Note: The terms of reference below were agreed at the February 2008 meeting of SG 15, consequently the term T-MPLS is used. As noted above in December 2008 both the IETF and the ITU-T will use the term MPLS-TP when refering to the extensions to MPLS technology being developed by the IETF to meet the requirements of the transport network.
1. Introduction
The IETF sent a liaison statement published as TD 435 (WP3) expressing concerns that certain inconsistencies exist between MPLS and T-MPLS. The IETF therefore requested that the ITU-T either: (1) Work in cooperation to extend the IETF's MPLS technologies through the IETF Standards Process or: (2) Decide to use its own Ethertypes and maintain separation of codepoints in the future, change the name of the technology so it is not easily confused with IETF MPLS and work independently.
Discussion of this topic at the Q12/15 interim meeting in Stuttgart with IETF leadership who attended that meeting resulted in an agreement for a collaborative approach for T-MPLS standardization. The agreement includes the creation of a joint working team (JWT) involving appropriate experts from ITU-T and IETF (see TD447(WP3) Annex 4). The JWT is the union of the ITU-T ad hoc group on T-MPLS and the IETF T-MPLS design team. The JWT will allow the IETF and ITU-T to work in close collaboration on T-MPLS to understand the implications of these options and facilitate the subsequent development of solutions that ensure that the required degree of MPLS/T-MPLS compatibility, consistency, and coherence, recognizing that the sole design authority for MPLS resides in the IETF, and the domain of expertise for Transport Network Infrastructure resides in ITU-T SG15. The JWT has a limited lifetime with extensions requiring approval from both organizations. The Joint Working Team has no official affiliation or status with either the ITU-T or the IETF but provides a forum for open communication and cooperative work.
The ad hoc group on T-MPLS was established by SG15 in February 2008 and is expected to complete its work by September 2009. The ad hoc group on T-MPLS provides the organizational structure that will allow experts from the ITU-T to participate in the work of the JWT and provide reports to the ITU-T. The IETF will have it’s own organizational construct (T-MPLS Design Team).
2. Objectives and Tasks
The work under consideration on T-MPLS and MPLS includes:
- Forwarding Plane
- OAM
- Control Plane
- Network survivability (e.g. Protection Switching, restoration)
- Transport equipment and network management. (e.g. Transport network OSS integration in a multi technology/multi vendor environment).
Neither the ad hoc group on T-MPLS nor the joint working team has the authority to create or modify any existing ITU-T Recommendations or IETF RFCs. Any such work will be progressed via the normal process of the respective standards body.
The joint working team will provide regular reports on the progress of its work to both the IETF and the ITU-T.
The first task for the joint working team is to select an option from the IESG and IAB liaison and propose a work plan. This proposal will be based on an evaluation of the impact and the estimated of the effort required to execute either option. Following the endorsement (or modification) of the proposal by the ITU-T and the IETF the joint working team will be responsible for the execution of the plan.
With respect to the first option, harmonization of MPLS and T-MPLS:
Transport equipment and network management. (e.g. Transport network OSS integration in a multi technology/multi vendor environment).
The joint working team will examine existing approved or consented ITU-T Recommendations, and will report on the results of their review. If inconsistencies, incompatibilities or omissions are identified with the use of IETF MPLS technology, then they will be resolved either by proposing amendments to ITU-T Recommendations or by initiating new work in the IETF using the normal ITU-T or IETF processes as appropriate.
Future work will be progressed by first analyzing the requirements and desired functionality within the joint working team. While T-MPLS makes extensive use of IETF MPLS technology, there are aspects that lie outside the domain of expertise in the IETF (e.g. management of transport equipment). The joint working team will be responsible for identifying and recommending what aspects of the requirements, solutions and architecture should be formally documented in IETF RFCs using the IETF Standards Process or, ITU-T Recommendations using the ITU-T process. It is also realized that there are areas of technology (e.g. OAM and network survivability) that straddles the interests and technology of both groups. The joint working team will examine these technologies to create a proposal on the modifications necessary to develop an architecture that it is compatible, coherent and consistent between both transport and IETF MPLS technologies. In these areas both standards processes will be used in order to create an environment that will complement and validate each other. The output of the joint working team will be a roadmap which provides the requirements, scope and framework for future standardization to progress in each organization. In all cases, the actual standardization work will be progressed under the process of the appropriate organization (IETF or ITU-T).
With respect to the second option (ensuring full separation): The joint working team will evaluate the implication of separation and make proposals on the following areas:
- The required degree of separation;
- How the separation will be achieved (e.g. different code points);
- What other code points will be affected as the technology evolves:
- What supporting protocols and technologies will be impacted (e.g. control plane)
- How will any common aspects of MPLS and T-MPLS will be documented in ITU-T Recommendations for example should the ITU-T Recommendations:
- Retain references to RFCs or should new material be developed
- Retain the IP/MPLS description of the frame structure (e.g. label 14, TTL, EXP, TLV)
- Should G.8110.1 (T-MPLS Architecture) continue to be based on G.8110 (MPLS architecture).
- Any other relevant aspects that are identified during the evaluation
- The name for the ITU-T technology
- The degree of cooperation or joint work required for future development of T-MPLS.
Depending on the information provided by the JWT and the decision made on option 1 or 2 by SG15, the subsequent work and continuation of the JWT will be determined at that time.
3. Participation
Participation is open to individuals from organizations with expertise and specifications applicable to T-MPLS, including the following:
- ITU-T Q5/13 Note: Moved to Q10/15 for the 2009-2012 Study period
- ITU-T Q3/15
- ITU-T Q9/15
- ITU-T Q11/15
- ITU-T Q12/15
- ITU-T Q14/15
- IETF MPLS Working Group
- IETF PWE3 Working Group
- IETF L2VPN Working Group
- IETF CCAMP Working Group
- IETF BFD Working Group
4. Time Schedule
- The initial evaluation of the options will be completed by April 2008.
For tasks related to harmonization or separation of ITU-T Recommendations and IETF RFCs related to currently standardized T-MPLS capabilities:
- Any modifications required to existing ITU-T Recommendations should be identified and submitted into the ITU-T standards process no later than the December 2008 plenary of ITU-T Study Group 15.
- Any additions or modifications to IETF MPLS or PW RFCs necessary to support the T-MPLS functionality currently approved ITU-T Recommendations should be submitted into the IETF standards process by August 2008.
For tasks related to future evolution of T-MPLS:
- The scope and requirements for new ITU-T Recommendations and next phases of existing ITU-T Recommendations should be identified no later than the September 2009 plenary of ITU-T Study Group 15.
- The scope and requirements for IETF MPLS or PW standards necessary to support the future evolution of T-MPLS should be identified by December 2008. At the conclusions of these tasks, an assessment will be performed to determine whether:
- The roles and responsibilities of each group are sufficiently well understood that the joint working team can be disbanded and future coordination can be done using the normal liaison statement process; or
- Remaining work still requires a great deal of joint discussion and active work, in which case a request should be made for continuation of the group beyond September 2009 with potentially a new charter.
5. Method of Working
Registration is required to participate in the activities of the ad hoc group on T-MPLS or to access its documents. For registration and other information, see the ad hoc group on T-MPLS web site at:
Communication of the ad hoc group will be facilitated by a joint mailing list ahmpls-tp@lists.itu.int, and it will regularly report to both ITU-T and IETF on its progress. General announcements (e.g., meeting notices) regarding the ad hoc group on T-MPLS will also be disseminated via the ITU-T SG 15 general reflector t09sg15all@lists.itu.int. Use of electronic means, including email, teleconferences, collaborative software, etc. is preferred. However face-to-face meetings are also possible. In general, face-to-face meetings should be planned in conjunction with a meeting of one of the participating organizations to minimize travel expenses for participants.
The ad hoc group will make its decisions by consensus at meetings or via email.
The ad hoc group may generate liaison statements to participating organizations as needed.
If necessary, more detailed working procedures may be generated by the ad hoc group. Specifically the creation of the JWT. The JWT is intended to be a small focused group of technical experts who will make rapid progress on the analysis of the problem. The membership of this group will be controlled by the co chairs. The results of the analysis and any proposals will be made available to the members of the ad hoc group as rapidly as possible.
6. Document Submission Process
TIES user can upload documents directly to the site using the following details:
Via FTP: File Transfer Protocol (FTP) client
- Host Name: ifa.itu.int
- Host Type: Unix(Standard)
- Remote Host Name: /t/2009/sg15/ahmpls-tp/
- Log in with your TIES or GUEST credentials
Material such as text, diagrams, etc., submitted as input to the work of this ad hoc group is presumed by the ad hoc group to have no restrictions in order to permit the normal distribution of this material for discussions within the ad hoc group and possible use, in whole or in part, in any resulting ad hoc group document submitted to SG 15 for standardization. By submitting input to the ad hoc group, authors acknowledge this condition of submission. In addition, authors may state any specific conditions on other uses of their contribution. The chairs may be forced to moderate the email list to achieve consensus.
7. Document Usage Policy
Usage of ad hoc group documents, published on the web/ftp site, will be governed by the following policy:
"The documents on this web/ftp site are provided to further the aims of the ad hoc group only. Participants are not allowed to use these documents for purposes that go beyond the scope of the ad hoc group work, without prejudice to other rights a participant may have with respect to any of these documents. If any material contributed to the ad hoc group on T-MPLS is shared with others not participating in the ad hoc group on T-MPLS, the sharer is requested to make the recipients aware of the above constraint."
8. Finances
The ad hoc group will work primarily electronically. Face-to-face meetings may be held, when considered necessary by both co chairs, in conjunction with otherwise scheduled meetings of any of the participating groups with the agreement and support of the host, or if necessary, a host may offer to sponsor a standalone meeting of the ad hoc group. The ad hoc group will make use of already existing electronic tools and facilities that are available through ITU-T and IETF. Therefore, the expectation is that any incremental expenses for either organization will be minimal. | 