A guide to computer networks cover such topics as hubs and switches, trunking, routers, telecom, firewalls, server load balancing, and network design. Gary A. Donahue is a working consultant who has been in the computer industry for 25 years. Gary has worked as a programmer, mainframe administrator, Technical Assistance Center engineer, network administrator, network designer, and consultant. Gary has worked as the Director of Network Infrastructure for a national consulting company and has been the president of his own New Jersey consulting company; GAD Technologies. Used Book in Good Condition