Community Broadband Master Plan Guidebook

these are peak speeds, and that the capacity is shared by all customers on a particular segment ofcoaxial cable; this is typically hundreds of homes or businesses. Speeds decrease during bandwidth“rush hours” when more users simultaneously use greater amounts of data. For example, residentialbandwidth use typically goes up a great deal during evening hours when more people use streamingvideo services and other large data applications.Figure 26 illustrates sample DOCSIS 3.0 network architecture.Figure 26: Sample DOCSIS 3.0 NetworkUltimately, the maximum speed over an HFC network is limited by the physics of the cable plant;although an HFC network has fiber within certain portions of the network, the coaxial connection to thecustomer is generally limited to less than 1 GHz of usable spectrum in total. By comparison, the capacityof fiber optic cable is orders of magnitude greater and is limited, for all intents and purposes, only by theJamie, “Virgin Media trials 1.5 Gbps speeds using DOCSIS 3.0,” telecoms.com, Sept. 14, 2011.http://www.telecoms.com/32896/virgin-media-trials-1-5-gbps-speeds-using-docsis-3-0/ (accessed Sept. 4, 2012).NMBB Program: Community Broadband Master Plan Guidebook 37