Subject: [conex] Fwd: RFC 6040 on Tunnelling of Explicit Congestion Notification

From: Bob Briscoe <[email-masked]>
Date: Fri, 03 Dec 2010 19:37:03 +0000

Folks,

RFC6040 has just been published.

As it gets deployed, it will remove an otherwise awkward barrier to 
ConEx deployment. Because it ensures ECN is visible in the outer 
header of all IP-in-IP tunnels (IPsec tunnels were OK in this 
respect, but non-IPsec tunnels were not).

This is particularly important for LTE, which uses IP-in-IP tunnels 
everywhere. So, it's important to ensure that LTE equipment is all 
compliant with RFC6040.

This means IP-in-IP, MPLS-in-IP and MPLS-in-MPLS all now expose 
upstream ECN congestion markings in the outer header,... at least if 
they comply with the latest specs: RFC6040 and RFC5129.

This also makes it more likely that future standardisation of ECN for 
other link layers (esp IEEE802) will follow the same model.

Over a year ago I wrote a pre-Internet Draft giving guidelines on 
adding ECN to other technologies below IP (e.g. IEEE802). It used 
text removed from the early I-D that became RFC6040 - when we decided 
to narrow its scope to just IP-in-IP:
<http://www.bobbriscoe.net/projects/ipe2eqos/pcn/marking/draft-briscoe-tsvwg-ecn-encap-guidelines-00a.txt>
Would anyone support taking this through the IETF? Probably as a BCP? 
Probably through tsvwg?

Bob

PS. Being a change to IP and to IPsec, it took some heavy lifting to 
get through. I submitted the first individual draft at the time we 
were thinking about the Trilogy proposal (Mar 1997).
<http://www.arkko.com/tools/lifecycle/draft-ietf-tsvwg-ecn-tunnel-timing.html>

>To: <[email-masked]>, <[email-masked]>
>Subject: RFC 6040 on Tunnelling of Explicit Congestion Notification
>From: <[email-masked]>
>Date: Mon, 29 Nov 2010 22:27:37 -0800
>CC: <[email-masked]>, <[email-masked]>
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>A new Request for Comments is now available in online RFC libraries.
>
>
>         RFC 6040
>
>         Title:      Tunnelling of Explicit Congestion Notification
>         Author:     B. Briscoe
>         Status:     Standards Track
>         Stream:     IETF
>         Date:       November 2010
>         Mailbox:    [email-masked]
>         Pages:      35
>         Characters: 89412
>         Updates:    RFC3168, RFC4301, RFC4774
>
>         I-D Tag:    draft-ietf-tsvwg-ecn-tunnel-10.txt
>
>         URL:        http://www.rfc-editor.org/rfc/rfc6040.txt
>
>This document redefines how the explicit congestion notification
>(ECN) field of the IP header should be constructed on entry to and
>exit from any IP-in-IP tunnel.  On encapsulation, it updates RFC 3168
>to bring all IP-in-IP tunnels (v4 or v6) into line with RFC 4301
>IPsec ECN processing.  On decapsulation, it updates both RFC 3168 and
>RFC 4301 to add new behaviours for previously unused combinations of
>inner and outer headers.  The new rules ensure the ECN field is
>correctly propagated across a tunnel whether it is used to signal one
>or two severity levels of congestion; whereas before, only one
>severity level was supported.  Tunnel endpoints can be updated in any
>order without affecting pre-existing uses of the ECN field, thus
>ensuring backward compatibility.  Nonetheless, operators wanting to
>support two severity levels (e.g., for pre-congestion notification --
>PCN) can require compliance with this new specification.  A thorough
>analysis of the reasoning for these changes and the implications is
>included.  In the unlikely event that the new rules do not meet a
>specific need, RFC 4774 gives guidance on designing alternate ECN
>semantics, and this document extends that to include tunnelling
>issues.  [STANDARDS-TRACK]
>
>This document is a product of the Transport Area Working Group 
>Working Group of the IETF.
>
>This is now a Proposed Standard Protocol.
>
>STANDARDS TRACK: This document specifies an Internet standards track
>protocol for the Internet community,and requests discussion and suggestions
>for improvements.  Please refer to the current edition of the Internet
>Official Protocol Standards (STD 1) for the standardization state and
>status of this protocol.  Distribution of this memo is unlimited.
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________________________________________________________________
Bob Briscoe,                                BT Innovate & Design

---

From: "Toby Moncaster" <[email-masked]>
Date: Sat, 4 Dec 2010 16:12:33 -0000

inline

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf
> Of Bob Briscoe
> Sent: 03 December 2010 19:37
> To: ConEx IETF list
> Subject: [conex] Fwd: RFC 6040 on Tunnelling of Explicit Congestion
> Notification
> 
> Folks,
> 

Congratulations. A useful new RFC that addresses some of the more silly
inconsistencies in IP-in-IP tunnelling...

> everywhere. So, it's important to ensure that LTE equipment is all

Unfortunately I suspect there may already be quite a lot of kit out there
that isn't compliant!

> Would anyone support taking this through the IETF? Probably as a BCP?

I think this would be a good idea. Might it also be sensible to start
working out if any liaison is needed with other standards bodies (since this
impacts their standards)?

As I see it there are two approaches - a very broad guidelines document
stating what the end result should be or a number of more specific documents
for groups of sub-IP technologies. Although the first approach is cleaner it
runs a risk of just getting ignored. 

Toby

> _______________________________________________
> conex mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/conex

---

From: "Joe Babiarz" <[email-masked]>
Date: Sat, 4 Dec 2010 11:55:49 -0500

Thanks Bob for getting the ECN marking when tunneling issue resolved. 
Regards, Joe.
[email-masked]

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Bob Briscoe
Sent: Friday, December 03, 2010 2:37 PM
To: ConEx IETF list
Subject: [conex] Fwd: RFC 6040 on Tunnelling of Explicit Congestion
Notification

Folks,

Over a year ago I wrote a pre-Internet Draft giving guidelines on 
adding ECN to other technologies below IP (e.g. IEEE802). It used 
text removed from the early I-D that became RFC6040 - when we decided 
to narrow its scope to just IP-in-IP:
<http://www.bobbriscoe.net/projects/ipe2eqos/pcn/marking/draft-briscoe-tsvwg
-ecn-encap-guidelines-00a.txt>
Would anyone support taking this through the IETF? Probably as a BCP? 
Probably through tsvwg?

Bob

PS. Being a change to IP and to IPsec, it took some heavy lifting to 
get through. I submitted the first individual draft at the time we 
were thinking about the Trilogy proposal (Mar 1997).
<http://www.arkko.com/tools/lifecycle/draft-ietf-tsvwg-ecn-tunnel-timing.htm
l>