ReadyNas NVX and GS108T Jumbo Frames

Did you enable jumbo frames on the switch? It is a managed switch with its own web page for configuration.

StephenB wrote:
Did you enable jumbo frames on the switch? It is a managed switch with its own web page for configuration.

Thanks for the quick response Stephen.

I have set the maximum frame size to 9000 under >port configuration. I have sleep mode and short cable mode to disable, but link trap to enable.
My LAG settings are: link trap - enable, admin mode - enable, LAG type - LACP and shows link up.

I have fixed IP addresses to all devices. My default gateway is my router (fixed again). IPv6 off in all cases.

Hope something there gives a clue.

Thanks again.
Graham

You might need to raise the max frame size on the switch, since I think it includes the ethernet framing (unlike most NICs configurations). Note the minimum is 1518. Perhaps try 9018. (or a bit higher if you use vlans).

Are you seeing anything in the port statistics? You could also try using ping to probe the mtu on the connection path from the PC to the NAS.

BTW, I run with jumbo frames off, so there could be some limitations I haven't run into here.

Well, I tried that and no go (went to the max of 9216). Again, when I check the 'use jumbo frames' checkbox on the nas config screen it seems unhappy. After a reboot, I can't access the admin page of the nas (It goes to a blank page with no choices on the left). I have to go into the switch settings and disable the members of the LAG. Then all is well again. I can use raidar to confirm that it is seen on the fixed ip address as expected, so I'm really confused.

I appreciate it may make no difference, but I have invested in a new switch by the same manufacturer and can't believe they won't play together. I'm just hoping I have made a simple mistake in one of the settings. But which one? I'm on a mac and most of this is going straight over my head - the gs108t gives a huge number of esoteric settings with very limited explanations and none that mean anything to me.

Hope someone can shed some light on what might be happening.

Graham

Did you enable global flow control on the GS108T? It is on by default on a new unmanaged switch, but is off by default on the GS108T. Lots of things don't work well if flow control is off.

Did you attempt to use ping to probe the mtu?

You could also try some intermediate MTU sizes on the NAS (maybe start with 3000)

Thanks for sticking with this Stephen.

Yes, flow control is on.

I'm a bit lost on how to ping the mtu on a mac. But raidar always finds the nas, even though I can't access the setup page fully.

To be honest, I don't think it is connected to the size of the MTU as it immediately starts to wobble when I check the 'use jumbo frames' checkbox with the nas - takes an age to confirm and immediately becomes unresponsive as if someone has pulled the plug somewhere.

Happy to keep trying any suggestions, so keep any thoughts coming please.

Graham

Jumbo Frame settings determine the MTU (in your case you are expanding the MTU to 9000 bytes by turning jumbo frames on). Though if there is an issue, the packets are generally blocked or fragmented.

http://muzso.hu/2009/05/17/how-to-deter ... icmp-pings has a mac example on how to measure the actual MTU. You might try this first with LACP turned off, since that appears to be stable.

Thanks again Stephen. When I plug the computer into the gs108t, I get all sorts of problems connecting to the readynas. I've spent days on this and not come to any specific conclusions. I guess I've wasted my money on the gs108t as it's actually worse than the regular switch. I did believe that it was just a case of selecting two ports to combine to give a bonded connection. I'm not a network engineer and I would advise anyone else not to waste their time buying a 'smart' switch unless they have a high degree of knowledge in the subject and lots of time to experiment.
Very disappointed as I've never heard of this problem and can't even decide if I have a faulty device.