Neuron: Batch File + Excel FTW!

Excel is every network engineer's favorite way to organize lists of IPs for documentation, even though they wish they had a better solution.  Have you ever needed to add a large amount of IPs that happen to be in order?  There is a better way than typing them by hand.

So let's say you need to list out 10.10.10.1 - 10.10.10.240...

C:>for /l %i in (1 1 240) do echo 10.10.10.%i > outfile.txt


This produces a text file with an IP per line.  Copy and past that into an excel column and you're done.  If you need something more fun like say 10.10.10.0/30 - 10.10.10.252/30 you can change the first number in the parentheses to 0, the second number to 2 and the third to 252.  The syntax is that the first is the start for %i, the second is the amount to increment and the third is the stopping point.

Backup Your VLAN Database

A junior admin at XYZ corporation was tasked with adding a switch to the XYZ network.  He grabbed a spare switch out of stock that had been previously used.  After he plugged in the switch, most users were complaining that they couldn't connect to company resources over the network.  Your manager has tasked you with determining the cause of the problems and fixing them.

Sounds like a test question doesn't it?  Well unfortunately it happens often enough in real production networks.  A new switch is added with VTP server mode turned on and a higher revision number than the current VLAN database.  This can cause a totally bogus VLAN database to be propagated to the network via VTP if it is enabled on the production switches.  While there are plenty of ways to prevent this from happening, even the best network team can occasionally have a bad day.

Cisco's EEM provides a handy way of backing up your vlan.dat file so that you can quickly and relatively easily restore your VLAN database.

event manager session cli username "user" ! Determines the user that the script runs as.  If you use TACACS+ command authentication this is important.
event manager applet backup-vlan
 event timer cron cron-entry "0 23 * * *" maxrun 60000 ! Schedules the script to run at 23:00 every day.
 action 1 cli command "enable"
 action 2 cli command "configure terminal"
 action 3 cli command "file prompt quiet" ! Eliminates the "Are you sure?" prompts.
 action 4 cli command "end"
 action 5 cli command "copy const_nvram:/vlan.dat scp://user:password@FQDN/vlan.dat" ! Copies vlan.dat to a SCP server.
 action 6 cli command "configure terminal"
 action 7 cli command "no file prompt quiet" ! Restores the "Are you sure?" prompts.
 action 8 cli command "end"