1. Business Data Communications, 4e
Chapter 15: LAN Systems
Business Data Communications, 4e

2. Business Data Communications, 4e
High-Speed LANs
Why?
Extraordinary growth in speed, power, and storage capacity of PCs
Increasing use of LANs as computing platforms
Examples
Server farms
Workgroups with “power” requirements
High-speed backbones
Business Data Communications, 4e

3. Business Data Communications, 4e
Traditional Ethernet
Ethernet and CSMA/CD (IEEE 802.3)
Carrier sense multiple access with collision detection
Four step procedure
If medium is idle, transmit
If medium is busy, listen until idle and then transmit
If collision is detected, cease transmitting
After a collision, wait a random amount of time before retransmitting
Business Data Communications, 4e

4. Business Data Communications, 4e
802.3 Medium Notation
Notation format: <data rate in Mbps><signaling method><maximum segment length in hundreds of meters>
e.g 10Base5 provides 10Mbps baseband, up to 500 meters
T and F are used in place of segment length for twisted pair and fiber
Business Data Communications, 4e

5. Business Data Communications, 4e
BaseX Media Options
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6. Business Data Communications, 4e
Fast Ethernet (100Mbps)
Easy to integrate with existing systems
Can use UTP (-TX) or fiber (-FX)
Uses star-wired topology, using a central multiport repeater (broadcast method)
If NICs support full-duplex mode, switched hub must be used
Business Data Communications, 4e

7. Business Data Communications, 4e
Base-T Options
Business Data Communications, 4e

8. Business Data Communications, 4e
BaseX Media Options
Business Data Communications, 4e

9. Business Data Communications, 4e
Gigabit Ethernet
Still under development
Retains CSMA/CD protocol and Ethernet format, ensuring smooth upgrade path
Uses optical fiber over short distances
1-gbps switching hub provides backbone connectivity
Business Data Communications, 4e

10. Gigabit Ethernet Media Options
Business Data Communications, 4e

11. Example 100-Mbps Ethernet Backbone Strategy
Business Data Communications, 4e

12. Token Ring LANs (802.5): Medium Access Control
Token “seized” by changing a bit on the circulating frame to indicate start of frame rather than token
Default configuration requires sender to complete transmission and begin receiving transmitted frame before releasing the token
“Early token release” allows release of token after transmission but before receipt of frame
Business Data Communications, 4e

13. Business Data Communications, 4e
802.5 Transmission Media
Original specified shielded twisted pair with data rates of 4 and 16mbps
New addition to standard allows use of UTP for 4mbps
Utilizes differential Manchester encoding
1997 update to IEEE introduced dedicated token ring (DTR).
Business Data Communications, 4e

14. Business Data Communications, 4e
Fibre Channel
combine the best features of channel and protocol-based technologies
the simplicity and speed of channel communications
the flexibility and inter-connectivity that characterize protocol-based network communications.
more like a traditional circuit-switched or packet-switched network, in contrast to the typical shared-medium LAN
Business Data Communications, 4e

15. Business Data Communications, 4e
Fibre Channel Goals
Full-duplex links with two fibers per link
Performance from 100 Mbps to 800 Mbps on a single link (200 Mbps to1600 Mbps per link)
Support for distances up to 10 km
Small connectors
High-capacity utilization with distance insensitivity
Greater connectivity than existing multidrop channels
Broad availability (i.e., standard components)
Support for multiple cost/performance levels, from small systems to supercomputers
Ability to carry multiple existing interface command sets for existing channel and network protocols
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16. Fibre Channel Elements
Nodes
The end systems
Includes one or more N_ ports for interconnection
Fabric
Collection of switching elements s between systems
Each element includes multiple F_ ports
Responsible for buffering and for routing frames between source and destination nodes
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17. Fibre Channel Protocol Architecture
FC-0 Physical Media: Includes optical fiber, coaxial cable, and shielded twisted pair, based on distance requirements
FC-1 Transmission Protocol: Defines the signal encoding scheme
FC-2 Framing Protocol: Defines topologies, frame format, flow/error control, and grouping of frames
FC-3 Common Services: Includes multicasting
FC-4 Mapping: Defines the mapping of various channel and network protocols to Fibre Channel
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18. Business Data Communications, 4e
Wireless LANS
LAN extension
Wireless network connected to a main wire-based network
Cross-building interconnect
Point-to-point link between networks in separate buildings
Nomadic access
Wireless link between a LAN hub and a mobile data terminal
Ad hoc networks
a peer-to-peer network (no centralized server) set up temporarily to meet some immediate need.
Business Data Communications, 4e

19. Wireless LAN Requirements
Throughput
Number of nodes:
Connection to backbone LAN
Service area
Battery power consumption
Transmission robustness and security
Co-located network operation
License-free operation
Handoff/roaming
Dynamic configuration
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20. Business Data Communications, 4e
IEEE Standards
Association/Re-Association/Disassociation
Authentication
Privacy
Physical Media
Infrared at 1 or 2 Mbps at a wavelength of nm
Direct-sequence spread spectrum in the 2.4-GHz ISM band
Frequency-hopping spread spectrum in the 2.4-GHz ISM band, at data rates of 1 and 2 Mbps.
Business Data Communications, 4e