Hi,
For configuring ssh in switches you should have cryptography images with switches it will be in names like K9 in ios name and configuraing aaa check ou the below link hope this helps out your query !!
http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/aaa.html#wp1084748
http://www.cisco.com/en/US/tech/tk59/technologies_tech_note09186a0080093c81.shtml
The message genrally indicates to avoid for packet to move to radius/tacas server.so that login can happen via local database.
Regards
Ganesh.H