broadband and high speed LANS Chapter06.ppt

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1. Chapter 6 High-Speed LANs
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Chapter 6
High-Speed LANs

2. Chapter 6 High-Speed LANs
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Introduction
Fast Ethernet and Gigabit Ethernet
Fibre Channel
High-speed Wireless LANs

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Table 6.1

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Emergence of High-Speed LANs
2 Significant trends
–Computing power of PCs continues to grow
rapidly
–Network computing
Examples of requirements
–Centralized server farms
–Power workgroups
–High-speed local backbone

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Classical Ethernet
Bus topology LAN
10 Mbps
CSMA/CD medium access control
protocol
2 problems:
–A transmission from any station can be
received by all stations
–How to regulate transmission

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Solution to First Problem
Data transmitted in blocks called frames:
–User data
–Frame header containing unique address of
destination station

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Figure 6.1

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CSMA/CD
Carrier Sense Multiple Access/ Carrier Detection
1.If the medium is idle, transmit.
2.If the medium is busy, continue to listen until
the channel is idle, then transmit immediately.
3.If a collision is detected during transmission,
immediately cease transmitting.
4.After a collision, wait a random amount of
time, then attempt to transmit again (repeat
from step 1).

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Figure 6.2

10. Chapter 6 High-Speed LANs
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Figure 6.3

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Medium Options at 10Mbps
<data rate> <signaling method> <max length>
10Base5
–10 Mbps
–50-ohm coaxial cable bus
–Maximum segment length 500 meters
10Base-T
–Twisted pair, maximum length 100 meters
–Star topology (hub or multipoint repeater at central point)

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Figure 6.4

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Hubs and Switches
Hub
Transmission from a station received by central
hub and retransmitted on all outgoing lines
Only one transmission at a time
Layer 2 Switch
Incoming frame switched to one outgoing line
Many transmissions at same time

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Figure 6.5

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Bridge
Frame handling done
in software
Analyze and forward
one frame at a time
Store-and-forward
Layer 2 Switch
Frame handling done
in hardware
Multiple data paths
and can handle
multiple frames at a
time
Can do cut-through

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Layer 2 Switches
Flat address space
Broadcast storm
Only one path between any 2 devices
Solution 1: subnetworks connected by
routers
Solution 2: layer 3 switching, packet-
forwarding logic in hardware

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Figure 6.6

18. Chapter 6 High-Speed LANs
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Figure 6.7

19. Chapter 6 High-Speed LANs
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Figure 6.8

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Figure 6.9

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Figure 6.10

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Figure 6.11

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Benefits of 10 Gbps Ethernet over
ATM
No expensive, bandwidth consuming
conversion between Ethernet packets and
ATM cells
Network is Ethernet, end to end
IP plus Ethernet offers QoS and traffic
policing capabilities approach that of ATM
Wide variety of standard optical interfaces
for 10 Gbps Ethernet

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Fibre Channel
2 methods of communication with
processor:
–I/O channel
–Network communications
Fibre channel combines both
–Simplicity and speed of channel
communications
–Flexibility and interconnectivity of network
communications

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Figure 6.12

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I/O channel
Hardware based, high-speed, short
distance
Direct point-to-point or multipoint
communications link
Data type qualifiers for routing payload
Link-level constructs for individual I/O
operations
Protocol specific specifications to support
e.g. SCSI

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Fibre Channel Network-Oriented
Facilities
Full multiplexing between multiple
destinations
Peer-to-peer connectivity between any pair
of ports
Internetworking with other connection
technologies

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Fibre Channel Requirements
Full duplex links with 2 fibres/link
100 Mbps –800 Mbps
Distances up to 10 km
Small connectors
high-capacity
Greater connectivity than existing multidrop
channels
Broad availability
Support for multiple cost/performance levels
Support for multiple existing interface command
sets

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Figure 6.13

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Fibre Channel Protocol
Architecture
FC-0 Physical Media
FC-1 Transmission Protocol
FC-2 Framing Protocol
FC-3 Common Services
FC-4 Mapping

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Wireless LAN Requirements
Throughput
Number of nodes
Connection to backbone
Service area
Battery power consumption
Transmission robustness and security
Collocated network operation
License-free operation
Handoff/roaming
Dynamic configuration

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Figure 6.14

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IEEE 802.11 Services
Association
Reassociation
Disassociation
Authentication
Privacy

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Figure 6.15

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Figure 6.16