Help!! Need advice regarding switch speed!

[bbrontosaurus]

Hey all,

I've posted this question on the Networking Forum, but I'd thought I'd cross-post it over here to get some more opinions.......

A little background info:

Our client PC's are connected to a Cisco Catalyst 2950 Switch with a port speed of 10MBPS/Half Duplex. We also have a server connected to this same switch, but the switch port speed for this server is set to 100Mbps/Full Duplex. The client NIC's are set to autonegotiate. Cabling is Cat5e.


I would like to have the port speed for the client PC's changed to 100MBPS/Full Duplex. I was told the following when I requested the change to 100/Full:

"The reason that we would not want 100MB for PCs is that if there were a rogue NIC card in a PC on a 100MB port it would cause far more problems to the network."


As I don't have a networking background, I need some help in refuting this statement. Can someone point me to some whitepapers that will disprove this statement and/or offer some advice?

Thanks!

 

[Electric Amish]

I thought that's the reason they have utilities to monitor switches to watch out for screwy port accesses. IMO it's just stupid to limit everyone for the "possibility" angle.

Just turn everyone up and monitor the damn network. :|

amish

 

[dman]

Hmmm... wouldn't switch limit the traffic from the 'rogue' port?

I'm not an expert, probably best to post in a forum like DSLREPORTS.COM's networking forum...

here

 

[Netopia]

I don't think the Net Admin knows what he's doing. To have a switch and then not even take advantage of its benefits over a hub is stupid! If you had some super lowend switch with a 100MB backplane, then MAYBE it would make sense so that no one machine could take huge amounts of bandwidth, but the Catalyst 2950 has a backplane speed of 8.8 Gb/s! If EVERY SINGLE PORT (24 PORTS) was sending AND receiving (FULL DUPLEX) at 100 Mb/s, that would only be 4.8 Gb/s! The extra backplane (4 Gb/s) is probably for the two Gigabit Ports, which if used in full duplex and were actually maxed out would be another 4 Gb/s which adds up to the 8.8 Gb/s advertised backplane.

In other words... if ALL of your attached machines were "rogue", it would barely eat HALF of the throuput of the switch!

Let me know what he says... this could be funny!

Joe

 

[ATLien247]

What's your/his definition of a "rogue" NIC?

I'm thinking that he means what I would call a "chattering" NIC. If that's the case, then your admin has no clue what he is talking about.

Each port has it's own collision domain, so there would be no effect on the other ports in that regard. Additionally, if you had a chattering NIC on your network, while you might see increased utilization of the switch, it shouldn't affect your overall throughput.

If you notice increased utilization then obviously you should investigate.

You could even use QoS if you really were worried about this kind of thing.

 

[bbrontosaurus]

Originally posted by: ATLien247
What's your/his definition of a "rogue" NIC?

I'm thinking that he means what I would call a "chattering" NIC. If that's the case, then your admin has no clue what he is talking about.

Each port has it's own collision domain, so there would be no effect on the other ports in that regard. Additionally, if you had a chattering NIC on your network, while you might see increased utilization of the switch, it shouldn't affect your overall throughput.

If you notice increased utilization then obviously you should investigate.

You could even use QoS if you really were worried about this kind of thing.

ATLien247, I'm trying to get a better understanding what the network admin meant by "rogue" NIC, but I believe you are correct. He mentioned something about a bad NIC flooding the network. What is QoS? Sorry if this is a newb question!

 

[bbrontosaurus]

Thanks for all the good info guys!! Keep it coming!!

However, I do need white papers or some type of professional document to pwn the Network Admin with his faulty statement. Other than looking at the documentation of Cisco's Catalyst 2950 Switch, can anyone else recommend documention I can use to back me up?

 

[n0cmonkey]

Wrong forum.