Date: Tue, 14 May 1996 09:17:36 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: Lisko@SInet.net Cc: questions@freebsd.org Subject: Re: alias IP_number Message-ID: <199605132347.JAA20880@genesis.atrad.adelaide.edu.au> In-Reply-To: <199605131205.MAA15987@spectrum.nil.si> from "Valentin Lisjak" at May 13, 96 02:05:56 pm
next in thread | previous in thread | raw e-mail | index | archive | help
Valentin Lisjak stands accused of saying: > > I'd like to know how many alias IP numbers, could be applied to the > ethernet interface. I'm currently running 26 aliases. If it's possible, > explain me, how are theese aliases stored in kernel: list, tree, ... ? Hashed list, if I remember correctly (dg?). > I'm very interested in this information, because with a lot of hits > to many different aliases, performance degradation could be quite a > big problem. You're thinking of Linux 8) This was discussed a while back, the consensus was : - the 150'th IP takes about 1/2-1ms longer to respond than the 1st. - It's possible to alias several full class-C addresses to an interface with no noticed harmful side effects. Note that IP's outside the netmask of the original interface address can be aliased on with non-all-ff netmasks. For example, let's take an interface : inet 10.0.0.1 netmask 255.255.255.0 We can add aliases 10.0.0.2 netmask 255.255.255.255 10.0.0.3 netmask 255.255.255.255 etc. If we run out of room and want more addresses, we can add a whole slab at once with 10.0.5.1 netmask 255.255.255.0 Because this doesn't overlap the original address/netmask, this is fine. And it also only counts as _one_ entry in the lookup process. > |__\|__| \__/ |__| Valentin Lisjak Fax: +386 (61) 1405-381 -- ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ]] Collector of old Unix hardware. "Where are your PEZ?" The Tick [[
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199605132347.JAA20880>