Wireless Access

I have AP-275's connected to HP switches. On most of these ports, I get the error:

Too many undersized/giant packets on port #

And the message details indicates it may be a malfunctioning NIC.

Is this a setting - MTU or something? All of the (thousands of) errors are giants.

I tried the

 jumbo max-frame-size 2048

config command and will keep an eye on the error count

which didn't help - still clocking giant errors.

What's the MTU size of a 275?

Kevets,

I'm a little surprised that setting the value above 2000 didn't resolve the issue. The APs natively send out Path MTU frames which can result in errors on switch ports but they are normally no larger than 1576. Take a look at this KB article.

https://arubanetworkskb.secure.force.com/pkb/articles/FAQ/ArubaOS-AP-MTU-Support

Are you sure you don't have Jumbo Frame support enabled in the AP-Group?

Best regards,

Madani

where would I look for that? I see SAP MTU (which is blank) and RAP MTU (1200 bytes, but I don't have any RAPs anyway). I don't see anything in the controller AP Group config that contains the word Jumbo.

Sorry I mispoke earlier, I was thinking about the global Jumbo enable command which is a firewall setting and not under the AP-Group.

http://www.arubanetworks.com/techdocs/ArubaOS_64x_WebHelp/Content/ArubaFrameStyles/Network_Parameters/Jumbo_Frame_Support.htm

What kind of Controller are your 275's terminating to?

Also when the SAP MTU is blank it means that the AP is going to send Path MTU discovery frames but again, I believe those are only supposed to be as large as 1576. I looking to see if there was any change in that behavior.

Controller is a 7210 runnung 6.4.2.1

Are you tunneling traffic through the controller or are you using bridge mode?

You could try and enable jumbo frames on the HP switch (this is disabled by default), you can enable this on the VLAN: 

vlan 1000

  jumbo

  exit

I am tunneling traffic on a VLAN that the switch is unaware of.

You could enable jumbo on the VLAN the AP is a member of.

Kevets,

Reading up on the HP's implementation of JUMBO frames, the "jumbo max-frame-size <value>" is a global command but you still need to turn on JUMBO on the VLAN level to take advantage of it. As arjan_k says, enable jumbo at the VLAN level for the VLAN that the AP is in. You can then use "show vlans ports <port-list>" to verify that JUMBO has been enabled.

Best regards,

Madani

Coming back to this after a long delay!

I have discovered that setting a jumbo max-frame-size (I went with 8196) on the switch in general, and then putting Jumbo in the VLAN section makes most of these go away. Unfortunately, I have a 2615 switch which has 100 Mbps ports and doesn't support Jumbo. I'll replace that soon and my logs should be quieter.

I have 100Mbps HP procurve 2615-8-PoEs and they have jumbo support.  Even the 2610s do 9216 MTUs.

It's the older cisco catalysts that do not support it on the 100Mbps interfaces (but you can trunk through them with jumbos fine.)

If you actually have some models that don't you may be able to tame the error messages by tuning the fault-finder sensitivity (bad-driver is the category on the switches I've looked at.)

Huh, you're right (bet you hear that a lot). For some reason I thought the jumbo commands weren't available in 2615's, but I just did it.

I'm trying to get rid of those anyway. Having an expensive AC AP connected to 100mbps port just seems wrong!

I had the same experience with an AP-315 on an HP 2530. Just curious, anyone see an AP drop connection to a controller or reboot due to this issue? 

Never... we were running months before getting jumbo turned on across the network.  There's still a few corners we haven't done.  The APs do PMTUD; they are expecting to have to run on traditional 1500 MTU LANS, just ready to use jumbo if you clear them a path.