Date: Sat, 2 Feb 2002 11:41:12 +1300 (NZDT) From: Cameron Kerr <cameron.kerr@paradise.net.nz> Cc: "dunlug@lists.ethernal.org" <dunlug@lists.ethernal.org>, "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: [dunlug] Re: Is ADSL modem + NAT the same as an ADSL Router? Message-ID: <Pine.LNX.4.43.0202021125070.11321-100000@glissarok> In-Reply-To: <20020201190934.9D4684844F@wastegate.net>
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On Fri, 1 Feb 2002, Doug Reynolds wrote: >the difference between a modem and a router is that a router is an >ethernet switch with a dhcp server and a ADSL modem built in.. >where as the modem is just a modem to connect into one computer. Close, but not quite. A router is a layer 3 device (which means it works at the IP level). It is _not_ and ethernet switch. A router, technically speaking, is a layer 3 device that demarcates a (in the case of ethernet) broadcast zone, which basically means that an ethernet MAC address of ff:ff:ff:ff:ff:ff, which is the ethernet broadcast address, will not make it though a router, but will through a switch (which is a layer 2 device) Routers are often employed to route IP packets between two different layer 2 mechanisms, or to more effectively seperate traffic. Routers generally have more smarts (and higher latency) than switches, and are more expensive. It is not uncommon to find routers that can serve DHCP requests, or prioritize/shape traffic, but if they don't, it doesn't means its not a router. Indeed, my Ni500 ADSL router (which has an ADSL modem _in_ it, as well as an ethernet interface), only does NAT, it doesn't serve DHCP. On the other hand, a M1122 (both of these are Nokia) which I will upgrading to shortly) does DHCP, NAT, Port Forwarding, Web Interface. Not all routers do NAT, but you'll be hard pressed to find an ADSL router that doesn't, I believe. >now if you don't want to have a server on 24/7, routers are the shit. >my sister (knows little about computers) has a ZyXel router/modem, and >it works great.. Very true. If you want to provide services (so you can ssh to home from the internet, say), and have a router doing this job, be sure to get a router that supports Port Forwarding (M1122, not Ni500, if you want Nokia) If you want to do anything tricky with your connection, such as traffic shaping, you might like to use an ADSL modem instead, and make your own router using an old _quiet_ 486 (the quieter the better, preferably only one spindle, in the power supply) and some kind of solid state hard drive. Myself, I'm looking at using a compact flash drive, I just need to find a CF - IDE fully internal connector. Anyone know where I can get one cheap? Cameron Kerr -- cameron.kerr@paradise.net.nz http://homepages.paradise.net.nz/~cameronk/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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