(1) Interface and active status (2) Hardware fields provide you with hardware types (3) Internet addresses (4) MTU (5) BW (6) DLY (7) Reliability (8) Load (9) Package ( 10) Recycle (11) ARP Type (12) ARP Timeout (13) Last Input and Output (14) Output Interrupt (15) Last Clear (16) Queue Policy (17) Queuing Message (18) 5- Minute I / O Rate (19) Group and byte Enter (20) Unbuffered (21) Receive Broadcast (22) Runts (23) Giants (24) THROTTLES
Examples: 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 (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 / Sec5 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
(1) Interface and activity status
In the above display, the content indicates that the hardware interface is active, and the software process of the processing row protocol is believed to be available. If the router operator disassembles this hardware interface, the first field will display information is administrative down. If the router receives more than 5,000 errors in the activity interval, the word disabled will appear in this field to display the connection router automatically disable this. port. The line agreement field also displays one of the three descriptions previously mentioned: Up, Down, Administrative Down. If the field item is UP, the process line protocol and software process believes that this interface is available because she is receiving KeePalives is also the same. Other devices can determine if an idle connection is still active. For Ethernet interfaces, Keepalives's default is 10s. We will not pay noteworthy, Keepalives settings can be obtained by using the show interfaces command for a particular interface. You can change the Keepalives settings with the Keepalive Interface command. The format of this command is as follows: KeePalive Seconds (2) Hardware fields provide you with hardware types for interfaces
In the above example, hardware is a Cisco Extension Bus (CXBUS) Ethernet, i.e., the 533-Mbps data bus of the interface processor. Therefore, hardware notifies us that high-speed CXBUS interface processors are used to support Ethernet connections. At the same time, pay attention to the display field includes the MAC address of the interface. Mac is 48-bit long. Because the head 24 bits of the MAC address are the identifier of the IEEE to the CSICO, the hexadecimal number 00-10-79 is assigned to the CSICO.
(3) Internet address
If an interface is configured for the IP routing, it will allocate an Internet address for it. This address is behind his subnet mask. The IP address is 205.141.192.1/24. The backslash (/) indicates that the head 24 of this address represents the network, and he is equal to subnet mask 255.255.255.0.
(4) MTU
Maximum Transmission Unit (MTU) represents the maximum number of bytes supported by the information fields running on the interface. Because the maximum length of the information field of Ethernet is 1500 bytes, its MTU is displayed as 1500 bytes. For almost all Ethernet applications, the default 1500-byte MTU should be valid. For the token ring, the default MTU value is 8192 bytes; however, it should be noted that the RFC1191 proposed MTU value is 16-Mbps token loop selects 17914, and selects 4464 bytes for the 4-Mbps token ring. The smallest MTU is 64 bytes, while the largest value is 65535 bytes. If the IP datagraries exceed the largest MTU, it will segment it, which will increase additional overhead because each of the last datagrams contains its own headers. Although in high speed LAN connections, there is usually no need to worry about additional overhead associated with segmentation, but in low speed serial interfaces, this may be a more serious problem. You can change the default MTU with the MTUInterface command, this command format is as follows:
MTU BYTES
The number of bytes can be from 64 to 6553.
(5) BW
Interface Bandwidth (BW) is usually referred to as the operating rate of the interface, represented by kilobyte per second. Because the Ethernet operating rate is 10 Mbps, the BW value is displayed as 10 000kB.
The information bandwidth value can be set with the bandwidth command, but do not need it to adjust the bandwidth of the interface, because for some type of media, such as Ethernet, bandwidth is fixed. For other media, such as serial lines, it is usually adjusted by adjusting the hardware. The running rate of the serial interface is improved or reduced, for example, by setting different clock rates on the DSU / CSU. Therefore, the BANDWIDTH command is the main purpose to communicate the current bandwidth and high-level protocol. The bandwidth value can be set by the following command format, and thousands represent the bandwidth indicated by thousands of each second. Bandwidth Kilobits
(6) DLY
This field indicates the latency of the interface and is represented by microseconds. The delay of the Ethernet (DLY) is 1000 s. You can use the delay interface command to set the delay value for the interface. The format of this command is as follows: Delay Tens-of-Microseconds
(7) Reliability
The reliability field represents the reliability of the interface and is represented by a few 255. The value displayed in this field is calculated from the power average value within 5 minutes. Because the Ethernet calculates the CRC for each, the reliability is based on the CRC error rate, not the bit error rate. 255/255 indicates that the interface is 100% reliable within 5 minutes.
Although there is no reliability command, an important command that can be considered for regular use is the Clear Conuter Exec command. The functionality of this command is a clear or reset interface counter. The general format of this command depends on the router being used. The following is shown in the second format for the Cisco7000 Series:
Clear counter [Type Number]
Clear Counter [Type Slot / Port]
TYPE represents a specific interface type. If you don't specify a particular interface, all the counters of all interfaces are cleared.
(8) load
The transmission and reception load on the interface are shown to 255. Similar to the reliability field, the load field is also a power average of 5 minutes. As can be seen from the above, the TXLOAD load is represented as 3/255, and the receiving (RXLoad) load is 39/255. Because the Ethernet operating rate is 10Mbps, the general instructions of the interface activity can be obtained by multiplying each score with run rate. This is because each Ethernet is at least 26 additional bytes, and when the information field is less than 45 bytes, the PAD characters will be added to the information field.
9) Package
This field represents a package method assigned to the interface. In the above example, the package is displayed as ARPA, his standard Ethernet 2.0 package method. Other packages also include IEEE 802.3 Ethernet keyword ISO1, and keyword SNAP (subnet access protocol) variation of IEEE 802.3.
(10)
The return field indicates whether the interface is running. If you set a loop, this is when the technician puts the interface in the return interface in the night, and forgets the common problems that occur when resetting the return, this can cause some interesting phones to play the control center the next morning.
You can use the loopback interface setting command to place the interface in the running loop mode. The loopback command does not have a parameters, you should use the no loopback command to delete or disable the loopback. The following example shows setting the Ethernet interface to a loopback mode.
Interface Ethernet0 / 0
Loopback
You can use Show Interface Loopback
The exec command views the status of the loopback. If your router has a large number of interfaces, and the technicians perform regularly, then this command is used in the morning to avoid unnecessary problems is a good idea.
(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 package on the IP interface. You can change the package to HP Probe or Snap by using the ARP interface command, this command format is as follows:
ARP {ARPA / Probe / Snap}
Please pay attention to HP
Probe is used by iOS to try to parse IEEE802.3 or Ethernet local data link addresses. The ARP type should be set to ProBe so that one or more router interfaces are transparently communicated with HP IEEE 802.3 hosts that use address resolution techniques called "virtual address requests and replies".
(12) ARP timeout
This field indicates that the ARP item remains in the cache in the cache when it is cleaned. The default value of the ARP timeout is 4 hours, as shown in the example above:
You can adjust the length of time in the cache item in the cache by using the ARP TIMEOUT command. This command format is like:
ARP TIMEOUT Seconds
(13) Last input and output
This field indicates the last packet or the number of hours, minutes, and seconds since the interface is successfully received or transmitted. You can use the value in this field to determine if the active interface is still activated or when the dead interface is faulty. About the former, in the first show interface command indicates the new last output of the interface (this can also indicate if there is a problem occurrence) 10 seconds or 1 minute, and then enter the second show interface command. It also indicates that if there is a problem, it is not unable to receive a group. For example, in the above example, the last successful input occurs before 2 seconds. If we wait a few seconds, and release another show interface command, you can get an update to this counter.
(14) Output interrupt
The output interrupt field indicates that the self-interface is performed for the last reset due to too long the transmission time. The value of this field is specified by hours, minutes, and seconds, or if there is no interrupt (HANG), it will never be displayed. If the number of hours since the last reset exceeds 24, the number of days and hours will be displayed until the field is beneficial. When this situation occurs, an asterisk (*) will be displayed in this field.
(15) The last clearance
This field indicates the time to be reset to 0 when the interface counter of the measurement cumulative statistics is last reset. Clear will affect almost, in addition to routing statistics such as load and reliability.
The last clearance displayed is based on the use of 32-bit MS counters. Show an asterisk indicates that the time is too long to display, and the display 0:00:00 indicates that the counter is cleared before the 32 power MS to 2 of 2. The last clearance value on many routers will be expressed in weeks and months or days. For example, in the above example, the Show Interfaces Counter last cleared is 1W2D.
(16) Queue strategy
This field represents a pairing policy assigned to the interface. The default is the first subsequent (FIRST IN FIRST OUT, FIFO). This pairing method will be listed in this field if the priority pairing method is assigned to the interface.
(17) Queue message
For output and input queues, the number of M / N forms is displayed, followed by the number of packets lost due to queue. Here, the value of M represents the number of packets in the queue, and the value of the replacement N represents the maximum queue size with the packet. By checking the number of lost packets and between M and N within a period of time, it is possible to determine whether it is recommended to adjust the queue length of a particular interface to reduce the loss of packets. However, media and use levels connected to the interface should also be considered to determine whether debugging the length of the output queue is beneficial. The medium using high usage is most likely to cause loss of grouping in queues: When transmitting data, the router will encounter difficulties, resulting in output packet queuing, and this is over, there are other packets to arrive to pass interface Packet loss occurs when transmitting to the medium. In the input party, the larger ratio of the lost packets and M and N indicates that the router is busy with other operations, and cannot process the entry group in a timely manner. If the time is longer, it usually refers to a more powerful router to meet the need. Typically, this situation can be observed by a large number of lost packets in the direction of entering the direction of the router interface.
The queue information field value in the above SHOW Interfaces displays no grouping in any of the queues. Moreover, although the output queue is full, 63 packets are lost, but no grouping is lost due to the input queue. The latter is a common situation because most routers (unless excessive) should not have problems in processing accessible data.
(18) 5- minute I / O rate
The next field displays the average number of bits and the average number of bits and average packets transmitted and received through the interface 5 minutes. When explaining the data displayed in this field, several factors must be considered. First, you must consider the operation mode of the interface and the configuration of the network connected to the interface. For example, if the interface is a LAN interface, you can run in the chaos, so that each of the degree lan can also run in a non-chaotic mode, that is, only broadcast hazeling and direct delivery to the interface. If the port is in chaos, all packets are read and provide a method of testing data flowing in the network. If the interface is not in the confusing state, it is only a feeling that the traffic sent and received, which may only account for a small part of all traffic in the network.
Considering the network configuration, if the interface is connected to only one station's LAN, such as a web server, all traffic will flow through the router interface. This means a relatively accurate test network activity method, without considering the mode where the interface is located.
Another factor in need to consider is a 5 minute I / O rate represents one of the power averages of a 5 minute time constant. Therefore, any 5 minutes I / O rate is a probably worth of flow rate per second during this time. However, the average of 4 5 minutes of time span will be within 2% of the unified flow of 20 minutes.
Because the length of the packet varies, each second rate is usually more useful than an activity on the interface from a transmission medium. In the above example, the input rate 1540000 bps represents 1/6 of the operating rate of the interface. You may be strange, why the input rate is nearly one quantity than the interface output rate, answering the connection of the interface. In this particular router usage environment, the Ethernet interface is connected to a 10BASE-TLAN having only one additional station (ie the company's web server). The web page requests flow in the form of a Unified Resource Locator (URL), and the response to the URL request is a web page; this explains why the flow level in the input and output directions is not proportional. Now, we understand the 5-minute I / O rate, let us introduce the input and output information of a specific packet that can be displayed for an interface.
(19) Group and byte input
This field first represents the total number of error-incorrect packets received by the router. Second, it also represents the total number of bytes of error-incorrect packets received by the router.
If the byte number is divided by the number of packets, the average packet length of byte representation can be obtained. This information can be used to provide general representation for the flow type flowing on the interface. For example, relatively short packets typically transmit interactive query / response traffic, while relatively long packets typically transmit files including web pages and include graphics in most of these pages.
(20) No buffer
There is no buffer field indicating that the interface received is received due to the lack of buffer space, and the number of packets have to be discarded. Do not make this buffer space with the internal buffer of the interface. When a continuous "bicycle" situation occurs, the router usually needs more memory. However, if the NO Buffers value is encountered periodically, it may be due to the broadcast storm on the LAN or the noise on the serial port. You can determine if the next field is determined whether there is a non-buffered value is caused by the broadcast storm.
(21) Received broadcast
This field indicates the total number of broadcasts or multicast packets received by the interface. It is important to note that many broadcasts are part of the natural communication process. For example, the ARP used to resolve the third layer IP address to the Layer 2 MAC address depends on the release of a broadcast to query the LAN of the LAN of the LAN of the Layer 2 address that must be obtained, so Correctly form an audio to transmit the group. Similarly, in the Novell IPX environment, the server is grouped every 30s Broadcast Service Declaration Protocol (SAP). These define the services provided by the server.
If you are a strict IP environment, it is more likely to get part of the broadcast from the ARP request. If you have an application since time, you can indeed set up two problems with an action by setting the fixed item as the Router's ARP cache to the running application. Don't only avoid the router must perform ARP operations, but also allow the parsing process to happen by checking memory, which is much more faster than waiting for broadcast. Because the data traffic is interrupted during the ARP broadcast, reducing the information transmission function of the ARP broadcast can increase the interface. Because the ARP table is maintained inside the router. (22) Runts
Runt is an error scenario that is less than a minimum length associated with its associated packet length than a certain protocol. In an Ethernet environment, the minimum packet length is 64 bytes on the adapter card, while 72 bytes on the LAN. Therefore, if an interface receives the Ethernet division less than 72 bytes, it will be an error scenario, the packet will be discarded. Typically, the conflict can cause the generated of the Runt, and the failed adapter card can also cause this situation.
(23) GIANTS
Giants is another error scenario. It indicates that the packet exceeds the maximum packet length of the protocol. In an Ethernet environment, the maximum packet length of the adapter card is 1518 bytes, while the maximum length of the packet flowing in the network is 1526 bytes. So the length (including the preamble and the starting sense field) exceeds 1526 bytes of packets are treated as giant. Such grouping will also be discarded, and the number of gratists represents the number of packets discarded due to this situation. The usual reason that causes GIANT groups is a fault in lag conflict or adapter card.
(24) THROTTLES
Although this case rarely occurs, it will turn off its receiver if the router sense buffer or processor overload. This situation is called THROTTLES, which is actually not communicating. Instead, it is a router function problem that requires you to check the status of the system buffer and processor. If you use the show interfaces command to indicate a large amount of "bless" and THROTTLE, you usually indicate that you should consider adding memory to the router.
