Viewing Statistics

Recent Rate/s: displays the event rates, per second, averaged over the last 10 seconds.
Total: displays the number of events that occurred since the statistics were last cleared.
Average Rate/s: displays the average event rates, per second, since the statistics were last cleared.
Highest Rate/s: displays the highest rate recorded since the statistics were last cleared.
Packets: displays the number of packets transmitted or received.
Bytes: displays the total number of data bytes in all the packets transmitted or received.
Filtered: displays the number of packets that were discarded as a result of an address filter being set.
Errors: displays the number of errors that did occur.
Multicasts: displays the number of multicast packets transmitted.
Misses: displays lost packets.
Enter space to redisplay, C[lear stats], q[quit]: redisplays statistics. To clear the statistics, type capital C. To exit the Statistics Menu, type q.

Error Statistics (Radio)

The Radio Error Statistics display provides a detailed summary of the radio transceiver errors that have occurred on the bridge.

Navigation: Main > Statistics > Radio

The following list describes the items appearing in the screen above:

Buffer full frames lost: number of frames lost because of a lack of buffer space in the bridge.
Duplicate frames: number of frames that were received more than once. This is usually because of a frame acknowledgment being lost.
CRC errors: number of frames received with an invalid CRC. Usually caused by interference from nearby radio traffic. Occasional CRC errors can also occur because of random noise when the receiver is idle.
Decrypt errors: packets were received without errors but could not be decrypted with available encryption keys.
Retries: cumulative count of the number of times a frame had to be retransmitted because of an acknowledgment not being received.
Max retries / frame: maximum number of times any one frame had to be retransmitted. Excessive retries may indicate a poor quality radio link.
Excessive retries: number of times a packet has taken four or more retries before it was successfully transmitted.
Queue full discards: number of times a packet was not transmitted because of too many retries to the same destination. Discards only occur if packets destined to this address are taking up more than their share of transmit buffers.
Holdoffs: indicates that another node was transmitting when this node tried to start a transmit of its own. This is a usual occurrence but a high rate of holdoffs is an indication of a congested cell.
Holdoff timeouts: indicates that a transmission was held off by other activity longer than the length of time it would take to transmit the longest allowed 802.11 packet. This is usually an indication of some sort of outside interference.

Error Statistics (Ethernet)

The Ethernet Error Statistics display provides a detailed summary of the transmitter errors that have occurred on the bridge.

Navigation: Main > Statistics > Ethernet

The following list describes the items appearing in the screen above:

Buffer full frames lost: number of frames lost because of a lack of buffer space in the bridge.
CRC errors: number of frames received with an invalid CRC. Usually caused by interference from nearby radio traffic. Occasional CRC errors can also occur because of random noise when the receiver is idle.
Collisions: number of times a collision occurred while the frame was being received. This would indicate a hardware problem with an Ethernet node on the infrastructure.
Frame alignment errors: number of frames received whose size in bits was not a multiple of 8. Occasionally, extra bits of data are inadvertently attached to a transmitted packet causing a frame alignment error.
Over-length frames: number of frames received that are longer than the configured maximum packet size.
Short frames: number of frames received that are shorter than the allowed minimum packet size of 64 bytes.
Overruns: number of times the hardware receive FIFO buffer overflowed. This should be a rare occurrence.
Misses: number of Ethernet packets that were lost because of a lack of buffer space on the unit.
Excessive Collisions: number of times transmissions failed because of excessive collisions. Usually indicates the frame had to be continuously retried because of heavy traffic on the Ethernet infrastructure.
Deferrals: number of times frames had to wait before transmitting because of activity on the cable.
Excessive deferrals: number of times the frame failed to transmit because of excessive deferrals. Usually indicates the frame had to be continuously retried because of heavy traffic on the Ethernet infrastructure.
No carrier sense present: number of times the carrier was not present when a transmission was started. Usually indicates a problem with a cable on the Ethernet infrastructure.
Carrier sense lost: number of times the carrier was lost during a transmission. Usually indicates a problem with a cable on the Ethernet infrastructure.
Out of window collisions: number of times a collision occurred after the 64th byte of a frame was transmitted. Usually indicates a problem with a cable on the Ethernet infrastructure.
Underruns: Number of times the hardware transmit FIFO buffer became empty during a transmit. This should be a rare occurrence.
Bad length: Number of times an attempt was made to transmit a packet larger than the specified maximum allowed.

Displaying Overall Status (Status)

The Status display shows the settings of the most important configuration parameters of the bridge as well as important run-time statistics. Use the display to verify correct configuration. The display is broken into sections describing:

The radio
Any LAN connections
Any filtering being done

All items in the display are self-explanatory or are explained in other sections of this guide.

Displaying the Network Map (Map)

The Map command causes the bridge to poll all of the other Cisco Aironet devices in the local infrastructure for information about the radio nodes associated to them. Nodes that are associated to parents are displayed one level from their parents.

The other Cisco Aironet devices in the infrastructure are polled once every 30 seconds. Because all radio nodes will respond, this could generate a significant amount of traffic. You may not want to leave these displays running constantly.

Recording a Statistic History (Watch)

The Watch option records the values of a chosen statistic over time. After you select a statistic and a time interval, the bridge starts a timer. At each timer expiration, the bridge records the current value of the statistic. The last 20 samples are saved.

Follow these steps to record a statistic history.

Step 1 Choose Main Menu > Statistics > Watch. The following menu appears:

Step 2 Type the applicable category number and press Enter.

For example, if you choose 1 to select Radio, the following menu appears:

Step 3 Type the applicable statistic index number and press Enter.

Step 4 The following prompt appears:

Enter a sample time in seconds from 1 to 3600 :

Type a time interval between samples and press Enter. The longer the time you specify, the further back in time the samples are saved (up to 20 samples).

Displaying a Statistic History (History)

The History option displays the history of the statistic being recorded.

To display a statistic history, choose Main > Statistics > History.

Depending on your watch option selections, a display screen similar to the one below will appear.

The following list describes the items appearing in the screen above:

Time (sec): displays the number of seconds elapsed from the time the statistic sample was recorded.
Rate/s: displays the actual value of the statistic. The chart will change scale based on the largest value displayed.

Displaying Node Information (Nodes)

The Nodes command displays current information about the radio link between the bridge and its parent Access Point.

Navigation: Main > Statistics > Nodes

The following list describes the items appearing in the screen above:

Id: displays node ID given to the WGB by its parent Access Point.
Address: displays the address of the parent Access Point.
Signal: displays the signal strength of the RF link.
Tx Pkt: displays the number of packets transmitted.
Tx Byte: displays the actual number of bytes transmitted.
Retry: displays the number of transmitted packets that were resent.
Rx Pkt: displays the number of packets received.
Rx Byte: displays the actual number of bytes received.
Rate: displays the current RF data rate in Mbps.

Displaying ARP Information (ARP)

The ARP (Address Resolution Protocol) command displays the ARP table of IP to MAC addresses. It also displays whether the node supports Ethernet Type II or IEEE 802.2 framing. The last column displays the time until the entry stales out.

Navigation: Main > Statistics > ARP

Setting Screen Display Time (Display_time)

The Display_time option sets the time interval for the automatic redisplay of any screen that automatically refreshes. The default value is 10 seconds.

Table of Contents

Viewing Statistics