2.1 WAN Technology
2.1.4 WAN line types
WAN links can be ordered from the WAN provider at various speeds that are stated in bits per second (bps) capacity. This bps capacity determines how fast data can be moved across the WAN link. WAN bandwidth is often provisioned in the United States by using the North American Digital Hierarchy.
Web Links
Cisco Connection Online
Cisco Documentation
Search Cisco