4500 Switch loses part of its configuration on reboot (service compress-config)

[David Chancusi]

Hello. I would like to ask support with an issue I have.

I have a I have a WS-C4510R-E Switch implemented in the network. It runs version 12.2(54)SG1, RELEASE SOFTWARE (fc1) as seen in Figures 1 and 2.

Figure 1: show inventoryFigure 2: show version

I have had this issue: Even when I save the running config (via copy runn start or with write) a couple of times when the switch has been rebooted (due to various reasons), the switch loses some random parts of its configuration (the configuration in some of its ports, an interface vlan creation, a user/password creation, a route in its routing table, etc).

It's like the switch retains 99% of its configuration, but loses specific parts of its config. Always the same parts of the configuration. (I already know what they are, so every time this issue happens, I already know what things to manually configure in the switch to restore its proper configuration).

I have checked some information here in Cisco Support Community from a similar discussion, and people advice: "Check for the service compress-config option. Disable it, and it should fix the problem". So I can confirm this 4510 switch has that configuration enabled as seen in Figures 3 and 4:

Figure 3: compressed configurationFigure 4: service compress-config

But as I have been checking the switch configuration, I noticed some weird stuff:
- The switch has the service compress-config enabled, but it seems to also have enabled some sort of backup service that points somewhere (I guess, since I am not familiar with those commands or feature) as seen in Figure 5.

Figure 5: archive command
- I am not able to figure out what file the switch uses as its startup config file when it reboots, because I have checked its nvram and its bootvar outputs, but I cannot see that info. Here i present the contents of nvram, bootflash: and bootvar in Figures 6, 7 and 8.

Figure 6: dir nvram:Figure 7: show bootflash:Figure 8: show bootvar

With those ideas in mind, I have several questions regarding this topic:

- To solve the issue of "loss of random configuration when reboot", I guess it's because of the service compress-config option, so I should just disable it. But is that service compress-config related to that archive configuration of Figure 5 that the switch has? What does that archive thing do? Will that no service compress-config disrupt that archive configuration?

- Given the contents of the nvram as shown in Figure 6, and the lack of info for the variables shown in Figures 7 and 8, Is it possible that the switch does not load the startup-config file (that I write every time) when it reboots, but some other file of nvram? How can I confirm what file of its nvram does the switch use for its startup-config when rebooted?

- So, the idea is, Could it be possible that the Switch somehow uses some backup-config file (different from the startup-config file that I write every time) because of that archive option, so that may be the root problem?

Thanks a lot in advance for some answers about my questions, and some clarification regarding the contents of that nvram and the identification/location of the startup-config file in this device.

[Leo Laohoo]

IOS version ends with a "1".  I would attribute this behaviour to a bug.

[David Chancusi]

Hey Leo. Thanks for the reply.

Yes. As you mention, the switch runs version 12.2(54)SG1, RELEASE SOFTWARE (fc1) as seen in Figure 2.

How could I confirm that this behaviour is from a Bug? Do you thinlk the no service compress-config could be a solution for this case?

[marce1000]

          - Also check the value of the configuration register.

 M.

[David Chancusi]

Hey Marce. Thanks for the reply.

As seen in Figures 2 and 8, this switch shows that Configuration register is 0x2102

How does that value affect the behaviour of the switch?. Is that value somehow incorrect?

[marce1000]

    - Yes, that is a a defaulted value, hence not related to  your original problem.

 M.