1 UNIT I (Contd..) High-Speed LANs

2 Introduction Fast Ethernet and Gigabit Ethernet Fast Ethernet and Gigabit Ethernet Fibre Channel Fibre Channel High-speed Wireless LANs High-speed Wireless LANs

3 Table 6.1

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

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

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

7 Figure 6.1

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 Figure 6.2

10 Figure 6.3

11 Medium Options at 10Mbps 10Base5 10Base5 10 Mbps 10 Mbps 50-ohm coaxial cable bus 50-ohm coaxial cable bus Maximum segment length 500 meters Maximum segment length 500 meters 10Base-T 10Base-T Twisted pair, maximum length 100 meters Twisted pair, maximum length 100 meters Star topology (hub or multipoint repeater at central point) Star topology (hub or multipoint repeater at central point)

12 Figure 6.4

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

14 Figure 6.5

15 Bridge Frame handling done in software Frame handling done in software Analyze and forward one frame at a time Analyze and forward one frame at a time Store-and-forward 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 Layer 2 Switches Flat address space Flat address space Broadcast storm Broadcast storm Only one path between any 2 devices Only one path between any 2 devices Solution 1: subnetworks connected by routers Solution 1: subnetworks connected by routers Solution 2: layer 3 switching, packet-forwarding logic in hardware Solution 2: layer 3 switching, packet-forwarding logic in hardware

17 Figure 6.6

18 Figure 6.7

19 Figure 6.8

20 Figure 6.9

21 Figure 6.10

22 Figure 6.11

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

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

25 Figure 6.12

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

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

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

29 Figure 6.13

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

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

32 Figure 6.14

33 IEEE Services Association Association Reassociation Reassociation Disassociation Disassociation Authentication Authentication Privacy Privacy

34 Figure 6.15

35 Figure 6.16