description [text]
The 'description' command in interface configuration mode adds a text description to an interface to identify its purpose, connection, or other administrative information, aiding in documentation and troubleshooting.
description [text]When to Use This Command
- Labeling a router interface connected to a specific customer or site, e.g., 'Link to HQ'.
- Documenting the type of connection or circuit ID on a WAN interface, e.g., 'T1 Circuit #12345'.
- Noting the VLAN or subnet assigned to a switch interface, e.g., 'VLAN 10 - Sales'.
- Marking an interface as a backup or failover link, e.g., 'Backup link to DR site'.
Command Examples
Basic Interface Description
Router(config-if)# description Link to HQ - GigabitEthernet0/0No output is generated by the 'description' command itself. The description is stored in the running configuration and can be viewed with 'show interfaces' or 'show running-config'. This example sets a description for GigabitEthernet0/0 indicating it connects to HQ.
Verifying Description in Show Output
Router# show interfaces GigabitEthernet0/0GigabitEthernet0/0 is up, line protocol is up
Hardware is CN Gigabit Ethernet, address is 0011.2233.4455 (bia 0011.2233.4455)
Description: Link to HQ - GigabitEthernet0/0
Internet address is 192.168.1.1/30
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full Duplex, 1000Mbps, media type is RJ45
output flow-control is unsupported, input flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (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
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
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
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped outThe 'show interfaces' output includes a line 'Description: Link to HQ - GigabitEthernet0/0' that displays the configured description. This helps identify the interface's purpose without needing to check the configuration file. The rest of the output shows interface status, IP address, MTU, bandwidth, reliability, load, encapsulation, duplex, speed, and counters for errors and traffic.
Understanding the Output
The 'description' command itself produces no output. To view the description, use 'show interfaces' or 'show running-config'. In 'show interfaces', the description appears on a line starting with 'Description:'. This field is purely administrative and does not affect interface operation. A missing or generic description (e.g., 'Description:') indicates the interface has not been documented. Good practice is to include meaningful text that helps network engineers quickly understand the interface's role, such as the connected device, location, or circuit ID. Watch for descriptions that are too long (max 240 characters) or contain special characters that might cause parsing issues in scripts.
CCNA Exam Tips
CCNA exam tip: The 'description' command is used in interface configuration mode and does not affect interface functionality; it is purely for documentation.
CCNA exam tip: You may be asked to identify the command that adds a description to an interface; remember it is 'description' (not 'name' or 'label').
CCNA exam tip: Descriptions can be viewed with 'show interfaces' or 'show running-config interface [interface]'. The exam may test your ability to locate the description in output.
CCNA exam tip: Descriptions are often used in troubleshooting to quickly identify interface connections; a missing description might indicate incomplete documentation.
Common Mistakes
Mistake 1: Using 'name' instead of 'description' — the correct command is 'description', not 'name'.
Mistake 2: Forgetting to enter interface configuration mode before using the command — results in '% Invalid input detected' error.
Mistake 3: Including spaces or special characters that break the description — keep it alphanumeric with spaces and hyphens only.
Related Commands
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