Wrapping The Package

1. Wrapping The Package Devices & Data Encapsulation Paul Flynn

2. Evolution of LAN Devices • NICs, Repeaters, & Hubs • Bridges • Switches • Routers

3. NIC Specifics • NICs provide hosts with access to media by using a MAC address. • MAC stands for Media Access Control • NICs operate at Layer 2 !!

4. NIC NIC NIC NIC NICs, Repeaters, & Hubs The First LAN To connect two computers, you must... • Install a NIC card in each. Attach computers using a crossover cable You will make a crossover cable in Ch. 5

5. NIC NIC NICs, Repeaters, & Hubs Repeaters can be used to increase the distance So what can we use if this distance is greater than 100 meters? What’s the maximum distance for Cat 5 cable? Repeaters amplify and retime signals 100 meters or approx. 300 feet

6. NIC NIC NIC NIC NICs, Repeaters, & Hubs Using repeaters was fine as long as a business only needed two computers networked. What if a business wanted a third computer attached? Or a fourth? What device would they need?

7. NIC NIC NIC NIC NICs, Repeaters, & Hubs A multi-port repeater! Also called a... Hub

8. NIC NIC NIC NIC As businesses expanded their networks, they began to cascade hubs. A Dilemma!

9. What’s The Problem? • Hubs share bandwidth between all attached devices. • Hubs are stupid, Layer 1 devices. They cannot filter traffic. • Most LANs use a “broadcast topology,” so every device sees every packet sent down the media. Let’s take a look at how broadcasting works

10. In this picture, all hubs forward all traffic to all devices. Broadcasts

11. So, if Host 1 wants ping Host 2, all hosts see the ping. This is what we mean by a broadcast topology Broadcasts 1 2 The red arrows show that all hosts receive the ping request. Only Host 2 will respond.

12. What’s The Solution? • We need a smarter hub! • What’s a “smarter hub” called? • A Bridge! • Bridges filter network traffic based on MAC addresses. • Let’s take a look at how this works.

13. To lessen the amount of LAN traffic, businesses began to uses bridges to filter frames based on MAC addresses. Bridge

14. Now, if Host 1 pings Host 2, only the hosts on that LAN segment see the ping. The bridges stop the ping. Bridge 1 2

15. A switch (also know as a multi-port bridge), can effectively replace these four bridges. Switch

16. 10 Mbps 10 Mbps The Cloud 10 Mbps 10 Mbps Another benefit of a switch is that each LAN segment gets dedicated bandwidth. Switch 10 Mbps

17. Since a switch is a multi-port bridge, we know it will stop local pings from traveling to other network segments. But a switch cannot stop a ping destined for a different LAN segment from traveling to all other LAN segments. Switch 1 1 2

18. For example, Host 1 pings Host 16. Since Host 16 is on another LAN segment, the switch will flood the ping request out all ports. What device will solve this problem? Switch 1 16

19. Routers filter traffic based on IP addresses. The IP address tells the router which LAN segment the ping belongs to. Router 1 1 16

20. Devices Function At Layers Know These!

21. Devices Function At Layers Also know that each device not only works at its layer, but all layers below it.

22. Devices Function At Layers For example, a router is a layer 3 device but also uses MAC addresses (layer 2) and repeats the signal (layer 1)

23. The Cloud Devices Function At Layers One last bit of information from Chapter 3 At what layers do these two operate? ALL 7 LAYERS!!

24. Luck Good On The Test!!