Optimal port settings on Nortel 450 switch?

[JGliddon]

My company uses Nortel 450 switches exclusively. We are currently have all of our Novell servers set to communicate at 100-full on the server and the switch port with auto-neg turned off.

We are in the process of setting all of the clients to 10-full and their corresponding port on the switch to 10-full with auto-neg off. Auto-neg is currently on at the PC and at the switch so they are all getting 100-full.

Does it make sense to set the users back to 10-full no auto, or set them hard at 100-full no auto-neg? The theory is that we will save bandwidth by only giving general users 10-full and the power users that need it will get 100-full. Does it really make a difference? Can someone explain this to me? Thanks.

 

[jimbopalmer]

An interesting theory. Not one I like, but interesting.

http://www.stuartcheshire.org/rants/Latency.html

is a great article, but I want to point out the subtopic Bandwidth Still Matters. Response time will suffer

The Auto in auto negotiate allows your devices to have bad days: "It works fine, until I plug in my space heater" "Why does my computer lose the network whenever I talk on the radio?" Leaving all the network with out special needs on auto saves personnel that would be out debugging this stuff. (Some eqquipment on my network needs special settings, mostly fiber optic gear, old Suns and printers, say one in 25)

Historically, the 10 full setting is very rare, you are not using the most tested code or electronics. full duplex did not it it's stride until after 10/100 was common. (I still have some 28115s that will do 100 full but only 10 half)

Do you back up the clients? The Backup person will choke when told he has less bandwidth and the same time window to get it all done.


But in the end, it WILL work, if you choose to do it. I tried to remain child-like, all I acheived was childish.

 

[jimbopalmer]

Viewed from a position IN the switch, it will be much more congested if the end ports are at 10 full rather than auto (100 full, usually) you should see more deferred packets on the 10/full ports than the 100/full ports. in very badly congested ports, you may get collisions even in full duplex mode

Viewed from the server's NIC the network should be less busy until you start getting collisions, then it starts having to do twice as much work, or more. While it is better in my view to speed up the server's NIC than to slow the clients, only you can tell if either is needed.

Late Collisions is almost always a duplex issue . Sometimes if you are seeing FCS or Frame errors on a port, duplex should be suspect, try Auto again or slow down the port. (it is bad wiring or bad NIC if slowing it helps)

Flooding and filtering can mean a hub is still (or back) in your network Filtered packets found their destination in the same port they started in, the 450 floods packets when the destination cannot be determined.

Deferred packets indicates the paek load is sometimes more than the speed of the connection can keep up with. if it is a sustained over load, collisions, even excessive collisions may occur. (Remember, collisions are normal at half duplex, don't panic until they are excessive on half duplex links)


(you are going to have 1 or2 errors to per million packets even on good networks, if it seems to be over 1 in 100, I sure would investigate) I tried to remain child-like, all I acheived was childish.