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[Hitman]

Hey guy's,

I have a VMG1312-B10A with v17 modified firmware for 1500, but when i set pfsense to 1500 on MTU and MRU, (ipconfig pppoe0 - now reports MTU 1500 (instead of the default 1492)).

However ping 1472 doesn't work, web pages stop loading correctly or don't load at all :/

In the Pfsense PPP log it shows...
Error in 'set link mtu 1500': max MTU on type "pppoe" links is 1492
Error in 'set link mru 1500': max MRU on type "pppoe" links is 1492

I'm with Zen FTTC and read they support BJF 1500 (rfc 4638).

Any help on whats wrong?

Thanks

[meritez]

Hi Hitman,

What have you set MTU to on the VMG?

[underzone]

You need to ping 1472 length for 1500, not 1492:

Linux command:
ping -c4 -M do -s 1472 1.1


Windows command:
ping -f -l 1472 1.1

[Hitman]

Hi Hitman,

What have you set MTU to on the VMG?

I don't think you can set MTU on the VMG - it's also in modem mode, Does 1500 mtu need to be set on the VMG, if so how (CLI?).

You need to ping 1472 length for 1500, not 1492:

Linux command:
ping -c4 -M do -s 1472 1.1


Windows command:
ping -f -l 1472 1.1

Yeah sorry typo, ping packet size 1472, fails - I've updated my OP.


Thanks Guys.

[Alex Atkin UK]

Hey guy's,

I have a VMG1312-B10A with v17 modified firmware for 1500, but when i set pfsense to 1500 on MTU and MRU, (ipconfig pppoe0 - now reports MTU 1500 (instead of the default 1492)).

However ping 1472 doesn't work, web pages stop loading correctly or don't load at all :/

In the Pfsense PPP log it shows...
Error in 'set link mtu 1500': max MTU on type "pppoe" links is 1492
Error in 'set link mru 1500': max MRU on type "pppoe" links is 1492

I'm with Zen FTTC and read they support BJF 1500 (rfc 4638).

Any help on whats wrong?

Thanks

Correct, this should indeed work although it did suddenly break on my line some time ago so I gave up on it.

Unfortunately I can't test now as using different modems as they sync faster which more than offsets not having baby-jumbo support.

[Hitman]

Correct, this should indeed work although it did suddenly break on my line some time ago so I gave up on it.

Unfortunately I can't test now as using different modems as they sync faster which more than offsets not having baby-jumbo support.

Thanks alex, yeah it should as pfsense is set to negotiate a 1508 connection, wierd thing i now find is running with the 1500 settings removed from pfsense, ppoe0 reporting an mtu of 1492, the 1472 packet ping then works 

[underzone]

When I was using my Zyxel VMG8924-B10A modem with pfsense & pppoe two months ago, I had the WAN mtu manually set to 1500, which worked well.
Then when you look at interface statistics in pfsense, pfsense auto nudges some settings to the required 1508 values.

Of course you need johnsons (or equivalent) firmware on the Zyxel device.

[Hitman]

Thanks underzone, yeah i'm using Johnsons latest/last 17_jumbo_v1.1 for my vmg1312.

Tried 1500 inder the - WAN pppoe0, and does the same as adding to MTU/MRU under PPP, either will work and still breaks web loading and the 1472 packet ping :/

[Alex Atkin UK]

Thanks alex, yeah it should as pfsense is set to negotiate a 1508 connection, wierd thing i now find is running with the 1500 settings removed from pfsense, ppoe0 reporting an mtu of 1492, the 1472 packet ping then works 

Look in Advanced, Firewall & NAT, check if IP Do-Not-Fragment compatibility is enabled.  I was confused by it saying "Clear invalid DF bits instead of dropping the packets", it seems it instead actually removes ALL DF bits, not just invalid ones.

Enabled:

Code: [Select]

ping -M do -s 1472 -c 4 1.1.1.1
PING 1.1.1.1 (1.1.1.1) 1472(1500) bytes of data.
1480 bytes from 1.1.1.1: icmp_seq=1 ttl=58 time=14.7 ms
1480 bytes from 1.1.1.1: icmp_seq=2 ttl=58 time=13.8 ms
1480 bytes from 1.1.1.1: icmp_seq=3 ttl=58 time=13.7 ms
1480 bytes from 1.1.1.1: icmp_seq=4 ttl=58 time=14.6 ms
 
Disabled:

Code: [Select]

ping -M do -s 1472 -c 4 1.1.1.1
PING 1.1.1.1 (1.1.1.1) 1472(1500) bytes of data.
From 192.168.1.254 icmp_seq=2 Frag needed and DF set (mtu = 1492)
ping: local error: message too long, mtu=1492
ping: local error: message too long, mtu=1492


[Hitman]

Look in Advanced, Firewall & NAT, check if IP Do-Not-Fragment compatibility is enabled.  I was confused by it saying "Clear invalid DF bits instead of dropping the packets", it seems it instead actually removes ALL DF bits, not just invalid ones.

No, that option is disabled.