Telecommunications Transmission Methods and Network Components

21 Transmit Asynchronous and Synchronous Data

• Synchronous: Transmits a group of characters in a continuous flow of bits.
• Asynchronous: Transmits or receives a character by adding a start bit and stop bits to indicate the end of a data packet. This separates packets, synchronizing the receiver with the transmitter.

22 Transmit Serial and Parallel Data

• Serial: Bits comprising a character are transmitted sequentially on a single line.
• Parallel: Bits representing a character are transmitted simultaneously over multiple lines.

23 Wavelength Windows in Fiber Optics

• 850nm window
• 1310nm window
• 1550nm window
• 1620nm window

24 Understanding Network Switching

Switching connects different nodes at various locations and distances to establish an appropriate connection between two users in a telecommunications network.

25 Types of Network Switching

• Packet Switching: A message is divided into small units called packets, transmitted through shared physical media.
• Circuit Switching: Establishes a dedicated physical path between users before communication begins.
• Cell Switching: Uses fixed-size cells as the smallest unit of data, unlike variable-length packets.

26 Components of a Public Telephone Network

• Subscribers
• Local loop
• Central office
• Main lines

27 Difference Between ATM and Frame Relay

• Frame Relay (FR):
  • Variable-size packets
  • Data transfer rates up to 2 Mbps (serial links)
  • Data traffic only
• Asynchronous Transfer Mode (ATM):
  • Fixed-size cells
  • Higher bitrates (e.g., 10/100 Mbps Ethernet links)
  • Voice, data, and video traffic

28 Devices Connected to a Frame Relay Switch

PC (DTE) -------- SW.FR -------- SW.FR ----- DCE (DCE) -------- PC (DTE)

29 DLCI in Frame Relay

DLCI (Data Link Connection Identifier) is a logical connection identifier between two DTE devices.

30 Items in an ATM Link

• Switch
• ATM Virtual Paths (VP)
• Virtual Channels (VC)

(X) ----------------------------------------------- -------------- (X)

-------------------------------------------------- ------------

Transmission via Virtual Channel

• Virtual Paths (VP)
• Virtual Channels (VC)