From owner-freebsd-isp Tue Jan 9 15:37:50 2001 Delivered-To: freebsd-isp@freebsd.org Received: from marius.org (marius.org [216.88.115.170]) by hub.freebsd.org (Postfix) with ESMTP id 681C437B400 for ; Tue, 9 Jan 2001 15:37:29 -0800 (PST) Received: (from marius@localhost) by marius.org (8.11.0/8.11.0) id f09NbIt02515; Tue, 9 Jan 2001 17:37:18 -0600 (CST) Date: Tue, 9 Jan 2001 17:37:18 -0600 From: Marius Strom To: Troy Settle Cc: Colin Campbell , freebsd-isp@FreeBSD.ORG Subject: Re: Hosting with multiple subnets Message-ID: <20010109173718.C1302@marius.org> Mail-Followup-To: Troy Settle , Colin Campbell , freebsd-isp@FreeBSD.ORG References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from troy@psknet.com on Tue, Jan 09, 2001 at 06:09:24PM -0500 Sender: owner-freebsd-isp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org But man would that make for a nasty routing table. =] On Tue, Jan 09, 2001 at 06:09:24PM -0500, Troy Settle wrote: > > Colin, > > I'm breaking netiqet by copying this back to the list, but I think that many > folks will find this useful or even educational. > > You are correct, in that on a /26 subnet, you only have 62 usable IP > addresses, however, if you treat it as a group of 64 /32 subnets, you can > use all 64 addresses in the /26 that you allocated for web hosting. The > same thing applies to dynamic IP pools on your NAS. > > Keep in mind, though, that this does not work if you are not properly > subnetted. If the subnet on your LAN is a /24, you can not use the network > or broadcast addresses. If, however, you use the first /26 (0-31) for your > LAN, then route the last /26 (192-255) to your web server at .10, you can > treat all 64 addresses in 192/26 as /32 subnets, giving you use of all 64 > addresses (including .255). > > This concept does extend to a /24. If you treat it as a group of 256 /32 > subnets, you can use all 256 addresses for web hosting or dialup. It works > for /any/ size CIDR block of IP addresses. Give me a /16, and I'll give you > 65,536 usable addresses for web hosting. > > -- > Troy Settle > Pulaski Networks > 540.994.4254 > > It's always a long day, 86400 doesn't fit into a short > > > > ** -----Original Message----- > ** From: Colin Campbell [mailto:sgcccdc@citec.qld.gov.au] > ** Sent: Tuesday, January 09, 2001 5:38 PM > ** To: Troy Settle > ** Subject: RE: Hosting with multiple subnets > ** > ** > ** Hi, > ** > ** On Tue, 9 Jan 2001, Troy Settle wrote: > ** > ** > Agreed, but you could have given an example of one of the good > ** ways to do > ** > it. Here's how I set up for hosting: > ** > > ** > 192.168.10.1/26 - gw address > ** > 192.168.10.8/26 - fxp0 on my web server > ** > 192.168.20.0/23 - bound to lo1 on the web server > ** > > ** > I use zebra to implement OSPF to get the routes kicked around > ** my network, > ** > but it could easily be done with a static route on the gateway router. > ** > > ** > Doing it like this keeps the arp tables small. I don't know > ** if it really > ** > matters or not, but I like it like that. > ** > > ** > I also use a script rather than rc.conf to do my bindings: > ** > > ** > for i in `jot 256 0` > ** > do ifconfig lo1 inet 192.168.20.${i} netmask 0xffffffff alias > ** > done > ** > > ** > And, yes, I do bind the /whole/ subnet. I won't use .0 or > ** .255, but with a > ** > /26, I will use all 64 addresses. > ** > ** You cannot use ALL addresses in a subnet. A /26 gives you 62 usable > ** addresses. The host address that is all 0's is the sub-network > ** address and > ** the host address that is all 1's is the broadcast address. With > ** a /26 mask > ** you have four subnets as follows: > ** > ** Subnet 1 > ** -------- > ** 192.168.10.0 = network address > ** 192.168.10.1-192.168.10.62 = usable host addresses > ** 192.168.10.63 = broadcast > ** > ** Subnet 2 > ** -------- > ** 192.168.10.64 = network address > ** 192.168.10.65-192.168.10.126 = usable host addresses > ** 192.168.10.127 = broadcast > ** > ** Subnet 3 > ** -------- > ** 192.168.10.128 = network address > ** 192.168.10.129-192.168.10.190 = usable host addresses > ** 192.168.10.191 = broadcast > ** > ** Subnet 4 > ** -------- > ** 192.168.10.192 = network address > ** 192.168.10.193-192.168.10.254 = usable host addresses > ** 192.168.10.255 = broadcast > ** > ** Colin > ** > ** > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-isp" in the body of the message > -- Marius Strom Professional Geek/Unix System Administrator URL: http://www.marius.org/ http://www.marius.org/marius.pgp 0x55DE53E4 "Never underestimate the bandwidth of a mini-van full of DLT tapes traveling down the highway at 65 miles per hour..." -Andrew Tanenbaum, "Computer Networks" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message