This field may
be 0 unless mentioned otherwise in the description of the Disconnect
Codes in section 3.
Direction: A single octet value; specifies the direction in which the
Disconnect Code applies.
The valid values of this field are:
0: global error
1: at peer
2: at local
3-255: Reserved
This field SHOULD be 0 unless documented otherwise in the description
of the specific Disconnect Code.
3. Disconnect Codes
This section contains the list of well-known values of the Disconnect
Code field in the PPP Disconnect Cause Code AVP. The IANA will main-
tain a registry of the up-to-date values (see section 5 of this docu-
ment). These values should be used in conjunction with the Direction
value and the Control Protocol Number field to interpret the specific
error condition.
Unless documented otherwise for a specific Disconnect Code, the
Direction value SHOULD be 0.
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3.1. Global Errors
The global error codes, given in the list below, are Disconnect Codes
that do not relate to one particular PPP Control Protocol. The Con-
trol Protocol Number for these errors thus MUST be set to 0.
0 No information available.
1 Administrative disconnect.
2 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: By peer
2: 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
3.2. LCP Errors
The LCP error codes, listed below, are disconnect reasons that are
directly related to the failure of PPP peers to negotiate mutually
agreeable link parameters. The Control Protocol Number for these
errors MUST be set to C021 hexadecimal (LCP).
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 MP
bundle.
10 Peer has unexpected MRRU for existing MP bundle.
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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 value are:
1: Required by local; refused by peer
2: Required by peer; refused by local
3.3. Authentication Errors
The authentication error codes, listed below, are disconnect reasons
that are directly related to authentication failures between the PPP
peers. The Control Protocol Number for such errors MUST correspond
to the PPP Control Protocol number for the authentication protocol in
use.
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.
3.4. Network Control Protocol (NCP) Errors
NCP Errors are disconnect reasons that are directly related to the
failure of PPP peers to negotiate a mutually agreeable set of
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parameters for the network protocols. The Control Protocol Number
for such errors MUST correspond to the PPP Network Control Protocol
number in use. Where multiple network protocols are in use, multiple
copies of this AVP MAY be given to indicate failure reasons for each
NCP. Otherwise, if only one copy of the AVP is given, the Control
Protocol Number SHOULD correspond to the last failing NCP.
17 FSM Timeout error.
18 No NCPs available (all disabled or rejected); no NCPs went to
Opened state.
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 from 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.
4. Notes
This AVP MAY may be sent by either the LNS or LAC. It is generally
expected that this AVP will be most useful in sending notification
from the LNS to LAC in the compulsory tunneling case, although it is
not precluded from use in any other case.
A draft form of this AVP used Vendor ID 43 (3Com Corporation) and
vendor-specific Attribute Type 46. Implementations MAY accept AVPs
with these values as equivalent to the message described in this
document, but MUST NOT transmit an AVP using these values.
5. IANA Considerations
This AVP includes an enumerated cause code value, called the "Discon-
nect Code." Values 0 through 20 are described in this document.
Values 21 through 32767 (inclusive) are assigned by the IANA subject
to IESG Approval. Values 32768 through 65279 (inclusive) are
assigned by the IANA on a First Come First Served basis, and are
intended for vendor-specific features. Values 65280 through 65535
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(inclusive) are allocated for Private or Experimental Use, and no
assignment through the IANA is expected.
6. References
[1] W. Townsley, A. Valencia, A. Rubens, G. Pall, G. Zorn, B. Palter,
``Layer 2 Tunnel Protocol (L2TP)'', RFC 2661, August 1999
[2] S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels," BCP 14 and RFC 2119, March 1997
[3] F. Yergeau, "UTF-8, a transformation format of Unicode and ISO
10646," RFC 2044, Alis Technologies, October 1996
7. Acknowledgments
The authors thank W. Mark Townsley and Thomas Narten for their com-
ments and help.
8. Contacts
8.1. L2TP Working Group Chair
W. Mark Townsley
Cisco Systems
7025 Kit Creek Road
PO Box 14987
Research Triangle Park, NC 27709
Email: <townsley@cisco.com>
8.2. Authors
Rohit Verma
180 N. Stetson Avenue
Chicago IL 60601
Phone: +1 312 374 2475
Fax: +1 312 870 2475
Email: <rverma@dc.com>
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Madhvi Verma
1800 W. Central Road
Mount Prospect IL 60056
Phone: +1 847 797 6528
Fax: +1 847 222 2424
Email: <Madhvi_Verma@3com.com>
James Carlson
Sun Microsystems
1 Network Drive MS UBUR02-212
Burlington MA 01803-2757
Email: <james.d.carlson@sun.com>
Phone: +1 781 442 2084
Fax: +1 781 442 1677
9. Standard Notices
9.1. IETF Intellectual Property Statement
"The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to per-
tain to the implementation or use of the technology described in this
document or the extent to which any license under such rights might
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any effort to identify any such rights. Information on the IETF's
procedures with respect to rights in standards-track and standards-
related documentation can be found in BCP-11. Copies of claims of
rights made available for publication and any assurances of licenses
to be made available, or the result of an attempt made to obtain a
general license or permission for the use of such proprietary rights
by implementers or users of this specification can be obtained from
the IETF Secretariat.
"The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights, which may cover technology that, may be required to practice
this standard. Please address the information to the IETF Executive
Director."
9.2. ISOC Copyright Statement
"Copyright (C) The Internet Society 2001. All Rights Reserved.
"This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
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or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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