RED Interface MTU same as WAN MTU?

What result do you see from:

ping -I 10.10.10.1 10.10.10.2 -s 1500 -M do

Where .1 is the IP on your end of the tunnel and .2 is at the other end.

Cheers - Bob

Hi Bob,

with:

ping -I 192.168.221.1 (UTM) 192.168.221.2 (Remote PC) -s 1500 -M do

i got:

From 192.168.221.1 icmp_seq=10 Frag needed and DF set (mtu = 1500)

1472 is the only MTU that works.

Interface settings: WAN MTU 1492; RED MTU 1500

Is there a general recommendation for this?

1472, I guess there is a VDSL line related? Maybe on the RED side?

My feeling would be to adjust the RED MTU to that value.

But the question is interesting.

Best

Alex

Hi Alex,

thank you for your post.

I am still wondering why nobody came direct with a clear recommendation.

Kind of a VDSL is included in this construct.. a PPPoE connection.

Maybe the 1472 is resulting from 1492 WAN MTU - 20 byte IP Header.

"My feeling would be to adjust the RED MTU to that value."

->Same here

It would be nice to hear more ideas

Maybe interesting too

So it seems the MTU setting affects only UTM side!?

Best

Alex

Interesting feature request!

I cant say that without further testing.

But it can be, that the RED MTU interface settings in UTM are affecting the local RED. Like for example the vlan interface you can configure on top of an RED interface.