Date: Wed, 19 Jan 2000 14:57:30 +0200 From: Ruslan Ermilov <ru@FreeBSD.ORG> To: Jim Flowers <jflowers@ezo.net>, Mikhail Teterin <mi@kot.ne.mediaone.net> Cc: net@FreeBSD.ORG Subject: Re: Natd with Pmtu Discovery Message-ID: <20000119145729.A11150@relay.ucb.crimea.ua> In-Reply-To: <Pine.BSI.3.91.1000106091555.29680A-100000@lily.ezo.net>; from Jim Flowers on Thu, Jan 06, 2000 at 09:31:27AM -0500 References: <20000106143722.A2080@relay.ucb.crimea.ua> <Pine.BSI.3.91.1000106091555.29680A-100000@lily.ezo.net>
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[Redirected to -net, Bcc'ed to -hackers] On Thu, Jan 06, 2000 at 09:31:27AM -0500, Jim Flowers wrote: > OK. I followed this a little further. The problem is that the natd read > of the interface mtu precedes the skip routine that modifies it. > Unfortunately, when the skip routine modifies the interface mtu it does > not send a message to the socket as it does when the address is changed > so the -dynamic flag doesn't help. > > Currently, I moved the the initiation of natd to rc.local to follow the > skip change to the interface mtu but this is less than ideal. > > A better approach would be to notify the natd module of any > interface mtu change via the socket, similar to when the address is > changed with the -dynamic flag set. This would also pick of manual > changes. > Hmm, I thought of this too, but this will not fix the problem with natd. Consider the case when natd(8) is not bound to any specific interface, and it sends packets via multiple interfaces (in my case, for example). I think the only workable solution would be to just report some smaller MTU value, which will trigger an originator to repeat with the smaller packets. If this new (smaller) packet won't fit again, the procedure is repeated, and MTU is decreased again (down to 576). Another approach would be to allow natd(8) to drop the DF bit... See also: PR kern/15494. Cheers, -- Ruslan Ermilov Sysadmin and DBA of the ru@ucb.crimea.ua United Commercial Bank, ru@FreeBSD.org FreeBSD committer, +380.652.247.647 Simferopol, Ukraine http://www.FreeBSD.org The Power To Serve http://www.oracle.com Enabling The Information Age To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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