If you find that the information provided by the show interfaces command isn’t enough information, you can try the detail version of the same command. When you get to this level of detail, you’re usually troubleshooting the interface. This view of the interface gives you even more information, including (but not limited to) the following:

  • Traffic statistics: The counters displayed here indicate the total number of bytes and packets both received by and transmitted out of the interface. These numbers give you an indication of how much traffic your interface is handling. Note that these statistics are cumulative from the last time the statistics were cleared (displayed in the field Statistics last cleared, which is harder to find than it seems it should be).

  • Egress queues: The egress queues correspond to the total number of outbound CoS queues you’ve configured on the box. In this case, the default CoS queues are the only ones configured. Each queue is listed, along with the number of packets in each queue as well as the number of transmitted packets. The dropped packets should be 0 unless you’re experiencing congestion.

When you execute a show interface detail command, this is the level of detail that will be in your output:

user@router> show interfaces detail
Physical interface: fe-0/0/0, Enabled, Physical link is Down
 Interface index: 128, SNMP ifIndex: 23, Generation: 303
 Link-level type: Ethernet, MTU: 1514, Speed: 10m, Loopback: Disabled,
 Source filtering: Disabled, Flow control: Enabled
 Device flags  : Present Running Down
 Interface flags: Hardware-Down SNMP-Traps Internal: 0x4000
 Link flags   : None
 CoS queues   : 4 supported, 4 maximum usable queues
 Hold-times   : Up 0 ms, Down 0 ms
 Current address: 00:05:85:02:a4:00, Hardware address: 00:05:85:02:a4:00
 Last flapped  : 2008-03-05 14:30:58 PST (4w3d 23:03 ago)
 Statistics last cleared: Never
 Traffic statistics:
  Input bytes :       0        0 bps
  Output bytes :       0        0 bps
  Input packets:       0        0 pps
  Output packets:       0        0 pps
  IPv6 transit statistics:
  Input bytes :          0
  Output bytes :          0
  Input packets:          0
  Output packets:          0
 Egress queues: 4 supported, 4 in use
 Queue counters:  Queued packets Transmitted packets  Dropped packets
  0 best-effort         0          0         0
  1 expedited-fo        0          0         0
  2 assured-forw        0          0         0
  3 network-cont        0          0         0
 Active alarms : LINK
 Active defects : LINK

If you find that you still lack the information you need to troubleshoot your network or even a particular interface, you can use another level of detail: the show interfaces extensive command.

The output for that command is a superset of the detailed version of the same command. It includes the same information presented here, along with a detailed listing of input and output errors, and a slew of MAC (Layer 2) statistics.