netstat -v command

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The netstat -v command displays the statistics for each Common Data Link Interface (CDLI)-based device driver that is in operation.

Interface-specific reports can be requested using the tokstat, entstat, fddistat, or atmstat commands.

Every interface has its own specific information and some general information. The following example shows the Token-Ring and Ethernet part of the netstat -v command; other interface parts are similar. With a different adapter, the statistics will differ somewhat. The most important output fields are highlighted.

# netstat -v
-------------------------------------------------------------
ETHERNET STATISTICS (ent1) :
Device Type: 10/100 Mbps Ethernet PCI Adapter II (1410ff01)
Hardware Address: 00:09:6b:3e:00:55
Elapsed Time: 0 days 17 hours 38 minutes 35 seconds

Transmit Statistics:                          Receive Statistics:
--------------------                          -------------------
Packets: 519                                  Packets: 30161
Bytes: 81415                                  Bytes: 7947141
Interrupts: 2                                 Interrupts: 29873
Transmit Errors: 0                            Receive Errors: 0
Packets Dropped: 0                            Packets Dropped: 0
                                              Bad Packets: 0
Max Packets on S/W Transmit Queue: 3
S/W Transmit Queue Overflow: 0
Current S/W+H/W Transmit Queue Length: 1

Broadcast Packets: 3                          Broadcast Packets: 29544
Multicast Packets: 2                          Multicast Packets: 42
No Carrier Sense: 0                           CRC Errors: 0
DMA Underrun: 0                               DMA Overrun: 0
Lost CTS Errors: 0                            Alignment Errors: 0
Max Collision Errors: 0                       No Resource Errors: 0
Late Collision Errors: 0                      Receive Collision Errors: 0
Deferred: 0                                   Packet Too Short Errors: 0
SQE Test: 0                                   Packet Too Long Errors: 0
Timeout Errors: 0                             Packets Discarded by Adapter: 0
Single Collision Count: 0                     Receiver Start Count: 0
Multiple Collision Count: 0
Current HW Transmit Queue Length: 1

General Statistics:
-------------------
No mbuf Errors: 0
Adapter Reset Count: 0
Adapter Data Rate: 200
Driver Flags: Up Broadcast Running
        Simplex AlternateAddress 64BitSupport
        ChecksumOffload PrivateSegment DataRateSet

10/100 Mbps Ethernet PCI Adapter II (1410ff01) Specific Statistics:
--------------------------------------------------------------------
Link Status: Up
Media Speed Selected: Auto negotiation
Media Speed Running: 100 Mbps Full Duplex
Receive Pool Buffer Size: 1024
Free Receive Pool Buffers: 1024
No Receive Pool Buffer Errors: 0
Receive Buffer Too Small Errors: 0
Entries to transmit timeout routine: 0
Transmit IPsec packets: 0
Transmit IPsec packets dropped: 0
Receive IPsec packets: 0
Receive IPsec packets dropped: 0
Inbound IPsec SA offload count: 0
Transmit Large Send packets: 0
Transmit Large Send packets dropped: 0
Packets with Transmit collisions:
 1 collisions: 0           6 collisions: 0          11 collisions: 0
 2 collisions: 0           7 collisions: 0          12 collisions: 0
 3 collisions: 0           8 collisions: 0          13 collisions: 0
 4 collisions: 0           9 collisions: 0          14 collisions: 0
 5 collisions: 0          10 collisions: 0          15 collisions: 0
-------------------------------------------------------------
ETHERNET STATISTICS (ent0) :
Device Type: 10/100/1000 Base-TX PCI-X Adapter (14106902)
Hardware Address: 00:02:55:6a:a5:dc
Elapsed Time: 0 days 17 hours 0 minutes 26 seconds

Transmit Statistics:                          Receive Statistics:
--------------------                          -------------------
Packets: 15                                   Packets: 14
Bytes: 1037                                   Bytes: 958
Interrupts: 0                                 Interrupts: 13
Transmit Errors: 0                            Receive Errors: 0
Packets Dropped: 0                            Packets Dropped: 0
                                              Bad Packets: 0
Max Packets on S/W Transmit Queue: 4
S/W Transmit Queue Overflow: 0
Current S/W+H/W Transmit Queue Length: 0

Broadcast Packets: 1                          Broadcast Packets: 0
Multicast Packets: 1                          Multicast Packets: 0
No Carrier Sense: 0                           CRC Errors: 0
DMA Underrun: 0                               DMA Overrun: 0
Lost CTS Errors: 0                            Alignment Errors: 0
Max Collision Errors: 0                       No Resource Errors: 0
Late Collision Errors: 0                      Receive Collision Errors: 0
Deferred: 0                                   Packet Too Short Errors: 0
SQE Test: 0                                   Packet Too Long Errors: 0
Timeout Errors: 0                             Packets Discarded by Adapter: 0
Single Collision Count: 0                     Receiver Start Count: 0
Multiple Collision Count: 0
Current HW Transmit Queue Length: 0

General Statistics:
-------------------
No mbuf Errors: 0
Adapter Reset Count: 0
Adapter Data Rate: 2000
Driver Flags: Up Broadcast Running
        Simplex 64BitSupport ChecksumOffload
        PrivateSegment LargeSend DataRateSet

10/100/1000 Base-TX PCI-X Adapter (14106902) Specific Statistics:
--------------------------------------------------------------------
Link Status: Up
Media Speed Selected: Auto negotiation
Media Speed Running: 1000 Mbps Full Duplex
PCI Mode: PCI-X (100-133)
PCI Bus Width: 64-bit
Jumbo Frames: Disabled
TCP Segmentation Offload: Enabled
        TCP Segmentation Offload Packets Transmitted: 0
        TCP Segmentation Offload Packet Errors: 0
Transmit and Receive Flow Control Status: Enabled
        XON Flow Control Packets Transmitted: 0
        XON Flow Control Packets Received: 0
        XOFF Flow Control Packets Transmitted: 0
        XOFF Flow Control Packets Received: 0
Transmit and Receive Flow Control Threshold (High): 32768
Transmit and Receive Flow Control Threshold (Low): 24576
Transmit and Receive Storage Allocation (TX/RX): 16/48

The highlighted fields are described as follows:

Transmit and Receive Errors
Number of output/input errors encountered on this device. This field counts unsuccessful transmissions due to hardware/network errors.

These unsuccessful transmissions could also slow down the performance of the system.
Max Packets on S/W Transmit Queue
Maximum number of outgoing packets ever queued to the software transmit queue.

An indication of an inadequate queue size is if the maximal transmits queued equals the current queue size (xmt_que_size). This indicates that the queue was full at some point.

To check the current size of the queue, use the lsattr -El adapter command (where adapter is, for example, ent0). Because the queue is associated with the device driver and adapter for the interface, use the adapter name, not the interface name. Use the SMIT or the chdev command to change the queue size.
S/W Transmit Queue Overflow
Number of outgoing packets that have overflowed the software transmit queue. A value other than zero requires the same actions as would be needed if the Max Packets on S/W Transmit Queue reaches the xmt_que_size. The transmit queue size must be increased.
Broadcast Packets
Number of broadcast packets received without any error.

If the value for broadcast packets is high, compare it with the total received packets. The received broadcast packets should be less than 20 percent of the total received packets. If it is high, this could be an indication of a high network load; use multicasting. The use of IP multicasting enables a message to be transmitted to a group of hosts, instead of having to address and send the message to each group member individually.
DMA Overrun
The DMA Overrun statistic is incremented when the adapter is using DMA to put a packet into system memory and the transfer is not completed. There are system buffers available for the packet to be placed into, but the DMA operation failed to complete. This occurs when the MCA bus is too busy for the adapter to be able to use DMA for the packets. The location of the adapter on the bus is crucial in a heavily loaded system. Typically an adapter in a lower slot number on the bus, by having the higher bus priority, is using so much of the bus that adapters in higher slot numbers are not being served. This is particularly true if the adapters in a lower slot number are ATM adapters.
Max Collision Errors
Number of unsuccessful transmissions due to too many collisions. The number of collisions encountered exceeded the number of retries on the adapter.
Late Collision Errors
Number of unsuccessful transmissions due to the late collision error.
Timeout Errors
Number of unsuccessful transmissions due to adapter reported timeout errors.
Single Collision Count
Number of outgoing packets with single (only one) collision encountered during transmission.
Multiple Collision Count
Number of outgoing packets with multiple (2 - 15) collisions encountered during transmission.
Receive Collision Errors
Number of incoming packets with collision errors during reception.
No mbuf Errors
Number of times that mbufs were not available to the device driver. This usually occurs during receive operations when the driver must obtain memory buffers to process inbound packets. If the mbuf pool for the requested size is empty, the packet will be discarded. Use the netstat -m command to confirm this, and increase the parameter thewall.

The No mbuf Errors value is interface-specific and not identical to the requests for mbufs denied from the netstat -m output. Compare the values of the example for the commands netstat -m and netstat -v (Ethernet and Token-Ring part).

To determine network performance problems, check for any Error counts in the netstat -v output.

Additional guidelines:

To check for an overloaded Ethernet network, calculate (from the netstat -v command):
```
(Max Collision Errors + Timeouts Errors) / Transmit Packets
```
If the result is greater than 5 percent, reorganize the network to balance the load.
Another indication for a high network load is (from the command netstat -v):
If the total number of collisions from the netstat -v output (for Ethernet) is greater than 10 percent of the total transmitted packets, as follows:
```
Number of collisions / Number of Transmit Packets > 0.1
```