NA Week 4 - Reference notes PDF

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Network Administration – Lecture 2

1

OSI Encapsulation Summary

Layer 7 Data hi 7. Application Layer

0110100001101001

Layer 6 Data The following data is ASCII

011010

6. Presentation Layer

Layer 5 Data This is to the session with Jane

01101000110101

5. Session Layer

Layer 4 Data 4. Transport Layer

This is the first of five segments

01101000110101011011000

Layer 3 Data To 136.186.143.15

3. Network Layer

0110100011010101100010111011100

Layer 2 Data 2. Data-link Layer

To A13E F956 D4B1

FCS

0110100011010101100010111011100011010001

Layer 1 Data 1. Physical Layer

1010111010011011100010101001

011010001101010110001011101110001101000110001101000110001

Next: Bus

Reference: Dean (2015)- Chapter 1 2

Bus Topology

 Classic CSMA/CD Topology All devices connected to backbone  WiFi networks use this topology

Next: Star

Reference: Dean (2015)- Chapter 1

Star Topology

All devices are connected to a central concentrator

A Concentrator can be: Hub – Regenerates Bit to all devices. Switch – Regenerates Frame to destination device Router – Forwards Packet according to IP address Next:Ring

Reference: Dean (2015)- Chapter 1

Ring Topology All devices are connected to a central MAU Or – to other devices to form a ring eg FDDI Undersea cables currently use a self-healing ring topology

Next:Mesh

Reference: Dean (2015)- Chapter 1

Fully Meshed Topology

• The safest and greatest redundancy • Very difficult to administer • Very expensive to maintain

Next: Bus Problem

Reference: Dean (2015)– p. 345

Bus Topology

Next: Devices knowing

Reference: Dean (2015)- Chapter 1 7

Addressing

> How do devices know if data is for them? > How do switches know which port to send data out?

> How do routers choose the best path?

Next: 1s & 0s

8

Interpreting the 1’s and 0’s

Imagine for a moment that you are a computer on a network. From the Physical layer, you would need to process this:

010000000000000000100000000000000010110000101100010011000110

But at about 10,000 times faster! In other words, within 1/1000th of a second! Next: Physical

9

Physical layer Data

101010101010101010101010101010101010101010101010101010101010 101000000000001000010110101000110100011111110000011000000000 000101001111000100000010011110000000000000001000000000000100 010100000000000000000011110000010100111100010000000000000000 001111110000000101111001011000001000100010111010000000010110 111110001000101110101101101010001100000000000000000001010101 010110100000000000000001000000000000000101100001011000100110 001101100100011001010110011001100111011010000110100101101010 011010110110110001101101011011100110111101110000011100010111 001001110011011101000111010101110110011101111100001011000100 110001101100100011001011100110011001110110100001101001

Next: Data Link 1

10

Data-Link 1 – break it down into bytes

1010 1010

1010 1010

1010 1010

1010 1010 1010 1010

1010 1010

1010 1010

1010 1010

0000 0000

0010 0001

0110 1010

0011 0100 0111 1111

0000 0110

0000 0000

0001 0100

1111 0001

0000 0010

0111 1000

0000 0000 0000 1000

0000 0000

0100 0101

0000 0000

0000 0000

0011 1100

0001 0100

1111 0001 0000 0000

0000 0000

0011 1111

0000 0001

0111 1001

0110 0000

1000 1000

1011 1010 0000 0001

0110 1111

1000 1000

1011 1010

1101 1010

1000 1100

0000 0000

0000 0000 0101 0101

0101 1010

0000 0000

0000 0001

0000 0000

0000 0001

0110 0001

0110 0010 0110 0011

0110 0100

0110 0101

0110 0110

0110 0111

0110 1000

0110 1001

0110 1010 0110 1011

0110 1100

0110 1101 0110 1110

0110 1111

0111 0000

0111 0001

0111 0010 0111 0011

0111 0100

0111 0101

0111 0110

0111 0111

110 0001

0110 0010

0110 0011 0110 0100

0110 0101

110 0110

0110 0111

0110 1000

0110 1001

0110 0111

0110 1000 0110 1001

0110 1010

Next:

Forouzan , B. A. (2007) Data Communications and Networking, Fourth Edition, Ch. 11 , McGraw-Hill , New York 11

Data-Link 2: Assigns meaning based on location in FRAME

PRE-AMBLE DESTINATION ADDRESS -ADDRESS TYPE/LENGTH

SOURCE-

ENCAPSULATED DATA FROM UPPER LAYERS FRAME CHECK This is a frame from the ethernet 802.3 standard Next: Data Link 2

Kurose, J. (2010) Computer Networking a Top-down Approach 5th Ed, Pearson, Boston. pp. 501-507)

12

Data-Link 2: Assigns meaning based on location in FRAME

1010 1010 0000 0000 1111 0001 0000 0000 0111 1001 1101 1010 0000 0000 0110 0111 0110 1111 0111 0111 0110 1000

1010 1010 0010 0001 0000 0010 0011 1100 0110 0000 1000 1100 0000 0001 0110 1000 0111 0000 110 0001 0110 1001

1010 1010 0110 1010 0111 1000 0001 0100 1000 1000 0000 0000 0110 0001 0110 1001 0111 0001 0110 0010 0110 0111

1010 1010 0011 0100 0000 0000 1111 0001 1011 1010 0000 0000 0110 0010 0110 1010 0111 0010 0110 0011 0110 1000

1010 1010 0111 1111 0000 1000 0000 0000 0000 0001 0101 0101 0110 0011 0110 1011 0111 0011 0110 0100 0110 1001

1010 1010 0000 0110 0000 0000 0000 0000 0110 1111 0101 1010 0110 0100 0110 1100 0111 0100 0110 0101 0110 1010

1010 1010 1010 1011 0000 0000 0001 0100 0100 0101 0000 0000 0011 1111 0000 0001 1000 1000 1011 1010 0000 0000 0000 0001 0110 0101 0110 0110 0110 1101 0110 1110 0111 0101 0111 0110 110 0110 0110 0111

Next: L2 Add

13

Network Addressing – Layer 2

> Physical Address: •

Operates at Layer 2 – the Data-Link Layer

•

Is ‘burned in’ to the device when manufactured

•

Cannot be divided into separate sub-networks

•

e.g. MAC Address

Next: L3 Add

14

Network Addressing – Layer 3

> Logical Address: •

Operates at Layer 3 – the Network Layer

•

Is configured by the Network Administrator

•

Is used to group devices into sub-networks

•

e.g. IP Address

Next: L2&3 Link

Reference: Dean (2015)– page 52 15

Linking the Layers 2-3

> The Address Resolution Protocol (ARP) enables the two layers to resolve each other – At a windows command line type:

arp –a to display the arp table – arp –d clears the table

Next: IP

Reference: Dean (2015)– page 120 16

IP Addresses

> 32 bits ( i.e. 1111 1111 1111 1111 1111 1111 1111 1111 ) > This gives 4,294,967,296 different possibilities > For ease on eyes and brain we break it down to 4 octets ( i.e. 1111 1111 . 1111 1111 . 1111 1111 . 1111 1111 ) > We generally represent each octet as a decimal number > This gives us the range of addresses 0 . 0 . 0 . 0 to 255 . 255 . 255 . 255 > IP Addresses are hierarchical

Next: Hierarchy 1

Reference: Dean (2015)– Ch.2 17

Hierarchical Addressing

0011 61 3 9214 5325 International

Australia

Rhys

Victoria

Swinburne

The position of the numbers determine the meaning

18

Next: Hierarchy 2

Changing the position changes the meaning

0011 5325 61 9214 3 Will not call Rhys

Next: Kramer

19

Similarly with IP Addresses

136.186.143.15 = kramer.tafe.swin.edu.au 15.136.143.186 ≠ anything at Swinburne

Next: SN

20

Subnetting

> Subnetting enables the hierarchy

> Administrators use Subnet Masks to configure devices to a place in the hierarchy.

Next: Subnet Mask rules

Reference: Dean (2015)– pp 487 - 497 21

Subnet mask

> The subnet mask is all 1’s on the left and 0’s on the right e.g. in binary – 1111 1111 1111 1111 1111 1111 0000 0000 as decimal – 255.255.255.0 as CIDR – /24 (count of 1’s, expressed at end of address)

> This mask is used to determine the Network, Sub-Network and Host portions of the IP address > Hint: As they always begin at the significant end of the byte decimal subnet masks can only contain the numbers: 0, 128, 192, 224, 240, 248, 252, 254 and 255 Next: AND

22

ANDing

When applying the AND operator, every bit must be 1 for the result to be 1

Data Set A

0

1

1

0

Data Set B

0

1

0

1

Result

0

1

0

0

Next: Apply SN

Dye, M. (2008) Network Fundamentals – CCNA Exploration Guide, pp. 207-209 23

Applying a subnet mask

Address

172

.

16

240

.

1

Mask

255

.

255

0

.

0

Address in bin. 10101100 . 00010000

11110000 . 00000001

Mask in binary 11111111 . 11111111

00000000 . 00000000

And result (bin) 10101100 . 00010000

00000000 . 00000000

And result (dec)

172

.

16

Network Portion of Address

0

.

0

Host Portion of Address Next: GD SN1

24

Subnet ID - 1

Address

Visual Subnet Calculator 172 . 16 . 126

.

1

Mask

255

.

0

.

255

.

0

Add.Bin Msk.Bin And Result

Next: GD SN2

Subnet ID - 2

Address

Visual Subnet Calculator 192 . 168 . 126

.

1

Mask

255

.

0

.

255

.

255

Add.Bin Msk.Bin And Result

Next: GD SN 3 – Demo only

Subnet ID - 3

Address

Visual Subnet Calculator 192 . 168 . 126

.

1

Mask

255

.

0

.

255

.

224

Add.Bin Msk.Bin And Result

Next: SN determines hierarchy

27

The Subnet Mask determines the level

Next: OSI

28

OSI Model No.

Layer

Purpose

Datagram/PDU

Device

7

Application

Network services to user

6

Presentation

Translates data formats

5

Session

Establishes, manages, and terminates sessions between end hosts

4

Transport

Reliable transit of data between end hosts

Segment

3

Network

Path selection between end hosts

Packet

Router

2

Data-link

Reliable transit over physical link

Frame

Bridge/Switch

1

Physical

Specifications of cables, voltages, etc

Bit

Repeater/Hub Next: GD OSI Address Encap.

Reference: Dean (2015) Ch.1 29

OSI Through the Network

Where is this MAC address?

Jack

IP: 11.1.1.1 MAC:AAAA Layer 7 Data

IRC – To Jill: hi

hi 0110100001101001

0 1 1 0 1 0

Where is this IP address?

IP: 11.1.1.3 MAC:CCCC

IP: 11.1.1.2 MAC:BBBB

Jill

IP: 22.2.2.1 MAC:DDDD

IP: 22.2.2.2 MAC:EEEE

Layer 7 Data hi

Switch

IRC – From Jack: hi

Router

0110100001101001

0 1 1 0 1 0

Layer 6 Data

Layer 6 Data

The following data is ASCII The following data is ASCII

Layer 5 Data Layer 5 Data 0110100 0110101

This is to the session with Jane This is to the session with Jane

Layer 4 Data 0110100011010 1011011000

0110100 0110101

Layer 4 Data This is the first of five segments

This is the first of five segments

0110100011010 1011011000

Layer 3 Data To 136.186.143.15 Layer 3 Data 01101000110101011000 10111011100

01101000110101011000 10111011100

Layer 3 Data To 136.186.143.15

To 136.186.143.15

01101000110101011000 10111011100

Layer 2 Data Layer 2 Data Layer 2 Data F C S

01101000110101011000101110 11100011010001

To A13E F956 D4B1 To A13E F956 D4B1

Layer 1 Data 01101000110101011000101110111000110100 0110001101000110001

1010111010011011100010101001

01101000110101011000101110 11100011010001

To A13E F956 D4B1

F C S

F C S

Layer 2 Data To A13E F956 D4B1

01101000110101011000101110 11100011010001

F C S

Layer 1 Data

Layer 1 Data 1010111010011011100010101001

01101000110101011000101110 11100011010001

Layer 1 Data

1010111010011011100010101001

01101000110101011000101110111000110100 0110001101000110001

01101000110101011000101110111000110100 0110001101000110001

1010111010011011100010101001

Next: Rules

Reference: Dean (2015) Ch.1 30

01101000110101011000101110111000110100 0110001101000110001

Logical address rules

> Addresses in the same subnet must be connected to the same LAN (i.e. connected to the same bus, hub or switch)

> Communication with other subnets must be sent to a router or gateway

Next: Log Const 1

31

Logical Address Constraints – IP - 1

> 224.0.0.0 – 239.255.255.255 are reserved for multicast purposes

> 240.0.0.0 – 255.255.255.254 are reserved for IETF research purposes > 127.0.0.1 – 127.255.255.255 is reserved for this device (loopback address)

> 255.255.255.255 is reserved for all devices (universal broadcast address)

Next: Log Const 2

Reference: Dean (2015)– p.490 32

Logical Address Constraints – IP - 2 > Private IP addresses – are addresses reserved for private networks, and cannot be used for internet traffic (note: NAT provides a work around)

– 10.0.0.0 – 10.255.255.255 – 172.16.0.0 – 172.31.255.255 – 192.168.0.0 – 192.168.255.255 > Automatic private IP addresses (APIPA) 169.254.0.0 – 169.254.255.255 > First address and last address of each subnet e.g. for the subnet 136.186.0.0, 255.255.0.0 136.186.0.0 is the network ID for this subnet 136.186.255.255 is the broadcast address for this subnet Next: GD Rule application

Reference: Dean (2015) Ch.2 33

Which of these IP addresses are valid for a device?

A. 238.

1.

2.

3

255.255.255.

0

B. 129.254.256.127

/24

C. 172. 16.129.255

255.255.255.

0

D. 172. 16. 10.

0

255.255.255.

0

E. 172. 16. 10.

0

255.255.

0.

0

0.

0

F. 172. 16. 10.255

/16

G. 169.254. 97.123

255.255.

Next: GD Advanced

34

Which devices can communicate?

PC 1 IP: 10. 10. SN: 255.255.

Server 1 IP: 10. 10. 0. SN: 255.255. 0.

Laptop 1 IP: 10. 10. 10. 20 SN: 255.255. 0. 0

PC 2 IP: 10. 10. SN: 255.255.

0.101 0. 0

PC3 IP: 10. 10. 0.102 SN: 255.255.255. 0

0.100 0. 0

Next: Must Remember Rules

35

2 0

You Must Remember!

> Devices must be in the same subnet to communicate in the same LAN Thus an IP address and a Subnet Mask must be configured at a minimum > In order to communicate with other subnets a router must be used

Thus a default gateway address must be configured in order to communicate outside the local LAN

Next: GD B’cast

36

Calculating Subnet ID and Subnet Broadcast Address

Address Mask Add.Bin Msk.Bin And Result

172 255 10101100 11111111 10101100 172

. 16 . 255 . 1 . 255 . 0 . 0 . 00010000 . 11111111 . 00000001 . 11111111 . 00000000 . 00000000 . 00010000 . 00000000 . 00000000 . 16 . 0 . 0

Host portion all 0's

10101100 172 10101100 172

. 00010000 . . 16 . . 00010000 . . 16 .

Subnet ID Host portion all 1's

Broadcast

Dye, M. (2008) Network Fundamentals – CCNA Exploration Guide, pp. 209-211 Next: Intro PM

37

Current Jobs >$150K per year (Seek.com.au 10/3/19)

Source: http://www.seek.com.au/information-communication-technology-jobs Next: Why?

38

Why does Project Management pay more

> Senior IT professionals with years of experience tend to fill the ranks of project managers > You need lots of ‘soft’ skills in order to be an effective project manager. You need to be a: – Great communicator – increasing in frequency in more than one language – Great people manager – Great management skills (e.g. in documentation, time, cost, resources) – Great understanding of the technology at the core of the project

Next: 9 PMBOK

Schwalbe (2010), pp 21-26 39

Nine Areas of PM Knowledge

1. Integration Management 2. Scope Management 3. Time Management 4. Cost Management 5. Quality Management 6. Human Resource Management 7. Communications Management 8. Risk Management 9. Procurement Management 10 Stakeholder Management

Next: 3 Const

References: Schwalbe, K. (2014), Info. Tech. Project Management 6th Ed., Course Tech., Boston. Page 13 A guide to the project management body of knowledge (PMBOK guide).(2017) Sec. 1.2.4.6 40

The Project Management Triple Constraint

All projects are restricted by th...