In this article, we will use an example to comprehensively introduce and analyze the router network interface. We divide it into three parts to explain the "Router Network Interface Analysis Collection (I), "Router Network Interface Analysis Collection (II), and "Router Network Interface Analysis Collection (II).
(1) Interface and activity status
(2) The hardware field provides you with the hardware type of the interface
(3) Internet address
(4) MTU
(5) BW
(6) DLY
(7) Reliability
(8) Load
(9) Packaging
(10) Rebate
(11) ARP type
(12) ARP timeout
(13) The final input and output
(14) Output interrupt
(15) Last clear
(16) Queuing strategy
(17) Queue message
(18) 5-min I/O rate
(19) Packet and byte input
(20) No buffering
(21) Received broadcast
(22)Runts
(23)Giants
(24)Throttles
Example:
Router# show interface e0/0
Ethernet0/0 is up, line protocol is down
Hardware is AmdP2, address is 0009.4375.5e20 (bia 0009.4375.5e20)
Internet address is 192.168.1.53/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 172/255, txload 3/255, rxload 39/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:07, 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 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 input packets with dribble condition detected
50 packets output, 3270 bytes, 0 underruns
50 output errors, 0 collisions, 2 interface resets
0 babbles, 0 late collision, 0 deferred
50 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
(9) Packaging
This field represents the encapsulation method assigned to the interface. In the example above, the package is shown as ARPA, its standard Ethernet version 2.0 package method. Other encapsulation methods include IEEE 802.3 Ethernet keyword iso1, and IEEE 802.3 frame keyword snap (subnet access protocol) frame mutation.
(10) Rebate
The loopback field indicates whether the interface is in running loopback mode. If you set up a loopback, this is a common problem that occurs when a technician puts the interface into the loopback interface for testing at night and forgets to reset the loopback, which can lead to some interesting calls to the control center the next morning.
The interface can be placed in the running loopback mode using the Loopback interface setting command. The Loopback command has no parameters, and the no Loopback command should be used to delete or disable loopback. The following example shows setting the Ethernet interface to loopback mode.
Interface ethernet0/0
Loopback
You can use show interface loopback
EXEC command to check the status of the loopback. If your router has a large number of interfaces and technicians perform regular inspections, it is a good idea to use this command early in the morning to avoid unnecessary problems.
(11) ARP type
This field represents the assigned address resolution protocol (ARP) type. In an IP environment, the ARP type is ARPA. By default, the Ethernet interface uses the ARPA keyword to specify the ARPA encapsulation on the IP interface. The encapsulation can be changed to HP PROBE or SNAP by using the arp interface command, and the format of this command is as follows:
arp {arpa/probe/snap}
Please note HP
Probe is used by IOS to attempt to parse IEEE802.3 or Ethernet local data connection addresses. The ARP type should be set to probe so that one or more router interfaces transparently communicate with an HP IEEE802.3 host using an address resolution technology called "virtual address requests and replies".
(12) ARP timeout
This field indicates the length of time that the ARP item remains in the cache before cleaning when inactive. The default value of ARP timeout is 4 hours, as shown in the above example:
The length of time the ARP cache item is in the cache can be adjusted by using the ARP timeout command. This command format is as follows:
arp timeout seconds
(13) The final input and output
This field indicates the number of hours, minutes, and seconds since the last packet or detector was successfully received or sent by the interface. You can use the values in this field to determine whether the active interface is still active or when the dead interface fails. Regarding the former, enter the second show interface command 10 seconds or 1 minute after the first show interface command indicates the interface's new last output (which can also indicate if there is a problem) . It also means that if a problem occurs, it is not because the packet cannot be received. For example, in the above example, the last successful input occurs 2 seconds ago. If we wait a few seconds and issue another show interface command, we can get an update to this counter.
(14) Output interrupt
The output interrupt field indicates the time since the interface was last reset due to the long sending time. The value of this field is specified in hours, minutes, and seconds, or will never be displayed if no interrupt (hang) occurs. If the number of hours since the last reset exceeds 24, the number of days and hours will be displayed until the field gets better. When this happens, an asterisk (*) will be displayed in this field.
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(15) Last clear
This field indicates the time when the interface counter that measures the accumulated statistics was last reset to 0. Clearing can affect almost all statistics, in addition to routing statistics such as load and reliability.
The actual value displayed in the last clear is based on the use of the 32-bit ms counter. Displaying asterisk means that the elapsed time cannot be displayed, while displaying 0:00:00 means that the counter is cleared before the 31 power ms of 2 to the 32 power ms of 2. The last clear value on many routers will be expressed in week and month or day and hour. For example, in the above example, the last clear of the show interfaces counter is displayed as 1w2d.
(16) Queuing strategy
This field represents the pairing policy assigned to the interface. The default is First in first out (FIFO). If the interface has previously assigned a priority pairing method, this pairing method is listed in this field. 【To be continued】
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