Network Working Group N. McGill
Internet-Draft C. Pignataro, Ed.
Intended status: Standards Track Cisco Systems
Expires: July 4, 2008 Jan 2008
L2TPv3 Extended Circuit Status Values
draft-nmcgill-l2tpext-circuit-status-extensions-00.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
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.
This Internet-Draft will expire on July 4, 2008.
Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract
This document defines additional Layer 2 Tunneling Protocol (L2TPv3)
bit values to be used within the "Circuit Status" Attribute-Value
Pair (AVP) to communicate more granular error states for Access
Circuits and Pseudowires.
McGill & Pignataro Expires July 4, 2008 [Page 1]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Specification of Requirements . . . . . . . . . . . . . . . 3
2. L2TP Extended Circuit Status Values . . . . . . . . . . . . . . 3
3. Clarifications . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . . . 9
McGill & Pignataro Expires July 4, 2008 [Page 2]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
1. Introduction
Currently the L2TPv3 Circuit Status AVP [RFC3931] is able to convey
the UP/DOWN status of an access circuit. However, a finer
granularity is often useful to determine the direction of the fault
as has been added for MPLS-based pseudowires, see [RFC4446].
Additionally, it is useful (in redundancy scenarios) to be able to
indicate if a pseudowire is in a standby state, where it is fully
established but is not switching data. Again, such functionality is
available for MPLS based pseudowires, see
[I-D.muley-dutta-pwe3-redundancy-bit].
The proposal is to provide extended circuit status bit values for
L2TPv3 and to add them in a manner such that it is backwards
compatible with the current Circuit Status AVP. These new bits are
applicable to all pseudowires types.
1.1. 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 [RFC2119].
2. L2TP Extended Circuit Status Values
The Circuit Status AVP (ICRQ, ICRP, ICCN, OCRQ, OCRP, OCCN, SLI),
Attribute Type 71, indicates the initial status of or a status change
in the access circuit to which the session is bound.
The Attribute Value field for this AVP has the following format:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |N|A|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(A) 0x0001 Local Attachment Circuit is up/active/ready
(N) 0x0002 Notification is for a new circuit.
Where, the A (Active) bit indicates whether the circuit is up/active/
ready (1) or down/inactive/not-ready (0).
The N (New) bit is provided to emulate (Frame Relay) NNI signalling
between PEs. It MAY be used to convey that a circuit has been
McGill & Pignataro Expires July 4, 2008 [Page 3]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
reprovisioned or newly provisioned at the PE. It is uncertain as to
what use the receiving PE can make of this bit, although it MAY
include logging. It is proposed to deprecate this bit as it is of
little or no use, hence this bit SHOULD be ignored on receipt and is
OPTIONAL to send. For reference, see section 3.4 of [RFC4591] which
does not specify any additional usage beyond the setting of in the
ICRQ, ICRP and clearing in all other control messages.
The proposal is to extend this bitmap of values to allow for finer
granularity of status reporting.
The new values are:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |S|E|I|T|R|0|A|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Bit Bit-Value Name
--------------------------------------------------------------------
(A) 0x0001 Active: Pseudowire has no faults
(R) 0x0004 Local Attachment Circuit (ingress) Receive Fault
(T) 0x0008 Local Attachment Circuit (egress) Transmit Fault
(I) 0x0010 Local PSN-facing PW (ingress) Receive Fault
(E) 0x0020 Local PSN-facing PW (egress) Transmit Fault
(S) 0x0040 Pseudowire is in standby mode
Where the new bits values have the following meanings:
(R), Local Attachment Circuit (ingress) Receive Fault
Fault Here
|
|
| +----------------------+ +----------------------+
| Rx| LCCE |Egress | Peer LCCE |
--X-->| |-------->| |
| L2TPv3 | | L2TPv3 |
Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit |
<-----| |<--------| |
+----------------------+ +----------------------+
An alarm or fault has occurred at the local attachment circuit
such that it is unable to receive traffic. It can still transmit
traffic.
McGill & Pignataro Expires July 4, 2008 [Page 4]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
(T), Local Attachment Circuit (egress) Transmit Fault
+----------------------+ +----------------------+
Rx| LCCE |Egress | Peer LCCE |
----->| |-------->| |
| L2TPv3 | | L2TPv3 |
Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit |
<--X--| |<--------| |
| +----------------------+ +----------------------+
|
|
Fault Here
A fault has occurred at the local attachment circuit such that it
is unable to transmit traffic. It can still receive traffic.
(I), Local PSN-facing PW (ingress) Receive Fault
+----------------------+ +----------------------+
Rx| LCCE |Egress | Peer LCCE |
----->| |-------->| |
| L2TPv3 | | L2TPv3 |
Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit |
<-----| |<---X----| |
+----------------------+ | +----------------------+
|
|
Fault Here
A fault has occurred in the receive direction between the local
endpoint and the remote L2TP endpoint.
Note that a fault at the session level would not necessarily
trigger a L2TP control channel timeout. The means of detecting
this fault are outside the scope of this document; as an example,
detection may be via BFD.
(E), Local PSN-facing PW (egress) Transmit Fault
Fault Here
|
|
+----------------------+ | +----------------------+
Rx| LCCE |Egress| | Peer LCCE |
----->| |------X->| |
| L2TPv3 | | L2TPv3 |
Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit |
<-----| |<--------| |
McGill & Pignataro Expires July 4, 2008 [Page 5]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
+----------------------+ +----------------------+
A fault has occurred in the transmit direction between the local
endpoint and the remote L2TP endpoint.
Note that a fault at the session level would not necessarily
trigger a L2TP control channel timeout. The means of detecting
this fault are outside the scope of this document; as an example,
detection may be via BFD.
(S), Pseudowire is in standby mode
Standby
|
|
+----------------------+ | +----------------------+
Rx| LCCE |Egress | Peer LCCE |
----->| |---X---->| |
| L2TPv3 | | L2TPv3 |
Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit |
<-----| |<--X-----| |
+----------------------+ | +----------------------+
|
|
Standby
The pseudowire has been placed into a standby mode which means
that although it can be signalled and is operational, it is NOT
switching traffic. Any received traffic SHOULD be dropped.
Traffic MUST NOT be transmitted.
3. Clarifications
The following are clarifications regarding the usage of these new
bits:
(*) If multiple faults occur, they MUST be bitwise-OR-d together.
(*) The (A) bit MUST NOT be set until all fault flags are cleared.
This behavior allows an endpoint to be backwards compatible with a
remote endpoint that does not understand these new status bits.
(*) [RFC3931] defined the (A) bit as pertaining to local access
circuit state only. This draft redefines it as meaning that "no
faults are present on the local pseudowire endpoint."
(*) If any of the (R), (T), (I) or (E) bits are set, then the (A) bit
McGill & Pignataro Expires July 4, 2008 [Page 6]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
MUST be cleared. That is, (R, T, I, E) are a more granular
definition of (A), such that OR-ing the bits provides an inverted
(A).
(*) If (A) is clear and (R, T, I, E) are clear, it means that there
is no extended circuit status.
(*) The (S) bit can be set in conjunction with any other bit,
including (A). i.e. an access circuit may be experiencing a fault or
be active and also be in standby.
(*) Leaving standby mode is indicated by the clearing of the (S) bit.
(*) The (N) bit has been deprecated.
4. Security Considerations
No additional security considerations exist with extending this
attribute.
5. IANA Considerations
All values provide above are tentative prior to adoption by IANA.
6. Acknowledgements
The author wishes to thank Carlos Pignataro, Muhammad Yousuf, Mark
Townsley and George Wilkie for comments received.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[RFC4591] Townsley, M., Wilkie, G., Booth, S., Bryant, S., and J.
Lau, "Frame Relay over Layer 2 Tunneling Protocol Version
3 (L2TPv3)", RFC 4591, August 2006.
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446, April 2006.
McGill & Pignataro Expires July 4, 2008 [Page 7]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
[RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.
[I-D.muley-dutta-pwe3-redundancy-bit]
Muley, P., Bocci, M., Newton, J., and L. Martini,
"Preferential Forwarding Status bit definition",
draft-muley-dutta-pwe3-redundancy-bit-02 (work in
progress), November 2007.
Authors' Addresses
Neil McGill
Cisco Systems
7025-4 Kit Creek Rd
PO Box 14987
Research Triangle Park, NC 27709
USA
Email: nmcgill@cisco.com
Carlos Pignataro (editor)
Cisco Systems
7200 Kit Creek Road
PO Box 14987
Research Triangle Park, NC 27709
USA
Phone: +1-919-392-7428
Fax: +1-919-869-1438
Email: cpignata@cisco.com
McGill & Pignataro Expires July 4, 2008 [Page 8]
Internet-Draft L2TPv3 Extended Circuit Status Values Jan 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat 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 on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
McGill & Pignataro Expires July 4, 2008 [Page 9]