Date: Mon, 1 Feb 1999 09:00:23 +0100 (MET) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: yu.shi@research.nokia.com Cc: freebsd-net@FreeBSD.ORG Subject: Re: drop packets? Message-ID: <199902010800.JAA20229@labinfo.iet.unipi.it> In-Reply-To: <36B5735E.1760FA79@research.nokia.com> from "Shi Yu" at Feb 1, 99 05:26:36 pm
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> Thanks for those who gave me help. > After reading the replies, I am still not very clear about some points. > Why 50 pkts for an interface queue? > 50 sounds like not enough, if I use FreeBSD as a router. > How many should I specify if I custmize the kernel or I use as large as > possible?? There is not an easy answer. First of all, you should only experience queueing if your output link is slower (either natively, or because of congestion e.g. on an ethernet) than the input link. If you are using ethernets on both sides, you should not see significant queues build up unless you are dumping from a loaded 100Mbit segment to a 10Mbit one. And if you do, having the router dropping packets is a good thing because it is the way end-to-end congestion control works. Second, in general you don't want large queues (except to absorb occasional bursts) -- they slow down response of congestion control, cause additional delay in the delivery of packets etc. etc. I think you should leave this parameter as it is now until you have a clear picture of the problems and you can figure out by yourself what is the best setting for your situation -- and this usually implies reducing the value quite a bit, especially with slow interfaces. cheers luigi -----------------------------------+------------------------------------- Luigi RIZZO . EMAIL: luigi@iet.unipi.it . Dip. di Ing. dell'Informazione HTTP://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL/FAX: +39-050-568.533/522 . via Diotisalvi 2, 56126 PISA (Italy) -----------------------------------+------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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