Valve's current network is struggling to keep up with Steam's massive traffic growth, so the company has enlisted Level 3 Communications to deliver extra 100 Gbps pipes to their game delivery servers.
According to a press release from Level 3, traffic to Steam's servers is increasing by around 75 percent year over year. In terms of total usage, Steam delivers 450 to 500 petabytes of data to its worldwide user base per month, which mostly consists of large game downloads in the 10 to 40 GB range.
To keep up with these demands, Valve has needed to increase their internet infrastructure's capacity through the addition of Level 3's 100 Gbps pipes, which Level 3 says are available in 26 markets across North America and Europe. It's not clear how many pipes Valve has purchased (Level 3 has over 42 Tbps of capacity in total), but they'd need to have a significant number in their arsenal to meet the growing demands of its user base.
Steam Download Bandwidth Used (most recent 48 hours)
100 Gbps of bandwidth does sound like a lot, but that's just a fraction of Steam's peak bandwidth usage. Over the past 48 hours, Steam users consumed 2.4 Tbps of bandwidth at peak, with Europeans accounting for the largest share of that bandwidth (1.2 Tbps). These figures are just for a typical day, too; you'd imagine Steam's bandwidth would jump dramatically during major game launch periods.
However, Valve's bandwidth requirements are insignificant compared to the biggest consumers of bandwidth worldwide, which include BitTorrent, Netflix, YouTube and regular HTTP traffic. Despite Steam's growing bandwidth demands, the service doesn't make the list of the top ten internet bandwidth consumers.