The growth of total web traffic that travels between carriers slowed slightly in 2008, according to Arbor Networks, a company that sells deep packet inspection gear and other telecommunications equipment. Arbor passed along some data late yesterday as part of the launch of ATLAS (Active Threat Level Analysis System), its second-generation Internet threat assessment tool. ATLAS takes data from more than 100 ISPs around the world and uses that to track attacks, the rise of popular programs such as Adobe Flash, and general traffic. Here are some tidbits:

• Globally, intercarrier traffic grew an average of 30-40 percent per ISP last year (a less than 10 percent slow-down from previous year)
• HTTP is responsible for nearly 75 percent of the overall increase in Internet traffic, but that category grew substantially more slowly than services such as streaming (particularly Flash video) and secure network news, which doubled.
• The two most significant traffic drivers included Google, as a source of traffic, and China, as a destination of traffic.

Below is a slide of traffic patterns from various carriers. Tier 2 providers are typically regional carriers in the U.S. or a national carrier in Europe. They typically have a peak during average working hours, while MSOs, or cable providers, have a huge peak late at night. P2P file sharing perhaps?