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I am using Netonix switch model WS-24-400B switches with firmware version 1.4.8rc7. I have a customer that uses jumbo packets, and I am finding that I am not able to set mtu setting to 9000 ( jumbo packet size ) on the fiber ports 25 and 26 and continue to pass data out the port. Data passage stops.

I am able to successfully pass jumbo packets out Ethernet ports 1 thru 24 with no problem. when I set ports 25 or 26 to jumbo packet size (9000 mtu setting) all data transfer through port stops. when I set mtu size back to 1528 I can then send data through port at packet sizes up to 1518 with no problem. The sfp that I am using in ports 25 and 26 is Alcatel Lucent model#3HE00027CA 01
MFGR: Finisar MFGR P/N FTLF8519P3BTL-AS

Are there any known issues with passing jumbo packets through the fiber ports?
Are There any compatibility issues with sfp and Netonix switches?

critical issue, will have to change to a different manufacture for my switches if problem not fixable.

with a rfc2544 tester I can prove that problem is with fiber ports. When I set port 26 (fiber port) to mtu setting of 1528 and port 1 (ethernet port) to mtu setting of 1528. I can successfully pass all packet sizes up to 1518 size packet between these ports.

When I change port 26 (fiber port) to mtu size 9000 and port 1 (ethernet port) to mtu size 9000. I can not pass any size of packet between these ports. all data passage stops.

When I set port 1 (ethernet port) to mtu setting of 9000 and set port 2 (ethernet port) to mtu setting 9000. I am able to successfully send data packets of all sizes including jumbo packets between these ports.

Did you try setting the MTU to 9600 ?
Why did you pick 9000 ?

We have a list of modules that have been reported to work/not work.

https://forum.netonix.com/viewtopic.php?f=6&t=293

Both Alcatel Lucent and Finisar model are listed under "don't work". They aren't the exact models you mentioned, but maybe they are close enough that they also don't work.

I tested several models of modules in my lab and they all work correctly with a 9000 MTU. If you get any of the modules listed above under the "WORKS" section you should be fine.

I did try 9600 also because I seenm that it was max setting.
was using 9000 after researching on internet jumbo packet size and also because it worked on all other ports.

Try another SFP module like Eric suggested ?

Not so sure that would be the cause since you say it works with smaller MTU ?

Weird.

Thanks for the help
Ordering sfp from approved list of compatible sfp's
I hope it works

bill.vincent wrote:Thanks for the help
Ordering sfp from approved list of compatible sfp's
I hope it works

Eric had a personal issue to deal with today but he is going to spend some time looking into this later this evening and tomorrow to make sure.

Dave (Engineer) and Me(Schmuck) feel that since you said that port 25 worked with your existing SFP module with normal MTU of 1528 but did not work at an MTU of 9000 or 9600 that this may indeed possibly be something in the software and not hardware issue (SFP Module).

If Eric is not correctly setting the packet size the switch would be dropping the packets as oversized which you should see by examining the Port Detail by clicking on the little gear on the far right column of the Main Status Tab and selecting Port Details.

If this is the case you will see under Receive Error Counters in the lower left corner a large number of Rx Oversize packets?

But either way if using jumbo I would suggest setting MTU to MAX of 9600 not 9000.

I have seen that it is dropping oversized received packets under port detail.

I was going to ask what I should set for a jumbo packet, I will use 9600.

Also want you to understand that the fiber port 25 and the sfp have been in use and operational at mtu 1528 for several months.
the need to pass jumbo packets only recently been a need with a new customer.

thanks for the Help.
This support method has been awesome. very responsive by everybody.

bill.vincent wrote:Also want you to understand that the fiber port 25 and the sfp have been in use and operational at mtu 1528 for several months.
the need to pass jumbo packets only recently been a need with a new customer.

thanks for the Help.
This support method has been awesome. very responsive by everybody.

Yea this is why I and Dave are thinking this is a firmware issue. We do not write the code in the switch core that handles the actual packet handling but we do configure the core based on what values you put in the interface and I am thinking maybe Eric might not be passing the value to the core that you set for the MTU.

Now Eric thinks not but he said he would look into this tonight and or tomorrow and let us know.