From owner-freebsd-hackers Thu Sep 19 10:42:08 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id KAA13091 for hackers-outgoing; Thu, 19 Sep 1996 10:42:08 -0700 (PDT) Received: from brasil.moneng.mei.com (brasil.moneng.mei.com [151.186.109.160]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id KAA13059 for ; Thu, 19 Sep 1996 10:42:03 -0700 (PDT) Received: (from jgreco@localhost) by brasil.moneng.mei.com (8.7.Beta.1/8.7.Beta.1) id MAA11243; Thu, 19 Sep 1996 12:39:37 -0500 From: Joe Greco Message-Id: <199609191739.MAA11243@brasil.moneng.mei.com> Subject: Re: Routers - hardware received wisdom To: dennis@etinc.com (Dennis) Date: Thu, 19 Sep 1996 12:39:37 -0500 (CDT) Cc: jfarmer@sabre.goldsword.com, hackers@FreeBSD.ORG In-Reply-To: <199609191531.LAA12464@etinc.com> from "Dennis" at Sep 19, 96 11:31:14 am X-Mailer: ELM [version 2.4 PL24] Content-Type: text Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > You could easily run 2 T1 on a 386....Joes machine has 2 ethernet cards > in it, which adds an extra 10Mbs of bandwidth. :-) Dennis :-) Yeah, but that's a PCI 486DX5/133. :-) See the other thread about this. Your limit is generally how much work the CPU needs to do. At some point, ISA bus bandwidth becomes a consideration, but I doubt it will become a consideration before CPU does on a 386. I highly recommend you consider ET's products... they use DMA transfers and basically work like Ethernet cards from a "system overhead" point of view. Very efficient... much more so than some others I have looked at. The CPU you save by using DMA can then be used for Real Work such as actually routing the packets someplace. My _best_ suggestion is to try it and see how it works. You can always upgrade motherboards if CPU time becomes a problem. % vmstat 1 procs memory page disks faults cpu r b w avm fre flt re pi po fr sr f0 w0 in sy cs us sy id 0 0 0 35124 660 1 0 0 0 0 0 0 0 1111 52 9 2 41 57 0 0 0 35124 660 1 0 0 0 0 0 0 0 861 52 8 1 33 66 0 0 0 35124 660 1 0 0 0 0 0 0 0 1211 62 13 1 56 43 0 0 0 35124 660 1 0 0 0 0 0 0 0 1268 52 9 1 54 45 0 0 0 35124 660 1 0 0 0 0 0 0 0 976 78 13 1 38 61 0 0 0 35124 660 1 0 0 0 0 0 0 0 854 65 11 1 34 65 0 0 0 35124 660 1 0 0 0 0 0 0 0 1116 55 10 1 46 53 0 0 0 35124 660 1 0 0 0 0 0 0 0 763 52 8 1 25 75 0 0 0 35124 660 1 0 0 0 0 0 0 0 634 52 9 0 15 85 0 0 0 35124 660 1 0 0 0 0 0 0 0 661 52 8 2 15 83 0 0 0 30956 660 1 0 0 0 0 0 0 0 718 52 9 0 25 75 0 0 0 35124 660 1 0 0 0 0 0 0 0 488 58 9 1 11 89 0 0 0 35124 660 1 0 0 0 0 0 0 0 659 52 8 1 15 84 0 0 0 30948 660 1 0 0 0 0 0 0 0 763 52 9 0 20 80 0 0 0 30948 660 1 0 0 0 0 0 0 0 640 62 8 1 17 83 0 0 0 30948 660 1 0 0 0 0 0 0 0 639 52 8 2 16 83 % netstat -I ed0 1 input (ed0) output input (Total) output packets errs packets errs colls packets errs packets errs colls 231 0 159 0 0 392 0 392 0 0 108 0 132 0 0 242 0 242 0 2 220 0 172 0 0 398 0 399 0 5 193 0 135 0 0 328 0 327 0 1 292 0 164 0 3 458 0 458 0 7 295 0 174 0 1 478 0 477 0 8 317 0 192 0 0 511 0 510 0 7 221 0 163 0 0 386 0 386 0 4 168 0 138 0 0 307 0 312 0 1 274 0 150 0 0 427 0 427 0 3 134 0 150 0 0 285 0 285 0 1 105 0 97 0 0 204 0 204 0 0 102 0 115 0 0 219 0 219 0 3 107 0 121 0 0 230 0 230 0 0 66 0 64 0 0 135 0 134 0 0 82 0 98 0 1 182 0 182 0 1 129 0 141 0 0 275 0 275 0 2 The snapshots should be within a few seconds of each other... Anyways this is a 386DX/40 with six SMC ISA Ethernet cards in it. You can see that there is a fair amount of traffic flowing through it, and even so it is pretty idle. The traffic is mainly a mix of NNTP and various other traffic, so the packet sizes tend to be smaller than if you were just doing FTP and Web traffic... I personally get nervous when I see idle < 70% or so. You can basically stick as many interfaces in a machine as you want, just as long as the traffic does not swamp the machine. That is a function of several variables: o Number of interfaces o Average traffic on each interface (less = better) o Average packet size (larger = less CPU utilized) o Machine speed and bus speed (most easily adjusted variable) o OS speed (relatively constant) Once you understand the concept that you could support a million 56K lines with the CPU power of an HP-35 as long as nobody tried to send any traffic, you have mastered the concept. I really encourage you to _try_ it.. stress test it.. and draw your own conlusions. That is really the best answer. ... JG