1. WAN & Technology Introduction of WAN Switching & Routing Congestion control WAN Technologies: DQDB (Distributed queue dual bus) SDH, SONET, ATM, Frame Relay, etc.. Wireless link CH 4 WAN

2. DQDB Distributed queue dual Bus IEEE 802.3,5 LAN IEEE 802.6? Cover entire city(up to 16 km at 44 mbps) Data stream 53 byte cell (5 header+ 48 payload) Each Cell bit (B,R) if cell occupied it’s B bit is 1 CH 4 WAN

3. DQDB Architecture CH 4 WAN Each bus supports traffic in only one direction Beginning of bus is denoted by a square. Bus B traffic moves from right to left and Bus A traffic from left to right Each bus connects to stations directly through input and output ports

4. What is DQDB? Distributed Queue Dual Bus Protocol for MAN DQDB is an IEEE standard: 802.6 Designed for both voice & video Topology used: Dual Bus - uses 2 unidirectional logical buses Extend up to 30 miles at 34-55 Mbps Uses optical fibre links Queued-packet distributed switch (QPSX) algo. CH 4 WAN

5. About DQDB? Works on Data-link layer (specially in MAC sub-layer) Used in data, voice and video transmissions Based on Cell Relay Technology (like ATM) Provides connection-oriented services connection less services asynchronous services CH 4 WAN

6. Technical fact and Medium Medium: Copper or Fiber up to 160 KM approx speed is 44 Mbps (Copper) up to 100 KM approx speed is 150 Mbps (Fiber) Transmission Rate: 34 Mbps to 150 Mbps Working: head end generate fixed size cells in both direction (Cell Generator) CH 4 WAN

7. DQDB User’s queue up, they became ready to send & transmit in FIFO order Achieved without central queue control called distributed queue MAC Protocol: –Be polite to your data stream station, & let them have to go first, if they requested before yours. CH 4 WAN

8. SONET To be continue..in Next session. CH 4 WAN.