Is it correct to say bridging is just a dumb routing?

carbon · Guru Joined: 27 Jun 2003 Posts: 455 Location: New York

i am a little confused with bridging and routing.
routing routes traffic in a flexible way between many interfaces, while bridging copies whatever on 1 end to the other end as tho it was trasparent?

so is it correct to say bridging is just a dumb routing?
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Carbon

fusion · Tux's lil' helper Joined: 02 Nov 2002 Posts: 119

I wouldn't call it that as a router connects to different networks a bridge is used to make segments of a single network. A router works at layer 3 and a bridge works at layer 2
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OdinsDream · Veteran Joined: 01 Jun 2002 Posts: 1057

It's dumb in the sense that a bridge understands nothing of the data it's processing. To a bridge, it's just electrical signals. To a router, those electrical signals form codes, which form addresses, which allow it to further clarify where packets should go.
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michael-reilly · n00b Joined: 20 Sep 2003 Posts: 9

If a bridge has only two interfaces (i.e., only 1 path for any given received packet to go) then it behaves like a wire - everything it sees on one interface is sent out over the other interface.

If it has more than 1 path for a given received packet than the bridge usually filetrs traffic based on MAC addresses. It keeps track of which path a given MAC address is on and forwards traffic for that MAC addresses over the correct path.

Used to link two LANs the bridge behaves as previously described, linking the two LANs into one larger LAN.

With three or more LANs (or LAN segments) it gets smarter and "routes" based on MAC addresses.

The bridge can be smart about locally generated packets and keep track of which interface to use.