Re: I-D Action: draft-herbert-6man-eh-limits-00.txt
Brian E Carpenter <brian.e.carpenter@gmail.com> Mon, 28 June 2021 23:23 UTC
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Subject: Re: I-D Action: draft-herbert-6man-eh-limits-00.txt
To: 6man <ipv6@ietf.org>
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From: Brian E Carpenter <brian.e.carpenter@gmail.com>
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Date: Tue, 29 Jun 2021 11:22:59 +1200
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I think the basic proposal is to limit extension headers to a total of 64 bytes, if outside a limited domain (TL;DR: see page 9 of the draft). Now, I'm well aware that shim6 (RFC5533) is not used; the main reason being that the Internet is largely opaque to its extension headers. Nevertheless, shim6 is a fully worked out use case for extension headers that would need to cross the open Internet. I wrote in 2016 as part of the RFC2460bis discussion that "I was surprised a while back to discover that a legal shim6 extension header could in fact exceed a kilobyte, specifically it is only limited to 1240 bytes by the standard." More to the point, a typical "large" shim6 extension header would be 40 bytes between dual-homed hosts. If hosts were more-than-dual-homed and therefore needed to exchange more addresses, the extension header would increase by 16 bytes per extra address. So, if we prescribed a 64 byte limit, we would also limit what extension headers can achieve. Regards Brian On 23-Jun-21 13:01, internet-drafts@ietf.org wrote: > > A New Internet-Draft is available from the on-line Internet-Drafts directories. > > > Title : Limits on Sending and Processing IPv6 Extension Headers > Author : Tom Herbert > Filename : draft-herbert-6man-eh-limits-00.txt > Pages : 18 > Date : 2021-06-22 > > Abstract: > This specification defines various limits that may be applied to > receiving, sending, and otherwise processing packets that contain > IPv6 extension headers. The need for such limits is pragmatic to > facilitate interoperability amongst hosts and routers in the presence > of extension headers and thereby increasing the feasibility of > deployment of extension headers. > > > The IETF datatracker status page for this draft is: > https://datatracker.ietf.org/doc/draft-herbert-6man-eh-limits/ > > There is also an htmlized version available at: > https://datatracker.ietf.org/doc/html/draft-herbert-6man-eh-limits-00 > > > Internet-Drafts are also available by anonymous FTP at: > ftp://ftp.ietf.org/internet-drafts/ > > > _______________________________________________ > I-D-Announce mailing list > I-D-Announce@ietf.org > https://www.ietf.org/mailman/listinfo/i-d-announce > Internet-Draft directories: http://www.ietf.org/shadow.html > or ftp://ftp.ietf.org/ietf/1shadow-sites.txt >
- Re: I-D Action: draft-herbert-6man-eh-limits-00.t… Brian E Carpenter
- Re: I-D Action: draft-herbert-6man-eh-limits-00.t… Nick Hilliard
- Re: I-D Action: draft-herbert-6man-eh-limits-00.t… Tom Herbert