show interfaces ethernet field descriptions.

Table 4-6 show interfaces ethernet Field Descriptions

Field

Description

Ethernet . . . is up . . . is administratively down

Indicates whether the interface hardware is currently active and whether it has been taken down by an administrator. “Disabled” indicates that the router has received more than 5,000 errors in a keepalive interval, which is 10 seconds, by default.

line protocol is {up | down | administratively down}

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

Hardware

Specifies the hardware type (for example, MCI Ethernet, SCI, cBus Ethernet) and address.

Internet address

Specifies the Internet address, followed by the subnet mask.

MTU

Gives the maximum transmission unit of the interface.

BW

Gives the bandwidth of the interface in kilobits per second.

DLY

Gives the delay of the interface in microseconds.

rely

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

load

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

Encapsulation

Specifies the encapsulation method assigned to interface.

ARP type

Specifies the type of Address Resolution Protocol assigned.

loopback

Indicates whether loopback is set.

keepalive

Indicates whether keepalives are set.

Last input

Gives the number of hours, minutes, and seconds since the last packet was successfully received by an interface. This is useful for knowing when a dead interface failed.

Last output

Gives the number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.

output

Gives the number of hours, minutes, and seconds since the last packet was successfully transmitted by the interface. This is useful for knowing when a dead interface failed.

output hang

Gives the 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.

Last clearing

Gives the time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Note that variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.

“***” indicates that the elapsed time is too large to be displayed.

“0:00:00” indicates that the counters were cleared more than 231ms (and less than 232ms) ago.

Output queue, input queue, drops

Gives the 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

Gives the average number of bits and packets transmitted per second in the past 5 minutes. If the interface is not in promiscuous mode, it senses network traffic it sends and receives (rather than all network traffic).

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 2 percent of the instantaneous rate of a uniform stream of traffic over that period.

packets input

Gives the total number of error-free packets re

ceived by the system.

bytes input

Gives the total number of bytes, including data and MAC encapsulation, in the error-free packets received by the system.

no buffers

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

Received . . . broadcasts

Shows the total number of broadcast or multicast packets received by the interface.

Runts

Gives the number of packets that are discarded because they are smaller than the medium’s minimum packet size. For instance, any Ethernet packet that is less than 64 bytes is considered a runt.

giants

Gives the number of packets that are discarded because they exceed the medium’s maximum packet size. For example, any Ethernet packet that is greater than 1518 bytes is considered a giant.

input error

Includes runts, giants, no buffer, CRC, frame, overrun, and ignored counts. Other input-related errors can also cause the input error count to be increased, and some datagrams may have more than one error; therefore, this sum may not balance with the sum of enumerated input error counts.

CRC

Indicates that the cyclic redundancy checksum generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of collisions or a station transmitting bad data.

frame

Shows the number of packets received incorrectly having a CRC error and a noninteger number of octets. On a LAN, this is usually the result of collisions or a malfunctioning Ethernet device.

overrun

Shows the number of times that the receiver hardware was incapable of handing received data to a hardware buffer because the input rate exceeded the receiver’s capability to handle the data.

ignored

Shows the number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different from the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be increased.

input packets with dribble condition detected

Gives the dribble bit error, which indicates that a frame is slightly too long. This frame error counter is incremented just for informational purposes; the router accepts the frame.

packets output

Shows the total number of messages transmitted by the system.

bytes

Shows the total number of bytes, including data and MAC encapsulation, transmitted by the system.

underruns

Gives the 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

Gives the 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 because 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

Gives the number of messages retransmitted due to an Ethernet collision. This is usually the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). A packet that collides is counted only once in output packets.

interface resets

Gives the number of times that an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds. 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

Gives the number of times a Type 2 Ethernet controller was restarted because of errors.

Source

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