Netstructure 470T and Fiber Slow

[ICBM]

I got a little bored so I thought I would play with some fiber cable and my file server here at the house. I jumped on ebay and found a new 3com 3c985B-SX pci-x card and an Intel Netstructure 470T switch. Being new to this I bought a fiber cables at newegg which was 8.3/125 single mode, but with both ends being an SC connectors so I thought all was cool.

Using my desktop pcie card to the server on copper I was getting around 67MB/sec measured through Sandra. I changed out to the new 3com card, plugged in my cable. Again, my first time with fiber so when the lights came on I was thrilled. I ran my sandra test and it was only doing around 30MB/sec and I was getting a large amount of packet loss. I started reading through the manual which is 10+ years old, but I discovered what I thought my problem was. It said I need multimode fiber of either 50/125 or 62.5/125. I checked on the Intel gbic units and they showed the same spec, so I figured I was just using the wrong time of cable.

I ordered both the 50 and 62.5 from amazon (like $5 apiece!) and try them each out. Now it is showing like 5000KB/sec with both cables, which is way slower than before! I know the fiber cable is sensitive to bends etc. but are we talking about this type of speed drop? Intel has no support or documents for the switch on their website anymore, so I am not even sure how to log into it and see what all the settings are, though I don't even think that is a problem. I am not sure what the next step would be to troubleshoot this. I am hoping someone can point me in the right direction.

 

[Emulex]

go spend $20 on a gigabit nic and some cat6 and you should see better performance.

the gbic you select dictates the cabling you select. both ends need to obviously use the same gbic for the cabling you selected.

seems like alot of trouble for gigabit??

 

[spidey07]

Multimode fiber is correct. Not single mode. Sc connectors will have a very firm click when seated properly.

 

[Red Squirrel]

Wow I'm glad my boredom does not cost me that much lol, that's easly a couple grand worth of fiber equipment.

Gigabit is simple and easy to setup so it's best bet for a home network really.

 

[ICBM]

Being that I got the stuff on ebay and it being 10 years old more or less I got it all for under 100 bucks. That is part of the problem, apparently Intel doesn't have any support info for their older products online. It will not even show up on their website if you type in my model of switch.

I have been running gigabit without issues for a few years, I just wanted to start messing with the fiber to see how it worked. Since the stuff on ebay was very inexpensive, I decided to give it a shot. Part of the reason I wanted to experiment with fiber was to be able to have a run longer that 100m to another building. I figured it would be easier to start with 10ft of cable before I was going 300+ft.

Spidey you mentioned the SC connectors have a very firm click. Would it be possible for them to still show connection and not be completely seated in their sockets?

 

[spidey07]

Being that I got the stuff on ebay and it being 10 years old more or less I got it all for under 100 bucks. That is part of the problem, apparently Intel doesn't have any support info for their older products online. It will not even show up on their website if you type in my model of switch.

I have been running gigabit without issues for a few years, I just wanted to start messing with the fiber to see how it worked. Since the stuff on ebay was very inexpensive, I decided to give it a shot. Part of the reason I wanted to experiment with fiber was to be able to have a run longer that 100m to another building. I figured it would be easier to start with 10ft of cable before I was going 300+ft.

Spidey you mentioned the SC connectors have a very firm click. Would it be possible for them to still show connection and not be completely seated in their sockets?

Absolutely - link doesn't mean you have a good connection, only that it's "good enough to get link pulse". The nick-name for SC is "stick and click". You should be able to pull on the actual fiber cable without it coming out. It sometimes takes decent finger force to fully seat an SC connector, always handle by the connector. Oh, and make sure the dustcaps are removed.

MM fiber isn't super sensitive. As long as you don't bend it severely (you could wrap it around a coke can and be OK) and it isn't kinked you'll be fine. Given the age of this gear I'm not sure if it would work with 50 micron fiber, better to use 62.5 to eliminate that.

 

[ICBM]

Both NIC and switch are rated for both 50 and 62.5 but I am sticking with the 62.5 right now since I read it is less sensitive. In regards to wraps, the cable came wrapped in approximately 9" diameter. I was prepared to string it out straight to see if it made a difference, but I figured that would be impractical in a real world install, so that is most likely not the problem.

I did take the dust covers off, and it kind of threw me because it looked like the plastic tips were white. I assumed the fiber would be clear, and not white. I am able to snap all the ends into their sockets and I can get a nice sounding click, and to remove I have to slide back on them and get a nice click as well. Could there be more than one dust cover?

To see if I could still get the 30MB/sec out of the single mode cable, I swapped back, but I am stuck to the slower ~5000KB/sec with that as well now. Strange that it was faster before. I am going to try blowing out the ends of the connectors with some air to make sure they are clean and keep playing around with it.

I guess I should also take into account something could be wrong with the equipment, but I am not sold on that. There are 6 copper ports and 2 gbic ports on the switch. I have two SC connectors for it, and both do the same thing in either of the ports. The copper ports work quite well.

 

[ICBM]

I found my problem, at least part of it. I checked my device manager settings on the nic in Windows, found that Jumbo Packets was turned on. Turned it off, and I am pushing around 44MB/sec using the 3com driver, 35MB/sec with the Windows supplied driver. This is still far slower than my copper nics. At this point I think I will assume this slow down is due to drivers and XP. The 3c985 has non-supported 3com drivers that were apparently rushed out the door for XP. Due to the age of the card, I am guessing they dropped support and didn't develop their drivers further. I may try and find a card that has current support and see what kind of performance I get. Thanks all very much for the help and insight.