netdev - Re: [PATCH net-next] ipv6: RTAX_FEATURE_ALLFRAG causes inefficient TCP segment sizing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <171c22af5ae0b0f70e7b81baad260de6@greed.fud.no>
Date:	Wed, 25 Apr 2012 11:51:37 +0200
From:	Tore Anderson <tore@....no>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Maciej Żenczykowski <maze@...gle.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Tom Herbert <therbert@...gle.com>
Subject: Re: [PATCH net-next] ipv6: RTAX_FEATURE_ALLFRAG causes inefficient TCP segment sizing

* Eric Dumazet

> Hmm, but what if we change linux to choice a) instead of b) ?
>
> That is, not cap mtu to minimum value 1280 (and not use anymore
> RTAX_FEATURE_ALLFRAG) : dst_allfrag() would be always false.

Yep.

> In this case, do we still need to send the frag header ?

No - the (translated) IPv4 packet should then fit onto the small-MTU
IPv4 link without any fragmentation (by the IPv4 router) required. So
you end up with perfectly regular end-to-end Path MTU Discovery.

Tore
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html