How many 3750-E switches can an RPS 2300 backup?

The Q&A sheet mentions that with dual 1150W power supplies, an RPS can backup 1 or 2 3750-E switches.  This is assuming the switches also have 1150W power supplies installed.

But what if they’re only using 750W?  The RPS would have a total of 2300W of power, while three of the switches would only require 2250W.    So it should be able to backup three switches, right?

Nope.  You can only backup two.  So, there’s actually really no point of installing 1150W power supplies in the RPS.

Switch#show env rps
DCOut State Connected Priority BackingUp WillBackup Portname SW#
----- ------- --------- -------- --------- ---------- --------------- ---
 1 Active Yes 6 Yes Yes FDO1525Y1T5 1
 2 Active No 6 No No <> -
 3 Active Yes 6 Yes Yes FDO1417R07E 3
 4 Active No 6 No No <> -
 5 Active Yes 6 No No FDO1406R1KU 5
 6 Active No 6 No No <> -

Yet another reason why the RPS sucks and StackPower on the 3750X and 3850 series is so much better.


DNS Resolution via VRF on Cisco IOS

For several years I’ve been using VRFs for all management functions.  This greatly improves security since all management functions can be locked down to a certain interface, and also recover-ability in the even of routing problems.  The downside I keep finding is certain things either don’t work, or require special work-rounds. Case in point: DNS resolution.

Per Cisco, VRF-aware DNS functionality has been supported for quite a while.  However, I’m completely stumped on how to actually use it.  Sample config on an 2921 router running IOS 15.5(3)M4:

ip vrf Mgmt-intf
 rd 12345:123
ip domain-lookup 
ip domain list vrf Mgmt-intf
ip name-server vrf Mgmt-intf

interface Port-channel1.123
 encapsulation dot1Q 123
 ip vrf forwarding Mgmt-intf
 ip address
ip domain-lookup vrf Mgmt-intf source-interface po1.123

Still no joy.  Really seems there was a goof here in enabling this feature.  I’ll complain to Cisco and hopefully it will be fixed by the time I die.

Commands to Restore Cisco ACS from backup

We’re still running ACS 5.4 patch 4, which was always buggy, but has gotten especially painful to manage via modern browsers.  Over the last few weeks I’ve realized this has now gone to catastrophic.  If editing a policy with say FireFox 49, trying to make a change will cause the entire policy to be deleted without being prompted.  It’s definitely time to patch, but in the meantime I needed to restore from backup.  So I SSH in to ACS, find last night’s backup file, and go to restore:

acs01/admin# restore acs01-backup-161004-0000.tar.gpg repository MyFTP  application acs 
Restore may require a restart of application services. Continue? (yes/no) [yes] ? yes
Initiating restore.  Please wait...
Backup file does not match installed application
% Application restore failed

Hmm….the application name is ‘acs’.  Maybe I have to put it in UPPER case?!?

acs01/admin# restore acs01-backup-161004-0000.tar.gpg repository MyFTP application ACS
Restore may require a restart of application services. Continue? (yes/no) [yes] ? yes
Initiating restore.  Please wait...
Calculating disk size for /opt/backup/restore-acs01-backup-161004-0000.tar.gpg-1475607189
Total size of restore files are 331 M.
Max Size defined for restore files are 105573 M.
% Backup file does not match installed application(s)

OK, now I’m concerned.  Wait – leave it to Cisco to throw a gotcha.  The “restore” command restores both ACS and the appliance OS.  To restore just ACS configuration, use the “acs restore command”:

acs01/admin# acs restore acs01-backup-161004-0000.tar.gpg repository MyFTP
Restore requires a restart of ACS services. Continue?  (yes/no) yes
Initiating restore.  Please wait...

Bingo!  And a few minutes later, everything is happy.  I logged in using IE8 and was able to make the policy changes without issue.