1. Networking and Internetworking Devices Networks and Protocols Prepared by: TGK First Prepared on: Last Modified on: Quality checked by: Copyright 2009 Asia Pacific Institute of Information Technology

2. Networks and Protocols Networking and Internetworking Devices Slide 2 of 27 Topic & Structure of the lesson Introduction Repeaters Bridges Hubs Switches Routers Gateways

3. Networks and Protocols Networking and Internetworking Devices Slide 3 of 27 Learning Outcomes At the end of this module, YOU should be able to: Discuss the operations and implementations for the different networking and internetworking devices. Discuss the benefits and considerations for choosing the appropriate device for use in a network.

4. Networks and Protocols Networking and Internetworking Devices Slide 4 of 27 Key Terms you must be able to use If you have mastered this topic, you should be able to use the following terms correctly in your assignments and exams: Regenerate signals Segmenting networks Directing traffic Determining routes Connecting networks OSI layers

5. Networks and Protocols Networking and Internetworking Devices Slide 5 of 27 Main Teaching Points Repeater Bridging Forwarding Ethernet Star topology Routing Physical layer Data link layer Network layer

6. Networks and Protocols Networking and Internetworking Devices Slide 6 of 27 Introduction In order to link multiple networks, devices are required to determine where a particular packet is headed. This devices is responsible for careful routing of packets such that it would not end up in the wrong network

7. Networks and Protocols Networking and Internetworking Devices Slide 7 of 27 Repeaters The most basic of these devices is the repeater. The function of the repeater is to simply regenerate the signal which it receives and retransmits a refreshed signal back into the network towards the sink. A repeater has no other function except for its duty to increase the physical length of a network.

8. Networks and Protocols Networking and Internetworking Devices Slide 8 of 27 Repeaters A repeater would receive a packet and reconstruct it bit by bit and retransmits the signal as if it was the source. A repeater does not amplify the signal. It simply regenerates the signal so that the sink would be able to receive a clear copy of the packet.

9. Networks and Protocols Networking and Internetworking Devices Slide 9 of 27 Bridges A bridge handle data packets in a more intelligent manner than a repeater. Where a repeater only have the capability to increase the range of a network, a bridge can segment a network. Very simply, it divides a network in different partitions so as to facilitate functions of security and privacy. When a bridge receives a packet, it would have the capability to scan the address of the packet and determine which network the packet should be placed into. By doing so, a large LAN can be segmented.

10. Networks and Protocols Networking and Internetworking Devices Slide 10 of 27 Bridges A bridge handle data packets in a more intelligent manner than a repeater. Where a repeater only have the capability to increase the range of a network, a bridge can segment a network. Very simply, it divides a network in different partitions so as to facilitate functions of security and privacy. When a bridge receives a packet, it would have the capability to scan the address of the packet and determine which network the packet should be placed into. By doing so, a large LAN can be segmented.

11. Networks and Protocols Networking and Internetworking Devices Slide 11 of 27 Bridges In short, a bridge is simply a device to determine which network should a packet be deployed on so as to facilitate traffic between 2 or more networks.

12. Networks and Protocols Networking and Internetworking Devices Hubs When a device is capable of determining for itself the address of a packet, it can be applied to other forms of networks. One of this is of course the Ethernets, which uses a hub. Where a hub is physically a star topology, it is logically a bus. A switch utilizes this intelligence in the Ethernet to more effectively cater to the network.

13. Networks and Protocols Networking and Internetworking Devices Slide 13 of 27 Switches By scanning the address of a network packet, a switch can route the packet directly towards the destination, thereby it reduces collisions on the Ethernet. The other advantage is that each packet does not use up the entire capacity of the Ethernet. This would, then, allow for simultaneous packet transmissions. In this sense, a switch would function better than a hub in Ethernet networks.

14. Networks and Protocols Networking and Internetworking Devices Slide 14 of 27 Internetworking There are times when where we would have to connect multiple networks together. In this case, a bridge is unable to solve the problems arising from having to route a packet to its destination. When a bridge reads a packet which does not belong to any nodes on its table, it would absorb the packet, terminating it from the network.

15. Networks and Protocols Networking and Internetworking Devices Thus, routers are used instead. Routers have yet another level of intelligence where it is still capable of determining the sink of a packet. If it fails to find the sink of a packet in the networks it is connected into, a router is capable of determining which of its connection would be the best one to relay the packet. Routers

16. Networks and Protocols Networking and Internetworking Devices Slide 16 of 27 Routers

17. Networks and Protocols Networking and Internetworking Devices Slide 17 of 27 Routers An intelligence of this level would require a logic to match it. A router should have the capability to choose which route is best for a packet to reach its destination. To this end, there are many routing techniques to determine which is the best route for a data packet from source to sink.

18. Networks and Protocols Networking and Internetworking Devices Slide 18 of 27 Gateways Gateways operate at the network layer and use network layer addresses in processing messages. Gateways connect two or more LANs that use the same or different (usually different) data link and network protocols. The may connect the same or different kinds of cable. Gateways process only those messages explicitly addressed to them. Gateways translate one network protocol into another, translate data formats, and open sessions between application programs, thus overcoming both hardware and software incompatibilities.

19. Networks and Protocols Networking and Internetworking Devices Slide 19 of 27 Gateways A gateway may be a stand-alone microcomputer with several NICs and special software, a FEP connected to a mainframe computer, or even a special circuit card in the network server. One of the most common uses of gateways is to enable LANs that use TCP/IP and Ethernet to communicate with IBM mainframes that use SNA. The gateway provides both the basic system interconnection and the necessary translation between the protocols in both directions.

20. Networks and Protocols Networking and Internetworking Devices Slide 20 of 27 Gateways

21. Networks and Protocols Networking and Internetworking Devices Slide 21 of 27 Quick Review Question

22. Networks and Protocols Networking and Internetworking Devices Slide 22 of 27 Follow Up Assignment

23. Networks and Protocols Networking and Internetworking Devices Slide 23 of 27 Summary of Main Teaching Points

24. Networks and Protocols Networking and Internetworking Devices Slide 24 of 27 Q & A Question and Answer Session

25. Networks and Protocols Networking and Internetworking Devices Slide 25 of 27 Topic and Structure of next session TCP/IP Protocol Suite ARP ICMP IP UDP TCP Next Session