GigaBit Ethernet Bandwidth send & receive

For a duplex 1 GigBit NIC, [134,217,728 Mbytes], does this mean it can receive AND send both at 134MNBytes per second, which is 268 MByte total capacity; Or Send and Receive share the 134 Mbytes, so each can have about 67 MByes per second?

Solution 1:

Full-duplex means that your transmit and receive are independent: you can transmit at 1Gbps and receive at 1Gbps at the same time.

The question of whether you'll achieve full line rate or not is another matter - there's plenty of factors which will prevent you getting full line rate. That's beyond the scope of this question though.

Also, minor point, but network bandwidth is measured using SI units, so a gigabit is 10^9 bits per second, not 2^30 bits per second. So your theoretical maximum is (1000*1000*1000)/8, not (1024*1024*1024)/8, or in other words, it's 125MB/sec in each direction.

Solution 2:

It depends on it being configured for full-duplex or half-duplex.

Usually, it should be full-duplex (full bandwidth in each direction).