Jumbo Frame Support on N5200PRO

[_egd]

The Jumbo Frame Support options on the N5200PRO running firmware 2.00.00.11 allow 4,000, 8,000, 12,000 or 16,000 bytes.

My NIC drivers allow for 4,088 or 9,014 bytes. My unmanaged gigabit switch supports a maximum jumbo frame size of 9,014 bytes.

What Jumbo Frame size should I set the N5200PRO to use to ensure compatibility across the network?

What is the reason the N5200PRO jumbo frame sizes do not correspond with the frame sizes typically supported by NICs and switches? Are there any plans to change this in future firmware revisions?

I would really appreciate your assistance in configuring the N5200PRO to maximise throughput to other devices on the network.

[cheburashka]

8000.

[Thecus - Yvon]

Dear Sir,

The Jumbo Frame size depends on the NIC driver. Say, NVidia GbE LAN has 1500, 2500, 4500, and 9000 bytes, and Intel PRO1000MT has 4088, 9014, and 16128 bytes. However, it's not a problem because two NIC will nego the frame size with each other automatically.

Yvon.

[cheburashka]

Dear Sir,

The Jumbo Frame size depends on the NIC driver. Say, NVidia GbE LAN has 1500, 2500, 4500, and 9000 bytes, and Intel PRO1000MT has 4088, 9014, and 16128 bytes. However, it's not a problem because two NIC will nego the frame size with each other automatically.

Yvon.

As I have learned from experience, they definitely will not negotiate frame size safely. As long as all of your settable devices are set for 9000 or less (9014 is the same as 9000 -- the extra 14 is the ethernet frame itself), and all your non-settable devices (switches) are jumbo frame "clean" up to that size, then you'll be fine. This isn't negotiation--there is something similar to negotiation, which is that either ethernet or TCP will shrink the frames it uses if packets fail until they start succeeding, but this process costs you the benefit of jumbo frames and ultimately can end up slower than 1500--its just that no matter what you set the size for in most NICs, they're smart enough to receive bigger frames even if they don't send them.

I have a PC set for 9000, a Thecus set for 8000, and an NSLU2 set for 7200, and they all talk to each other fine. Just don't try to go above 9000 unless you're positive that your switches can handle it, which they probably can't.

[_egd]

I have a PC set for 9000, a Thecus set for 8000, and an NSLU2 set for 7200, and they all talk to each other fine. Just don't try to go above 9000 unless you're positive that your switches can handle it, which they probably can't.

Ok, my Marvell Yukon 88E8052 PCI-E ASF NIC's Jumbo Frames is configured to 9014 (has been all along), my N5200PRO has been changed from Jumbo Frames off to 9000 and rebooted. Now I cannot connect to my Thecus. I know for sure my gigabit switch (SMC GS5) supports Jumbo Frames up to 9014.


Seems I get an initial connection and then nothing - seems the connection times out. Any ideas/ tips on how to resolve this?

[mickey]

I was concerned about just such an occurance when I was playing around with frame sizes and so I made sure to have both ports active and experimented with one only.

If you have the pro model, and did not change the Jumbo setting for it, you could change the IP address of your PC to match the subnet of the second ethernet port and access the device from this network interface.

Short of that, try a cross over cable between your PC and the n5200 to get the switch out of the equation.

Mickey