Subodha Gunawardena Plesiochronous Digital Hierarchy (PDH) Overview Quiz

Plesiochronous Digital Hierarchy (PDH)

• PDH is a digital hierarchy developed by Dr. Subodha Gunawardena
• It consists of multiple levels, with each level having a specific number of 64Kbps channels
• The hierarchy has different standards for North America, Europe, and Japan

Digital Mux Level

• Level 0: 1 x 64Kbps channel
• Level 1: 24 x 64Kbps channels = 1.544Mbps (T1 in North America, E1 in Europe)
• Level 2: 3 x 64Kbps channels = 1.544Mbps (T2 in North America, E2 in Europe)
• Level 3: 48 x 64Kbps channels = 3.152Mbps
• Level 4: 96 x 64Kbps channels = 6.312Mbps
• Level 5: 120 x 64Kbps channels = 8.448Mbps

ISDN (Integrated Services Digital Network)

• ISDN stands for Integrated Services Digital Network
• ISDN has three standards: E (Equipment), I (Ideas), and S (Signaling/Switching)
• Access options include BRI (Basic Rate Interface) and PRI (Primary Rate Interface)

BRI (Basic Rate Interface)

• 2 x B channels (64Kbps each) and 1 x D channel (16Kbps)
• Used for small-scale applications

PRI (Primary Rate Interface)

• North American standard: 23 x B channels (64Kbps each) and 1 x D channel (64Kbps) = 1.544Mbps (full T1 link)
• European standard: 30 x B channels (64Kbps each) and 1 x D channel (64Kbps) and 1 frame synchronization channel = 2.048Mbps (full E1 link)

ISDN Terminals and Network Termination

• Terminal equipment type 1 (TE1): Specialized ISDN terminals that connect to the ISDN network through a four-wire, twisted-pair digital link
• Terminal equipment type 2 (TE2): Non-ISDN terminals that connect to the ISDN network through a terminal adapter (TA)
• Terminal adapter (TA): Connects non-ISDN TE2 devices to the ISDN network
• Network termination type 1 (NT1): Connects customer premises equipment to the ISDN network, covering the physical layer
• Network termination type 2 (NT2): Connects multiple customer premises equipment to NT1, mostly found in PBXs