mousek801

whats the diff between a bridge, router, switch, hub, and crossover?

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Dead_Man

Ok I'll kick this off:

Router: Splits 1 internet connection into several. Main feature is it gives each computer connected its own internal ip. Creating a network. ISP only sees the router connected.

Switch: Splits 1 internet connection into many, ISP would see each computer connected and they would be assigned an ip from the ISP.

HUB: I might be wrong on this but I believe it does the same thing as a switch.

Bridge: I dunno

haider254

Quote: Originally Posted by Dead_Man Ok I'll kick this off: Router: Splits 1 internet connection into several. Main feature is it gives each computer connected its own internal ip. Creating a network. ISP only sees the router connected. Switch: Splits 1 internet connection into many, ISP would see each computer connected and they would be assigned an ip from the ISP. HUB: I might be wrong on this but I believe it does the same thing as a switch. Bridge: I dunno

Well I beleive a bridge is designed to join seperate networks together. It's been a while since I brushed up on the old CCNAs but meh

A bit more technicality on the Hub/Switch point. A switch is "smarter" than a hub. A hub will simply repeat all data to all hosts connected to it and the hosts filter out what is meant for them, where a switch will look at a packet, see who it's meant for and direct it to them. Clears up the network a bit, hence the difference in price generally...

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DickNervous

If you want to get really technical you have to look at which layer of the 7 Layer OSI model each operate on, but I am not going to go into that. If you want that level of information the best thing to do is Google it.

As for what they actaully do, here we go:

Crossover: A crossover cable is a RJ-45 cable that allows you to connect two comp[uters directly to each other. RJ-45, or twisted pair, cableing works by using two wires for transmit and two for receive. Network interface cards expect the transmist and recieve pairs to be configured as 2&3 for transmit and 4&6 for revceive (I think). Hubs, routers, and switches are configured to expect them the opposite, so the transmit pair from the PC matches the receive pair on the device. However, most modern devices can auto-configure this on the fly. So for two PCs to talk, you need a cross-over cable which simply switches the pairs at one end of the cable.

Hubs and Switches: At the most basic level these two devices do the same thing, they allow multiple connections to be on the same network segment and therefore easily communicate. All devices on a network segmet will have an IP address that is in the same range, ie: 192.168.0.x. The difference between the two comes into play when you look at how ehternet works. Ethernet has a set amount of bandwidth per network segment and all the devices share that bandwidth. All devices connected to a hub are considered on the same physical network segment and therefore share the bandwidth. A switch creates seperate physical networks and therefore each port, as far as ehternet is concerned, has the full bandwidth available to it instead of sharing it with the other devices.

Bridges: Bridges are devices that connect two physically different networks into one. For example, a wireless access point is a bridge. It connectes a wireless and wired network into one logicval network. Bridges are generally used to connect two networks that work on different media, such as wired and wireless. Two networks that are bridged would share the same IP sub-net. Honestly though, bridges, like hubs, are pretty much not used anymore since routers and switches are so cheap.

Routers: Routers are devices that sit at the edge of a network and create the connection between two separate logical and/or physical networks. A perfect example is a home router that you connect to your cable modem. One "side", the WAN side, has an IP address that is on the cable companies network while the LAN side has the IP addresses that you assign. The router is what allows those two subnets to talk to each other. Routers are also intelligent. They know the "least cost route" to get from point a to point b on a network. They can do NAT, Network Address Translation, filter ports on a specific IP address, and much more.

In the corporate world routers have more then two ports and can connect networks that use different topologies and technologies. A router is what allows twisted pair network to communicate with a Fiber Optic one, ehternet and token ring to talk to each other, or WAN technologies like ATM, Frame Relay, MLPS, etc to connect to a LAN in an office.

I think that about covers it without getting too technical.

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Aselus

just to clerify there IS a difference between a switch and a hub. A HUB will echo anything that comes into it to all connected devices, which will in tern decide if it's for them. A switch on the other hand is 'smarter' and will only communicate to the needed device.

The router itself is a "switch" with the actual HDCP (as desribed above) behind it, so if you hook up more switches beinhd the router, it is able to distinguish these and send things through the appropriate shortened pathe.

In practicality switches should only be placed behind routers in order to be effective, and HUBs should be used stand-alone(for non-HDCP networks).

if you guys want mroe details on how the switch ACTUALY accomplishes this..I can go off and explain it ;-) but onyl if i'm asked.

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