Martin James Duggan, CCIE No. 7942, is a network architect for AT&T. He designs network solutions for customers globally and specializes in data center networking and QoS. Martin mentors colleagues through their Cisco qualifications and holds regular internal training classes. Previous to this, Martin was a network architect for IBM, performing IP network designs and global network reviews. Martin has been in the industry for 23 years, focusing on Cisco solutions for the past 14 years. Martin is the author of the Cisco Press CCIE Routing and Switching v4.0 TroubleShooting Practice Labs, First Edition.