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WAN Concepts - Coggle Diagram

- - - - Wireless
        
        Municipal Wi-Fi
        
        Cellular
        
        Satellite Internet
        
        WiMAX
        
        They use radio waves instead of wired media to transmit data.
      - Wired
        
        Cable
        
        Optical Fiber
        
        Use permanent cabling (e.g., copper or fiber) to provide consistent bandwidth, and reduce error rates and latency.
        
        xDSL
  - - - The DSL modem converts the Ethernet signals from the teleworker device to a DSL signal, which is transmitted to a DSL access multiplexer (DSLAM) at the provider location.
  - - - PPP can be used to authenticate the subscriber.
      - PPP can assign a public IPv4 address to the subscriber.
      - PPP provides link-quality management features.
  - - - Fiber to the Home (FTTH)
      - Fiber to the Building (FTTB)
      - Fiber to the Node/Neighborhood (FTTN)
  - - - Some of these networks provide high-speed internet access for free, or for substantially less than the price of other broadband services.
    - - WAN technology being used to connect users and remote locations where no other WAN access technology is available.
    - - Typically used by rural users or in remote locations where cable and DSL are not available. To access satellite internet services, subscribers need a satellite dish, two modems (uplink and downlink), and coaxial cables between the dish and the modem.
    - - WiMAX operates in a similar way to Wi-Fi, but at higher speeds, over greater distances, and for a greater number of users. It uses a network of WiMAX towers that are like cell phone towers.
  - - - Bandwidth is shared by many users. Therefore, upstream data rates are often slow during high-usage hours in areas with over-subscription.
    - - Limited bandwidth that is distance sensitive (in relation to the ISP central office). Upload rate is proportionally lower compared to download rate.
    - - This option requires fiber installation directly to the home.
    - - With this option, coverage is often an issue, even within a small office or home office where bandwidth is relatively limited.
    - - Most municipalities do not have a mesh Wi-Fi network deployed. If is available and in range, then it is a viable option.
    - - This option is expensive and provides limited capacity per subscriber. Typically used when no other option is available.
- - - - Layer 1 – Physical: Transmission media, connectors, signaling.
      - Layer 2 – Data Link: WAN protocols like HDLC, PPP, Frame Relay.
      - Layer 3 – Network: IP addressing and routing.
      - Each layer defines how data is transmitted, framed, and routed across networks.
  - - - SDH (Synchronous Digital Hierarchy) and SONET (Synchronous Optical Network):
      - High-speed fiber optic transmission technologies.
      - Use precise synchronization to carry large amounts of data.
      - SONET is mainly used in North America; SDH is the international version.
      - DWDM (Dense Wavelength Division Multiplexing):
      - Allows multiple optical signals to travel through a single fiber, each with a unique wavelength.
      - Greatly increases bandwidth capacity of backbone networks.
- - - - Point-to-Point: Direct connection between two sites; simple but expensive when scaled.
      - Hub-and-Spoke: A central hub connects multiple remote sites (spokes), but the hub is a single point of failure.
      - Dual-Homed: Two hub routers provide redundancy, load balancing, and reliability, though at higher cost and configuration complexity.
      - Full or Partial Mesh: Multiple interconnections ensure high availability and fault tolerance.
  - - - Single-carrier: Simpler and cheaper but introduces a single point of failure if the link or provider fails.
      - Dual-carrier: Improves redundancy and performance by using two providers, but increases cost and setup complexity.
  - - - Small network: A single LAN using DSL internet for a small office.
      - Campus network (CAN): Connects multiple LANs within one building or area, adding dedicated servers and security through firewalls.
      - Branch network (MAN/WAN): Links remote offices through private lines or internet connections, requiring additional security measures.
      - Distributed global network: Uses VPNs, teleworking, and cloud-based collaboration tools to connect employees worldwide efficiently and securely.
- - - - ADVANTAGES
      - Simplicity
      - Quality
      - Availability
  - - - Frame Relay was a Layer 2 packet-switching technology widely used in the 1990s and 2000s to interconnect branches over a provider network.
      - Key concepts
        
        PVCs and SVCs: deployments commonly used Permanent Virtual Circuits (PVCs) between sites.
        
        DLCI: local identifiers for each PVC on a physical interface.
        
        LMI: management protocol between CPE and the FR cloud to signal PVC status (ANSI, Cisco, Q933a).
        
        CIR/Bc/Be: the provider offers a Committed Information Rate with allowed bursts. Frames above the commitment can be marked DE (Discard Eligible).
        
        Basic QoS: no strict guarantees. Congestion and drops may occur.
      - Encapsulation and addressing
        
        Layer 2: header with DLCI, FECN/BECN (forward and backward explicit congestion notification), and DE.
        
        Layer 3: typically carries IPv4. CPE can use multipoint or point-to-point subinterfaces.
    - - ATM is a switching technology based on fixed 53‑byte cells, designed to integrate voice, video, and data with quality-of-service control.
      - Key concepts
        
        Cells: 53 bytes total, 5‑byte header and 48‑byte payload. Fixed size enables fast hardware switching and tighter jitter control.
        
        Virtual connections: VPI/VCI identify virtual paths and virtual channels.
        
        AAL (Adaptation Layer): adapts frames/packets to cells. Common types: AAL5 for IP data, AAL1 for PCM voice.
        
        Service classes: CBR, VBR‑rt, VBR‑nrt, ABR, UBR, each with different bandwidth, loss, and delay commitments.
      - QoS and traffic
        
        Policing and shaping via PCR/SCR/MBS to meet traffic profiles.
        
        Stronger guarantees than Frame Relay, suitable for traditional voice/video.