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Module 7: Wan Concepts - Coggle Diagram

- - - - There are several WAN access connection options that the enterprise edge can use to connect over the local loop to the provider. These WAN access options differ in technology, bandwidth, and cost. Each has distinct advantages and disadvantages.
  - - - Point-to-point lines could be leased from a service provider and were called “leased lines”.
      - Leased lines are available in different fixed capacities and are generally priced based on the bandwidth required and the distance between the two connected points.
        
        There are two systems used to define the digital capacity of a copper media serial link:
        
        T-carrier - Used in North America, T-carrier provides T1 links supporting bandwidth up to 1.544 Mbps and T3 links supporting bandwidth up to 43.7 Mbps
        
        E-carrier - Used in Europe, E-carrier provides E1 links supporting bandwidth up to 2.048 Mbps and E3 links supporting bandwidth up to 34.368 Mbps.
        
        Advantages
        
        Simplicity
        
        Quality
        
        Availability
        
        Disadvantages
        
        Cost
        
        Limited Flexibility
  - - - Public Service Telephone Network (PSTN)
        
        Traditional local loops can transport binary computer data through the voice telephone network using a voiceband modem. The modem modulates the digital data into an analog signal at the source and demodulates the analog signal to digital data at the destination.
        
        The physical characteristics of the local loop and its connection to the PSTN limit the rate of the signal to less than 56 kbps.
      - Integrated Services Digital Network (ISDN)
        
        ISDN is a circuit-switching technology that enables the PSTN local loop to carry digital signals. This provided higher capacity switched connections than dialup access. ISDN provides for data rates from 45 Kbps to 2.048 Mbps
  - - - Frame Relay
        
        Frame Relay is a simple Layer 2 non-broadcast multi-access (NBMA) WAN technology that is used to interconnect enterprise LANs.
      - Asynchronous Transfer Mode (ATM)
        
        Asynchronous Transfer Mode (ATM) technology is capable of transferring voice, video, and data through private and public networks. It is built on a cell-based architecture rather than on a frame-based architecture.
        
        ATM networks have been largely replaced by faster Metro Ethernet and internet-based solutions.
- - - - Dedicated Broadband
        
        In the late 1990s, many telecommunication companies built optical fiber networks with enough fiber to satisfy projected next generation needs. However, optical technologies such as wavelength division multiplexing (WDM) were developed and dramatically increased the transmitting ability of a single strand of optical fiber. Consequently, many fiber-optic cable runs are not in use. Fiber-optic cable that is not in use, and therefore, “un-lit” (i.e. dark) is referred to as dark fiber.
      - Packet-Switched
        
        Metro Ethernet proporciona enlaces rápidos de ancho de banda y ha sido responsable de la sustitución de muchas opciones tradicionales de conectividad WAN.
        
        Multi-protocol Label Switching (MPLS) enables the WAN provider network to carry any protocol as payload data. This enables different sites to connect to the provider network regardless of its access technologies.
      - Internet-based Broadband
        
        Organizations are now commonly using the global internet infrastructure for WAN connectivity. To address the security concerns, the connectivity options are often combined with VPN technologies.
  - - - Newer Ethernet standards using fiber-optic cables have made Ethernet a reasonable WAN access option.
        
        Service providers now offer Ethernet WAN service using fiber-optic cabling.
        
        Metropolitan Ethernet (Metro E)
        
        Ethernet over MPLS (EoMPLS)
        
        Virtual Private LAN Service (VPLS)
        
        Benefits
        
        Reduced expenses and administration
        
        Enhanced business productivity
  - - - MPLS supports a variety of client access methods. MPLS can encapsulate all types of protocols including IPv4 and IPv6 traffic.
        
        An MPLS router can be a customer edge (CE) router, a provider edge (PE) router, or an internal provider (P) router
        
        MPLS also provides services for QoS support, traffic engineering, redundancy, and VPN
- - - - A Digital Subscriber Line (DSL) is a high-speed, always-on, connection technology that uses existing twisted-pair telephone lines to provide IP services to users.
      - DSL Connections
        
        Service providers deploy DSL connections in the local loop. As shown in the figure, the connection is set up between the DSL modem and the DSL access multiplexer (DSLAM).
      - DSL and PPP
        
        Point-to-Point protocol (PPP) is a Layer 2 protocol that was commonly used by telephone service providers to establish router-to-router and host-to-network connections over dial-up and ISDN access networks.
        
        Host with PPPoE Client
        
        he host runs a PPPoE client to obtain a public IP address from a PPPoE server located at the provider site. The PPPoE client software communicates with the DSL modem using PPPoE and the modem communicates with the ISP using PPP.
        
        Router PPPoE Client
        
        The router is the PPPoE client and obtains its configuration from the provider. The client(s) communicate with the router using only Ethernet and are unaware of the DSL connection. In this topology, multiple clients can share the DSL connection.
    - - Cable technology is a high-speed always-on connection technology that uses a coaxial cable from the cable company to provide IP services to users. Like DSL, cable technology is a popular choice for home users and for enterprise IT departments to support remote workers.
    - - Many municipalities, cities, and providers install fiber-optic cable to the user location. This is commonly referred to as Fiber to the x (FTTx) and includes the following
        
        Fiber to the Home (FTTH) - Fiber reaches the boundary of the residence. Passive optical networks and point-to-point Ethernet are architectures that can deliver cable TV, internet, and phone services over FTTH networks directly from an the service provider central office.
        
        Fiber to the Building (FTTB) - Fiber reaches the boundary of the building, such as the basement in a multi-dwelling unit, with the final connection to the individual living space being made via alternative means, like curb or pole technologies.
        
        Fiber to the Node/Neighborhood (FTTN) - Optical cabling reaches an optical node that converts optical signals to a format acceptable for twisted pair or coaxial cable to the premise.
  - - - Municipal Wi-Fi
      - Cellular
      - Satellite Internet
      - WiMAX
  - - - Cost savings
      - Security
      - Scalability
      - Compatibility with broadband technology
- - - - LAN
        
        Local networks provide network services within a small geographical area (i.e., home network, office network, building network, or campus network).
        
        LANs are used to interconnect local devices, peripherals, and other equipment.
        
        A LAN is owned by an organization or a domestic user and is administered by them.
        
        Apart from network infrastructure costs, there is no charge to use a LAN.
        
        LANs provide high bandwidth speeds via Ethernet and Wi-Fi for network services.
      - WAN
        
        WANs provide network services over large geographical areas (i.e., in and between cities, countries, and continents).
        
        WANs are used to interconnect users, networks, and remote sites.
        
        WANs are owned and administered by Internet, telephone, cable, and satellite service providers.
        
        WAN services are provided for a fee.
        
        WAN providers offer bandwidth speeds ranging from low to high over long distances, utilizing complex physical networks.
    - - An ISP or telecommunications that wants to interconnect ISPs
      - An ISP that wants to connect customers to the internet
      - An organization that wants to connect users in different locations
    - - Guaranteed service level
      - Consistent bandwidth
      - Security
    - - Point-to-Point Topology
        
        Hub-and-Spoke Topology
        
        Dual-homed Topology
        
        Fully Meshed Topology
        
        Partially Meshed Topology
    - - Single-Carrier WAN Connection
        
        A single-carrier connection is when an organization connects to only one service provider, as shown in the figure. An SLA is negotiated between the organization and the service provider. The disadvantage of this design is the carrier connection and service provider are both single points of failure. Connectivity to the internet would be lost if the carrier link or the provider router failed.
      - Dual-Carrier WAN Connection
        
        A dual-carrier connection provides redundancy and increases network availability, as shown in the figure. The organization negotiates separate SLAs with two different service providers. The organization should ensure that the two providers each use a different carrier. Although more expensive to implement
- - - - ISO - International Organization for Standardization
      - IEEE - Institute of Electrical and Electronics Engineers
      - TIA/EIA - Telecommunications Industry Association and Electronic Industries Alliance
  - - - SDH - Synchronous Digital Hierarchy (SDH) is a global standard for transporting data over fiber-optic cable.
      - SONET - Synchronous Optical Networking (SONET) is the North American standard that provides the same services as SDH.