My adventure in considering to upgrade to a gigabit switch

So I recently built a RAID 5 system to be used primarily as a media file server. I transfer large home video files over my network to this machine on a continual basis. Since both my server and personal machine have gigabit nic cards in them I thought it might be a good idea to get a gigabit switch now that they’ve come down to reasonable price points.

So today I saw my local Fry’s ad and saw an Airlink Gigabit switch on sale for $29.99. I started to do a little research on the switch and came to find out about “jumbo frames” which is a feature that some switches had to increase speed that this router lacked. The network cards also need to support this as well as the switch for it to work.

I tapped on my friend Will’s shoulder to glean more info on “jumbo frame” and here’s an excerpt from his email reply:

“Jumbo frames allows a larger chunk of data to go through each frame so there’s not so much start-and-stop, CRC checking, packet unwrapping, etc and you get more throughput- like when running Xmodem with it’s 128byte frames vs. Ymodem’s 1K frames back in the old days.”

This was a great analogy and helped me understand the benefits quite easily.

So I started to try to determine if both my machines (Dell 400sc server & Dell Dimension 8400 personal machine) supported “jumbo frame”. Well both systems have integrated nic’s on the motherboard. I quickly found out that the 400sc did support it. But trying to determine if the 8400 did was another story.

I started by googling for the info which was very difficult to find but ultimately found this posting which was the closest I could get but still no answer. So I had to dig further.

I wondered onto the dell support site which led me to the driver download page. From here I downloaded the html manual which once I opened it in a browser I searched various pages for the word “jumbo”. Upon reaching the introduction page I saw that under features the following line was listed:

“Jumbo frames (up to 9 KB) (only for the BCM5702 device)”

Ahh…getting warmer. So I try to see if I can determine the device number from wandering into the device manager in windows. Unfortunately I couldn’t find the info in there. So I also read in the html manual about the Broadcom Advanced Control Suite 2. So I ran that little utility and voila, under the hardware tab I see that my device is the “BCM5751”. So based on this I’m pretty sure that my nic doesn’t support jumbo frames.

Ok, that took a while and was a bit of a pain but I got my answer. Now think I’ll hold off and buy a gigabit switch that supports jumbo frames. It looks like a good candidate that’s been on sale for ~$35 in the past is the SMC 8505T. Of course now I will have to buy another nic for my Dell 8400 to support it, but oh well.

Decisions…Decisions….

It’s funny, I haven’t even weighed or tested the benefits of moving to gigabit in the first place (although from what i’ve read the performance gains appear to be good for my situation). Yet I find a way to further complicate things with this jumbo frame functionality. This is a case where trying to keep up with cutting edge technology can be a curse and ignorance can be blissful…oh well.

7/29/05 Update
I found this great article that explains Jumbo Frames

NIC’s with Jumbo Frame Support
D-Link DGE-530T
SMC SMC9452TX
NETGEAR GA311

Netgear KB Article on Jumbo Frame Support
http://kbserver.netgear.com/kb_web_files/n101539.asp

This Post Has 6 Comments

  1. You shoulda just asked me first. I got the “Universal Jumbo Frames Book” that ‘splains all that stuff.

  2. You shoulda just asked me first. I got the “Universal Jumbo Frames Book” that ‘splains all that stuff.

  3. I went thru this exercise for a business/technical reason. According to Dell tech support NO current Dell laptops support jumbo frames. I was also trying to determine if the TCP/UDP checksumming offload was enabled: the NIC configuration does not have an option for this feature. Bcom tech support agrees that the BCM5751 does have checksum offload but that Dell’s implementation has it permanently enabled. Dell wanted $50 to verify that statement.

    All in all, the Dell/Bcom experience was dissapointing, especially that Dell would save 50 cents by using a non-jumbo frame GbE controller. Every Intel GbE NIC that I’ve run across has jumbo frame support…

    The new Dell 2716 and 2724 switches upport jumbo frmaes AND have a management agent. The 2716 is a good deal if you can get it for $100 off it’s regular $269 price.

  4. I went thru this exercise for a business/technical reason. According to Dell tech support NO current Dell laptops support jumbo frames. I was also trying to determine if the TCP/UDP checksumming offload was enabled: the NIC configuration does not have an option for this feature. Bcom tech support agrees that the BCM5751 does have checksum offload but that Dell’s implementation has it permanently enabled. Dell wanted $50 to verify that statement.

    All in all, the Dell/Bcom experience was dissapointing, especially that Dell would save 50 cents by using a non-jumbo frame GbE controller. Every Intel GbE NIC that I’ve run across has jumbo frame support…

    The new Dell 2716 and 2724 switches upport jumbo frmaes AND have a management agent. The 2716 is a good deal if you can get it for $100 off it’s regular $269 price.

  5. ‘jumbo frames’ is a carryover from the ‘olden days’, when PC CPUs

  6. Your post is quite interesting when I found it over google on Wednesday by my search for ipad. I have your blog now in my bookmarks and I will check out your weblog again, soon. Take care.

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