Bridging a Bridged Network

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I was wondering if it was possible to bridge a bridged network. Put simply, and in more mental vision-friendly terms, if you used the Windows XP bridge function to link two LAN segments (two seperate local area networks), could you also bridge a third network onto this new, larger network, by having one computer on either network bridge to the third network? Reading over this, it seems pretty complicated, so here is a diagram:

compnet2uz2.png


Basically, I was wondering if the creation of a network where all computer nodes could communicate with eachother at the data and application layers would be possible using this method to cover a very wide area with LAN cabling.

Thanks in advance for any info. :)
- Matt
 
Matt,
Therotically that *should* work. I am not exaclty sure how XP briding works. As long as all the PC's are on one flat LAN, i don't see why it wouldn't work.(providing XP allows you to do such thing) IMHO, it would be easier just to use each PC doing the "bridging" as a router.
 
By "router" do you mean any old switch you can pick up at your local computer shop? I thought about this but I didn't think it would work... Though when I think about it, a PC using bridging and a router/switch/hub are exactly the same thing, aren't they? Maybe I ought to try this out sometime on a small scale to test if my theory works.
 
This is another configuration that's a bit simpler and involves less complicated Windows XP bridging. This is also something I've thought of (it'd just need slightly longer cables for inter-network links:

compnet22vg0.png
 
Matt,
No. A router and a switch are two diffrent things. A router connects two seprate networks together, a swich expands one network (for simplistics sake).

There are many ways of doing what you are trying to accompish here, simpiler than trying to use windows XP "bridging". XP bridging is diffrent than the term "bridge", a switch is essentially a multiport bridge. XP bridging is more of a etherchannel of sorts, load balances the two physical connections.

If the WAN or LAN in your diagram is one flat WAN/LAN (meaning on the same sub network), switches would be easier. Add a switch where your using XP "bridging".

If the WAN/LAN in your diagram is not a flat WAN/LAN (meaning on diffrent sub networks), you would have to use a router where your diagram is using XP "bridging". (In this case, a router can be any form or device. A hardware router like a linksys or a software router like a PC

Hope this helps, if not I can go more in depth.
 
It helps a lot, thanks. One thing I'm unclear of, though, is the difference between how a router and a switch direct traffic... You mention that a switch joins two networks on the same subnet (pretty sure I understand what's going on) but a router can connect two networks on different subnets, and that's where I kinda get lost. I don't understand how computers can not be on the same subnets. Are subnets like hierarchies? If you have computers on different layers of a LAN (with some being daisy-chained further down the line) would those lower layers be on a lower subnet?
 
Matt,
A switch is a multi port bridge. It is also considered a "smart device". Switches direct traffic on layer 2, which is MAC address based. (no 2 devices have the same MAC address)

Say you have 3 PC's, A - C plugged into a switch. A, B and C all have diffrent MAC addresses, the switch inspects the PC's traffice to find the source and destinations MAC address and puts them in a table. So when A wants to talk to C, A's traffic goes to the switch which is inspected by the switch to find the destination and source address then directs the traffice to the correct port that C is on. As more devices are connected the switch learns which PC has what mac address and enters it in its table. So when B wants to talk to C it already knows what C's mac address is and instantly forwards the traffic to the correct port.

See more here: http://en.wikipedia.org/wiki/Network_switch

A router is a Layer 3 device, which is IP Address based.

Routers use routing tables of IP addresses. Basically it keeps a table of the best way to get to the next network.

For example: PC's A - C want to get to PC's D-F, however they are on diffrent sub networks. A's default gateway is 192.168.0.1 (which is the A-C's routers IP address), all traffic that is not local or on the same sub network gets forwarded to 192.168.0.1. A wants to goto 10.0.0.2 (D's ip address), so the traffic gets forwarded to 192.168.0.1, when the router sees the destination address it looks in its routing table to see how to get to 10.0.0.2 and determines the best way to get to it is via D-F's router 10.0.0.1. So it forwards A's traffic to 10.0.0.1 which then forwards the traffic to D (10.0.0.2).

Now routing gets a little more complicated. Say 192.168.0.1 does not know how to get to 10.0.0.1. Uh oh.. problem here. A router can only carry/forward traffic as far as it "knows". (what has been specified in its config) All routers have a default gateway as well, so if 192.168.0.1 doesn't know how to get to 10.0.0.1 your screwed. Now if 192.168.0.1 is directly connected to 10.0.0.1 with an ip route or default gateway of 10.0.0.1 they will be able to talk to each other.

See more about routers here: http://en.wikipedia.org/wiki/Network_router

I hope this helps some more, routing is complicated and kinda hard to explain so i hope you got the jest of it.
 
Thanks a ton! I really do get a lot of what you said... I definetely want to be using switches for my application. Thanks again for all the info!
 
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