Is the higher the IOS, the better?

Source: Internet
Author: User

The higher the version, the better. Because of the new version of the operating system, it has high hardware requirements. There are also many vulnerabilities. Therefore, when selecting an operating system for users, we generally choose an operating system with a relatively higher version instead of an operating system with a higher stability. Vro is still a computer in nature, so this aspect is also considered when you select the IOS vroios. I suggest you do not rush to upgrade the router's IOS. Otherwise, selecting a relatively high IOS version for the router will lead to router faults, such as continuous restart. In this article, I will illustrate this issue with my own case to avoid unnecessary mistakes.

Fault reproduction:

When I used to work as a network administrator in an enterprise, I used a Cisco 3640 router and IOS 12.0. Later, a new version of 12.2 was released, and I upgraded it to the latest version. However, after the upgrade, the problem arises. After the router is configured, the router will frequently crash and restart. When the network is not busy at night, it is not very good to restart. However, it will be restarted several times during the day. Check the log and find that it is restarted every one or two hours. There are basically no rules for restarting.

The router did not have this fault before the version was updated. For this reason, I think there is a problem with the new IOS software. I upgraded it again. However, the problem persists after the upgrade. Isn't this router supported by the new IOS software? I went to Cisco's official website to query relevant information, and did not find that IOS of this version cannot be used on routers of this specification.

Fault Cause Analysis:

After a period of exploration, I think the problem may still be caused by the software version. In addition, when the network is not busy, there is basically no crash restart. Therefore, I think this may also be related to the network load. After the vro is restarted, I use the show processes command and the show processes memory command to view the CPU and memory usage of the vro. I don't know, but I was shocked. The router does not have much time to run, so I found that the memory usage and CPU usage remain high. After the CPU or memory usage reaches 100% and is maintained for a period of time, the router will crash. Then the vro restarts. If a fault occurs repeatedly.

Although the reason is found, it seems that there are no other solutions except for the hardware upgrade of the router. However, upgrading hardware, such as increasing the memory of the vro, costs too much. I have no choice but to downgrade the vro version and use the original version 12.0. Fortunately, I made a full backup before the IOS upgrade. At this time, you only need to use the original backup file to restore. After the old version of IOS is used, the problem of frequent restart is solved.

Conclusion: vrouters are not suitable for using new IOS systems.

The features of the new IOS version have been greatly improved. However, the addition of its functions also requires higher hardware configurations. Because the new IOS version occupies a large amount of system resources, when the network is busy, the CPU or memory load rate of the router may reach 100%. If the load does not decrease within the specified period, the router crashes and restarts.

In fact, the Single Machine Fault is very similar. When a common computer encounters a virus or Trojan attack, the CPU or memory usage will reach 100%. In a period of time, if it does not significantly improve, the computer will crash. After I upgraded the IOS version, the frequent crash of the router is similar to that of this single machine, mainly because IOS consumes too much CPU or memory resources. That is to say, although the new version of IOS is compatible with this router. However, when the network is busy, its hardware configuration cannot meet the IOS running requirements. In this case, the new version of IOS is barely used, and the router is basically operating at full capacity. When the network traffic increases suddenly, the router will become a machine.

For this reason, I suggest you pay attention to the following points if you need to upgrade the IOS of the router.

First, you need to note that although the new IOS version has been added, it requires additional resources. In fact, many administrators have a misunderstanding here. It is believed that the CPU or memory resources of the vro will not be occupied if the new functions of IOS are not used. In fact, this is a big misunderstanding. In order to make the router meet the increasingly complex network environment, many functions are often added to the new IOS version. However, if the operating system or mobile phone is the same, the added many functions may not be used by enterprises. However, these functions do not run because they are not used by the enterprise. Generally, after the vro is restarted, related jobs are loaded into the memory. That is to say, even if some functions are not used by enterprises, they will also occupy system resources, such as memory. This means that the Administrator should evaluate the necessity of IOS upgrade before the upgrade. Check whether the new IOS Enterprise version is used. Upgrade IOS only when necessary. Do not blindly worship new IOS technologies. Otherwise, the network administrator may not be able to get around.

Second, the requirements of the new version for router hardware need to be evaluated in advance. Generally, a new IOS version of software has some minimum configuration suggestions on the official website. Although these configurations are only for reference, the configuration we take is a little higher than the lowest configuration for security purposes in our actual work. This is mainly because some burst traffic in the enterprise network is under control. If the user may use BT or other software to download movies, or the sudden network traffic caused by viruses, Trojans, or other malware. If the routers are usually at full capacity, the routers will not be able to cope with these sudden network traffic. As a result, the router becomes faulty. Therefore, I suggest that you evaluate the hardware requirements before upgrading IOS. Because of the different network sizes of enterprises, you cannot view the lowest configuration of IOS software. Generally, you can take two steps. First, evaluate the memory and CPU usage of the current IOS version. If the current resource load is relatively high, such as more than 75%, I suggest you do not want to upgrade it. Unless you upgrade the hardware first, such as increasing the memory of the router. Second, if conditions are met, perform the test first. If an enterprise has redundant routers, it can first establish a test environment for testing. Check how high the hardware resources are required for the new IOS version. In most cases, the new version of IOS requires higher configurations than the old version of IOS. Unless the new version of IOS is technically revolutionary.

The third is to back up the old version of IOS before the upgrade. During the upgrade process, if an accident occurs, such as a power outage, the IOS upgrade may fail. If the upgrade fails, the new IOS cannot be used, and the old IOS version cannot work normally. Therefore, there are some risks during the upgrade process. Besides, even after the upgrade, the new version of IOS cannot be used properly due to various reasons, such as the failure of the hardware mentioned above. In case of such a situation, if the old version of IOS has a backup, it will be easy to do. In the above case, it takes only a few minutes for the author to restore the old version of IOS.

Fourth, compatibility between the old version and the new version must be considered. During the upgrade, we require that the original configuration file still be available in the new version. You do not need to reconfigure the relevant security policies. Otherwise, the workload will be large. Generally, functions of the old version can be implemented in the new version. However, the possible means or methods will change. Before the upgrade, you need to consider whether the configuration files of the old version can be used directly in the new version or need to be reconfigured. If there is any incompatibility, You need to configure it in time after the upgrade. To avoid unnecessary security risks. Generally, this information can be found on the official website. What we need to do is to carefully read these materials before upgrading.

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