To enable the Cisco IOS software to receive incoming remote shell (rsh) protocol and remote copy (rcp) protocol requests, customers must configure an authentication database to control access to the router. This configuration is accomplished by using the ip rcmd remote-host command.

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ftAuth.html

The no ip rcmd rsh-enable command does not prohibit a local user of the router from executing a command on other routers and UNIX hosts on the network using rsh. The no form of this command only disables remote access to rsh on the router.

For more information on rsh please click following link:

http://www.cisco.com/en/US/docs/ios/12_1/configfun/command/reference/frd2006.html#wp1018286