Chapter 8:Backbone Networks

Backbones used to be built with special technologies, but today most BNs use________.

high-speed Ethernet

What the two basic components to a BN?

1) The network cable

2) The hardware devices that connect other networks to the BN

What type of cable is usually used in a BN?

Fiber optic

Switches operate at the ______ layer.

Data link

Routers operate at the _______ layer.

Network

VLAN switches are a special combination of ______ switches and routers

layer two(data link layer)

What is the most common type of BN used in the distribution layer?

Switched backbones

What kind of topology do Switched BNs use?

a star topology with one switch at its center.

There is a switch serving each LAN that is connected to the backbone swtich.

True

Most organizations use switched backbones where all network devices are physically located in the same room. This is called a ____

rack of equipment

The room contain the rack of equipment is called what?

1) Main distribution facility (MDF)
OR
2) Central distribution facility (CDF)

How are the devices in the rack connected?

Using very short cables called patch cables.

With an MDF, not all cables run into the MDF

False

Sometimes, for an MDF, a ____ is used instead of a rack

chassis switch

What is a chassis switch and what is the advantage of using one?

A chassis switch enables users to plug modules directly into the switch. The advantage is its flexibility.

______ move packets along the backbone on the basis of their network layer address

routed backbones

What are routed backbones sometimes called?

subnetted backbones or hierarchical backbones

What are routed backbones most commonly used for?

Connecting different buildings on the same enterprise campus backbone network.

What does a routed backbone ensure when it comes to broadcast messages?

That they stay in one network segment

What are virtual LANs?

Networks in which computers are assigned to LAN segments by software rather than hardware

VLANs are faster and provide greater opportunities to mange the flow of traffic on the ____ or ____.

LAN; BN

A single-switch VLAN does what?

VLAN only operates inside one switch

Virtual LANs can be designed so they act like….

computers that are connected via hubs or switches

With VLANs we can put computers in different physical locations in the same subnet

True; We can create subnets based on who you are rather than where you are

What is a multi-switch VLAN?

Several switches are used to build VLANs

VLANs are most commonly used in building ___

BNs

List the advantages and disadvantages of VLANs

Advantage:
1) Ability to manage the flow of traffic on the LAN and BN
2) Ability to prioritize traffic
Disadvantage:
1) Their cost and management complexity

Explain how VLANs work: Each computer assigned to a VLAN has a _____

VLAN ID number

Each VLAN ID is matched to an…

IP subnet

Each computer connected to a VLAN switch also has an IP address assigned by the VLAN switch

True

Computers are assigned into the VLAN based on the ______ on the switch in which they are connected.

physical port

VLAN switches use Ethernet 802.1q to…

move frames from one switch to another

When a VLAN switch receives and Ethernet fram taht needs to go to a computer on another VLAN switch it…

changes the Ethernet from by inserting the VLAN ID number and a prioity code into the VLAN tag field.

The router is a layer 3 device, so when it receives a message it…

strips off the Ethernet frame and reads the IP packet.

When a computer issues a broadcast message, the switch identifies the VLAN ID of the ______ and then sends the frame to all other computers that have the same ______

sending computer; VLAN ID (These computers can be on same or different switches)

Today, the most effective architecture for the distribution layer in terms of cost and performance is a….

switched backbone

The best practice architecture is a switched backbone or VLAN for the ____ layer and a routed backbone for the ____ layer.

distribution; core

The best practice recommendation for backbone technology is….

gigabit Ethernet

The network cable to connect BNs is usually twisted pair.

False

A hardware device that operates at the application layer is a router.

False

A VLAN network assigns computers to LAN segments by hardware.

False

Which of the following would be least effective in improving backbone performance?

addingnew keyboards to the client computers

A ______type of BN is a new type of LAN/BN architecture made possible by intelligent, high-speed switches that assign computers to LAN segments via software, rather than by hardware.

Virtual LAN

Which of the following is a fundamental backbone network architecture?

Virtual LAN

Which of the following is a key advantage of using virtual LANs (VLANs) in a network architecture?

Better traffic management and broadcast control

A network operations manager is tasked with designing a backbone network to connect multiple LANs within a building. Which type of backbone network design would be most appropriate in this scenario?

Switched backbone design

How are broadcast messages like ARPs handled on a VLAN network?

Broadcast frames are forwarded only to computers within the same VLAN

How do VLANs allow communication between computers on different VLANs without the end systems needing to know about the VLAN architecture?

VLANs use 802.1Q tagging to move frames between switches without requiring changes on the end systems