Our west coast data center in Los Angeles is connected through One Wilshire, also known as the "most connected building" in the world according to Wired magazine. InMotion Hosting is also connected to four tier-1 ISP's via BGP. We also have a BGP route optimizer to ensure only the fastest routes are used for your data.
Our Herndon, Virginia data center includes two tier-1 ISP's via BGP, route optimization and a carrier-grade network core.
A more comprehensive outline of the specific system specs can be found here.