Flashcards
E4_6 Broadband Solutions
Cards in this deck (35)
- 1Employer Benefits of Teleworking: - Improved employee productivity - Reduced costs and expenses - Easier recruitment and retention - Reduced absenteeism - Improved morale* Improved corporate citizenship
- Improved customer service
Community and Government Benefits:
- Helps reduce traffic and infrastructure requirements
- Helps reduce urban drift
- Improved rural and suburban amenities - 2* Employer Benefits of Teleworking: - Improved employee productivity - Reduced costs and expenses - Easier recruitment and retention - Reduced absenteeism - Improved morale - Improved corporate citizenship - Improved customer service* Community and Government Benefits:
- Helps reduce traffic and infrastructure requirements
- Helps reduce urban drift
- Improved rural and suburban amenities
* Individual Benefits of Teleworking:
Productivity, Flexibility, Cost savings, Home and family - 3Detriments to Telework From an employer perspective: - Tracking of employee progress - Necessary to implement a new management styleFrom the employee perspective:
- Feeling of isolation
- Slower connections
- Distractions - 4Teleworker Solution * Broadband connections - The broadband term refers to advanced communications systems capable of providing high-speed transmission of services, such as data, voice, and video, over the Internet and other networks * IPsec VPNs - This is the most common option for teleworkers, combined with remote access over broadband, to establish a secure VPN over the public Internet. This type of WAN connection offers flexible and scalable connectivity. * Traditional private WAN Layer 2 technologies - These types of connections provide many remote connection solutions and include technologies, such as Frame Relay, ATM, and leased lines.
- 5Teleworker Connectivity Requirements * Home office components: ….and a VPN router or VPN client software installed on the computer "Travel" * Corporate compare VPN-capable routers, VPN concentrators, multifunction security appliances, authentication, and central management devices for resilient aggregation and termination of the VPN connections. ** This course presents the IP Security (IPsec) protocol as the favored approach to building secure VPN tunnels. Unlike earlier security approaches that apply security at the application layer of the OSI model, IPsec works at the network layer where packet processing occurs.
- 6What is a Cable System? The cable system uses a coaxial cable that carries radio frequency (RF) signals across the network. Coaxial cable is the primary medium used to build cable TV systems. Most cable operators use satellite dishes to gather TV signals. Early systems were one-way, with cascading amplifiers placed in series along the network to compensate for signal loss. These systems used taps to couple video signals from the main trunks to subscriber homes via drop cables.
- 7Cable and the Electromagnetic Spectrum Frequency is the rate at which current, or voltage, cycles occur. Frequency is computed as the number of waves per second. Wavelength is the distance from the peak of one wave to the peak of the next wave. Wavelength is calculated as the speed of propagation of the electromagnetic signal divided by its frequency in cycles per second. Radio waves, often called RF, constitute a portion of the electromagnetic spectrum between approximately 1 kHz and 1 THz
- 8Cable and the Electromagnetic Spectrum A cable network is capable of transmitting signals on the cable in either direction at the same time. The following frequency scopes are used: a. Upstream - The direction of the RF signal transmission from subscribers to the headend. Upstream frequencies are in the range of 5 to 42 MHz.b. Downstream - The direction of an RF signal transmission, such as TV channels and data, from the source, or headend, to the destination, or subscribers.
Transmission from source to destination is called the forward path. Downstream frequencies are in the range of 50 to 860 MHz. - 9DOCSIS ** The Data-over-Cable Service Interface Specification (DOCSIS) is an international standard developed by CableLabs, a non-profit research and development consortium for cable-related technologies. CableLabs tests and certifies cable equipment vendor devices, such as cable modems and cable modem termination systems, and grants DOCSIS-certified or qualified status.DOCSIS defines the communications and operation support interface requirements for a data-over-cable system, and permits the addition of high-speed data transfer to an existing CATV system.
Cable operators employ DOCSIS to provide Internet access over their existing HFC infrastructure - 10DOCSIS specifies the OSI Layer 1 and Layer 2 requirements: * Physical layer - For data signals that the cable operator can use, DOCSIS specifies the channel widths, or bandwidths of each channel, as 200 kHz, 400 kHz, 800 kHz, 1.6 MHz, 3.2 MHz, and 6.4 MHz. DOCSIS also specifies modulation technique, which is how to use the RF signal to convey digital data. * MAC layer - Defines a deterministic access method, Time-Division Multiple Access (TDMA), or Synchronous Code Division Multiple Access method (S-CDMA).TDMA divides access by time. Frequency-Division Multiple Access (FDMA) divides access by frequency. Code Division Multiple Access (CDMA) employs spread-spectrum technology and a special coding scheme in which each transmitter is assigned a specific code.
** An analogy that illustrates these concepts starts with a room representing a channel. The room is full of people needing to speak to one another. In other words, each person needs channel access. One solution is for the people to take turns speaking (time division). Another is for each person to speak at different pitches (frequency division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. - 11DOCSIS S-CDMA is a proprietary version of CDMA developed by Terayon Corporation for data transmission across coaxial cable networks ** S-CDMA scatters digital data up and down a wide frequency band and allows multiple subscribers connected to the network to transmit and receive concurrently. S-CDMA is secure and extremely resistant to noise.The main differences between DOCSIS and Euro-DOCSIS relate to channel bandwidths. TV technical standards vary across the world, which affects the way DOCSIS variants develop.
** International TV standards include NTSC in North American and parts of Japan; PAL in most of Europe, Asia, Africa, Australia, Brazil, and Argentina; and SECAM in France and some Eastern European countries. - 12Cable Components Two types of equipment are required to send digital modem signals upstream and downstream on a cable system: ** Cable Modem Termination System (CMTS) at the headend of the cable operator * Cable Modem (CM) on the subscriber end
- 13Cable Components ** A headend CMTS communicates with CMs located in subscriber homes. The headend is actually a router with databases for providing Internet services to cable subscribers. The architecture is relatively simple, using a mixed optical-coaxial network in which optical fiber replaces the lower bandwidth coaxial cable.** A web of fiber trunk cables connects the headend to the nodes where optical-to-RF signal conversion takes place.
In a modern HFC network, typically 500 to 2,000 active data subscribers are connected to a cable network segment, all sharing the upstream and downstream bandwidth. - 14Cable Components The actual bandwidth for Internet service over a CATV line can be up to 160 Mb/s downstream with the latest iteration of DOCSIS, and up to 120 Mb/s upstream. When high usage causes congestion, the cable operator can add additional bandwidth for data services by allocating an additional TV channel for high-speed data.This addition may effectively double the downstream bandwidth that is available to subscribers.
Another option is to reduce the number of subscribers served by each network segment. To reduce the number of subscribers, the cable operator further subdivides the network by laying the fiber-optic connections deeper into the neighborhoods. - 15What is DSL? Ej: shows a representation of bandwidth space allocation on a copper wire for ADSL. The area labeled POTS identifies the frequency range used by the voice-grade telephone service. The area labeled ADSL represents the frequency space used by the upstream and downstream DSL signals. The area that encompasses both the POTS area and the ADSL area represents the entire frequency range supported by the copper wire pair.
- 16What is DSL? Another form of DSL technology is symmetric DSL (SDSL). All forms of DSL service are categorized as ADSL or SDSL, and there are several varieties of each type. ADSL provides higher downstream bandwidth to the user than upload bandwidth. SDSL provides the same capacity in both directions.The different varieties of DSL provide different bandwidths, some with capabilities exceeding 40 Mb/s.
** The transfer rates are dependent on the actual length of the local loop (connecting the subscriber to the central office), and the type and condition of the cabling. For satisfactory ADSL service, the loop must be less than 3.39 miles (5.46 km - 17DSL Connections Service providers deploy DSL connections in the last step of a local telephone network, called the local loop or last mile. The connection is set up between a pair of modems on either end of a copper wire that extends between the customer premises equipment (CPE) and the DSL access multiplexer (DSLAM). A DSLAM is the device located at the Central Office (CO) of the provider and concentrates connections from multiple DSL subscribers. A DSLAM is often built into an aggregation router.
- 18DSL Connections The two components: 2. DSLAM - Located at the CO of the carrier, the DSLAM combines individual DSL connections from users into one high-capacity link to an ISP, and therefore, to the Internet.1. Transceiver - Connects the computer of the teleworker to the DSL. Usually the transceiver is a DSL modem connected to the computer using a USB or Ethernet cable.
Newer DSL transceivers can be built into small routers with multiple 10/100 switch ports suitable for home office use. - 19DSL Connections Ej: depicts modern DSL routers and broadband aggregation routers. ** The advantage that DSL has over cable technology is that DSL is not a shared medium. Each user has a separate direct connection to the DSLAM. Adding users does not impede performance, unless the DSLAM Internet connection to the ISP, or the Internet, becomes saturated.
- 20Separating Voice and Data in ADSL The major benefit of ADSL is the ability to provide data services along with POTS voice services. Transmissions of voice and data signals are propagated along the same wire pair ** The actual device that marks the demarcation point is the Network Interface Device (NID). At this point, a splitter can be attached to the phone line. The splitter forks the phone line; one branch provides the original house telephone wiring for telephones, and the other branch connects to the ADSL modem. The splitter acts as a low-pass filter, allowing only the 0 to 4 kHz frequencies to pass to or from the telephone.
- 21Separating Voice and Data in ADSL When the service provider puts analog voice and ADSL on the same wire pair, ADSL signals can distort voice transmission. For this reason, the provider splits the POTS channel from the ADSL modem at the customer premises using filters or splitters. This setup guarantees uninterrupted regular phone service even if ADSL fails. When filters or splitters are in place, the user can use the phone line and the ADSL connection simultaneously without adverse effects on either service.The POTS splitter is a passive device.
In the event of a power failure, the voice traffic still travels to the voice switch in the CO of the carrier. Splitters are located at the CO and, in some deployments, at the customer premises. At the CO, the POTS splitter separates the voice traffic, destined for POTS connections, and the data traffic destined for the DSLAM.
Installing the POTS splitter at the NID usually means that a technician must go to the customer site. - 22—
- 23Types of Broadband Wireless Technologies - Municipal Wi-Fi Some of these networks provide high-speed Internet access at no cost or for substantially less than the price of other broadband services. Other cities reserve their Wi-Fi networks for official use Most municipal wireless networks use a mesh topology rather than a hub-and-spoke model Each access point is in range and can communicate with at least two other access points.
- 24Types of Broadband Wireless Technologies - WiMAX A WiMAX network consists of two main components: * A tower that is similar in concept to a cellular telephone tower. A single WiMAX tower can provide coverage to an area as large as 3,000 square miles (7,500 square km). * A WiMAX receiver that is connected to a USB port or is built into a laptop or other wireless device.
- 25Types of Broadband Wireless Technologies - Cellular/Mobile Implementations Variations include 2G using GSM, CDMA, or TDMA; 3G using UMTS, CDMA2000, EDGE, or HSPA+; and 4G, using WiMAX or LTE. Three common terms that are used when discussing cellular/mobile networks include: * Wireless Internet - A general term for Internet services from a mobile phone or from any device that uses the same technology.* 2G/3G/4G Wireless - Major changes to the mobile phone companies’ wireless networks through the evolution of the second, third, and fourth generations of wireless mobile technologies.
* Long-Term Evolution (LTE) - A newer and faster technology considered to be part of 4G technology. - 26Types of Broadband Wireless Technologies - Satellite Implementations There are three ways to connect to the Internet using satellites: 1. One-way multicast - Satellite Internet systems are used for IP multicast-based data, audio, and video distribution. Even though most IP protocols require two-way communication for Internet content including web pages, one-way satellite-based Internet services can be used to push pages to local storage at end-user sites. Two-way interactivity is impossible.2. One-way terrestrial return - Satellite Internet systems use traditional dialup access to send outbound data through a modem and receive downloads from the satellite.
3. Two-way satellite Internet - Sends data from remote sites via satellite to a hub, which then sends the data to the Internet. The satellite dish at each location needs precise positioning to avoid interference with other satellites. - 27Types of Broadband Wireless Technologies - Satellite Implementations In a two-way satellite Internet systemUpload speeds are about one-tenth of the download speed, which is in the range of 500 kb/s. The primary installation requirement is for the antenna to have a clear view toward the equator, where most orbiting satellites are stationed. ** Two-way satellite Internet uses IP multicasting technology that allows one satellite to serve up to 5,000 communication channels simultaneously.** IP multicast sends data from one point to many points at the same time by sending data in a compressed format.
A company can create a private WAN using satellite communications and Very Small Aperture Terminals (VSAT).
A VSAT is a type of satellite dish similar to the ones used for satellite TV from the home and is usually about 1 meter in width. The VSAT dish sits outside, pointed at a specific satellite, and is cabled to a special router interface, with the router inside the building. - 28Comparing Broadband Solutions Some factors to consider in making a decision include: * Cable - Bandwidth is shared by many users, upstream data rates are often slow. * DSL - Limited bandwidth that is distance sensitive, upstream rate is proportionally quite small compared to downstream rate. * Fiber-to-the-Home - Requires fiber installation directly to the home* Cellular/Mobile - Coverage is often an issue, even within a SOHO, bandwidth is relatively limited.
* Wi-Fi Mesh - Most municipalities do not have a mesh network deployed; if it is available and the SOHO is in range, then it is a viable option.
* WiMAX - Bit rate is limited to 2 Mb/s per subscriber, cell size is 1 to 2 km (1.25 mi).
* Satellite - Expensive, limited capacity per subscriber; often provides access where no other access is possible. - 29PPPoE Motivation A commonly used data link layer protocol by ISPs is the Point-to-Point Protocol (PPP). PPP can be used on all serial links including those links created with dial-up analog and ISDN modems. To this day, the link from a dialup user to an ISP, using analog modems, likely uses PPP. ** PPP supports the ability to assign IP addresses to remote ends of a PPP link. With PPP enabled, ISPs can use PPP to assign each customer one public IPv4 address.
- 30PPPoE Motivation ** More importantly, PPP supports CHAP authentication. ISPs often want to use CHAP to authenticate customers because during authentication, ISPs can check accounting records to determine whether the customer’s bill is paid, prior to letting the customer connect to the Internet.These technologies came to market in the following order, with varying support for PPP:
1. Analog modems for dialup that could use PPP and CHAP
2. ISDN for dialup that could use PPP and CHAP
3. DSL, which did not create a point-to-point link and could not support PPP and CHAP - 31PPPoE Motivation ** Ethernet links do not natively support PPP. A solution to this problem was created, PPP over Ethernet (PPPoE). PPPoE allows the sending of PPP frames encapsulated inside Ethernet frames.
- 32PPPoE Concepts Ej: the customer’s router is usually connected to a DSL modem using an Ethernet cable. PPPoE creates a PPP tunnel over an Ethernet connection. This allows PPP frames to be sent across the Ethernet cable to the ISP from the customer’s router. The modem converts the Ethernet frames to PPP frames by stripping the Ethernet headers. The modem then transmits these PPP frames on the ISP’s DSL network.
- 33PPPoE Configuration With the ability to send and receive PPP frames between the routers, the ISP could continue to use the same authentication model as with analog and ISDN. To make it all work, the client and ISP routers need additional configuration, including PPP configuration.
- 34PPPoE Configuration 1. To create a PPP tunnel, the configuration uses a dialer interface. A dialer interface is a virtual interface. The PPP configuration is placed on the dialer interface, not the physical interface. The dialer interface is created using the interface dialer number command. The client can configure a static IP address, but will more likely be automatically assigned a public IP address by the ISP. 2. The PPP CHAP configuration usually defines one-way authentication; therefore, the ISP authenticates the customer. The hostname and password configured on the customer router must match the hostname and password configured on the ISP router. Notice in the figure that the CHAP username and password match the settings on the ISP router.
- 35PPPoE Configuration 3. The physical Ethernet interface that connects to the DSL modem is then enabled with the command pppoe enable that enables PPPoE and links the physical interface to the dialer interface. The dialer interface is linked to the Ethernet interface with the dialer pool and pppoe-client commands, using the same number. The dialer interface number does not have to match the dialer pool number. 4. The maximum transmission unit (MTU) should be set down to 1492, versus the default of 1500, to accommodate the PPPoE headers.
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- CCNA CCNA Flashcards on E4_6 Broadband Solutions, created by John Dedios on 31/08/2016.
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- John Dedios · Aug 2016
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- Nov 11, 2016
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