data collision problems

[muddog]

i bought a netgear network and it works fine, but for some reason when i play games or transfer large files over the network the collision LED on the hub flashes like crazy. is this much collision normal or is there something wrong with the network?

[mbossman2]

how many nodes on the network?

[mattssi]

Thats what you get when you use a hub... Data is sent to all ports and data can only be sent one way at a time using hubs, so when both computers are trying to send, you get a collision light..... If you get a router, which is a full duplex machine, you can send/receive at the same time on multiple channels, which is part of the reason they are a little more expensive. So I believe everything is working correctly, anyone else think differently?

[muddog]

Thanks. Is a router a replacement for the hub or an add-on?

[mattssi]

It would be a replacement. They also have specific routers for cable and DSL modems which are cool, because usually a cable company will give you 1 IP address for your cable modem....which in turn means you can only have 1 computer going on the net at a time. With the DSL/CABLE router, the router is configurable for DHCP and can give x amount of computers in the house a IP address and direct them all throught the 1 IP address that the cable company provided. (I hope that made sense)

of course, you can share that internet connection other ways also with a hub using Internet Connection Sharing features of windows 98 2nd edition and Windows 2000 (which is what I am doing since hubs are like $20)

[Dave22]

Collisions are normal. Excessive collisions can indicate problems, but a flashing light won't give you a true indication of the percentage of collisions.

Also...

A router is not a replacement for a hub. A switch would be a replacement for a hub.

Routers are meant to move traffic from one network to another, whereas a hub (or switch) does NOT move traffic between different networks... it is meant to move traffic within a particular network/subnet.

[mattssi]

Thats correct, my fault. But in the case of using the router for strictly internet conenction sharing, it would replace the hub if you have a cable/dsl router.

[muddog]

Would a switch help reduce or eliminate the data collision problem? Is a switch worth the money over a hub and would there be a performance difference?

[TK-87]

Dave22 is correct. I think what's confusing is that LinkSys, for example, has a device which is a router, but also happens to have built-in ethernet switch ports. So it is both a router AND a switch.

I suspect your collision problem has more to do with the fact that your PC NICs are configured for full-duplex mode when in fact they should be half-duplex because they're plugged into a hub. A hub is a shared device, so you can't send while you're receiving. Trying changing the NIC setup to use half-duplex and see if thing improve. They may be set to auto-sense, but change to half-duplex anyway. When using a hub, each node must "listen" for a quiet network before sending anything. In full-duplex they just blindly send stuff, thus the ensuing collisions.

Whether a switch is a good investment or not depends on a few things. You never answered how many nodes you have. If you only have 2 PCs, then a crossover cable will give you excellent throughput because they can run full-duplex.
If you have more than 2 PCs, then a switch would allow 2 simultaneous conversations to take place at full speed. For example, PC1 could speak to PC2, while at the same time PC3 speaks to PC4, each pair getting full bandwidth. With a hub, they'd all be contending for/sharing the same bandwidth.

[Dave22]

Originally posted by TK-87 Dave22 is correct. I think what's confusing is that LinkSys, for example, has a device which is a router, but also happens to have built-in ethernet switch ports. So it is both a router AND a switch. I suspect your collision problem has more to do with the fact that your PC NICs are configured for full-duplex mode when in fact they should be half-duplex because they're plugged into a hub..

Ok, but further clarification must be made here. If you were to tell your NIC to *explicitly* be full duplex and then try to plug into a hub, you'd either have NO connectivity or your throughput would be dead slow. The level of collision activity wouldn't be the issue (IOW, collision activity isn't a relevant indicator of duplex mismatches). If - like most people - you left your NIC set to "AUTO", then plugging it into a hub would cause the NIC to be half duplex (it may not be, but we'll assume it matched).

And yes, there is a "blurred" line with multi-function broadband connectivity devices with having "routing" capability along with a built-in switch or hub. What'll they think of next??

[muddog]

Well about the nodes i only have 2. My brother suggested a hub and he know more about networks than me so i got the hub. About the half duplex thing, the only options i have are full duplex or normal with do duplex thing. is there a way to enable it?

[Dave22]

If you're using a hub, set it to "Normal". If it's a switch, set it to "Full duplex".

"Normal" is synonymous with "half duplex" on a lot of NICs.

[muddog]

Thanks everyone!!

I did manage to cut down the collisions a bit by setting it to normal so i guess the network runs more efficiently now.

[TK-87]

thanks for the update muddog. glad to hear things improved.