From owner-freebsd-net Thu Oct 18 20:20: 5 2001 Delivered-To: freebsd-net@freebsd.org Received: from khavrinen.lcs.mit.edu (khavrinen.lcs.mit.edu [18.24.4.193]) by hub.freebsd.org (Postfix) with ESMTP id 3DB5B37B403 for ; Thu, 18 Oct 2001 20:20:02 -0700 (PDT) Received: (from wollman@localhost) by khavrinen.lcs.mit.edu (8.11.4/8.11.4) id f9J3Jx371649; Thu, 18 Oct 2001 23:19:59 -0400 (EDT) (envelope-from wollman) Date: Thu, 18 Oct 2001 23:19:59 -0400 (EDT) From: Garrett Wollman Message-Id: <200110190319.f9J3Jx371649@khavrinen.lcs.mit.edu> To: Lars Eggert Cc: net@FreeBSD.ORG, Yu-Shun Wang Subject: ARP & IP fragments In-Reply-To: <3BCF6A6E.5000302@isi.edu> References: <3BCF6A6E.5000302@isi.edu> Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org < said: > Hi, > we're seeing a strange thing happening, related to ARP and IP fragments. Not strange at all. The ARP cache only queues a single packet waiting for a reply, so the first few fragments you send get tossed. We could easily arrange it so that the first frag, rather than the last, gets sent, but it still wouldn't help you. Unfortunately, the FreeBSD codebase seems to be going in exactly the opposite direction of ILP, which would help. It might be an interesting exercise, and not terribly difficult, to restructure the network stack such that packets are queued before they are fragmented, and if the interface wants to fragment something it calls back up the stack to have it done. This would also allow smart network interfaces to provide hardware fragmentation assistance, which might be helpful on some media. -GAWollman -- Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the same wollman@lcs.mit.edu | O Siem / The fires of freedom Opinions not those of| Dance in the burning flame MIT, LCS, CRS, or NSA| - Susan Aglukark and Chad Irschick To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message