Texas-New Mexico Power (TNMP), a community-based electrical power generation and distribution company serving more than 216,000 subscribers in Texas and 490,000 subscribers in New Mexico, is dumping its T1 lines and replacing them with microwave backhaul systems from Exalt Communications. TNMP hired Houston-based telecommunications and IT engineering firm Lockard & White to assist in design, equipment selection and implementation.
The all-indoor microwave backhaul systems operate in the 2.4 GHz and 6 GHz frequency bands. Each is configured to carry four T1 lines, as well as 10 and 30 megabits per second (Mbps) of Ethernet, respectively. They are part of a network that reaches half a dozen cities along the Texas gulf coast south of Houston, including Alvin, Brazoria, Lake City and Sweeney, and carries traffic from power distribution and generation plants back to the regional network operations center in Lake City. The network carries SCADA, protective relaying, two-way radio, IP telephony, and TDM traffic.
Cities (and public utilities in particular) are replacing T1 lines with microwave systems to reduce cost and increase bandwidth. In an earlier article I wrote about Sioux Falls, South Dakota replacing fiber with microwave because the extreme temperatures in winter knocked out the city’s fiber optic links. I have spoken to other city IT managers who, because of tight municipal budgets, are replacing T1 lines primarily to save money.
How much can cities and utilities save by dumping their T1 lines
T1/E1 circuits provide 1.544 to 2.048 Mbps in each direction, with typical prices ranging from US$150 to US$750 per month, depending upon location, and set-up charges averaging US$625 per T1. The North American average price per T1 is US$337 per month. The major shortcoming of T1/E1 lines is that their prices increase linearly with capacity, so there are no price efficiencies associated with multiple T1/E1 lines. The price per megabit per second of throughput is the same at 1 Mbps as it is at 10 Mbps. Leased line price can be a function of distance, as well. As a result of these two dependencies – capacity and distance — this approach to backhaul quickly becomes cost-prohibitive.