День добрый.
Такая проблема, кто сталкивался.
Есть две одинаковые кошки, но в одной настройки такакса можно делать в другой нет.
Привожу sh ver и команду которая не проходит.

Первая где все нормально
our-1.pko.pechory-pskovskie#sh ver

Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9_NPE-M), Version 15.3(3)M, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2013 by Cisco Systems, Inc.
Compiled Mon 22-Jul-13 04:48 by prod_rel_team
ROM: System Bootstrap, Version 12.4(22r)YB5, RELEASE SOFTWARE (fc1)
our-1.pko.pechory-pskovskie uptime is 1 day, 18 hours, 25 minutes
System image file is "flash:c880data-universalk9_npe-mz.153-3.M.bin"

Cisco 888 (MPC8300) processor (revision 1.0) with 236544K/25600K bytes of memory.
Processor board ID FCZ175192CH
1 DSL controller
4 FastEthernet interfaces
1 ISDN Basic Rate interface
1 ATM interface
256K bytes of non-volatile configuration memory.
125440K bytes of ATA CompactFlash (Read/Write)

License Info:
License UDI:
-------------------------------------------------
Device#   PID                   SN
-------------------------------------------------
*0        CISCO888-K9           FCZ175192CH
License Information for 'c880-data'
    License Level: advsecurity_npe   Type: Permanent
    Next reboot license Level: advsecurity_npe
Configuration register is 0x2102
our-1.pko.pechory-pskovskie#

our-1.pko.pechory-ps(config)#tacacs?
tacacs  tacacs-server

our-1.pko.pechory-ps(config)#tacacs ?
  server  Server configuration

и настраивается
tacacs server Х.Х.Х.Х
address ipv4 Х.Х.Х.Х
key 7 000000000000000000
tacacs server Y.Y.Y.Y
address ipv4 Y.Y.Y.Y
key 7 000000000000000000

вторая  где нет возможности настроить правильно такакс.

our-1.ocor.dno#sh ver
Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9_NPE-M), Version 15.3(3)M, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2013 by Cisco Systems, Inc.
Compiled Mon 22-Jul-13 04:48 by prod_rel_team
ROM: System Bootstrap, Version 12.4(22r)YB5, RELEASE SOFTWARE (fc1)
System image file is "flash:c880data-universalk9_npe-mz.153-3.M.bin"
Cisco 888 (MPC8300) processor (revision 1.0) with 236544K/25600K bytes of memory.
Processor board ID FCZ175192FU
1 DSL controller
4 FastEthernet interfaces
1 ISDN Basic Rate interface
1 ATM interface
256K bytes of non-volatile configuration memory.
125440K bytes of ATA CompactFlash (Read/Write)
License Info:
License UDI:
-------------------------------------------------
Device#   PID                   SN
-------------------------------------------------
*0        CISCO888-K9           FCZ175192FU
License Information for 'c880-data'
    License Level: advsecurity_npe   Type: Permanent
    Next reboot license Level: advsecurity_npe
Configuration register is 0x2102
our-1.ocor.dno#

our-1.ocor.dno(config)#tacacs ?
% Unrecognized command
our-1.ocor.dno(config)#tacacs

Тут только стандартно

tacacs-server host X.X.X.X key 00000000000000
tacacs-server host Y.Y.Y.Y key 00000000000000