Cisco 4506E with SUP7LF-E

[ElwinMkanyika]

Guys, 

Please assist. We got a new replacement for existing 4500 SW to 4506E. I have just noticed that the confreg is 0x2101 instead of the usual 0x2102. After reading documentation, i understood that the two confregs are basically one and the same thing. 

However, one interesting thing that I have noted is that when i execute the show run command, I do not get an output and the session just handgs there. Need to disconnect then connect again. All other commands even startup are ok. Just this one. 

This command is there boot system flash bootflash:cat4500e-universalk9.SPA.03.05.00.E.152-1.E.bin

econdly, I have noted that vty sessions are also not getting expired despite the fact that the timer is set to disconnect after few minutes. 

line con 0
 exec-timeout 15 0
 privilege level 15
 login authentication local_auth
 stopbits 1
line vty 0 4
 session-timeout 3
 exec-timeout 3 0
 login authentication local_auth
 transport input telnet ssh
 transport output telnet ssh
line vty 5 15
 session-timeout 3
 exec-timeout 3 0
 login authentication local_auth
 transport input telnet ssh
 transport output telnet ssh

Even the disconnect and clear commands do not help. 

1) Is it the confreg that is causing these issues?

2) Should I change to the 2102 confreg or leave as is?

[Leo Laohoo · Accepted solution]

Config-registry value of 0x2101, particularly the last octet of "1" means that the supervisor card will ignore the boot variable string and boot the FIRST IMAGE found in the flash.  

On a Cat 2K and 3K, if you change the last octet to "2", it will look for a boot variable string if not fall back to the first image found in the flash.   Unfortunately, 4500 and 6500 supervisor cards do not like it when you've got 0x2102 config registry and you do NOT have a valid (or correct) boot variable string.  If you have 0x2102 and you either have no boot variable string or your boot variable string is incorrect (like wrong filename, for instance), your switch will boot into ROMmon.  

Supervisor cards are shipped with 0x2101 config-registry by default.  It is up to your discretion to change it.  It is also a good way to find out whether or not you're network engineers know what they are doing or not.  

That's the difference between the two.

[Leo Laohoo]

This is what an it looks like when you boot with a 0x2102 config registry looks like:  

 config-register = 0x2102 
 Autobooting using BOOT variable specified file.....

 Current BOOT file is --- bootflash:IOS_filename.bin 
 Loading image !!!!!!!!!!!!!!!!!!!!!!

And this is what it looks like when you use 0x2101 config-registry

 config-register = 0x2101 
 Autobooting using the first file from bootflash.....

 Loading image !!!!!!!!!!!!

Do you see the difference?

[ElwinMkanyika]

Thank you Leo for pointing out the difference. 

We also found that the IOS had a bug and that was why I could not perform the show run. This is what we were and still are using cat4500e-universalk9.SPA.03.05.00.E.152-1.E.bin. 

Rebooting the switch helps for some time but we do plan on upgrading IOS to completely solve the issue. 

https://tools.cisco.com/bugsearch/bug/CSCul95289