Networking DevicesHubs, Bridges, Switches, Routers, Oh My!

What makes a “computer network”?

What if there are more that 2 computers?

More than two computers connected using a networking device.

What if there are more that 2 computers?

“Networking Device” Hub / Bridge / Switch / Router

Hub - Layer 1● “Dumb” - Forwarding decisions - Send incoming bits out all other

ports.● Number of ports - More than 2.● Single collision domain.

Bridge - Layer 2● “Intelligent” - Decisions based on destination MAC address.● Store and Forward.● Number of ports - 2● Splits collision domain.

Switch - Layer 2● “More Intelligent” - Multiport bridge. Decisions based on

destination MAC address.● Store and Forward.● Number of ports - More than 2.● Splits collision domain.

Router - Layer 3● “Intelligence on a totally different level! Layer 3!”● Store and Forward.● Number of ports - More than 2.● Splits collision domain.

Devices and Layers

LAYER 3(Network Layer) ROUTER

LAYER 2(Data Link Layer) SWITCH , BRIDGE

LAYER 1(Physical Layer) HUB

Overview

TCP/IP Protocol Stack

Review of Spanning Tree Protocol

Why, What and How?

“Loopy” network● Network Admins love loops. They call it “redundancy”. ● But, loops are bad.● Lets walk through an example

Note : Project statusTest cases are up on the course site!

References● Bridging and Switching - http://cseweb.ucsd.edu/classes/fa13/cse123-

a/lectures/123-fa13-l9.pdf● http://www.routeralley.com/ra/docs/hubs_switches_routers.pdf● Internetworking - http://cseweb.ucsd.edu/classes/fa13/cse123-

a/lectures/123-fa13-l10.pdf

Thank You!Project due : Friday, next week.