Command Reference

show interfaces serial

Use the show interfaces serial privileged EXEC command to display information about a serial interface.
show interfaces serial [number] [accounting]

show interfaces serial [number[:channel-group] [accounting] (for the Cisco 4000 series)

show interfaces serial [slot/port] [accounting] (for the Cisco 7200 series)

show interfaces serial [slot/port [:channel-group]] [accounting] (for the Cisco 7000 series)

show interfaces serial [slot/port-adapter/port] [accounting] (for ports on VIP cards in the Cisco 7000 series and Cisco 7500 series)

Syntax Description

number (Optional) Port number.

accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.

:channel-group (Optional) On the Cisco 4000 with an NPM or Cisco 7000 series with a MIP, specifies the T1 channel group number in the range of 0 to 23 defined with the channel-group controller configuration command.

slot (Optional) On the Cisco 7000 series, slot location of the interface processor. On the Cisco 7200 series, slot location of the port adapter.

port (Optional) Port number on the interface. For the VIP card, the port value can be 0, 1, 2, or 3 for 4-port serial interfaces. On the Cisco 7200 series, the port numbers depend on the type of port adapters installed.

port-adapter (Optional) On the Cisco 7000 and Cisco 7500 series, specifies the ports on a VIP card. The value can be 0 or 1.

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0 for the Cisco 4000 series.
This command first appeared in Cisco IOS Release 11.0 for the Cisco 7000 series.

Sample Displays

The following is sample output from the show interfaces command for a synchronous serial interface:
Router# show interfaces serial

Serial 0 is up, line protocol is up
   Hardware is MCI Serial
     Internet address is 150.136.190.203, subnet mask is 255.255.255.0
     MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
     Encapsulation HDLC, loopback not set, keepalive set (10 sec)
     Last input 0:00:07, output 0:00:00, output hang never
     Output queue 0/40, 0 drops; input queue 0/75, 0 drops

     Five minute input rate 0 bits/sec, 0 packets/sec
     Five minute output rate 0 bits/sec, 0 packets/sec
           16263 packets input, 1347238 bytes, 0 no buffer
           Received 13983 broadcasts, 0 runts, 0 giants
           2 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort
1 carrier transitions 

     22146 packets output, 2383680 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets, 0 restarts

  
Table 48 describes significant fields shown in the display.

Table 48 Show Interfaces Serial Field Descriptions

Field Description

Serial ... is {up | down}
...is administratively down Indicates whether the interface hardware is currently active (whether carrier detect is present), inactive, or has been taken down by an administrator.

line protocol
is {up | down} Indicates whether the software processes that handle the line protocol consider the line usable (that is, whether keepalives are successful) or if it has been taken down by an administrator.

Hardware is Specifies the hardware type.

Internet address is Specifies the Internet address and subnet mask.

MTU Maximum Transmission Unit of the interface.

BW 1544 Kbit Indicates the value of the bandwidth parameter that has been configured for the interface (in kilobits per second). The bandwidth parameter is used to compute IGRP metrics only. If the interface is attached to a serial line with a line speed that does not match the Default (1536 or 1544 for T1 and 56 for a standard synchronous serial line), use the bandwidth command to specify the correct line speed for this serial line.

DLY Delay of the interface in microseconds.

rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over 5 minutes.

load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over 5 minutes.

Encapsulation Encapsulation method assigned to interface.

loopback Indicates whether loopback is set or not.

keepalive Indicates whether keepalives are set or not.

Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.

Last output Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.

output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.

Output queue, drops
input queue, drops Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.

Five minute input rate
Five minute output rate Average number of bits and packets transmitted per second in the last 5 minutes.
The 5-minute input and output rates should be used only as an approximation of traffic per second during a given 5-minute period. These rates are exponentially weighted averages with a time constant of 5 minutes. A period of four time constants must pass before the average will be within two percent of the instantaneous rate of a uniform stream of traffic over that period.

packets input Total number of error-free packets received by the system.

bytes input Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.

no buffers Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.

Received ... broadcasts Total number of broadcast or multicast packets received by the interface.

runts Number of packets that are discarded because they are smaller than the medium's minimum packet size.

giants Number of packets that are discarded because they exceed the medium's maximum packet size.

input error Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum may not balance with the other counts.

CRC Cyclic redundancy checksum generated by the originating station or far-end device does not match the checksum calculated from the data received. On a serial link, CRCs usually indicate noise, gain hits, or other transmission problems on the data link.

frame Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.

overrun Number of times the serial 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. Broadcast storms and bursts of noise can cause the ignored count to be increased.

abort Illegal sequence of one bits on a serial interface. This usually indicates a clocking problem between the serial interface and the data link equipment.

packets output Total number of messages transmitted by the system.

bytes output Total number of bytes, including data and MAC encapsulation, transmitted by the system.

underruns Number of times that the transmitter has been running faster than the router can handle. This may never be reported on some interfaces.

output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this may not balance with the sum of the enumerated output errors, as some datagrams may have more than one error, and others may have errors that do not fall into any of the specifically tabulated categories.

collisions Number of messages retransmitted due to an Ethernet collision. This usually is the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). Some collisions are normal. However, if your collision rate climbs to around 4 or 5%, you should consider verifying that there is no faulty equipment on the segment and/or moving some existing stations to a new segment. A packet that collides is counted only once in output packets.

interface resets Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds' time. On a serial line, this can be caused by a malfunctioning modem that is not supplying the transmit clock signal, or by a cable problem. If the system notices that the carrier detect line of a serial interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an interface is looped back or shut down.

restarts Number of times the controller was restarted because of errors.

carrier transitions Number of times the carrier detect signal of a serial interface has changed state. For example, if data carrier detect (DCD) goes down and comes up, the carrier transition counter will increment two times. Indicates modem or line problems if the carrier detect line is changing state often.

alarm indications, remote alarms, rx LOF, rx LOS Number of CSU/DSU alarms, and number of occurrences of receive loss of frame and receive loss of signal.

BER inactive, NELR inactive, FELR inactive Status of G.703-E1 counters for bit error rate (BER) alarm, near-end loop remote (NELR), and far-end loop remote (FELR). Note that you cannot set the NELR or FELR.

number	(Optional) Port number.
accounting	(Optional) Displays the number of packets of each protocol type that have been sent through the interface.
:channel-group	(Optional) On the Cisco 4000 with an NPM or Cisco 7000 series with a MIP, specifies the T1 channel group number in the range of 0 to 23 defined with the channel-group controller configuration command.
slot	(Optional) On the Cisco 7000 series, slot location of the interface processor. On the Cisco 7200 series, slot location of the port adapter.
port	(Optional) Port number on the interface. For the VIP card, the port value can be 0, 1, 2, or 3 for 4-port serial interfaces. On the Cisco 7200 series, the port numbers depend on the type of port adapters installed.
port-adapter	(Optional) On the Cisco 7000 and Cisco 7500 series, specifies the ports on a VIP card. The value can be 0 or 1.

Field	Description
Serial ... is {up \| down} ...is administratively down	Indicates whether the interface hardware is currently active (whether carrier detect is present), inactive, or has been taken down by an administrator.
line protocol is {up \| down}	Indicates whether the software processes that handle the line protocol consider the line usable (that is, whether keepalives are successful) or if it has been taken down by an administrator.
Hardware is	Specifies the hardware type.
Internet address is	Specifies the Internet address and subnet mask.
MTU	Maximum Transmission Unit of the interface.
BW 1544 Kbit	Indicates the value of the bandwidth parameter that has been configured for the interface (in kilobits per second). The bandwidth parameter is used to compute IGRP metrics only. If the interface is attached to a serial line with a line speed that does not match the Default (1536 or 1544 for T1 and 56 for a standard synchronous serial line), use the bandwidth command to specify the correct line speed for this serial line.
DLY	Delay of the interface in microseconds.
rely	Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over 5 minutes.
load	Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over 5 minutes.
Encapsulation	Encapsulation method assigned to interface.
loopback	Indicates whether loopback is set or not.
keepalive	Indicates whether keepalives are set or not.
Last input	Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
Last output	Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.
output hang	Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Output queue, drops input queue, drops	Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate Five minute output rate	Average number of bits and packets transmitted per second in the last 5 minutes. The 5-minute input and output rates should be used only as an approximation of traffic per second during a given 5-minute period. These rates are exponentially weighted averages with a time constant of 5 minutes. A period of four time constants must pass before the average will be within two percent of the instantaneous rate of a uniform stream of traffic over that period.
packets input	Total number of error-free packets received by the system.
bytes input	Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffers	Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
Received ... broadcasts	Total number of broadcast or multicast packets received by the interface.
runts	Number of packets that are discarded because they are smaller than the medium's minimum packet size.
giants	Number of packets that are discarded because they exceed the medium's maximum packet size.
input error	Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum may not balance with the other counts.
CRC	Cyclic redundancy checksum generated by the originating station or far-end device does not match the checksum calculated from the data received. On a serial link, CRCs usually indicate noise, gain hits, or other transmission problems on the data link.
frame	Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.
overrun	Number of times the serial 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. Broadcast storms and bursts of noise can cause the ignored count to be increased.
abort	Illegal sequence of one bits on a serial interface. This usually indicates a clocking problem between the serial interface and the data link equipment.
packets output	Total number of messages transmitted by the system.
bytes output	Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns	Number of times that the transmitter has been running faster than the router can handle. This may never be reported on some interfaces.
output errors	Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this may not balance with the sum of the enumerated output errors, as some datagrams may have more than one error, and others may have errors that do not fall into any of the specifically tabulated categories.
collisions	Number of messages retransmitted due to an Ethernet collision. This usually is the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). Some collisions are normal. However, if your collision rate climbs to around 4 or 5%, you should consider verifying that there is no faulty equipment on the segment and/or moving some existing stations to a new segment. A packet that collides is counted only once in output packets.
interface resets	Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds' time. On a serial line, this can be caused by a malfunctioning modem that is not supplying the transmit clock signal, or by a cable problem. If the system notices that the carrier detect line of a serial interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an interface is looped back or shut down.
restarts	Number of times the controller was restarted because of errors.
carrier transitions	Number of times the carrier detect signal of a serial interface has changed state. For example, if data carrier detect (DCD) goes down and comes up, the carrier transition counter will increment two times. Indicates modem or line problems if the carrier detect line is changing state often.
alarm indications, remote alarms, rx LOF, rx LOS	Number of CSU/DSU alarms, and number of occurrences of receive loss of frame and receive loss of signal.
BER inactive, NELR inactive, FELR inactive	Status of G.703-E1 counters for bit error rate (BER) alarm, near-end loop remote (NELR), and far-end loop remote (FELR). Note that you cannot set the NELR or FELR.