Shulou(Shulou.com)06/03 Report--

This article mainly introduces testing whether the Cisco ios router has the function of consistent hash, which can be used for reference by friends who need it. The following information is about the detailed steps of the test.

Purpose of the test:

According to the previous article, most network devices on the market do not have the feature of consistent hashing, so when a lvs fails, almost all session will be redistributed. The so-called redistribution means that users who are visiting will be forced to disconnect. But according to the article, some Cisco devices support this feature.

Benefits of consistent hashing:

The role of a consistent hash is that when there is a problem with a lvs, users using that lvs are reassigned to the remaining lvs, and other users are not affected. This feature minimizes the impact on users.

Preliminary survey:

By looking up relevant information about Cisco and asking Cisco pre-sales and after-sales engineers, there was no clear reply, there was no relevant configuration documentation online, and Cisco engineers knew nothing about it.

Test results:

Borrow an ISR4331 router from Cisco as a test machine.

The numbers in the figure represent the ip of client. For example, 172.16.97.65 is represented by 65.

In the steady state in the figure, six streams of traffic are allocated to three lvs.

When one of the lvs has a problem. We found that the six-share traffic has changed to varying degrees, in which the lvs3 outage led to the redistribution of all six-share traffic, that is, all six users were disconnected. When the lvs3 is restored, the traffic is redistributed, returning from a down state to a steady state, that is, six users are disconnected. [in the experiment, it is found that when a certain LVS goes down, the content of the web page does stop scrolling, and then manually click any icon on the web page (that is, restart the connection), and the scrolling content returns to normal. ]

Screenshot of lvs1 downtime test:

Conclusion:

Cisco ios routers do not have the feature of consistent hashing. When a lvs goes down, it is impossible to estimate the number of interrupted users. Users can resume use after reconnecting.

Limitations:

The simulation environment can only simulate a small number of client, and this time six are simulated, which is a big gap compared with the concurrency of 10 million level.

These are the test results of testing the Cisco ios router. Have you learned anything after reading it? If you want to know more about it, you are welcome to follow the industry information!

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