What precisely is a brouter?

x_Danny_x

I heard it can join two networks even if they are using two different protocols

Can it translate a protocol to another

Can a Hub do the samething?

Webmaster

A router is simply a device that combines bridge and router functionality, meaning it can forward both Layer 2 and Layer 3 information.

It does not translate. And a hub does not make forwarding decisions at all (i.o.w. it does not care about information from layer 2, 3, or higher) it just forwards received signal out of all its ports except the port it was received on.

Check out our Network Components TechNotes for more detailed info:
www.techexams.net/technotes/networkplus/networkcomponents.shtml

x_Danny_x

So a hub doesnt join two seperate subnets.

What a hub does is then make one subnet larger by having the ability to add more stations because of its multiple ports?

Im assuming also that a bridge and switches dont join two seperate subnets either like a router can, they just helped reduce traffic in a subnet or a whole network, Im I correct???

Webmaster

So a hub doesnt join two seperate subnets.

Yes indeed, it doesn't.

What a hub does is then make one subnet larger by having the ability to add more stations because of its multiple ports?

The terms subnet is not relavent when talking about hubs (subnet is layer 3 thingy, hub is a layer 1 thingy), but basically: yes.

Im assuming also that a bridge and switches dont join two seperate subnets either, they just helped reduce traffic in a subnet or a whole network, Im I correct???

Correct, although a switch with VLANs can separate broadcast domains. Those VLANs use different IP (sub-)networks, but if you want communication between them you would typically use a router (which is called inter-VLAN routing)

x_Danny_x

I see, I understand now, What you said is what is in this image



Here the Broadcast Domain which in this case is a subnet, has a bridge and it has reduced its collision domain into two smaller ones. In this case a segment is a collision domain


I have one question though, what is the device that all the computers are connecting too? Is that a hub?

Webmaster

Yes, indeed that is a hub.

Again, it does not necessarily have to be a single subnet. It can be divided into several subnets (but it would need a router to allow communication between those). Typically, if this was to be the entire network, that broadcast domain would be indeed a single subnet.

x_Danny_x

several subnets?

so instead of having hubs there you would of have bridge in that picture and the router connecting them?

Sorry for the numerous questions, If Im wrong do you have a picture explaining it with several subnets?

Webmaster

Just forget I mentioned that cause I probably shouldn't have... I'm saying it can, but it is not typical/common, because host from one IP subnet would not be able to communicate with hosts from the other. (remember that the logical subnet (based on IP addressing) is assigned by an admin, hence that admin could decide to assign different addresses to certain hosts. To use that example from my other post, one road could have been assigned two street names as in two separate IP subnets, ie. some hosts would use 192.168.1.0 other would use 172.16.0.0, again, they won't be able to communicate with eachother without a router routing information between the subnets.

The point here is that it is possible, there are situation in which you do not even want the hosts from different subnets to be able to communicate (on layer 3, i.o.w using IP) with eachother (hence no router needed, hence the picture stays the same) even though they may be on the same layer 2 broadcast and colission domain.

x_Danny_x

Oh okay so if the picture that I posted from your notes had two different subnets and you didnt wanted them to communicate you wouldnt change a thing! Is that what you were trying to say in your last post


In your diagram again and this time lets imagine that there is a 3rd collision domain with hub and 3 computers connected to the Bridge



A computer on the left side (lets call him "A") sends a data packet who destination is to one of the computers on the right (lets call him "B"), As "A" sends the packet, all the computers on its collision domain get the data packet also because of the Hub! Now when it reaches the Bridge, the bridge can tell to send it to the interface where "B" belongs to and not to the interface where the 3rd collision domain resides at.

Even though because of the Hub at where "B" is at, the other computers get the data packet as well, The Bridge helped reduced traffic because it was smart enough not to send it to the interface where the 3rd collision domain is located at

2lazybutsmart

xDannyX, I'm trying to understand your understanding of broadcast and collision domains. You really need to nail these two things down before you can move on to anything else. And you need to know where routers and bridges come into this whole broadcast/collision domain business.

Those TechNotes written by Johan are excellent material to help you understand all the basics. Read them and understand them. And as an advice, I think you should forget about the whole subnet business for now. Just assume it doesn't exist. Learn the basics first. I'm not putting you down, but it really really helps to do first things first.

2lbs.

p.s.. we're always happy to answers questions on the forum, so don't shy away

x_Danny_x

Im trying bro, Im trying