Date: Tue, 31 Jan 2006 05:23:39 -0500 From: tomasflyer@netscape.net To: freebsd-questions@freebsd.org Subject: How many IP address aliases can practically be used on one physical Ethernet interface? Message-ID: <8C7F4678970ACD2-1EFC-9D50@mblkn-m01.sysops.aol.com>
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Hi, 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=20 so I use IP aliases. Currently it runs on Linux and there is a limit of=20 256 IP addresses per interface, among other things due to a hard array=20 limit in Linux net-tools ifconfig. There also seems to be other=20 limitations like linear searches in net-tools as well as in kernel=20 networking code. Just changing the array limit changed the problem to=20 being one of stability and performance. So I became quite optimistic reading about Virtual Hosts and IP aliases=20 in the FreeBSD handbook chapter 11.9: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-vi rtual-hosts.html "A given network interface has one "real" address, and may have any=20 number of "alias" addresses". 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? I can add that there is no forwarding or routing through a simulator=20 box except IP traffic to and from the client simulation running inside. I am maybe willing to change to BSD if there is a chance of success,=20 most Guru UNIX sysadmins running real production say mostly good things=20 about the BSDs. I just need some encouragement... ;-) Best Regards Flyer ___________________________________________________ Try the New Netscape Mail Today! Virtually Spam-Free | More Storage | Import Your Contact List http://mail.netscape.com
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