Recommendation to Use the Ethernet Control Word
RFC 8469
Document | Type |
RFC - Proposed Standard
(November 2018; Errata)
Updates RFC 4448
|
|
---|---|---|---|
Authors | Stewart Bryant , Andy Malis , Ignas Bagdonas | ||
Last updated | 2020-04-11 | ||
Replaces | draft-bryant-pals-ethernet-cw | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Matthew Bocci | ||
Shepherd write-up | Show (last changed 2018-05-10) | ||
IESG | IESG state | RFC 8469 (Proposed Standard) | |
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Deborah Brungard | ||
Send notices to | Matthew Bocci <matthew.bocci@nokia.com> | ||
IANA | IANA review state | IANA OK - No Actions Needed | |
IANA action state | No IANA Actions |
Internet Engineering Task Force (IETF) S. Bryant Request for Comments: 8469 A. Malis Updates: 4448 Huawei Category: Standards Track I. Bagdonas ISSN: 2070-1721 Equinix November 2018 Recommendation to Use the Ethernet Control Word Abstract 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 PW packet can be misidentified as an IP packet by a label switching router (LSR). This may lead to the selection of the wrong equal-cost multipath (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 Media Access Control (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 PW CW in all but exceptional circumstances. This document updates RFC 4448. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8469. Bryant, et al. Standards Track [Page 1] RFC 8469 Ethernet CW Recommendation November 2018 Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction ....................................................3 2. Specification of Requirements ...................................3 3. Background ......................................................4 4. Recommendation ..................................................5 5. Equal-Cost Multipath (ECMP) .....................................5 6. Mitigations .....................................................6 7. Operational Considerations ......................................6 8. Security Considerations .........................................7 9. IANA Considerations .............................................7 10. References .....................................................7 10.1. Normative References ......................................7 10.2. Informative References ....................................8 Acknowledgments ....................................................9 Authors' Addresses .................................................9 Bryant, et al. Standards Track [Page 2] RFC 8469 Ethernet CW Recommendation November 2018 1. Introduction The pseudowire (PW) encapsulation of Ethernet, as defined in [RFC4448], specifies that the use of the control word (CW) is optional. It is common for label switching routers (LSRs) to search past the end of the label stack to determine whether the payload is an IP packet and then, if it is, select the next hop based on the so-called "five-tuple" (IP source address, IP destination address, protocol/next-header, transport-layer source port, and transport- layer destination port). In the absence of a PW CW, an Ethernet PW packet can be misidentified as an IP packet by a label switching router (LSR) selecting the ECMP path based on the five-tuple. This may lead to the selection of the wrong ECMP path for the packet, leading in turn to the misordering of packets. Further discussion of this topic is published in [RFC4928]. Flow misordering can also happen in a single-path scenario when traffic classification and differential forwarding treatment mechanisms are in use. These errors occur when a forwarderShow full document text