Shulou(Shulou.com)06/02 Report--

This article mainly introduces the method of link test when obvious packet loss is detected in ping, which has a certain reference value and can be used for reference by friends who need it. I hope you will learn a lot after reading this article. Next, let the editor take you to learn about it.

High packet loss delay for network access of Windows instances

When the website access is slow or unreachable, if other significant problems are eliminated and obvious packet loss is detected in ping, it is recommended that you do a link test. In the Windows environment, you can determine the source of the problem through link testing with the WinMTR tool (preferred) or the TRACERT command line tool.

In general, follow these steps:

Use link testing tools to detect network status and server status.

Analyze and process according to the link test results.

WinMTR tool (preferred)

As a network testing tool, mtr (My traceroute) integrates the graphical interface of tracert and ping commands. Ping and tracert are usually used to detect the status of the network and the server, as described below:

WinMTR is a graphical implementation of mtr tools in Windows environment, which is suitable for route tracking and ping testing under Windows. WinMTR sends ICMP packets to probe by default and cannot be switched.

Compared with the TRACERT command line tool, WinMTR can avoid the impact of node fluctuations on the test results, and the test results are more correct. In the Windows environment, it is recommended to give priority to using WinMTR for link testing. (click the official website to download and get. )

Operation steps

After downloading WinMTR on the official website, decompress and run it directly. After running the program, enter the target server domain name or IP in the Host field (do not include spaces before).

Click Start to start the test. (after starting the test, the corresponding button becomes Stop. )

After running for a while, click Stop to stop the test.

Note: you can test for a few more minutes and export the results when the test is over.

Copy Text to clipboard: copy the test results to the pasteboard in text format.

Copy HTML to clipboard: copy the test results to the pasteboard in HTML format.

Export TEXT: exports the test results to the specified file in text format.

Export HTML: exports the test results to the specified file in HTML format.

Options: optional parameter. The details include:

Interval (sec): the interval (expiration) of each probe, which defaults to 1 second.

Ping size (bytes): the packet size used by ping probes, which defaults to 64 bytes.

Max hosts in LRU list: the maximum number of hosts supported by the LRU list. The default is 128.

Resolve names: display the relevant nodes in the domain name by reverse checking IP.

View the results returned after the WinMTR is run.

Description: under the default configuration, the WinMTR test results are described as follows:

The first column (Hostname): host IP or domain name of each node to be passed by the destination server.

The second column (Nr): node number.

The third column (Loss%): node packet loss rate. The percentage of failure of the ping packet reply, which can be used to determine which node (line) failed, whether it was the server room or the international routing trunk road.

The fourth column (Sent): the number of packets sent.

Fifth column (Recv): the number of packets that have been successfully received.

Columns 6, 7, 8, and 9 (Best, Avg, Worst, Last): the minimum, average, maximum, and response time of the last packet, respectively.

TRACERT command line tool

TRACERT (Trace Route) is a network diagnostics command line utility that comes with Windows and is used to track the path that Internet Protocol (IP) packets take when they are delivered to the destination address.

TRACERT determines the route to the destination address by sending ICMP packets to the destination address. In these packets, TRACERT uses different IP lifetime (TTL) values. Because routers along the route are required to reduce TTL by at least 1 before forwarding packets, TTL is actually equivalent to a hop counter (hop counter). When the TTL of a packet reaches zero (0), the corresponding node sends an ICMP timeout message to the source computer.

TRACERT sends a packet with a TTL of 1 for the first time and increments the TTL by 1 on each subsequent transmission until the destination address responds or reaches the maximum value of TTL. The ICMP timeout message sent back by the intermediate router contains the information of the corresponding node.

Operation steps

Click the start menu at the bottom of the desktop and select run.

After opening the run box, enter cmd in the box and click OK.

In the command run interface, enter tracert, and after pressing enter, the interface will display instructions for the use of tracert.

According to the specific usage, enter the destination address to be tracked.

Example

C:\ > tracert-d 223.5.5.5 A 1 * request timed out through a route tracked to 223.5.5.5 with up to 30 hops. 2 9 ms 3 ms 12 ms 192.168.17.20 34 ms 9 ms 2 ms 111.1.20.41 4 9 ms 2 ms 1 ms 111.34.197 5 11 ms * * 211.140.57 6 3 ms 2 ms 2 ms 211.138.114.62 7 2 ms 2 ms 1 ms 42 .120.244.190 8 32 ms 4 ms 3 ms 42.120.244.238 9 * request timed out. 10 3 ms 2 ms 2 ms 223.5.5.5

Analyze link test results

It is based on the following sample diagram of link test results:

Operation steps

Judge whether there are anomalies in each area, and deal with them separately according to the situation of each region.

Area A: client local network, that is, local local area network and local network provider network. In view of the exception in this area and the node problems related to the client local network, please troubleshoot and analyze the local network; for the node problems related to the network of the local network provider, please feedback to the local operator.

Area B: operator backbone network. For an exception in this area, you can query the ownership of the operator according to the exception node IP, and then report the problem to the corresponding operator directly or through Aliyun's after-sales technical support.

Area C: the target server local network, that is, the target host belongs to the network provider network. In view of the exception in this area, the problem needs to be reported to the target host belonging to the network provider.

Combined with Avg (average) and StDev (standard deviation), we can judge whether there are abnormalities in each node.

If the StDev is very high, then synchronously observe the Best and Wrst of the corresponding node to determine whether there is an anomaly in the corresponding node.

If the StDev is not high, the Avg is used to determine whether there is an exception in the corresponding node.

Note: the above StDev is high or not high, and there is no specific time range standard. The relative evaluation needs to be carried out according to the delay value of other columns of the same node. For example, if the Avg is 30 ms, then when the StDev is 25 ms, it is considered a high deviation. If the Avg is 325 ms, then the same StDev (25 ms) is considered to be a low deviation.

Check the packet loss rate of the node. If the Loss% is not zero, there may be a problem with this hop network.

There are usually two reasons for node packet loss:

The ICMP sending rate of the node is artificially limited, resulting in packet loss.

There is indeed an exception on the node, resulting in packet loss.

Determine the cause of packet loss of the current exception node.

If there is no packet loss in the subsequent node, it means that the packet loss of the current node is due to the limitation of the operator policy and can be ignored. As shown in the example diagram of the previous link test results, hop 2.

If packet loss also occurs in the node, it means that there is a network anomaly in the current node, which leads to packet loss. As shown in the example diagram of the previous link test results, hop 5.

Note: the above two situations may occur at the same time, that is, there are both policy speed limits and network anomalies in the corresponding nodes. In this case, if the packet loss occurs continuously on the current node and its subsequent nodes, and the packet loss rate of each node is different, then the packet loss rate of the last few hops usually prevails. As shown in the example diagram of the previous link test results, packet loss occurred at hops 5, 6, and 7. So, in the end, 40% of hop 7 is used as a reference for packet loss.

Confirm whether there is an exception in the node by checking to see if there is a significant delay. Through the following two aspects of analysis:

If the delay increases sharply after a hop, it is usually judged that there is a network anomaly in the node. As shown in the example diagram of the previous link test results, from the subsequent node delay after hop 5, it is inferred that there is a network anomaly on the node of hop 5.

Note: high delay does not necessarily mean that there is an exception in the corresponding node, and large delay may also be caused in the data packet link. It is recommended to analyze it in conjunction with reverse link testing.

The speed limit of ICMP policy may also lead to a sharp increase in latency of the corresponding nodes, but subsequent nodes usually return to normal. As shown in the example diagram of the previous link test results, hop 3 has a 100% packet loss rate and a significant increase in latency. But then the delay of the node immediately returned to normal. Therefore, it is judged that the sharp increase in delay and packet loss of the node is due to the policy speed limit.

Other suggestions

Aliyun Chinese mainland regional computer room and other countries or regions have direct connect lines for network communication. To reduce the packet loss rate during communication, it is recommended to use high-speed channels.

If the host packet drop and latency are very high, it is recommended to do WinMTR two-way testing, that is, local-to-server and server-to-local testing. If you cannot log in remotely, log in through the administrative terminal.

Thank you for reading this article carefully. I hope the editor will share the method of link testing when there is an obvious packet loss in ping. At the same time, I also hope that you will support it, pay attention to the industry information channel, and find out if you encounter problems. Detailed solutions are waiting for you to learn!

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