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8.13.4 Statistics Gathered by Ethernet Driver
The Ethernet driver gathers various statistics (stats) on transmit and receive activity.
These can be useful to diagnose network problems or to simply determine network
loading. The stats are gathered into a contiguous group of 4-byte unsigned integers. The
first integer represents the number of receive stats. The second integer is a constant
representing the number of transmit stats. This is followed by all receive stats, then all
transmit stats. This format was chosen to allow extending the number of stats without
affecting software that read old stats. For example, regardless of the number of receive
stats, the first transmit stat will be offset by 2+number of receive stats. In the "C"
programming language, this means the first receive stat would be at array[2] and the first
transmit stat would be at array[array[0]+2]. The array content is:
ARRAY OFFSET DESCRIPTION
0
-
Number of receive statistics (constant == 14)
1
-
Number of transmit statistics (constant == 9)
2
0
Total received bytes (only multicast frames which pass logical address filter are counted)
3
1
Total received frames (multicast frames rejected by logical address filter are not counted)
4
2
Multicast bytes received (this is mainly OSI ES/IS Hello messages)
5
3
Multicast frames received
6
4
Broadcast bytes received (this is normally IP ARP messages)
7
5
Broadcast frames received
8
6
Broadcast frames accepted by hardware hash filter but rejected by software
9
7
Frames with CRC errors (does not included packets with non-integral number of bytes)
10
8
Frames with CRC errors and non-integral number of bytes
11
9
Frames with FIFO overflow (this are really bad errors indicating system malfunction)
12
10
Frames discarded because byte count exceeded Ethernet maximum of 1518
13
11
Frames with "BUFF" error (this is a really bad error indicating system malfunction)
14
12
Frames dropped because memory not available (this is a really bad error)
15
13
Frames dropped because infrequent interrupt response (this is a really bad error)
16
0
Total transmitted bytes
17
1
Total transmitted frames
18
2
Frames not sent on first try due to another device transmitting in half-duplex (deferred)
19
3
Frames never sent due to "excessive deferral" (this is a really bad network error)
20
4
Frames sent after one collision
21
5
Frames sent after between 1 and 16 collisions
22
6
Frames never sent due to more than 16 collisions ("excessive collisions").
23
7
Frames only partially sent due to transmit underflow (really bad system error)
24
8
Frames with late collisions (probably due to full-duplex network and we are half-duplex)
ML0021
August 15, 2018
117
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