During a pandemic such as the swine flu, students and commercial users would be likely to use the internet more as they telework at home to prevent becoming infected.
The problem could be particularly bad given the tendency for people to access high-bandwidth content from home, the report said. Streaming video and online games could consume large amounts of network capacity, while those caring for the sick may want to access health information and news on the swine flu.
The DHS has itself identified potential congestion on residential internet application points such as DSL subscriber line access multiplexers (DSLAMS) or cable modem termination systems (CMTS).
Residential users would begin experiencing congestion when the nation hit a 40% absenteeism level from work due to e.g. swine flu, according to its study, carried out in 2007. Networks might also suffer congestion at other points, such as points of exchange between service providers, and at the offices of companies trying to support large numbers of sudden teleworkers accessing a VPN.
Internet service providers may have to restrict access to certain types of site or simply choke back traffic altogether, which could require government authorization, said the GAO report.
"Although serving as the coordinating agency for internet recovery and pandemic response, DHS staff told us that their agency does not have a strategy to address internet congestion", said the report, which added that the Department has been busy focusing on other crises such as hurricane Katrina.
"A senior official at a financial markets regulator told us that leadership by the government have been lacking in addressing this potential risk to the financial sector", the report added.
In its response to the GAO report, the DHS argued that its responsibility does not include managing the internet during a pandemic such as the swine flu, or for developing an internet congestion strategy. "DHS agrees that its strategy for assuring national security/emergency preparedness should include addressing the possible consequences of a pandemic", it responded.