MIB: IF-MIB
An estimate of the interface's current bandwidth in bits per second.
For interfaces which do not vary in bandwidth or for those where no accurate estimation can be made,
this object should contain the nominal bandwidth.
If the bandwidth of the interface is greater than the maximum value reportable by this object then
this object should report its maximum value (4,294,967,295) and ifHighSpeed must be used to report the interace's speed.
For a sub-layer which has no concept of bandwidth, this object should be zero.