PVS MTU value

[RIcardo Diogo1709164140]

Hi,

 

I'm looking in making some optimizations regarding our current PVS deployment. I was always a bit in doubt about changing or not the MTU value.

 

When I do the ping with the default value (1506) I notice that exist fragmentation. If I ping it with 1472 there's no fragmentation. 

 

Is changing this value something that is worth a while? It will be noticeable that something is improved by changing this ?

 

@Kelan RoweI know that you've addressed this topic in the past.

 

Best regards,

[Simon Graham]

If your network is using the standard MTU size then you should not change the default MTU in PVS - the only reason to change is if you have some component in the path that reduces the max available size. 

 

The way MTU is configured in PVS is a bit odd as well -- the value you specify is actually the "traditional" Ethernet MTU + 6 - hence 1506 really means 1500 MTU.

 

When using ping, the buffer size you specify is the amount of data to include -- you have to add the IP/UDP header sizes (28) to that to get the actual transmission unit size - so for a 1500 MTU, you would specify a ping buffer size of 1472.

 

Confusing isn't it!

Simon

[RIcardo Diogo1709164140]

So if I understood correctly, when I ping with 1472, it's really 1500, because along the way it's including the +28 for the IP/UDP header ?

That's why when I ping with 1500 it's fragmenting? Because in reality the packet is using 1528 and not 1500 ?

 

Thanks,

[RIcardo Diogo1709164140]

Any feedback guys ?