Date: Tue, 15 Feb 2000 09:13:04 -0500 From: Jim C <jconner@enterit.com> To: "Duke Normandin" <01031149@3web.net>, <cjclark@home.com> Cc: <freebsd-questions@FreeBSD.ORG> Subject: Re: Routed and public IPs Message-ID: <4.2.0.58.20000215090338.00a4c548@mail.enterit.com> In-Reply-To: <000e01bf77b7$846b2c80$509ec5d1@webserver>
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At 06.18 15.02.00 -0700, Duke Normandin wrote: >On Monday, February 14, 2000 11:45 AM Crist J. Clark wrote: > > >On Mon, Feb 14, 2000 at 10:35:19AM -0700, Duke Normandin wrote: > >> Although I'm not involved in this thread, directly or indirectly, > >> I want to thank you for such a great reply. I can't believe you > >> and Ruslan et al -- I'm green with envy. I've saved this thread > >> for future reference, however would you mind defining for me (in > >> laymen's terms) the concept of bridge(4)ing? Something like: > >> "bridging is using a box to bridge a gap between (public & private > >> IPs??) or ?? ". I don't want your info to go to waste on this > >> newbie, so I thought I'd ask. Tia... > > > >A bridge is a network device that operates at layer two of the IP > >stack, the link layer. Hubs and switches are the other most common I thought hubs operated at layer one and switches operated at layer two...and of course routers are at layer three. Just tryin to get the info... Jim > >devices that work at layer two. A bridge does not know anything about > >IP addresses, and most often, it simply forwards _all_ packets it > >receives on one interface to the other. However, it is possible to run > >a filter on the bridge, as was the whole point of the thread you are > >following. > > > >I personally have only used a simple bridge that passes all > >packets. Some users want two computers (running different OSes) in > >their offices. There is only one RJ-45 connection coming into the > >room. Rather than give them each a hub, one computer gets an extra NIC > >and bridges for the other. As far as the second computer is concerned, > >its on the same LAN. > > >Thanks....to your reply and a tutorial I found on the net, I now >understand that a bridge is an external, physical device. Quoting >this tutorial: > >"In contrast to hubs, which are physical-level devices, bridges >operate on Ethernet frames and thus are layer-2 devices. In fact, >bridges are full-fledged packet switches that forward and filter >frames using the LAN destination addresses. When a frame comes into >a bridge interface, the bridge does not just copy the frame onto all >of the other interfaces. Instead, the bridge examines the destination >address of the frame and attempts to forward the frame on the >interface that leads to the destination." > >However, I'm confused with your term "physical-level device" as >opposed to "link-level (layer-2) devices. Are not both physical >devices? Do not both operate on Ethernet frames? I now understand >that a bridge will "examine" an Ethernet frame, as opposed to a hub, >i.e., "in-one-ear, out-the-other" ;^). Thanks for your time. > >-duke > > > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-questions" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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