show line

To display the status of a line, use the command show line. This is not a privileged command and can be executed by any user. On an eight-port terminal server, show line gives output like this:

Router>show line
 TTY TYP Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns
 0 CTY - - - - - 0 0 0/0
 1 TTY 9600/9600 - - - - - 3 542 0/0
* 2 TTY 9600/9600 - - - - - 1 0 0/0
 3 TTY 38400/38400 - RIisCD - - - 1 0 0/0
I 4 TTY 38400/38400 - inout - - - 25 0 0/0
I 5 TTY 38400/38400 - inout - - - 3940 0 0/0
I 6 TTY 38400/38400 - inout - - - 1483 0 0/0
I 7 TTY 38400/38400 - inout - - - 364 0 0/0
I 8 TTY 38400/38400 - inout - - - 12 0 0/0

Table 4-2 describes the fields in this report.

Table 4-2. Fields in a show line display



1st column

I = line is idle; * = line is active.


Actual line number.


Type of line: CTY (console), AUX, TTY, VTY, LPT.


Transmit and receive baud rates for this line.


Autobaud (automatic baud rate detection) is active.


Type of modem signal configured for this line (callin, callout, cts-req, dtr-act, inout, RIisCd).


Rotary group configured for this line.

AccO, AccI

Access lists for this line, both output and input (see access-class in Chapter 17).


Number of connections made to this line since the router was booted.


Number of times noise was detected on this line. Can be used to gauge line quality.


Number of buffer overruns that have occurred on this line, in the format hardware/software. Hardware overruns occur when the hardware receives data from the software faster than it can process it. Software overruns occur when the software receives data from the hardware faster than it can process it. A bad cable could cause overruns.

You can retrieve more detailed information by selecting a single line:

Router>show line 5
 Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns
A 5 TTY 38400/38400 - inout - - - 3969 0 0/0

Line 5, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 38400/38400, no parity, 1 stopbits, 8 databits
Status: Ready, Active, No Exit Banner, Async Interface Active
Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out
 Modem Callout, Modem RI is CD, Line usable as async interface
Modem state: Ready
Special Chars: Escape Hold Stop Start Disconnect Activation
 ^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
 0:00:30 never none not set
Session limit is not set.
Time since activation: 2:08:08
Editing is enabled.
History is enabled, history size is 10.
Full user help is disabled
Allowed transports are lat telnet rlogin mop. Preferred is lat.
No output characters are padded
No special data dispatching characters
Modem hardware state: CTS DSR DTR RTS
Line is running PPP for address
0 output packets queued, 1 input packets.
 Async Escape map is 00000000000000000101000000000000
Group codes: 0
 Interface Async5: (passive, compression on)
 Rcvd: 5711 total, 4516 compressed, 0 errors
 0 dropped, 0 buffer copies, 0 buffer failures
 Sent: 5085 total, 4032 compressed,
 138729 bytes saved, 3943290 bytes sent
 1.3 efficiency improvement factor
 Connect: 16 rx slots, 16 tx slots, 1275 long searches, 765 misses
 84% hit ratio, five minute miss rate 0 misses/sec, 1 max

The first part of this report has the same format given in Table 4-2. However, the rest of the report goes into great detail about the line's characteristics. Table 4-3 shows what these additional fields mean.

Table 4-3. Fields in a show line for a single port




TTY line number.


Value of the location keyword set for this line. See location in Chapter 17.


Value specified by the line configuration.


Terminal display length in characters.


Terminal display width in characters.


Transmit (TX) and receive (RX) baud rates.


State of the line (ready, connected/disconnected, active/inactive, exit banner).


How or for what this line can be used.

Modem state

Control state of the modem. If not Ready, suspect a modem problem.

Special chars

Settings of characters defined for this line.


Timeouts as specified by the configurations.

Session limit

Maximum number of sessions for this line. Controlled by the session-limit command.

Time since activation

Time elapsed since line activation (i.e., how long the line has been considered active).


Whether command-line editing is enabled.


Length of the command history buffer. Set by the user with the history command.

Full user help

Whether the full-help command has been activated for this line.

Transport methods

Transport mechanisms allowed on this line. See the transport command in Chapter 17 for more information.

Character padding

See the padding command in Chapter 17.

Data dispatching characters

Whether any data-dispatching characters are configured. See dispatch-character in Chapter 17 for more information.

Line protocol

The protocol and address specified for this line.

Output/input packets

Queued packet counts for this line.

Group codes

AT group codes for this line.

Getting Started

IOS Images and Configuration Files

Basic Router Configuration

Line Commands

Interface Commands

Networking Technologies

Access Lists

IP Routing Topics

Interior Routing Protocols

Border Gateway Protocol

Quality of Service

Dial-on-Demand Routing

Specialized Networking Topics

Switches and VLANs

Router Security

Troubleshooting and Logging

Quick Reference

Appendix A Network Basics


Cisco IOS in a Nutshell
Cisco IOS in a Nutshell (In a Nutshell (OReilly))
ISBN: 0596008694
EAN: 2147483647
Year: 2006
Pages: 1031
Authors: James Boney © 2008-2020.
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