Strange networking issue

cartman · 08-13-2009, 08:17 PM

Ok, I'm scratching my head over this one. I'm trying to see if I have a bad NIC or not.

I have a box with Ubuntu 8.04. It had an on-board 100MB NIC, and I upgraded to a Linksys EG1032 Gigabit card. It is connected to a D-Link Gigabit desktop switch.

Strange thing is, I'm getting about half the speed out of the gigabit NIC as I was out of the 100MB onboard NIC. Copying files to and from the server at work was going about 750k down and 220k up with the 100MB NIC, but the gigabit card is lucky to hit 200k down and 100k up with the same file.

I ran ethtool, and it says the NIC is 1000MB full duplex, and I've tried various MTU settings to see if maybe jumbo frames were messing things up. Anyone have other tips on settings to check?

Alan T · 08-13-2009, 08:23 PM

What type of switch/hub/whatever are you connecting to? What does it see the card coming up as? Does it come up on that side as 1000MB/full duplex? Are you seeing errors of any kind or drops on the interface there?

Are you sure that your cable that you are using is rated for gigabit communication and not poorer quality (only capable of 100Mbps)?

I just re-read and see you said a D-Link gigabit desktop switch. I actually have had issues with the Linksys Gig cards connecting to the low end D-Link dumb-switches and had to go to a higher end switch for some of them to connect right. Had a few issues with netgear dumb-switches too.

My advice would be to start by seeing what the D-link switch is seeing, does it see the card come up as Gig or 100Mb?

cartman · 08-13-2009, 08:28 PM

The D-Link is lighting up as gigabit. ifconfig on the linux box isn't reporting any errors, which is what I first thought might be happening. I can see it operating the same speed as 100MB, but not slower. That's why I next thought about jumbo frames, but that wasn't it either.

Alan T · 08-13-2009, 08:32 PM

Quote:

Originally Posted by cartman

The D-Link is lighting up as gigabit. ifconfig on the linux box isn't reporting any errors, which is what I first thought might be happening. I can see it operating the same speed as 100MB, but not slower. That's why I next thought about jumbo frames, but that wasn't it either.

Yeah, your issue does not sound like a jumbo frames issue to me. It sounds more like a duplex issue which shouldn't happen when both sides come up as Gig though.

Are you sure that you are using Cat5e rated cable or higher? I wouldn't think it would sync at Gigabit if you were only using Cat5 though.

Alan T · 08-13-2009, 08:35 PM

After that, off the top of my head without a sniffer to see what is actually occuring there, I would question to make sure there is no driver issue with the card in linux. If you have another windows system you could put the same card/cable into to see if the problem is with the hardware or linux side.

cartman · 08-13-2009, 08:38 PM

I've got Wireshark running right now to see if there is something strange in the packets.

SteveMax58 · 08-13-2009, 08:49 PM

Were you using the D-Link Desktop switch before as well? If not...what were you using before?

cartman · 08-13-2009, 08:49 PM

Yep, same switch. Only new component is the gigabit NIC.

cartman · 08-13-2009, 09:23 PM

ugh, must be sunspots. I move the card to the other PCI slot to eliminate that, and now the UUID of the drive changed and it won't boot up.

cartman · 08-16-2009, 05:54 PM

Finally got it figured out. Had to update the MAC address table on the firewall. Once I did that, it started working as expected.

SteveMax58 · 08-16-2009, 05:57 PM

Ah...makes perfect sense now.

Wish I thought of that the other night.

Alan T · 08-16-2009, 06:09 PM

Quote:

Originally Posted by cartman

Finally got it figured out. Had to update the MAC address table on the firewall. Once I did that, it started working as expected.

Are you doing some kind of QoS on your firewall based on mac address or something? I would think not having the proper entry there would have been the difference between it not working at all, not having issues with it just working slower.

cartman · 08-16-2009, 06:28 PM

Quote:

Originally Posted by Alan T

Are you doing some kind of QoS on your firewall based on mac address or something? I would think not having the proper entry there would have been the difference between it not working at all, not having issues with it just working slower.

Yeah, I do traffic shaping to make sure that particular box gets priority, since it is the server that gets the bulk of the traffic to/from our clients.

Alan T · 08-16-2009, 06:32 PM

Quote:

Originally Posted by cartman

Yeah, I do traffic shaping to make sure that particular box gets priority, since it is the server that gets the bulk of the traffic to/from our clients.

Ahh, ok. I guess when you said you were copying files to and from a system at work, I was assuming that both systems were on the same layer 2 network. I guess that is what I get for assuming!

08-13-2009, 08:23 PM	#2
Alan T Hall Of Famer Join Date: Dec 2002 Location: Mass.	What type of switch/hub/whatever are you connecting to? What does it see the card coming up as? Does it come up on that side as 1000MB/full duplex? Are you seeing errors of any kind or drops on the interface there? Are you sure that your cable that you are using is rated for gigabit communication and not poorer quality (only capable of 100Mbps)? I just re-read and see you said a D-Link gigabit desktop switch. I actually have had issues with the Linksys Gig cards connecting to the low end D-Link dumb-switches and had to go to a higher end switch for some of them to connect right. Had a few issues with netgear dumb-switches too. My advice would be to start by seeing what the D-link switch is seeing, does it see the card come up as Gig or 100Mb? __________________ Couch to ??k - From the couch to a Marathon in roughly 18 months.

08-13-2009, 08:28 PM	#3
cartman Death Herald Join Date: Nov 2000 Location: Le stelle la notte sono grandi e luminose nel cuore profondo del Texas	The D-Link is lighting up as gigabit. ifconfig on the linux box isn't reporting any errors, which is what I first thought might be happening. I can see it operating the same speed as 100MB, but not slower. That's why I next thought about jumbo frames, but that wasn't it either. __________________ Thinkin' of a master plan 'Cuz ain't nuthin' but sweat inside my hand So I dig into my pocket, all my money is spent So I dig deeper but still comin' up with lint

08-13-2009, 08:35 PM	#5
Alan T Hall Of Famer Join Date: Dec 2002 Location: Mass.	After that, off the top of my head without a sniffer to see what is actually occuring there, I would question to make sure there is no driver issue with the card in linux. If you have another windows system you could put the same card/cable into to see if the problem is with the hardware or linux side. __________________ Couch to ??k - From the couch to a Marathon in roughly 18 months.

08-13-2009, 08:38 PM	#6
cartman Death Herald Join Date: Nov 2000 Location: Le stelle la notte sono grandi e luminose nel cuore profondo del Texas	I've got Wireshark running right now to see if there is something strange in the packets. __________________ Thinkin' of a master plan 'Cuz ain't nuthin' but sweat inside my hand So I dig into my pocket, all my money is spent So I dig deeper but still comin' up with lint

08-13-2009, 08:49 PM	#8
cartman Death Herald Join Date: Nov 2000 Location: Le stelle la notte sono grandi e luminose nel cuore profondo del Texas	Yep, same switch. Only new component is the gigabit NIC. __________________ Thinkin' of a master plan 'Cuz ain't nuthin' but sweat inside my hand So I dig into my pocket, all my money is spent So I dig deeper but still comin' up with lint

08-13-2009, 08:49 PM	#7
SteveMax58 College Starter Join Date: Dec 2006	Were you using the D-Link Desktop switch before as well? If not...what were you using before?

08-13-2009, 09:23 PM	#9
cartman Death Herald Join Date: Nov 2000 Location: Le stelle la notte sono grandi e luminose nel cuore profondo del Texas	ugh, must be sunspots. I move the card to the other PCI slot to eliminate that, and now the UUID of the drive changed and it won't boot up. __________________ Thinkin' of a master plan 'Cuz ain't nuthin' but sweat inside my hand So I dig into my pocket, all my money is spent So I dig deeper but still comin' up with lint

08-16-2009, 05:54 PM	#10
cartman Death Herald Join Date: Nov 2000 Location: Le stelle la notte sono grandi e luminose nel cuore profondo del Texas	Finally got it figured out. Had to update the MAC address table on the firewall. Once I did that, it started working as expected. __________________ Thinkin' of a master plan 'Cuz ain't nuthin' but sweat inside my hand So I dig into my pocket, all my money is spent So I dig deeper but still comin' up with lint

08-16-2009, 05:57 PM	#11
SteveMax58 College Starter Join Date: Dec 2006	Ah...makes perfect sense now. Wish I thought of that the other night.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)