Network Infrastructure and Services

Communications Network Services (CNS) is a division of the Office of the Vice President for Information Technology, which provides ISP services including telephone and Internet to the university. Unlike most departments, CNS operates as an auxillary service, and therefore recieves funding through cost-recovery rather than university budgets. Individual departments and students must pay a per-port charge for each IP or phone device attached to the network.

Network Topology

CNS has about 4 Gbps aggregate bandwidth of commodity Internet from its Cogent uplink in the Andrews Information Systems Building, which is fed to campus via redundant fiber connections to both Burruss Hall and Cassell Colliseum. Owens Hall, Hillcrest Hall, and Shanks Hall also serve as routers for some buildings. Additional connections for Network Virginia, National Lamba Rail, and Internet2 exist at AISB. The vast majority of campus IPv4s come from two directly-allocated blocks (128.173.0.0/16 and 198.82.0.0/16).

CNS is a leader in the transition to IPv6, as their ASN consistently ranks in the top 5 in terms of percentage of IPv6 traffic, according to World IPv6 Launch Measurements. A dual-stack topology exists for the entirety of campus, with the notable exception of the main university website. However, Virginia Tech does not currently have its own IPv6 block; the addresses used are from a /48 sub-allocated from UMD.

Controversies

• CNS maintains a 4.9 GB/day upload cap for residential users, after which connections will be throttled.
• Port security is enabled, meaning that users are not permitted to attach a switch to the network and must pay for new connections for all devices.
• CNS has begun deploying NAT to dorm buildings, starting with Ambler Johnston Hall. This causes issues for students that need to forward ports for services such as SSH. IPv6 addresses, however, are global.
• In January 2013, emergency maintenance was done at Virginia Tech's uplink in Ashburn, but users were not informed in advance of the potential downtime. This initially took out VT's edge IPv4 access for several hours, and later resulted in intermittent routing issues at the BGP level until the next morning.