Laserfiche WebLink
<br /> 21 | P a g e <br />City of San Leandro, CA <br />Fiber Master Plan <br />Cable Modem <br /> <br />Cable operators provide broadband to subscribers using the same coaxial cable that has <br />historically delivered content to televisions through a cable modem across the same “tree <br />and branch” network used to distribute channelized broadcast television. Technically <br />termed DOCSIS (Data Over Cable Service Interface Specification), cable broadband <br />literally allocates channels for carrying data to and from customers instead of television. <br />Most cable modems are external devices that have two connections: one to the cable wall <br />outlet via coaxial cable that goes out to the internet, the other to a computer or router via <br />Ethernet cable. <br /> <br />On the cable network, where the coaxial physically ends, a DOCSIS interface strips out <br />the data and routes them all to their destinations via fiber optic cable. DOCSIS uses a <br />“multiple access” approach to network in which every user’s data is intermingled with <br />others on the wire from the house to the router. Transmission speeds vary depending on <br />the type of cable modem, cable network, and traffic load. <br /> <br />In response to growing consumer demand for bandwidth, DSL and cable network <br />operators upgrade outdated or underperforming equipment following their revenue <br />models and capital budget limitations to attempt to make the infrastructure faster and <br />more reliable. However, several fundamental issues exist that pose long-term challenges <br />to meeting the growing bandwidth demand through copper infrastructure: <br /> <br />• Broadband signals degrade significantly over copper as distances increase. <br />• Broadband signals over copper are susceptible to electrical interference and signal <br />degradation, particularly as they age. <br />• The amount of bandwidth available on portions of broadband networks is often <br />shared among multiple users, which can result in an uneven distribution of speed <br />to users, and slower speeds to all as facilities become congested. <br /> <br />Fiber-Optics <br /> <br />As previously stated, fiber-optic network technology converts electrical signals carrying <br />data into light and sends the light through transparent glass fibers about the diameter of <br />a human hair. Fiber transmits data at speeds far exceeding copper, typically by hundreds <br />of megabits per second. With fiber-optic broadband networks, speeds in the billions of <br />bits per second range are possible. The fiber-optic network today operates at nearly 300 <br />Terabits per second, which is so fast that a single fiber could carry all the traffic on the <br />internet. <br /> <br />More commonly, fiber-optic networks provide between 100 Mbps and 10 Gbps to users. <br />Fiber-optic networks can be designed to be highly reliable as well as fast. Fiber-optics are <br />used extensively by major corporations and institutions and are beginning to be at the <br />core of every telecom company’s network. There are numerous standards for fiber optic