Institute of Technology Sligo - Dept of Computing Wrapping The Package Devices & Data Encapsulation Paul Flynn

Institute of Technology Sligo - Dept of Computing Evolution of LAN Devices  NICs, Repeaters, & Hubs  Bridges  Switches  Routers

Institute of Technology Sligo - Dept of Computing 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 !!

Institute of Technology Sligo - Dept of Computing NICs, Repeaters, & Hubs To connect two computers, you must...  Install a NIC card in each. The First LAN NIC Attach computers using a crossover cable You will make a crossover cable in Ch. 5

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

Institute of Technology Sligo - Dept of Computing NICs, Repeaters, & Hubs NIC 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?

Institute of Technology Sligo - Dept of Computing NICs, Repeaters, & Hubs NIC A multi-port repeater! Also called a... Hub

Institute of Technology Sligo - Dept of Computing A Dilemma! NIC As businesses expanded their networks, they began to cascade hubs.

Institute of Technology Sligo - Dept of Computing What’s The Problem? 1) Hubs share bandwidth between all attached devices. 2) Hubs are stupid, Layer 1 devices. They cannot filter traffic. 3) 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

Institute of Technology Sligo - Dept of ComputingBroadcasts In this picture, all hubs forward all traffic to all devices.

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

Institute of Technology Sligo - Dept of Computing 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.

Institute of Technology Sligo - Dept of ComputingBridge To lessen the amount of LAN traffic, businesses began to uses bridges to filter frames based on MAC addresses.

Institute of Technology Sligo - Dept of ComputingBridge Now, if Host 1 pings Host 2, only the hosts on that LAN segment see the ping. The bridges stop the ping. 2 1

Institute of Technology Sligo - Dept of ComputingSwitch A switch (also know as a multi-port bridge), can effectively replace these four bridges.

Institute of Technology Sligo - Dept of ComputingSwitch Another benefit of a switch is that each LAN segment gets dedicated bandwidth. The Cloud 10 Mbps

Institute of Technology Sligo - Dept of Computing Since a switch is a multi-port bridge, we know it will stop local pings from traveling to other network segments. Switch But a switch cannot stop a ping destined for a different LAN segment from traveling to all other LAN segments.

Institute of Technology Sligo - Dept of ComputingSwitch 16 1 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?

Institute of Technology Sligo - Dept of ComputingRouter Routers filter traffic based on IP addresses. The IP address tells the router which LAN segment the ping belongs to.

Institute of Technology Sligo - Dept of Computing Devices Function At Layers Know These!

Institute of Technology Sligo - Dept of Computing Devices Function At Layers Also know that each device not only works at its layer, but all layers below it.

Institute of Technology Sligo - Dept of Computing 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)

Institute of Technology Sligo - Dept of Computing Devices Function At Layers At what layers do these two operate? The Cloud ALL 7 LAYERS!! One last bit of information from Chapter 3

Institute of Technology Sligo - Dept of Computing Good Luck On The Test!!