Smart Rendering Sorting IPS

Is there a built in function for sorting IPS in dhtmlxgrid or do I have to write a custom sort ?

Could you clarify what do you mean about the “sorting IPS”?
Here is the list of inbuilt sorting types:
docs.dhtmlx.com/grid__sorting.ht … ntheheader

For example lets say I have 70.0.0.0/28 and 71.1.0.0 I want it to sort by 70 followed by 71.

Akis in select filter when I have 1 12 6 66, is there anyway to sort by size rather then first number so 1 6 12 66

Unfortunately there is no such sorting types in dhtmlxGrid.
You need to create your custom sorting function.
Here you can find a tutorial:
docs.dhtmlx.com/grid__sorting.ht … ngfunction