Wildcard Pseudowire Type
The information below is for an old version of the document that is already published as an RFC.
This is an older version of an Internet-Draft that was ultimately published as RFC 4863.
|Authors||Luca Martini , George Swallow|
|Last updated||2015-10-14 (Latest revision 2006-10-17)|
|RFC stream||Internet Engineering Task Force (IETF)|
|Additional resources||Mailing list discussion|
|IESG||IESG state||RFC 4863 (Proposed Standard)|
|Responsible AD||Mark Townsley|
|Send notices to||(None)|
Network Working Group Luca Martini Internet Draft Cisco Systems, Inc. Category: Standards Track Expiration Date: April 2007 George Swallow Cisco Systems, Inc. October 2006 Wildcard Pseudowire Type draft-ietf-pwe3-wildcard-pw-type-02.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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Abstract Pseudowire signaling requires that the Pseudowire Type (PW Type) be identical in both directions. For certain applications the configuration of the PW Type is most easily accomplished by configuring this information at just one PW endpoint. In any form of LDP-based signaling, each PW endpoint must initiate the creation of a unidirectional LSP. In order to allow the initiation of these two LSPs to remain independent, a means of allowing the PW endpoint Martini & Swallow Standards Track [Page 1] Internet Draft draft-ietf-pwe3-wildcard-pw-type-02.txt October 2006 lacking a priori knowledge of the PW Type to initiate the creation of an LSP is needed. This document defines a Wildcard PW Type to satisfy this need. Contents 1 Introduction .............................................. 3 1.1 Conventions and Terminology ............................... 3 2 Wildcard PW Type .......................................... 4 3 Procedures ................................................ 4 3.1 Procedures when sending the wildcard FEC .................. 4 3.2 Procedures when receiving the wildcard FEC ................ 4 4 Security Considerations ................................... 5 5 IANA Considerations ....................................... 5 6 References ................................................ 5 Martini & Swallow Standards Track [Page 2] Internet Draft draft-ietf-pwe3-wildcard-pw-type-02.txt October 2006 1. Introduction Pseudowire signaling requires that the Pseudowire Type (PW Type) be identical in both directions. For certain applications the configu- ration of the PW Type is most easily accomplished by configuring this information at just one PW endpoint. In any form of LDP-based sig- naling, each PW endpoint must initiate the creation of a unidirec- tional LSP. By the procedures of [CONTROL] both label mapping messages must carry the PW type and the two unidirectional mapping messages must be in agreement. Thus within the current procedures the PW endpoint which lacks configuration must wait to receive a Label Mapping message in order to learn the PW Type, prior signaling the its unidirectional LSP. For certain applications this can become particularly onerous. For example, suppose that an ingress PE is serving as part of a gateway function between a layer two network and layer two attachment cir- cuits on remote PEs. Suppose further that the initial setup needs to be initiated from the layer 2 network, but the layer 2 signaling does not contain sufficient information to determine the PW Type. This information, however is known at the PE supporting the targeted attachment circuit. In this situation it is often desirable to allow the initiation of the initiation of the two LSPs which compose a pseudowire to remain independent. A means of allowing a PW endpoint lacking a piori knowledge of the PW Type to initiate the creation of an LSP is needed. This document defines a wildcard PW Type to satisfy this need. 1.1. Conventions and Terminology 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 [KEYWORDS]. This document introduces no new terminology. However it assumes that the reader is familiar with the terminology contained in [CONTROL] and RFC 3985, "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architec- ture" [ARCH]. Martini & Swallow Standards Track [Page 3] Internet Draft draft-ietf-pwe3-wildcard-pw-type-02.txt October 2006 2. Wildcard PW Type In order to allow a PE to initiate the signaling exchange for a pseu- dowire without knowing the pseudowire type, a new PW Type is defined. The proposed codepoint is 0x7fff [to be assigned by IANA]. The semantics are the following: 1. To the targeted PE, this value indicates that it is to determine the PW Type (for both directions) and signal that in a label mapping message back to the initiating PE. 2. For the procedures of [CONTROL] this PW Type is interpreted to match any PW Type other than itself. That is the targeted PE may respond with any valid PW Type other than the wildcard PW Type. 3. Procedures 3.1. Procedures when sending the wildcard FEC When a PE which is not configured to use a specific PW Type for a particular pseudowire, wishes to signaling an LSP for that pseu- dowire, it sets the PW Type to "wildcard". This indicates that the target PE should determine the PW Type for this pseudowire. When a Label Mapping message is received for the pseudowire, the PE checks the PW Type. If the PW Type can be supported, the PE uses this as the PW Type for both directions. If the PW Type cannot be supported or is "wildcard" it MUST respond to this message with a Label Release message with an LDP Status Code of "Generic Misconfiguration Error". Further actions are beyond the scope of this document but could include notifying the associated application (if any) or notifying network management. 3.2. Procedures when receiving the wildcard FEC When a targeted PE receives Label Mapping message indicating the wildcard PW Type, it follows the normal procedures for checking the AGI and TAII values. If the targeted PE is not configured to use a specific, non-wildcard PW Type it MUST respond to this message with a Label Release message with an LDP Status Code of "Generic Misconfigu- ration Error". Otherwise it treats the Label Mapping message as if it had indicated Martini & Swallow Standards Track [Page 4] Internet Draft draft-ietf-pwe3-wildcard-pw-type-02.txt October 2006 the PW Type it is configured to use. 4. Security Considerations This draft has little impact on the security aspects of [CONTROL]. The message exchanges remain the same. However a malicious agent attempting to connect to an access circuit would require one less piece of information. To mitigate against this, a pseudowire control entity receiving a request containing the wildcard FEC type SHOULD only proceed with setup if explicitly configured to do so for the particular AI in the TAI. Further, the reader should note the secu- rity considerations of [CONTROL] in general and those pertaining to the Generalized ID FEC Element in particular. 5. IANA Considerations This document requests the following allocation be made from the IETF consensus range of the "Pseudowire Type" registry as defined in [IANA]. PW Type Description 0x7FFF (TBA) Wildcard 6. References Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [ARCH] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005. [CONTROL] Martini, L., et al., "Pseudowire Setup and Maintenance using the Label Distribution Protocol", RFC 4447, April 2006. [IANA] Martini, L., and Townsley, M., "IANA Allocations for pseudo Wire Edge to Edge Emulation (PWE3)", RFC 4447, April 2006. Martini & Swallow Standards Track [Page 5] Internet Draft draft-ietf-pwe3-wildcard-pw-type-02.txt October 2006 Authors' Addresses Luca Martini Cisco Systems 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 Email: firstname.lastname@example.org George Swallow Cisco Systems 1414 Massachusetts Ave, Boxborough, MA 01719 Email: email@example.com Copyright Notice Copyright (C) The Internet Society (2006). 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. Expiration Date April 2007 Disclaimer of Validity 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 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. 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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 firstname.lastname@example.org. Martini & Swallow Standards Track [Page 7]