Date: Tue, 6 Aug 2002 17:13:38 -0700 From: "wlodek" <wlodek@infoserve.net> To: "freebsd questions List" <freebsd-questions@FreeBSD.ORG> Subject: about bridge, router, gateway Message-ID: <003a01c23da7$49717400$fc507240@infoserve.net>
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hi, I was wonder if I understand well the confusion with bridge = gateway = router. I was a bit confuse by the previous posts. The three are completely different Bridge A device that connects two LAN segments together, which may be of similar or dissimilar types, such as Ethernet and Token Ring. A bridge is inserted into a network to segment it and keep traffic contained within the segments to improve performance. Bridges learn from experience and build and maintain address tables of the nodes on the network. By monitoring which station acknowledged receipt of the address, they learn which nodes belong to the segment. Bridges work at the data link layer (OSI layer 2), whereas routers work at the network layer (layer 3). Bridges are protocol independent; routers are protocol dependent. Bridges are faster than routers because they do not have to read the protocol to glean routing information. Bridges with more than two ports (multiport bridges) perform a switching function. Today's LAN switches are really multiport bridges that can switch at full wire speed. router device that forwards data packets from one local area network (LAN) or wide area network (WAN) to another. Based on routing tables and routing protocols, routers read the network address in each transmitted frame and make a decision on how to send it based on the most expedient route (traffic load, line costs, speed, bad lines, etc.). Routers work at layer 3 in the protocol stack, whereas bridges and switches work at the layer 2 gateway 1) A computer that performs protocol conversion between different types of networks or applications. For example, a gateway can convert a TCP/IP packet to a NetWare IPX packet and vice versa or from AppleTalk to DECnet, from SNA to AppleTalk and so on. Gateways function at layer 4 and above in the OSI model. They perform complete conversions from one protocol to another rather than simply support one protocol from within another, such as IP tunneling. Sometimes routers can implement gateway functions. An electronic mail, or messaging, gateway converts messages between two different messaging protocols. See LAN and IP gateway. (2) A computer that acts as a go-between two or more networks that use the same protocols. In this case, the gateway functions as an entry/exit point to the network. Transport protocol conversion may not be required, but some form of processing is typically performed. the above common wisdom is from www.techweb.com/encyclopedia you can find a very nice drawing at http://www.techweb.com/encyclopedia/defineterm?term=LAN regards wlodek To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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