What is the best MTU size for BSNL FTTH connections?

[laboreddislodge]

Hello, I have a 30mbps FTTH connection with ONT in bridge mode My router Archer AX53 handle the PPPOE auth.
I have set the MTU size as 1460 in my router and it is been the same for few months. Today I noticed something in the PPPOE logs:


Source

Is the BSNL requesting 1492 MTU size? Do I need to modify my MTU to 1492?


My connection is pretty stable but I don't get 30mbps most of the time despite good signal quality

 

[WieldyBinkie]

Let archer negotiate MTU.

 

[Trex]

Yes, they changed/upgrade their network 2 months back.

 

[alap4m]

As pointed out by @WieldyBinkie let the Router negotiate the MTU size.
However, if you are determined to find the best MTU size, download Simple MTU Test program.
This small utility quickly goes through multiple MTU sizes and confirms the best MTU size.
For BSNL FTTH the best MTU size is 1460.

 

[WieldyBinkie]

@alap4m No, BSNL supports only 2 MTU sizes. If you are served from new gen BNGs 1492 bytes, otherwise 1480 bytes. These were the only ones my router has auto-negotiated.

 

[Adithya]

@WieldyBinkie there is no auto option on my c6. I don't think BSNL's equipment is giving out the right information. I am being offered 1492 so I tested it out.

300 INFO 5days, 22:36:15, [ppp][LCP]TX CONFIGURE_REQUEST
301 INFO 5days, 22:36:15, [ppp][LCP]TX CONFIGURE_ACK[mru=1492, auth=C223/5, magic=4937317B]
302 INFO 5days, 22:36:15, [ppp][LCP]RX CONFIGURE_ACK[mru=1492, magic=01D6043A]

Now speed test or fast.com doesn't even start it just sits there.

1480 works though, but that's just what I found out with ping test. Archer by default was configured with 1480.
Btw it used to be 1460, glad to see they're improving.

 

[WieldyBinkie]

@Adithya You are being served from new Nokia BNG at TVLA. MTU should 1492. Btw, it was never 1460.

 

[alap4m]

@WieldyBinkie, I have tested with MTU Test app. BSNL FTTH subscribers have had MTU 1460 for a LONG Time.

Incidentally, smaller fragments than 1460 can also work well. There's not much difference in using the biggest possible MTU size and slightly smaller packets.

 

[WieldyBinkie]

Good luck

 

[!!..PD..!!]

You can follow the steps from the below link and check which MTU size works for your connection. I've seen a person with 1460 MTU as well in Kolkata so you should test it out for yourself and set it accordingly.

Ping Test to determine Optimal MTU Size on Router/Firewall

1. In the Windows, go to “ Windows + R” and type “cmd”. 2. At the Command Prompt, type “ping google.com –f –l 1492” to check MTU Size: 3. The results above indicate that the packet needs to be frag…

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