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AX88U-Pro, Jumbo Frames?

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JSinFCVA

Regular Contributor
Didn't find a thread that discusses Jumbo Frames on the AX88U-Pro. I upgraded to the AX88U-Pro from the AX86U which explicitly allows the selection of jumbo frames in the firmware. The AX88U-Pro Merlin firmware doesn't have the settings to enable/disable jumbo frames. Does anyone know if this is a limitation of the embedded switch hardware, or just an omission in the firmware? I installed Merlin before I installed this router for the first time, so not sure if the ASUS official firmware supports jumbo frames. I wound up having to move my jumbo frame devices off the router ports to a separate switch that supports jumbo frames, so I have a workaround. Just curious about the router though. Thanks!
 
If you merely flashed the RMerlin firmware without doing a full reset to factory defaults afterward, you may not be seeing the GUI/options as intended.
 
If you merely flashed the RMerlin firmware without doing a full reset to factory defaults afterward, you may not be seeing the GUI/options as intended.
Hmm. I did not do a factory reset after Merlin flash. Since the AX88U-Pro was brand new "out of the box" and never configured when I flashed to Merlin, I didn't see the need to factory reset. Guess I'll try it unless someone else confirms Jumbo Frames are not an option on the AX88U-Pro. I did see another thread that confirmed they are not supported on the AX86U-Pro.
 
Just FYI, Jumbo frames aren't recommended any more as they often cause more problems than the benefits that are offered from enabling them.
 
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Just FYI, Jumbo frames aren't recommended any more as they often cause me problems than the benefits they offer.
Understood. I've been using 9K jumbo frames on my PCs and NAS devices for years to improve backup times. I use the NAS for automated backup storage, and Jumbo Frames measurably improved backup times. Never had a single issue until I connected one of the PC's to an ethernet port on the AX88U-Pro. Miserable performance on that PC until I disabled Jumbo Frames on it. With all jumbo frame devices connected to a separate switch that supports jumbo frames, no problems at all. I just daisy chain the switch to an ethernet port on the AX88U-Pro and make sure the WAN MTU on the router is set to 1500. I get full gigabit speed on my WAN connection, and all Jumbo Frame devices get full speed to the WAN without any performance issues.
 
This router doesn't support Jumbo frames...



...no matter how many times you reset and reconfigure.
Thats what I suspected. Thanks for confirming. Couldn't find any technical details on the 88U-Pro to confirm, though. As I mentioned, I moved all devices with Jumbo Frames enabled to a separate switch with Jumbo Frame support. Apparently they have no issue communicating from the separate switch to the AX88U-Pro and to the internet.
 
Understood. I've been using 9K jumbo frames on my PCs and NAS devices for years to improve backup times. I use the NAS for automated backup storage, and Jumbo Frames measurably improved backup times. Never had a single issue until I connected one of the PC's to an ethernet port on the AX88U-Pro. Miserable performance on that PC until I disabled Jumbo Frames on it. With all jumbo frame devices connected to a separate switch that supports jumbo frames, no problems at all. I just daisy chain the switch to an ethernet port on the AX88U-Pro and make sure the WAN MTU on the router is set to 1500. I get full gigabit speed on my WAN connection, and all Jumbo Frame devices get full speed to the WAN without any performance issues.
How much time have you saved? Jumbo frames aren't some kind of miracle solution, especially not in modern hardware with TCP/IP offloading and faster CPUs compared to a decade or two ago

On anything faster than Gigabit, it's not at all recommended.

I have honestly never seen any proof that it brings any tangible benefits on modern hardware.
 
How much time have you saved? Jumbo frames aren't some kind of miracle solution, especially not in modern hardware with TCP/IP offloading and faster CPUs compared to a decade or two ago

On anything faster than Gigabit, it's not at all recommended.

I have honestly never seen any proof that it brings any tangible benefits on modern hardware.
Perhaps. I just based it off looking at the real-time ethernet port throughput as measured by my NAS when backups were running across the net. I just saw a higher throughput with the 9K frames. My NAS is > 5 years old and that might be a factor. The NAS CPU is a i5-3470S - which arguably is not super fast by today's standards. Might be time to disable jumbo frames and retest. Thanks for responding!
 
Hmm. I did not do a factory reset after Merlin flash. Since the AX88U-Pro was brand new "out of the box" and never configured when I flashed to Merlin, I didn't see the need to factory reset. Guess I'll try it unless someone else confirms Jumbo Frames are not an option on the AX88U-Pro. I did see another thread that confirmed they are not supported on the AX86U-Pro.

Regardless of whether Jumbo Frames is available in the firmware or not, and regardless of whether or not you configured a brand new router before flashing RMerlin firmware, a full reset to factory defaults is required for the most stable and reliable router/network.

PS also, be sure you don't plug in a USB drive that was previously used for amtm/scripts (unless you first format it in a PC to NTFS format).
 
Regardless of whether Jumbo Frames is available in the firmware or not, and regardless of whether or not you configured a brand new router before flashing RMerlin firmware, a full reset to factory defaults is required for the most stable and reliable router/network.

PS also, be sure you don't plug in a USB drive that was previously used for amtm/scripts (unless you first format it in a PC to NTFS format).
Thanks! Fully aware of that... Been using ASUS / Merlin on more than 5 generations of ASUS routers. The new AX88U-Pro is working flawlessly without resetting to defaults after flashing Merlin to an otherwise unconfigured device and configuring Merlin from scratch. I was just curious about the lack of Jumbo Frame support. Otherwise, no issues whatsoever.
 

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