Book 1 Ch.3 Switches, Routers And Vlans

When was Ethernet invented and when did it become commercially available?

1973 and 1980

What are the key traits of an ethernet network?

All devices can access the data sent across the network\nEvery device on the network had a MAC address\nThe more devices on a network the more broadcast packets, the more collisions\nSecurity is difficult since every device examines every packet

What are the three functions of a Switch that enable it to communicate intelligently?

Learning, Forwarding, and Flooding?

How does the switch learn?

A switch receives a packet from a MAC address on a given port the switch and realizes it can reach that MAC address on that port. It stores this information in a forwarding database.

What is a forwarding database?

A table that the switch uses to match Mac Addresses to ports.

How does forwarding work?

The switch examines the packet's destination MAC address then looks into the forwarding database for which port is connected to that MAC address. Then the switch forwards that packet to the MAC address. The packet the destination receives is an exact replica of what was received by the switch.

What can happen to a packet prior to being sent to a destination port?

The packet can be stored in a memory buffer in case the destination port is busy sending or receiving a packet.

What is flooding?

This is when a switch sends a packet to all other ports except for the one from which the packet arrived because it has a destination MAC address that the switch is unfamiliar with.

How does flooding differ from a broadcast packet?

A broadcast packet is intended while flooding is not.

What is a collision domain?

A segment of a network where collisions are possible.

What does a collision domain consist of on a Switch?

It consists of the port a packet was sent from and the port where the packet is going.

What is a bridge?

A central device that can connect two different types of networks.

What are Small Form–Factor Pluggable (SFP) ports?

They're special ports used to connect a variety of different types of high speed networks. Usually to connect Cat5e and Fiber optics devices.

What are SFP ports commonly used for?

They connect switches to other switches and server computers.

What is the interconnection between two switches called?

An uplink

What is necessary in order for a switch and a server to connect to each other?

Both the server and the switch must have SFP ports.

What is a broadcast domain?

A scope of devices that broadcast packets are intended for.

What is the most common broadcast packet?

Address Resolution Protocol (APR) request.

What does an ARP request do?

It's the protocol used to determine a MAC address for a given IP address.

What is a managed switch?

An advanced switch that allows you to monitor traffic and configure functions for each port.

What is an unmanaged switch?

An inexpensive consumer switch that doesn't give you much control over your network.

How do routers facilitate communication?

They facilitate communication between IP networks with different subnets, essentially the gateway of a network.

What is Network Address Translation (NAT)?

A function used when routing traffic from within a private network to the outside where the router uses it's own IP as the sender address and internally keeps track of which device sent the packet.

What is a Virtual Private Network (VPN)?

It's a secure connection between two private networks over a public network (internet).

How does a VPN protect your data?

It encrypts the data sent with only the sender and receiver possessing the encryption key.

What are the two ways to set up a VPN?

You can set up a VPN on a router then providing users with the necessary credentials or you can set it up a software VPN client and having them run it on their computer.

What is a Virtual Local Area Network (VLAN)?

A virtual network that runs on top of your physical network.

How do you set up a VLAN?

You create a new name for a VLAN then configure the ports you want to that VLAN.

What is an Access Port?

A port that is configured to operate on a single VLAN.

What is a Trunk Port?

A port that is configured to operate on multiple VLANs.

What happens when a port configured to a VLAN sends a broadcast packet?

Only the other ports configured to the VLAN receive the broadcast packet.

Why is a router required to link two separate VLANs?

A router is required to link two separate VLANs because they are separate networks that need to communicate with one another.