The show interface output for physical interface
Router#sh interfaces FastEthernet 6/1
FastEthernet6/1 is up, line protocol is up (connected)
Hardware is C6k 100Mb 802.3, address is 0009.11f3.8848 (bia 0009.11f3.8848)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:14, output 00:00:36, output hang never
Last clearing of "show interface" counters never
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue :0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
1117058 packets input, 78283238 bytes, 0 no buffer
Received 1117035 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
285811 packets output, 27449284 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Show interface output (physical interface) explained
up, line protocol up (connected) - the "up" is the physical layer (OSI layer 1) status of the link; the "line protocol up" is the data link layer (OSI layer 2) status of the link. Possible output are as follows:
up, line protocol up
up, line protocol down
down, line protocol down
Hardware - the interface hardware type, as well as the hardware/MAC address.
Description - the user-specified interface description as configured in the interface configuration mode.
MTU 1500 bytes - Maximum Transmission Unit.
BW - Bandwidth.
DLY - Delay (in microseconds).
reliability - reliability, as fraction of 255 (where 255/255 = 100% reliability), exponential average over 5 minutes.
txload - current output load, as fraction of 255 (where 255/255 = 100% saturation), exponential average over 5 minutes.
rxload - current input load, as fraction of 255 (where 255/255 = 100% saturation), exponential average over 5 minutes.
Encapsulation - current data link/layer 2 encapsulation of the interface.
loopback - defines if loopback (hardware or software) is enabled or disabled.
Full-duplex, 100Mb/s - current duplex and speed settings of the interface.
ARP Type - the Address Resolution Protocol type enabled.
ARP Timeout - the time in hh:mm:ss for each entry remains in ARP cache before being removed.
Last input 00:00:14, output 00:00:36 - the time in hh:mm:ss when the last packet was received (input) or transmitted (output) by the interface.
output hang - the time in hh:mm:ss when the interface was reset because of a transmission that took too long.
Last clearing of "show interface" counters - the time when the interface counters are last cleared via "clear counter" command.
Input queue: 0/2000/0/0 (size/max/drops/flushes) - the input queue counters and thresholds; the first number (size) is the current number of frames in the queue; the second number (max) is the maximum number of frames in the queue before it starts dropping; the third number (drops) is the number of frames dropped because the max was exceeded; the last number (flushes) is the number of low-priority frames dropped due to Selective Packet Discard (SPD) algorithm when CPU is overloaded.
Total output drops: 0 - total number of packets dropped because the output queue is full; high output drops may indicate mismatched bandwidth settings of this and the remote connecting interface.
Queueing strategy - either First-In/First-Out (fifo), priority-list, custom-list, and weighted-fair.
Output queue :0/40 (size/max) - The number of packets in the output queue. Size is the current number of frames in the queue. Max is the number of frames the queue can hold before it starts dropping frames.
5 minute input/output rate - The average input and output rate seen by the interface in the last five minutes. The interval can be changed via the "load-interval
" interface command.
packets input, bytes - Total number of error-free packets received by the system. Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer - The number of packets received and discarded because there is no buffer space. Can be caused by broadcast storms.
Received broadcasts - The number of broadcast/multicast packets received by the interface.
runts - The number of packets that are discarded because they are smaller than the minimum packet size.
giants - The number of packets that are discarded because they exceed the maximum packet size (MTU).
throttles - The number of times the receiver on the port was disabled, possibly due to buffer or processor overload.
input errors - Includes runts, giants, no buffer, CRC, frame, overrun, and ignored counts.
CRC - Number of packets where the CRC generated by the originating far-end device does not match the checksum calculated from the data received; usually indicates noise or transmission problems on the LAN interface or the LAN bus itself.
frame - Number of packets received incorrectly having a CRC error and a noninteger number of octets A(elignment errors).
overrun - Number of times the receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored - Number of received packets ignored by the interface because the interface hardware ran low on internal buffers.
watchdog - Number of times watchdog receive timer expired. It happens when receiving a packet with length greater than 2048.
multicast - Number of multicast packets received.
pause input - Number of times the connected device requests for a traffic pause when its receive buffer is almost full. This counter is incremented for informational purposes, since the switch accepts the frame. The pause packets stop when the connected device is able to receive the traffic.
input packets with dribble condition detected - A dribble bit error indicates that a frame is slightly too long. This frame error counter is incremented for informational purposes, since the switch accepts the frame.
packets output, bytes - Total number of error-free packets transmitted by the system. Total number of bytes, including data and MAC encapsulation, in the error free packets transmitted by the system.
underruns - Number of times that the transmitter has been run faster than the switch can handle. This can occur in a high throughput situation where an interface is hit with a high volume of bursty traffic from many other interfaces all at once. Interface resets can occur along with the underruns.
output errors - Sum of all errors that prevented the final transmission of datagrams out of the interface.
collisions - Number of times a collision occurred before the interface transmitted a frame to the media successfully. Collisions are normal for interfaces configured as half duplex but must not be seen on full duplex interfaces. If collisions increase dramatically, this points to a highly utilized link or possibly a duplex mismatch with the attached device.
interface resets - Number of times the interface transitioned from up to down to up.
babbles - Number of times that the transmit jabber timer expired. A jabber is a frame longer than 1518 octets (which exclude framing bits, but include FCS octets), which does not end with an even number of octets (alignment error) or has a bad FCS error.
late collision - Number of times a late collision occured. A late collision occurs when two devices transmit at the same time, and neither side of the connection detects a collision. The reason for this occurrence is because the time to propagate the signal from one end of the network to another is longer than the time to put the entire packet on the network. The two devices that cause the late collision never see that the other is sending until after it puts the entire packet on the network. Late collisions are not detected by the transmitter until after the first 64 byte slot time. This is because they are only detected in transmissions of packets longer than 64 bytes.
deferred - Number of frames that have been transmitted successfully after they wait because the media was busy. This is usually seen in half duplex environments where the carrier is already in use when it tries to transmit a frame.
lost carrier - The number of times the carrier was lost in transmission. This is usually caused by a bad cable. Check the physical connection on both sides.
no carrier - Number of times the carrier was not present in the transmission. This is usually caused by a bad cable. Check the physical connection on both sides.
output buffer failures, output buffers swapped out - Number of failed buffers and the number of buffers swapped out. A port buffers the packets to the Tx buffer when the rate of traffic switched to the port is high and it cannot handle the amount of traffic. The port starts to drop the packets when the Tx buffer is full and thus increases the underruns and the output buffer failure counters. The increase in the output buffer failure counters can be a sign that the ports are run at an inferior speed and/or duplex, or there is too much traffic that goes through the port.
Reference: Troubleshooting Switch Port and Interface Problems
http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml
