On Fri, Jan 07, 2005 at 09:28:14PM -0500, SOTL wrote:
> Hi All
>
> What is the difference between a wireless router and a wireless bridge? Just
> so I do not confuse people I know a router goes on the line side and the
> bridge goes on the computer side but really is the difference?
Note: I'm a neophyte to this area. I've set up several simple networks
and know something about the theory of this area. I've never seen or
used a bridge but I know the definition of one. So feel free to correct
me. I'll also use this opportunity to ask questions of the more
knowledgeable in the group. Here's my understanding:
Bridges are specialized routers, designed to connect two or more
networks or LANs. They use info from the MAC layer (MAC addresses?) to
route packets.
Routers are more general purpose. They make decisions or where to route
packets based partially on info from higher up in the protocol stack (IP
addresses?). They can be made to function as bridges, though perhaps
less efficiently.
There are two factors at work. The first is the connection between IP
address and machine names, and the ability to resolve machine names into
addresses. This is handled either by a populated /etc/hosts file (which
contains the names and addresses of local machines), or access to an
active local DNS server. In the latter case, the DNS server serves to
translate machine names into IP addresses to the best of its ability.
The second factor is the routing of packets once the IP addresses are
known. The "route -n" command will show you what routing decisions will
be made on the machine it's run on. Your local machine will likely know
how to route all traffic on your LAN directly to the machines involved.
That is, the "route -n" command shows that for local addresses, there is
no gateway; packets to those addresses are routed directly. Any other
addresses will go to a "gateway" router somewhere on your network, which
shows on a separate line of the "route -n" command.
If your network is like mine, you've got a router for the LAN. It
accepts packets for addresses my local machine doesn't know how to deal
with. It knows how to address local traffic. But for any other traffic,
it has its own "gateway" route, which is to the DSL modem. The DSL modem
does whatever handwaving it needs to to get internet packets where
they're going.
Since part of specifying a route with the route command also entails
specifying what type of addresses will go on that route, you could
specify a secondary gateway for any traffic going to a different LAN or
network segment. That gateway would then hand off traffic to the proper
hosts on its network segment.
So the point here is that, while a bridge would directly route traffic
to specific machines on different network segments, a router whose
routing tables are properly set up (with a separate gateway on the other
network segment(s)) could perform the same function. It mainly depends
on how your routes are set up.
Right?
Paul
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