3Com can’t document their ass from their elbow.

When I inherited the network I administer, I inherited a bunch of 3Com switches.  Over time I have swapped them out with other 3Com products.  I find that switching is one of those things where everything works so much better if you use one vendor’s products… and since I didn’t change out all of the switches at once I continued purchasing 3Com products.  3Com fucked me today.  I got no courtesy reach around, it was rough, and horrible.  As a result I will never purchase another 3Com product.

I am setting up a vSphere cluster with a bunch of Dell R710 servers and an EqualLogic PS4000 SAN.  The recommendation is to use Jumbo Frames on the switch that connects the SAN to the servers.  I have a 3Com Baseline Switch 2948-SFP (3CBLSG48), actually I have several of these, but only one that matters in this case.  If you follow the previous link, you will notice that in the center column, ninth bullet point, it says “Jumbo Frame support for reduced network load.”  Well let me tell you, there is absolutely zero documentation on how to activate Jumbo Frames on this switch.  Let’s take a look at the user manual.  Search for the word “jumbo” in the user manual and you will find exactly one entry, on page 2 (or 13, depending on how Acrobat numbers the pages.)  It is a bullet point that says “The Switch 2948 features the following advantages: ... Jumbo frames”

All of this indicates to me that the switch supports Jumbo frames in some shape or form, but since the guide has only this entry, I have absolutely no idea how to configure them.  Going through 3Com’s bastardized web interface didn’t help either, nothing in there to suggest Jumbo frames.  the CLI offered little more than configuring the IP address, or resetting the entire config.  In short, completely useless.

But wait.  Jumbo frames are also called 9000 byte MTUs.  A search through the manual for “MTU”, “9000”, and “Maximum Transmission Unit” revealed absolutely nothing.  Basically you can’t configure them… and let me tell you, if they are “automatically configured” they sure don’t work worth a shit.

A call to 3Com resulted in no answer, but it is Labor day today, so I will give them that.

Searching through their knowledge base and their user forums, gleaned not a clue.

Most maddening of all, was a google search for “3com 2948 jumbo frames” reveals everybody who is trying to sell one of these switches, but doesn’t come up with anybody who is trying to make Jumbo frames actually work on this switch.

Basically, what should have been a 10 minute config issue has turned into hours of fruitless labor. 

3Com, I hate you.

Posted on Mon, 07 Sep 2009 18:06:36 -0700 in
Network Administration • Switches • Technology
(0) Trackbacks • Permalink