From owner-freebsd-questions@FreeBSD.ORG Tue Jan 31 15:38:13 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 705EE16A422 for ; Tue, 31 Jan 2006 15:38:13 +0000 (GMT) (envelope-from freebsd-listen@fabiankeil.de) Received: from smtprelay01.ispgateway.de (smtprelay01.ispgateway.de [80.67.18.13]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9284043D45 for ; Tue, 31 Jan 2006 15:38:12 +0000 (GMT) (envelope-from freebsd-listen@fabiankeil.de) Received: (qmail 1583 invoked from network); 31 Jan 2006 15:38:10 -0000 Received: from unknown (HELO localhost) ([pbs]775067@[217.187.180.130]) (envelope-sender ) by smtprelay01.ispgateway.de (qmail-ldap-1.03) with SMTP for ; 31 Jan 2006 15:38:10 -0000 Date: Tue, 31 Jan 2006 16:38:02 +0100 From: Fabian Keil To: tomasflyer@netscape.net Message-ID: <20060131163802.19300e98@localhost> In-Reply-To: <8C7F4678970ACD2-1EFC-9D50@mblkn-m01.sysops.aol.com> References: <8C7F4678970ACD2-1EFC-9D50@mblkn-m01.sysops.aol.com> X-Mailer: Sylpheed-Claws 2.0.0 (GTK+ 2.8.6; i386-portbld-freebsd6.0) X-PGP-KEY-URL: http://www.fabiankeil.de/gpg-keys/freebsd-listen-2006-08-19.asc Mime-Version: 1.0 Content-Type: multipart/signed; boundary=Sig_RDzFuy_6FWBNb+D0A808cRa; protocol="application/pgp-signature"; micalg=PGP-SHA1 Cc: freebsd-questions@freebsd.org Subject: Re: How many IP address aliases can practically be used on one physical Ethernet interface? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Jan 2006 15:38:13 -0000 --Sig_RDzFuy_6FWBNb+D0A808cRa Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable tomasflyer@netscape.net wrote: =20 > I am implementing and using a test bed simulating a huge amount of IP=20 > clients, each preferable having a unique IP address. There is no, no=20 > way to have an individual physical interface for each simulated > client so I use IP aliases. Currently it runs on Linux and there is a > limit of 256 IP addresses per interface, among other things due to a > hard array limit in Linux net-tools ifconfig. There also seems to be > other limitations like linear searches in net-tools as well as in > kernel networking code. Just changing the array limit changed the > problem to being one of stability and performance. >=20 > So I became quite optimistic reading about Virtual Hosts and IP > aliases in the FreeBSD handbook chapter 11.9: >=20 > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-vi > rtual-hosts.html >=20 > "A given network interface has one "real" address, and may have any=20 > number of "alias" addresses". >=20 > So is this really true and where is the catch? Will a FreeBSD 6.0=20 > accept for example 8190 IP address aliases each on say five physical=20 > Ethernet interfaces? Will IP addresses be manageable to add, list and=20 > delete? And how much will networking performance degrade compared to=20 > using just a few aliases? After a short test I don't think 8190 aliases will be a problem. root@africanqueen ~ #ifconfig re0| grep inet | wc -l 18008 root@africanqueen ~ #ifconfig re0 -alias 192.168.10.100 root@africanqueen ~ #ifconfig re0| grep inet | wc -l 18007 root@africanqueen ~ #ifconfig re0 alias 192.168.10.100 root@africanqueen ~ #ifconfig re0| grep inet | wc -l 18008 I don't know if there is a performance degradation on better hardware, but for my re0 the ftp performance seems to be the same as with only one IP. The only "catch" I can see is that it takes a while to create a few thousand aliases ;-) On my AMD Athlon(tm) XP 1900+ (1578.59-MHz 686-class CPU) I get about five aliases per second. Fabian --=20 http://www.fabiankeil.de/ --Sig_RDzFuy_6FWBNb+D0A808cRa Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFD34RmjV8GA4rMKUQRAiPjAKDpi3zHrHw1nBYYo2m3T9uSOFoGvwCfZu4Q b+BXu+aVaweJUxVKBW/JG4A= =Z02p -----END PGP SIGNATURE----- --Sig_RDzFuy_6FWBNb+D0A808cRa--