chapter six.

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

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

3. Chapter 6 High-Speed LANs
3
Table 6.1

4. Chapter 6 High-Speed LANs
4
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

5. Chapter 6 High-Speed LANs
5
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

6. Chapter 6 High-Speed LANs
6
Solution to First Problem
 Data transmitted in blocks called frames:
– User data
– Frame header containing unique address of
destination station

7. Chapter 6 High-Speed LANs
7
Figure 6.1

8. Chapter 6 High-Speed LANs
8
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).

9. Chapter 6 High-Speed LANs
9
Figure 6.2

10. Chapter 6 High-Speed LANs
10
Figure 6.3

11. Chapter 6 High-Speed LANs
11
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)

12. Chapter 6 High-Speed LANs
12
Figure 6.4

13. Chapter 6 High-Speed LANs
13
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

14. Chapter 6 High-Speed LANs
14
Figure 6.5

15. Chapter 6 High-Speed LANs
15
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

16. Chapter 6 High-Speed LANs
16
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

17. Chapter 6 High-Speed LANs
17
Figure 6.6

18. Chapter 6 High-Speed LANs
18
Figure 6.7

19. Chapter 6 High-Speed LANs
19
Figure 6.8

20. Chapter 6 High-Speed LANs
20
Figure 6.9

21. Chapter 6 High-Speed LANs
21
Figure 6.10

22. Chapter 6 High-Speed LANs
22
Figure 6.11

23. Chapter 6 High-Speed LANs
23
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

24. Chapter 6 High-Speed LANs
24
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

25. Chapter 6 High-Speed LANs
25
Figure 6.12

26. Chapter 6 High-Speed LANs
26
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

27. Chapter 6 High-Speed LANs
27
Fibre Channel Network-Oriented
Facilities
 Full multiplexing between multiple
destinations
 Peer-to-peer connectivity between any pair
of ports
 Internetworking with other connection
technologies

28. Chapter 6 High-Speed LANs
28
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

29. Chapter 6 High-Speed LANs
29
Figure 6.13

30. Chapter 6 High-Speed LANs
30
Fibre Channel Protocol
Architecture
 FC-0 Physical Media
 FC-1 Transmission Protocol
 FC-2 Framing Protocol
 FC-3 Common Services
 FC-4 Mapping

31. Chapter 6 High-Speed LANs
31
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

32. Chapter 6 High-Speed LANs
32
Figure 6.14

33. Chapter 6 High-Speed LANs
33
IEEE 802.11 Services
 Association
 Reassociation
 Disassociation
 Authentication
 Privacy

34. Chapter 6 High-Speed LANs
34
Figure 6.15

35. Chapter 6 High-Speed LANs
35
Figure 6.16