Any chance you can simply increase the timeout at the Cisco device end or as part of your telnet connection? Many years ago I used Net::Telnet to visit a series of Cisco routers. I found Net::Telnet to be very capable and configurable. Plus, once connected to the Cisco router I could issue local commands to configure my session. I don't recall all the Cisco syntax but maybe there is some at the Cisco device end to keep your connection alive or a setting in Net::Telnet (or Net::Telnet::Cisco which I've not yet used). Just some ideas...