I recently needed to reset a password on an older Cisco Router where the config register was set to 0×1.
According to Cisco documentation 0×1 means “Automatic boot up from ROM (IOS sw subset)”. It was not possible to interrupt the boot process to enter rommon mode. The solution is quite easy: Just send the break when the IOS is already booted. After that you can enter rommon, change the config register to 0×2142, reset the device and recover the password as usual.
In a previous post post I wrote that we had a problem when upgrading IOS on a switch.
In order to update you need to reboot the device. You should not reboot device that is in use (well you could but this is a completely different story). So on IOS you can use reload in or reload at (if the device is not that import that some will pay your overtime so that you stay and do the reload manually late at night and there is no big risk if the device is not running when you come to work the next day. You should be early. Just in case.).
So we decided to reload at 22:00 which resulted in something like the following log message:
*Dec 30 18:39:39.703: %SYS-5-SCHEDULED_RELOAD: Reload requested for 04:10:38 UTC Jan 12 2014 at 18:39:38 UTC Fri Dec 30 2011 by console. Reload Reason: Reload Command.
2014? show clock showed that the clock was working properly. Using reload in 400 gave us almost the same message. Again 2014.
The solution? One of us had to get up early and reload the switch manually.
The other day on a brand new Cisco 3750x:
Switch(config-if)#ipv6 ?
IPv6 interface subcommands:
mld MLD interface commands
nd IPv6 interface Neighbor Discovery subcommands
traffic-filter Access control list for packets
Switch(config-if)#ipv6 nd
% Incomplete command.
Switch(config-if)#ipv6 nd ?
% Unrecognized command
The subtitle
Everything you need to know that wasn’t on the CCNA exam
is absolutely correct. This book is a must read if you’re fresh in the businesses and have some basic Cisco know-how (like the CCNA). Unlike most (all?) Certifiation Books this book has many real live examples and covers quite a few advanced topics like Catalyst 6500 (VSS), QoS or the Nexus series.
Even I learned a thing or two while reading this book. And in case it doesn’t help you junior Cisco admins to do there job better: The book is heavy enough to hit them with. 
See the book content at O’Reilly.
Buy at amazon.de
Just got a new Cisco 2901 for my lab and noticed that there are no cables (neither console nor Ethernet) shipped with it. Fine for people like me having dozens of blue cables lying around. If you need these cables, remember to order them when you order the hardware.
NX-OS is almost like IOS. Cisco provides a good comparison between the two command sets
here.
I found this guide quite useful when I had to connect some HP ProCurve Switches to a Cisco Switch recently.
Finding out which IOS version on your network is affected by a Cisco security advisory can be a tedious.
I just came across a tool making the Job much easier:
Cisco IOS Software Checker.
When copying IOS images to a router using VRFs the ftp source interface, user name and password must be specified.
Here is a sample config:
router# conf t
router(config)# ip ftp username foo
router(config)# ip ftp password secret
router(config)# ip ftp source-interface GigabitEthernet0
Now the image can be copied:
router# copy ftp: flash:
...
