[SOLVED] Using Usb3 Port On Asus Rt-ax86u Router As Lan/wan

roieco

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Dec 4, 2020
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hi there,

i have 2.5 gbps fiber internet.
i'd like to use one of the usb-3 ports on my RT-AX86U router as a lan or wan in order to have both the wan (connection to the fiber modem) and my main computer connected at 2.5 gbps (RT-AX86U has only one 2.5 gbps ethernet port)

can it be done? i'm currently using merlin.

thanks!
 
Not very likely.

The first issues is there is not likely a driver for the USB ethernet. USB is mostly used for storage or some small list of modems. Now in theory you could add it yourself since it is third party firmware.

The much larger problem is the CPU can't run fast enough. To get high speed most modern routers use a hardware offload feature that lets the NAT run in the hardware bypassing the cpu chip. Even very powerful routers will only pass about 300mbps if you turn this feature off. Since the USB function is done by the CPU you would have to turn off the NAT bypass feature and allow the traffic to run via the CPU which defeats the whole purpose of your project. Pretty much doing anything fancy on the router forces you do disable this feature. Even something simple like parental controls or even very simple firewall rules require the CPU to see the traffic.

Now you might get a partial solution by using a switch that can do port bonding. I am not sure if that particular model does bonding. You would have to place a switch that has a 2.5g port and supports bonding between your pc and the router. BUT it will only actually work for certain types of traffic. 802.3ad (ie port bonding) does not load balance by packet. It selects the path based on ip addresses and port numbers. That means all traffic for a single session will always use the same connection. So a single thread file transfer can only use 1gbit. Now a multi thread data transfer might use both. Torrent and some game downloaders use multi stream. Problem is 802.3ad is really stupid it is pure math it does not look at utilization. It might place both streams on the same path leaving the other unused.

I suspect your only realistic option is to get a different router.

I would carefully think about how much actual value having 2.5g over 1g is when you look to spend money on a new router. Many internet sites artificially limit traffic to prevent someone with a large internet from hogging the server bandwidth. Also many sites are actually many smaller servers that only have 1gbit ports.

It all depends on what you actually plan to do. It will pretty much only help with large downloads. Almost all other applications do not need much bandwidth. This is the same as when I look at do I upgrade from 300mbps to 1gbit. Sure it will download very large game files a few minutes faster but how often do I really do that per month.
 
Not very likely.

The first issues is there is not likely a driver for the USB ethernet. USB is mostly used for storage or some small list of modems. Now in theory you could add it yourself since it is third party firmware.

The much larger problem is the CPU can't run fast enough. To get high speed most modern routers use a hardware offload feature that lets the NAT run in the hardware bypassing the cpu chip. Even very powerful routers will only pass about 300mbps if you turn this feature off. Since the USB function is done by the CPU you would have to turn off the NAT bypass feature and allow the traffic to run via the CPU which defeats the whole purpose of your project. Pretty much doing anything fancy on the router forces you do disable this feature. Even something simple like parental controls or even very simple firewall rules require the CPU to see the traffic.

Now you might get a partial solution by using a switch that can do port bonding. I am not sure if that particular model does bonding. You would have to place a switch that has a 2.5g port and supports bonding between your pc and the router. BUT it will only actually work for certain types of traffic. 802.3ad (ie port bonding) does not load balance by packet. It selects the path based on ip addresses and port numbers. That means all traffic for a single session will always use the same connection. So a single thread file transfer can only use 1gbit. Now a multi thread data transfer might use both. Torrent and some game downloaders use multi stream. Problem is 802.3ad is really stupid it is pure math it does not look at utilization. It might place both streams on the same path leaving the other unused.

I suspect your only realistic option is to get a different router.

I would carefully think about how much actual value having 2.5g over 1g is when you look to spend money on a new router. Many internet sites artificially limit traffic to prevent someone with a large internet from hogging the server bandwidth. Also many sites are actually many smaller servers that only have 1gbit ports.

It all depends on what you actually plan to do. It will pretty much only help with large downloads. Almost all other applications do not need much bandwidth. This is the same as when I look at do I upgrade from 300mbps to 1gbit. Sure it will download very large game files a few minutes faster but how often do I really do that per month.
 

gggplaya

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I would build your own router with an x86 processor. That's what I did. You can stuff two intel 2.5gbe or retired 10gbe server network cards into it and use a beefy enough processor to do traffic shaping with FQ_Codel or Cake algorithm.

You can run OpenWRT or DDWRT for software.

About 400-500mbps, ARM processor routers can't do traffic shaping. You have to build an x86 router or not have traffic shaping at higher speeds.
 

roieco

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Dec 4, 2020
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I would build your own router with an x86 processor. That's what I did. You can stuff two intel 2.5gbe or retired 10gbe server network cards into it and use a beefy enough processor to do traffic shaping with FQ_Codel or Cake algorithm.

You can run OpenWRT or DDWRT for software.

About 400-500mbps, ARM processor routers can't do traffic shaping. You have to build an x86 router or not have traffic shaping at higher speeds.
what level of hw would be required for the x86 system to pull this off?
 

gggplaya

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what level of hw would be required for the x86 system to pull this off?
I'm using an Athlon 3000G processor to fully traffic shape my gigabit internet. It handles it just fine. I'm not sure if it can handle 2.5gbe because I can't test that out. The Athlon 3000G is a $70 processor brand new with low power consumption, which is why I chose that. I put my system into a 4U rack case with a microATX motherboard.

The traffic shaping algorithm is single threaded. So no need for tons of processing cores, dual core processor is just fine for a router. To shape more traffic, get one with a higher clock speed and better IPC than what I have.
 
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roieco

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Dec 4, 2020
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I'm using an Athlon 3000G processor to fully traffic shape my gigabit internet. It handles it just fine. I'm not sure if it can handle 2.5gbe because I can't test that out. The Athlon 3000G is a $60 processor brand new with low power consumption, which is why I chose that. I put my system into a 4U rack case with a microATX motherboard.
thanks!
 
If all you need is a simple router with very little traffic filtering I would look at microtik they likely have something that will work for you for less than building it yourself. Read the specs carefully they like most commercial routers actually give you the throughput rates based on the packet size which will show you worst case you can expect.

If you plan to do any fancy traffic shaping or vpn your are going to have to use a general purpose cpu.
 
Dec 9, 2021
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I will add something i discoverd with this router with the latest firmware the normal 1gig wan port can be used a 5th lan port so its actully a wan/lan port as well, if you set the 2.5gig port as your wan port under dual wan it automactily sets the 1gig wan to a lan port, you can see this when u click on system status under the network map tab , i do remeber when i first got this router that wasnt possible, so it must have been changed in one of the firmware updates, also the Lan1 thats reading 100mbs thats just my PS5 in sleep mode when i boot it up it switches to 1gbs



router runs great as u can see here, i have a multigig 3.1 modem conntected to the 2.5 multigig wan port
 
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Dec 9, 2021
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oh i forgot i did do soem testing with a USB to 2.5 multigig dongle and connected my modem up with that, it does work but the speeds would never break 400mbs for some reason even though it showed a 2.5gb link, my orginal intent was to use the usb dongle with my modem and the 2.5gig port on my router connected back to my 5port 2.5gb switch so all my lan connections would be 2.5gig sadly using usb wan was just to slow, i guess it is ment for cellphones or cell based hotspots as a backup or something
 

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