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Propagating Explicit Congestion Notification Across IP Tunnel Headers Separated by a Shim

Document Type Expired Internet-Draft (tsvwg WG)
Author Bob Briscoe
Last updated 2021-11-26 (Latest revision 2021-05-25)
Replaces draft-briscoe-tsvwg-rfc6040bis, draft-briscoe-tsvwg-rfc6040update-shim
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Expired & archived
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Stream WG state WG Consensus: Waiting for Write-Up
Doc Shepherd Follow-up Underway
Associated WG milestone
Apr 2022
Submit 'Propagating Explicit Congestion Notification Across IP Tunnel Headers Separated by a Shim' as a Proposed Standard RFC
Document shepherd David L. Black
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to "David Black" <>
This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at:


RFC 6040 on "Tunnelling of Explicit Congestion Notification" made the rules for propagation of ECN consistent for all forms of IP in IP tunnel. This specification updates RFC 6040 to clarify that its scope includes tunnels where two IP headers are separated by at least one shim header that is not sufficient on its own for wide area packet forwarding. It surveys widely deployed IP tunnelling protocols that use such shim header(s) and updates the specifications of those that do not mention ECN propagation (L2TPv2, L2TPv3, GRE, Teredo and AMT). This specification also updates RFC 6040 with configuration requirements needed to make any legacy tunnel ingress safe.


Bob Briscoe

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)