L.O: STUDENTS WILL BE ABLE TO EXPLAIN NETWORK

REDUNDANCY.15-30 minutes (<1 class period)

DO NOW: READUnit 4 Lab 2: Reliable

Communication, Page 2

Given the enormous amount of data traveling around, the Internet needs to be

reliable.

The Internet is made reliable by building many redundant connections into the

physical systems of the Internet.

Wherever information is going, there is more than one way to get there, even if part of the Internet

fails, the rest remains connected even if the failed part is in the usual path from one place to another.

The internet’s redundancy increases the Internet's fault tolerance (ability to work around problems).

And it also helps the Internet scale (expand) to more devices and people.

Internet scalability: the ability of the net to keep working even as the size of the network and the

amount of traffic over the network increases.

For you to do:Describe what's going on in this animation.

what is the minimum number of nodes (connection points) that can stop working before the sender and the receiver can't communicate? (Other than the sender or the

receiver themselves, of course.)

1..2..3..4..5..

If the node with 6

connections goes down and also either of the two to its

left, the sender and receiver

can't communicate.

what is the maximum number of nodes that can fail and still let Sender and Receiver communicate?

• 10• 9• 8• 7• 6

If the 4 nodes on the right and also the 4 nodes on the left all fail, the remaining 2 nodes in the middle

will still allow the sender and receiver

to communicate.

Enduring Understandings:

• EU 6.1 The Internet is a network of autonomous systems.• EU 6.2 Characteristics of the

Internet influence the systems built on it.

Learning Objectives:• LO 6.1.1 Explain the abstractions in the

Internet and how the Internet functions. [P3]• LO 6.2.1 Explain characteristics of the

Internet and the systems built on it. [P5]• LO 6.2.2 Explain how the characteristics

of the Internet influence the systems built on it. [P4]

Essential Knowledge:

1. EK 6.1.1A The Internet connects devices and networks all over the world.

2. EK 6.1.1C Devices and networks that make up the Internet are connected and communicate using addresses and protocols.

3. EK 6.1.1D The Internet and the systems built on it facilitate collaboration.

4. EK 6.1.1G The domain name system (DNS) translates names to IP addresses

Essential Knowledge:• 5. EK 6.2.1A The Internet and the systems

built on it are hierarchical and redundant.• 6. EK 6.2.1B The domain name syntax is

hierarchical.• 7. EK 6.2.1C IP addresses are hierarchical.• 8. EK 6.2.2A Hierarchy and redundancy help

systems scale.

Essential Knowledge:

• 9. EK 6.2.2B The redundancy of routing (i.e., more than one way to route data) between two points on the Internet increases the reliability of the Internet and helps it scale to more devices and more people.

• 10. EK 6.2.2C Hierarchy in the DNS helps system scale.

• 11. EK 6.2.2I The size and speed of systems affect their use.