Recommendation to Use the Ethernet Control Word
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From: The IESG <firstname.lastname@example.org> To: IETF-Announce <email@example.com> Cc: The IESG <firstname.lastname@example.org>, email@example.com, Matthew Bocci <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com Subject: Protocol Action: 'Use of Ethernet Control Word RECOMMENDED' to Proposed Standard (draft-ietf-pals-ethernet-cw-07.txt) The IESG has approved the following document: - 'Use of Ethernet Control Word RECOMMENDED' (draft-ietf-pals-ethernet-cw-07.txt) as Proposed Standard This document is the product of the Pseudowire And LDP-enabled Services Working Group. The IESG contact persons are Alvaro Retana, Martin Vigoureux and Deborah Brungard. A URL of this Internet Draft is: https://datatracker.ietf.org/doc/draft-ietf-pals-ethernet-cw/
Technical Summary The pseudowire (PW) encapsulation of Ethernet, as defined in RFC 4448, specifies that the use of the control word (CW) is optional. In the absence of the CW an Ethernet pseudowire packet can be misidentified as an IP packet by a label switching router (LSR). This in turn may lead to the selection of the wrong equal-cost-multi- path (ECMP) path for the packet, leading in turn to the misordering of packets. This problem has become more serious due to the deployment of equipment with Ethernet MAC addresses that start with 0x4 or 0x6. The use of the Ethernet PW CW addresses this problem. This document recommends the use of the Ethernet pseudowire control word in all but exceptional circumstances. This document updates RFC 4448. Working Group Summary The document was developed to try to resolve observed misordering of packets on Ethernet PWs which can occur when ECMP is applied and the packet aliases for an IPv4 or IPv6 packet. Although this problem is already well understood, and a solution (the PW control word) is widely implemented and deployed. However the CW was defined as optional in RFC4448 and so there are some cases where it is not implemented or not enabled by operators. There are reports that this is becoming an increasing problem with the IEEE allocating MAC addresses starting with 0x4 or 0x6, and so stronger recommendations are required. Document Quality No concerns about the quality of the document. It represents WG consensus, and it has been widely reviewed and discussed on the list over a number of years. The document does not specify any MIB changes or additions which would need review. Personnel Who is the Document Shepherd for this document? Matthew Bocci Who is the Responsible Area Director? Deborah Brungard
RFC Editor Note Section 4 1st paragraph/2nd sentence: OLD: This document updates [RFC4448] to state that where both the ingress PE and the egress PE support the Ethernet pseudowire control word, then the CW MUST be used. NEW: This document updates [RFC4448] to state that both the ingress PE and the egress PE SHOULD support the Ethernet pseudowire control word, and that if supported the CW MUST be used.