From: IAB & IESG To: Malcolm Johnson (Malcolm.Johnson@itu.int) CC: Reinhard Scholl (Reinhard.Scholl@itu.int) Yoichi Maeda (yoichi.maeda@ntt-at.co.jp) Steve Trowbridge (sjtrowbridge@alcatel-lucent.com) Greg Jones (greg.jones@itu.int) Brian W Moore (brian@bwmc.demon.co.uk) Boguslaw Georges Sebek (georges.sebek@itu.int) Neil Seitz (neal@its.bldrdoc.gov) IESG (iesg@ietf.org) IAB (iab@ietf.org) Stewart Bryant (stbryant@cisco.com) Scott Bradner (sob@harvard.edu) statements@ietf.org Subject: T-MPLS use of the MPLS Ethertypes Response Contact: IAB (iab@ietf.org) Technical Contact: Stewart Bryant (stbryant@cisco.com) Purpose: For action We are pleased that the IETF and the ITU continue to work together with the mutual goal of providing the infrastructure needed to provide reliable global communications. In that context, it is important that we alert each other when issues arise that may be detrimental to this important mutual goal. To that end, we unfortunately have to draw your attention to the following issue that is causing us significant concern: In the liaison statement from the IETF MPLS WG to ITU-T Study Group 15 Dated 13th September 2006 (https://datatracker.ietf.org/documents/LIAISON/file366.txt), the IETF described a number of architectural concerns that arise as a result of the decision by ITU SG15 to use the MPLS Ethertypes for T-MPLS. The concluding paragraph of this liaison statement states: "We believe that a decision to use the MPLS Ethertypes to point to a label space other than as defined by the MPLS RFCs to be architecturally unsound and ultimately will prove to be limiting to the deployment options available in networks which employ both MPLS and T-MPLS". Working groups and leaders of the IETF's MPLS community have engaged in active dialogue with ITU-T Study Group 15 on the design of T-MPLS. We have explained that the IETF's MPLS and T-MPLS functionality and attributes are currently different and asked ITU-T representatives why the T-MPLS and MPLS Ethertypes must be identical as defined in current ITU-T recommendations. We have actively listened to explanations given by the ITU-T experts, who have stated that T-MPLS is a profile of IETF MPLS. We have met with the SG 15 T-MPLS editor, other T-MPLS experts and leaders of the IETF MPLS technologies at the IETF 69 meeting (IETF69) and agreed that in fact T-MPLS is not intended as a profile of IETF MPLS. It was mutually agreed that there is clear intention that T-MPLS would include complete duplication of IETF MPLS control, management (OAM) and forwarding planes. When IETF MPLS experts raised the issue of the coexistence of IETF MPLS and T-MPLS on the same Ethertypes, the response was the statement that IETF MPLS and T-MPLS will only be deployed in disjoint networks. Clear written and presented material by ITU representatives at IETF69 stated that there is a desire for complete interoperability of the forwarding, control and OAM planes of T-MPLS and IETF MPLS. This is also furthered by the stated desire to replicate the existing IETF PWE3 technology using identical protocol identifiers (codepoints). It is our experience that even with careful planning and design network elements rarely remain disjoint in practice. Accidental misconfiguration does occur and can be a significant factor in serious network outages and other problematic events. The future stated direction of T-MPLS is leading to the duplication of existing IETF work. Therefore, we believe that any discussion of disjoint networks and expectation that T-MPLS is or will remain a profile of IETF MPLS is unrealistic. Our long-standing experience has shown us that the only way of assuring that separation is maintained is through mutual exclusivity of codepoints. It is our opinion that the use of common Ethertypes for IETF MPLS and T-MPLS in the manner in which ITU-T SG 15 is currently progressing represents a mutual danger to both the Internet and the Transport network that will carry T-MPLS and this should not be advanced. We believe that there are two options for ITU-T and IETF to move forward. First, we could jointly agree to work together and bring T-MPLS requirements into the IETF and extend IETF MPLS forwarding, OAM and control plane protocols to meet those requirements through the IETF Standards Process. We believe this would fulfill the mutual goal of improving the functionality of the internet and transport networks and guaranteeing complete interoperability and architectural soundness. This is our preferred solution and there are historical precedents that this can be very successful for both groups. Alternatively, both organizations could jointly state that T-MPLS is a desired duplication of IETF MPLS technology and that T-MPLS and IETF MPLS must be on a different codepoints in the forwarding, OAM and control planes. We would insist that the ITU-T SG 15 make the necessary changes for complete codepoint separation of T-MPLS and IETF MPLS. We do not prefer this solution. We therefore conclude and insist that it is in the best interest of the telecommunications community that the ITU-T modify the status of current and consented T-MPLS documents to either: agree to work in cooperation to extend the IETF's MPLS technologies through the IETF Standards Process or, 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. We reiterate that our preference is to work cooperatively. It is in the best interest of all parties that the actions described in this statement are expedited so that it can be implemented before T-MPLS becomes widely deployed. On behalf of the IAB and IESG, Olaf M. Kolkman Chair, Internet Architecture Board Russell Housley Chair, Internet Engineering Task Force