Re: [IPv6] Comments on draft-ietf-6man-hbh-processing-12

["Eric Vyncke (evyncke)" <[e-mail]>]

Tim,

*Very* interesting return of information as R&E networks are probably easier to approach with a “research” topic such as EH drops.

If the R&E networks drops are not by policy, then I am afraid that either the policy is not correctly applied or there is a platform limitation (e.g., applying a L4 ACL forces line cards to parse the EH chain until either the L4 header is found or max size of EH is reached).

-éric

From: ipv6 <[e-mail]> on behalf of Tim Chown <Tim.Chown=[e-mail]>
Date: Wednesday, 6 December 2023 at 15:02
To: Geoff Huston <[e-mail]>
Cc: 6man <[e-mail]>
Subject: Re: [IPv6] Comments on draft-ietf-6man-hbh-processing-12
Hi,

> In the first part of this yer, with the assistance from Gorry Fairhust and Anna Costura ot the Univ of Aberdeen we conducted a related experiment using a server located at that institution (which does NOT drop EH packets,) connected to JANET (which also  does not drop EH packets). However, we found that the major transit providers in the UK DO drop EH packets, including BT, BSKYB, Level 3, H3GUK, EE and ZEN. So we found it hard to see further afield.

As someone who works for Jisc, who operate Janet, we noted from Gorry’s experiment that there was indeed at least one upstream transit provider we use to commercial networks who dropped packets with EHs. On contacting one they denied that such drops were configured or deliberate, despite the evidence being presented by Anna.  We found no way forward from there to determine the underlying cause.

> Within the UK the result we found was that most transit paths encounter EH dropping at some point, and that means we can't "leap over" these obstruction points and look behind them. So I'm unable to device a broad scale  measurement that measures EH drop rates in the larger Internet.

It would be interesting to determine the drop rates in the R&E networks. Our R&E connectivity is almost exclusively via GÉANT, who connect the European NREN backbones, save for a direct path to HEAnet in Ireland. We *think* that R&E networks don’t drop, but as yet have no evidence. I suppose you could tag the R&E networks as “limited domain” in that the new alt-mark and min mtu discovery RFCs published last year might be supported there.

Tim

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