Router Network Interface description

(1) interface and active state
&http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;
In the above display, the content indicates that the hardware interface is active, and the software process that handles the line protocol believes that the secondary interface is available. If the router operator dismantles This hardware interface, the first field displays the information is administratively down. If the router receives more than 5,000 errors during the active interval, the word disabled appears in this field to show that the router automatically disables the port. The Row agreement field also displays one of the three descriptions previously mentioned: up, down, administratively down. If the field item is up, then the processing line protocol and the software process believe that this interface is available because she is receiving keepalives's purpose as well, Other devices can determine whether an idle connection is still active. For Ethernet interfaces, the default value for Keepalives is 10s. We will soon notice that the keepalives settings can be obtained by using the show Interfaces command for a specific interface. You can change the keepalives setting by using the KeepAlive interface command. The format of this command is as follows:

Keepalive seconds

(2) The Hardware field provides you with the hardware type of the interface. In the example above, the hardware is the Cisco Extended Bus (Cxbus) Ethernet, the 533-mbps data bus for the interface processor. Therefore, the hardware informs us that the high-speed Cxbus interface processor is used to support Ethernet connections. Also note that the Display field includes the MAC address of the interface. The Mac is 48 bits long. Because the first 24 bits of the MAC address represent the manufacturer ID, the hexadecimal number 00-10-79 is the identifier assigned to Csico by the IEEE.

(3) Internet address

If an interface is configured for IP routing, it is assigned an Internet address. This address is followed by his subnet mask. The IP address is 205.141.192.1/24. The backslash (/) indicates that the first 24 digits of this address represent the network, and he is equal to the subnet mask 255.255.255.0.

(4) MTU

The Maximum Transmission Unit (MTU) represents the maximum number of bytes supported by the Information field of a protocol running on an interface. Because the maximum length of the information field for an Ethernet frame is 1500 bytes, its MTU is displayed as 1500 bytes. For almost all Ethernet applications, the default 1500-byte MTU should be valid. For token rings, the default MTU value is 8192 bytes, but it should be noted that the MTU value recommended by RFC1191 is 17 914 for the 16-mbps token ring, and 4464 bytes for the 4-mbps token ring.
The minimum MTU is 64 bytes, and the maximum value is 65535 bytes. If the IP datagram exceeds the maximum MTU, it is segmented, which adds extra overhead because each final datagram contains its own header. While in a high-speed LAN connection, there is usually no need to worry about the extra cost associated with fragmentation, this can be a more serious problem on a Low-speed serial interface. You can change the default MTU using the MTU Interface command, which is formatted as follows:
MTU bytes
The number of bytes can be from 64~6553.

(5) BW

Interface bandwidth (BW) typically refers to the running rate of the interface, expressed in kilobytes per second. Because the Ethernet runs at a speed of 10Mbps, the BW value is shown as 000Kb.
The information bandwidth value can be set with the bandwidth command, but it is not actually used to adjust the bandwidth of the interface, because bandwidth is fixed for certain types of media, such as Ethernet. For other media, such as serial lines, it is usually adjusted to adjust the hardware to the speed of the operation. For example, you can increase or decrease the running speed of the serial interface by setting different clock rates on the DSU. Therefore, the main purpose of the bandwidth command is to communicate current bandwidth to a high-level protocol.
You can set the bandwidth value in the following command format, which is the bandwidth represented by thousands per second.
Bandwidth kilobits

(6) DLY

This field represents the delay of the interface, expressed in microseconds. Ethernet Latency (DLY) is 1000s. You can use the delay interface command to set a delay value for an interface. The format of this command is as follows:
Delay Tens-of-microseconds

(7) Reliability

The Reliability field represents the reliability of the interface, with a 255-percent representation. The value shown in this field is computed by the power average in 5 minutes. Because Ethernet computes CRC for each frame, reliability is based on CRC error rate, not bit error rate. 255/255 indicates that the interface is 100% reliable in 5 minutes.
Although there is no reliability command, one important command that can be considered for regular use is the clear conuter EXEC command. The function of this command is to clear or reset the interface counters. The general format of this command depends on the router you are using. The second format is shown below for the Cisco7000 series:
Clear counter [type number]
Clear counter [type Slot/port]
Type represents a specific interface type. If you do not specify a specific interface, the counters for all interfaces are cleared.

(8) Load

The send and receive load on the interface is shown as 255 per cent. Similar to the Reliability field, the Load field calculates the power average within 5 minutes. As you can see from the above, the Send (txload) load is represented as 3/255 and the receive (rxload) load is 39/255. Because Ethernet runs at a speed of 10Mbps, you can get a general indication of the interface activity by multiplying each fraction by the rate of operation. This is because each Ethernet frame has at least 26 extra bytes, and when the information field is less than 45 bytes, the pad character is added to the information field.

(9) Package

This field represents the encapsulation method that is assigned to the interface. In the example above, the package is displayed as ARPA, his standard Ethernet 2.0 encapsulation method. Other encapsulation methods include the IEEE 802.3 Ethernet keyword ISO1, and the IEEE 802.3-Frame keyword SNAP (subnet access Protocol) hardwood variations.