What is this connection?

Vista Home Premium 32 bit Vista SP2

NIS2010  17.8.0.5

DSL connection via DSL Modem, no router

I notice that when I restart my computer, there is an entry in Norton Security History

under

Firewall- Network and Connections

Connected to a shared network

Details: Gateway Physical Address

(then it shows a pair of numbers, another pair of numbers, a letter and a number,  another letter and a number pair, another pair of numbers, and then a nother  letter and number pair)

what is this?  I only have 1 PC on my network so why does this show connected to a shared network??