Wireless Access

We have a client with AP-135s plugged into a stacked pair of S2500 switches. We are seeing octet errors on the switch ports that the APs are plugged into, and a certain number of jumbo frames. It is very consistent in that the number of octet errors is almost exactly 1522 octets per jumbo frame, across all the APs. Also, when you divide the number of jumbos by the AP uptime, it is almost exactly one jumbo frame every two minutes.

 

Can anyone confirm that this is what the AP-135 does? One Jumbo frame every two minutes of a size 1522 octets?

 

 

 

Please see the article here:  http://community.arubanetworks.com/t5/ArubaOS-and-Controllers/Oversize-jumbo-frame-errors/m-p/5421/highlight/true#M1860

 

 

Thanks for the info Collin

Welli wanted to ask the guy about the jumbo frame thing but there is no reply button  in there so ill ask here

 

I remenber i read sometthing about that on the VRD. And i went to search for it

 

Packet Sizing
Wherever possible the network should be configured to support jumbo frames to avoid fragmentation of the
packets. When this configuration is not possible due to lack of hardware support, the maximum MTU should be
configured on all devices. This setting is especially important for video transmissions, because the loss of key
video frames can cause the entire packet to be retransmitted. It is also important that transmitters are aware
of the frame size limitations. For instance, video servers should be configured to use the maximum MTU of the
network to limit their packet size to the network-supported maximum and avoid fragmentation.

 

Okay now i see its important to set the jumbo frame or at least thats what i understand so its basically telling me that

1-On the port of the switch that i connect the APS, i should configure the MTU value with a higher value than 1500? if im correct which value should be this one? it should be 1576?

2-In what benefits us having this jumbo frames why the 1576 packet instead the 1500? any reason for this?

 

Thanks

Cheers

Carlos

 

 

1. Not only the port that the AP is connected to, but every connecting switch must be configured with jumbo frames for jumbo frames to be sent and received successfully.

2. That would allows conversations to send more data in each frame and that *can* be more efficient. For some applications like voip , smaller frames are sent anyway, so that that efficiency is not realized.

Access points attempt to do path MTU discovery periodically to see what is the largest size frame that can be sent. That is why Jumbo frame counters go up. Most people limit the MTU in the ap system profile so that they don't see the jumbo frame counters go up.

Well wow that would be a major change...

ANd not all the clients will do this, they might get afraid something bad could happen...

 

There are some schools that im able to manage their switches and that wont be a problem but on other clients we got like banks, insurance i dont think they will do that just  because... and in all their switches if they dont have that configured...

 

Anyways just as presonal opinion Collin and is my last question on this topic

Do you actuallly recomend clients to do jumbo frames all over their switches(if they dont have it?) for example if they are managing Voip(which almost all of them do) to make it more efficient.

And which is the jumbo frame size you recommend?  or aruba recomends? there is not an specific number in the VRD

Like I said, "most people just set the MTU parameter in the ap system profile".

It is not worth configuring jumbo frames in all your switches, in general. If they support it out the box, it would be great.

Thanks for your Advice Collin! its really apreciated!

 

Cheers

Carlos