• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

LAN - slow performance w/ certain PCs

L

LuckyTaxi

Diamond Member
Our LAN runs off of 3 Dell switches 10/100 and all desktops have a 100mb switch.
I noticed some computers take anywhere from 4-6 minutes to copy a 50mb file.
Whereas, other computers can do it in half the time.

What should I be looking at? No local firewall and all computers have antivirus installed.
I can't think of anything else because we recently moved into this new office and the switches are new, so are the ports, and CAT5 wires.
 
First place would be the cabling. If it is a new install then the installer should have provided certification test results for each and every cable. If not, then you don't really know if it was installed properly.
 
Are all of the "problem" computers connected to the same Dell switch? If so, there could be a problem with the switch.

As Spidey said, check the wiring. Also try connecting them to a different switch to see if the problem persists. Changing ports on a central switch is easier than moving a physical PC around, so I would try that first. 🙂
 
Originally posted by: RadiclDreamer
Make sure the ones having the issue arent settling on 10/half or 100/half
Click to expand...

While this is a good thing to check I have to bring up a VERY COMMON misnomer with autonegotiation.

There is no cabling check, there is no "see what the wire can do" with autonegotiation. This is such a common misunderstanding that I have to point it out. LAN performance problems for the most part can be grouped into 90% cabling and 9% misconfiguration.

Autonegotiation is by far the biggest misconfiguration problem there is. There are two hard and fast rules - 1) Set both sides of the link to speed and duplex, or leave both sides to autonegotation. 2) Though shalt never have one side of the link set to auto and the other side of the link hard set to speed/duplex.

With autonegotiation each side of the link transmits it's max capabilities. There is no agreement on what the link should be, there is no acknoldgement, each side of the link just says in it's link pulse - hey, I can do this. If you hard set an end of the link then there is no capabilities contained in the link pulse. What happens is one end of the link will default, and you don't really know what this default is going to be. Most times it default to half duplex and the other end is full duplex, this cripples a LAN connection...it's a duplex mismatch. The primary cause for LAN performance problems second only to cabling.

So I guess what I'm saying is there is no "settling" involved. Each end of the link is doing exactly what it is supposed to do but people believe that autonegotiation does some kind of cable check and agrees upon which mode to operate on both ends. This just isn't how it works. Set both ends of the link or leave them to auto, they could have barbed wire between them but each link partner will exhibit the same behavior.
 
Let's take this from the top.

All our servers have a 1gb connection that's going to a 1gb switch. The gb switch is uplinked to two 10/100 managed switches where our desktops are plugged into.
My thought is the gb only comes into play between servers but it's a mute point when it's talking to our desktops which are maxed at 100mb.
My computer is one of the problematic computers. I played with the duplex setting and forced it to 100 full. That screwed my connection up as I couldnt transfer anything off the server.
I moved it back to AUTO and all was well but it still took a few minutes to copy over a 22mb file.

Having said this, what should the setting be on our servers? My boss wanted the gb connection for server-server (SQL->application) but other than that it's not doing any good since our desktops NICs
are standard 10/100. The only other place I need to check is our switches - where the ports of each workstation is hooked up to. So let's say desktop A is patched into Port 30 on the switch. Should i force
Port 30 to 100/full or leave it on auto?
 
Lucky - leave the triple speed ports (10/100/1000) ports and nics set to auto.

Leave the 10/100 set to auto. Leave all NICs to auto.

There just isn't any reason these days to force any speed or duplex and forcing it with gigethernet ports is just a bad idea. Look for errors on the switchport your client is on on both the NIC and switchport side. Also look for errors and negotiated speed/duplex on the inter switch links.

Apart from that your computer may be the problem and not the network, provided you follow these best practices of setting speed/duplex. You say that you forced your NIC to 100/full and couldn't transfer anything. This points me to a cabling problem. If you force your NIC to 100/full the switch port if set to auto will default to 100/half and you'll still move data but at a snails pace if you're using TCP, < 5 Mbs.

In other words, leave all ports and NIC to auto unless you have a very compelling reason and proof or bugs to not do otherwise.
 
spidey - thanks.

ok so i just tried something 20 mins ago remotely w/ two PCs.

I set EVERYTHING to AUTO except I need to check on the switch but the password to the console escapes me at the moment.

From the same workstation:

1 - Copying 122mb file from Server A to workstation.
Result: FAST!!!

2 - Copying 134mb file from Server B to workstation (new file sharing server in question)
Result: SLOWWWWW

I checked and made sure all NICs are auto. I also copied the 122mb file from Server A to Server B and it was FAST.

So we know between Servers, file transfer is fast. They both reside on gigabit switch.
We know copying from Server A to workstation is fast but from Server B to workstation is SLOW.

Now what?
 
I think you're still going through layer1 troubleshooting. Check all speed/duplex settings and errors on both ends of an ethernet link - the switchport and the network card.

You can't do network troubleshooting like you would PC stuff. You can't do the "eliminate something" methodology. You have to understand what is going on.

So, check all your layer1 stuff that is involved in the layer2 path. cabling, speed/duplex, errors checked on both ends, etc.
 
Yes, for now check for duplex mismatches between every L1/L2 path. Check for L1 errors on both ends - this points to L1.

For now leave everything to auto speed/duples on every single link involved in the L2 path. your server to gig switch, your gig switch to access switch, your access switch to NIC. Leave everything to autonegotiate and check every single end of that path for errors. You are working a L1 problem, treat it as such. If all of those speed/duplex match on every end of every link then you are still stuck at layer1 - cabling. Unless the cabling can be category certified with a proper scanner you will never know.
 
Ok so I just did some more troubleshooting. Everything was already on auto negotiation. The ports on the switches, the configs on the NICs on BOTH server and workstation.
I went as far as changing CAT5 wires and moving the patch cord from one port to another.

I did manage to get it to work if I force the port on the switch where the server is patched in to 100mb FULL. I was able to transfer a 100mb in under 1min.
Not sure why I would have to do this as another server is on the same gig switch and it's on AUTO and I was able to transfer a 110mb file in under 1min.
It seems for whatever reason, this new file sharing server (Win 2003) doesnt like to be set to AUTO. On AUTO it's set to 1gb but so is the server that transfers just fine.
That's a Win2k server and it's set on AUTO and currently on 1gb.

Worst case scenario I run the new server on 100mb.
 
Because 100 Base-T is slower than 1000 Base-T. 1000 uses all 4 pairs, 100 uses only two. You could have a pair that is not up to category spec.

I think I already mentioned something about most performance problems being cable related, it's so common that it's "common" knowledge. 😉

Remember:
DON'T MUCK WITH THE PHYSICAL LAYER. And by muck I mean something else.
 
Just noticed something on the server, under properties for the NIC, it shows 10/100 Half and full and auto but no 1000?
If i hover over the network icon next to the clock it shows 1gb.

I'm gonna get some CAT6 wires and try.
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top