Re: What does "bridge" mean?

From: Phillip Windell (_at_.)
Date: 02/03/05 

Date: Thu, 3 Feb 2005 08:52:19 -0600

"Larry David" <MysteriousAilment@HealthyChoice.org> wrote in message
news:q6adnVkL-ffxHpzfRVn-rw@giganews.com...
> A friend of mine has a similar situation to mine. He has two networks
in
> two locations connected by a T1 "local loop" with a Cisco on each end --
but
> in HIS case, all computers in both locations are on the same logical
> network: 192.168.112.0/24. I don't understand how this can be, but he said
> that the person who configured his Ciscos set up a "bridge."

I'll keep it simple. A bridge is what a switch does, the old bridges of
"days gone by" were effectively a regular Switch with only two ports,...now
days they build them with multiple ports and call them Switches instead and
they use them to replace the old Hubs to avoid "collisions" that is common
on Ethernet.

In the case of two networks separated by a distance,...a Router is used to
connect them when they are different subnets,...but if the two networks are
the same subnet then a Bridge is used instead. In this case it is usually
the same hardware device either way because most good routers can be set to
function as a bridge.

Bridging switches packets at the Layer2 level (MAC address). This is not
considered to be "routing" but is called "packet switching" (hence the name
"Switch"). They don't see the IP# and don't care about the IP#.

Routers switch packets at the Layer3 level (IP numbers).

But like I said, many of the Routers can be configure to do either one. 

-- 
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

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