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Functional Description
14.3.2.20.2 Tx-only Statistics Descriptions
The maximum and minimum transmit frame size is software controllable.
14.3.2.20.2.1 Good Tx Frames (Offset = 34h)
The total number of good frames received on the port. A good frame is defined to be:
• Any data or MAC control frame which matched a unicast, broadcast or multicast address, or matched
due to promiscuous mode
• Any length
• Had no late or excessive collisions, no carrier loss and no underrun
14.3.2.20.2.2 Broadcast Tx Frames (Offset = 38h)
The total number of good broadcast frames received on the port. A good broadcast frame is defined to be:
• Any data or MAC control frame which was destined for only address 0xFFFFFFFFFFFF
• Any length
• Had no late or excessive collisions, no carrier loss and no underrun
14.3.2.20.2.3 Multicast Tx Frames (Offset = 3Ch)
The total number of good multicast frames received on the port. A good multicast frame is defined to be:
• Any data or MAC control frame which was destined for any multicast address other than
0xFFFFFFFFFFFF
• Any length
• Had no late or excessive collisions, no carrier loss and no underrun
14.3.2.20.2.4 Pause Tx Frames (Offset = 40h)
This statistic indicates the number of IEEE 802.3X pause frames transmitted by the port.
Pause frames cannot underrun or contain a CRC error because they are created in the transmitting MAC,
so these error conditions have no effect upon the statistic. Pause frames sent by software will not be
included in this count.
Since pause frames are only transmitted in full duplex carrier loss and collisions have no effect upon this
statistic.
Transmitted pause frames are always 64 byte multicast frames so will appear in the Tx Multicast Frames
and 64octet Frames statistics.
14.3.2.20.2.5 Collisions (Offset = 48h)
This statistic records the total number of times that the port experienced a collision. Collisions occur under
two circumstances.
1. When a transmit data or MAC control frame:
• Was destined for any unicast, broadcast or multicast address
• Was any size
• Had no carrier loss and no underrun
• Experienced a collision. A jam sequence is sent for every non-late collision, so this statistic will
increment on each occasion if a frame experiences multiple collisions (and increments on late
collisions)
CRC errors have no effect upon this statistic.
2. When the port is in half-duplex mode, flow control is active, and a frame reception begins.
1215
SPRUH73H–October 2011–Revised April 2013 Ethernet Subsystem
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