In her post, Glover suggests friends and personal networks offer "breadth" or expansiveness to a professional network. This is exactly right. Friends are people who know you, know what you do, and willingly refer you to others. You would not want to ignore your buddy, risk insulting him and miss out on a good conversation. Instead, do two things: find out how your buddy might be able to help you meet others at the event, and, more importantly, find out who your buddy wants to meet, so you can make an introduction. Most organizers of conferences, trade shows and other events publish a list of attendees which they make available either prior to or during the event. Pick out a couple of people you definitely want to meet, and let your buddy know.
If you attend a new event, if your buddy doesn't show or if the only people you know are the people you walked in with, challenge yourself to step away from your colleagues, politely take the last empty seat at a table and smile as you get to know some new contacts... contacts who might someday be old friends.
Working together is what makes networking work all the way around. Bonus: if other people see you having a relaxed, open conversation with someone, they might be interested in getting to know you both. Now you're networking!