Propagating Explicit Congestion Notification across IP Tunnel Headers Separated by a Shim
RFC 9601, “Propagating Explicit Congestion Notification across IP Tunnel Headers Separated by a Shim”, is a Proposed Standard document published in August 2024 by B. Briscoe. It updates RFC 2661, RFC 2784, RFC 3931, RFC 4380, RFC 6040, RFC 7450. The canonical text is published by the RFC Editor.
Abstract
RFC 6040 on "Tunnelling of Explicit Congestion Notification" made the rules for propagation of Explicit Congestion Notification (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 headers and updates the specifications of those that do not mention ECN propagation (including RFCs 2661, 3931, 2784, 4380 and 7450, which specify L2TPv2, L2TPv3, Generic Routing Encapsulation (GRE), Teredo, and Automatic Multicast Tunneling (AMT), respectively). This specification also updates RFC 6040 with configuration requirements needed to make any legacy tunnel ingress safe.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
The canonical text of RFC 9601 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.
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- RFC 9602 Segment Routing over IPv6 Segment Identifiers in the IPv6 Addressing Architecture
- RFC 9599 Guidelines for Adding Congestion Notification to Protocols that Encapsulate IP
- RFC 9603 Path Computation Element Communication Protocol Extensions for IPv6 Segment Routing
- RFC 9598 Internationalized Email Addresses in X.509 Certificates
- RFC 9604 Carrying Binding Label/SID in PCE-Based Networks
- RFC 9597 CBOR Web Token Claims in COSE Headers
- RFC 9605 Secure Frame : Lightweight Authenticated Encryption for Real-Time Media