CCNA

Communications and Services Certifications
CCNA Exam
Exam Number - 640-801
Total Marks - 1000
Duration – 90 Mts
Passing score – 849
Questions -45-55
Multiple Choice
Simulations
Drag and Drop
Benefits
Peer Validation
Personal
Potential Employer
Career advancement
Cisco Icons and Symbols
Data Networks
Sharing data through the use of floppy disks is not an efficient or cost-effective manner.

Businesses needed a solution that would successfully address the following three problems:
How to avoid duplication of equipment and resources
How to communicate efficiently
How to set up and manage a network

Businesses realized that networking technology could increase productivity while saving money.
Networking Devices
Equipment that connects directly to a network segment is referred to as a device.

These devices are broken up into two classifications.
End-user devices
Network devices

End-user devices include computers, printers, scanners, and other devices that provide services directly to the user.

Network devices include all the devices that connect the end-user devices together to allow them to communicate.
Network Interface Card
A network interface card (NIC) is a printed circuit board that provides network communication capabilities to and from a personal computer. Also called a LAN adapter.
Hub
Connects a group of Hosts
Switch
Switches add more intelligence to data transfer management.
Router
Routers are used to connect networks together
Route packets of data from one network to another
Cisco became the de facto standard of routers because of their high-quality router products
Routers, by default, break up a broadcast domain
Network Topologies
Network topology defines the structure of the network.

One part of the topology definition is the physical topology, which is the actual layout of the wire or media.

The other part is the logical topology,which defines how the media is accessed by the hosts for sending data.
Bus Topology
A bus topology uses a single backbone cable that is terminated at both ends.

All the hosts connect directly to this backbone.
Ring Topology
A ring topology connects one host to the next and the last host to the first.

This creates a physical ring of cable.
Star Topology
A star topology connects all cables to a central point of concentration.  
Extended Star Topology
An extended star topology links individual stars together by connecting the hubs and/or switches.This topology can extend the scope and coverage of the network.
Mesh Topology
A mesh topology is implemented to provide as much protection as possible from interruption of service.
Each host has its own connections to all other hosts.
Although the Internet has multiple paths to any one location, it does not adopt the full mesh topology.
Physical and Logical Topology
LANs, MANs, & WANs
One early solution was the creation of local-area network (LAN) standards which provided an open set of guidelines for creating network hardware and software, making equipment from different companies compatible.

What was needed was a way for information to move efficiently and quickly, not only within a company, but also from one business to another.

The solution was the creation of metropolitan-area networks (MANs) and wide-area networks (WANs).
LANs
WANs
Virtual Private Network
A VPN is a private network that is constructed within a public network infrastructure such as the global Internet. Using VPN, a telecommuter can access the network of the company headquarters through the Internet by building a secure tunnel between the telecommuter’s PC and a VPN router in the headquarters.
Bandwidth
Measuring Bandwidth
Internetworking Devices
What Are The Components Of A Network ?
Main Office
Branch Office
Home
Office
Mobile Users
Internet
Network Structure & Hierarchy
Distribution
Layer
Core Layer
Access
Layer
Institute of Electrical and Electronics Engineers (IEEE) 802 Standards
IEEE 802.1: Standards related to network management.

IEEE 802.2: General standard for the data link layer in the OSI Reference Model. The IEEE divides this layer into two sublayers -- the logical link control (LLC) layer and the media access control (MAC) layer.

IEEE 802.3: Defines the MAC layer for bus networks that use CSMA/CD. This is the basis of the Ethernet standard.

IEEE 802.4: Defines the MAC layer for bus networks that use a token-passing mechanism (token bus networks).

IEEE 802.5: Defines the MAC layer for token-ring networks.

IEEE 802.6: Standard for Metropolitan Area Networks (MANs)
Why do we need the OSI Model?
To address the problem of networks increasing in size and in number, the International Organization for Standardization (ISO) researched many network schemes and recognized that there was a need to create a network model

This would help network builders implement networks that could communicate and work together

ISO therefore, released the OSI reference model in 1984.
Don’t Get Confused.
ISO - International Organization for Standardization

OSI - Open System Interconnection

IOS - Internetwork Operating System
To avoid confusion, some people say “International Standard Organization.”
The OSI Reference Model
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
The OSI Model will be used throughout your entire networking career!






Memorize it!
OSI Model
Data Flow
Layers
Transport
Data-Link
Network
Physical
Layer 7 - The Application Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Each of the layers have Protocol Data Unit (PDU)

Layer 6 - The Presentation Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Layer 5 - The Session Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Half Duplex
It uses only one wire pair with a digital signal running in both directions on the wire.

It also uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur.

If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions.

Half-duplex Ethernet—typically 10BaseT—is only about 30 to 40 percent efficient because a large 10BaseT network will usually only give you 3 to 4Mbps—at most.
Full Duplex
In a network that uses twisted-pair cabling, one pair is used to carry the transmitted signal from one node to the other node. A separate pair is used for the return or received signal. It is possible for signals to pass through both pairs simultaneously. The capability of communication in both directions at once is known as full duplex.
Layer 4 - The Transport Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Layer 3 - The Network Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Layer 2 - The Data Link Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Layer 1 - The Physical Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Data Encapsulation
Transport
Data-Link
Physical
Network
Upper-Layer Data
Upper-Layer Data
TCP Header
Data
IP Header
Data
LLC Header
0101110101001000010
Data
MAC Header
Presentation
Application
Session
Segment
Packet
Bits
Frame
PDU
Data Encapsulation
OSI Model Analogy
Application Layer - Source Host
After riding your new bicycle a few times in Bangalore, you decide that you want to give it to a friend who lives in DADAR, Mumbai.
OSI Model Analogy
Presentation Layer - Source Host
Make sure you have the proper directions to disassemble and reassemble the bicycle.
OSI Model Analogy
Session Layer - Source Host
Call your friend and make sure you have his correct address.
OSI Model Analogy
Transport Layer - Source Host
Disassemble the bicycle and put different pieces in different boxes. The boxes are labeled
“1 of 3”, “2 of 3”, and “3 of 3”.
OSI Model Analogy
Network Layer - Source Host
Put your friend`s complete mailing address (and yours) on each box.Since the packages are too big for your mailbox (and since you don’t have enough stamps) you determine that you need to go to the post office.
OSI Model Analogy
Data Link Layer – Source Host
Bangalore post office takes possession of the boxes.
OSI Model Analogy
Physical Layer - Media
The boxes are flown from Bangalore to Mumbai.
OSI Model Analogy
Data Link Layer - Destination
Dadar post office receives your boxes.
OSI Model Analogy
Network Layer - Destination
Upon examining the destination address, Dadar post office determines that your boxes should be delivered to your written home address.
OSI Model Analogy
Transport Layer - Destination
Your friend calls you and tells you he got all 3 boxes and he is having another friend named BOB reassemble the bicycle.
OSI Model Analogy
Session Layer - Destination
Your friend hangs up because he is done talking to you.
OSI Model Analogy
Presentation Layer - Destination
BOB is finished and “presents” the bicycle to your friend. Another way to say it is that your friend is finally getting him “present”.
OSI Model Analogy
Application Layer - Destination
Your friend enjoys riding his new bicycle in Dadar.
Data Flow Through a Network
Type of Transmission
Unicast
Multicast
Broadcast
Type of Transmission
Broadcast Domain
A group of devices receiving broadcast frames initiating from any device within the group

Routers do not forward broadcast frames, broadcast domains are not forwarded from one broadcast to another.

Collision
The effect of two nodes sending transmissions simultaneously in Ethernet. When they meet on the physical media, the frames from each node collide and are damaged.

Collision Domain
The network area in Ethernet over which frames that have collided will be detected.
Collisions are propagated by hubs and repeaters
Collisions are Not propagated by switches, routers, or bridges

Physical Layer
Defines
Media type
Connector type
Signaling type
Ethernet
802.3
V.35
Physical
EIA/TIA-232
802.3 is responsible for LANs based on the carrier sense multiple access
collision detect (CSMA/CD) access methodology. Ethernet is an example
of a CSMA/CD network.

Physical Layer: Ethernet/802.3
Hub
Hosts
Host
10Base2—Thin Ethernet
10Base5—Thick Ethernet
10BaseT—Twisted Pair
Device Used At Layer 1
Physical
All devices are in the same collision domain.
All devices are in the same broadcast domain.
Devices share the same bandwidth.
Hubs & Collision Domains
More end stations means more collisions.
CSMA/CD is used.
Layer 2
Data
Source Address
FCS
Length
Destination Address
Variable
2
6
6
4
0000.0C xx.xxxx
Vendor Assigned
IEEE Assigned
MAC Layer—802.3
Preamble
Ethernet II uses “Type” here and
does not use 802.2.
MAC Address
8
Number of Bytes
synchronize senders and receivers
Devices On Layer 2
(Switches & Bridges)
Each segment has its own collision domain.
All segments are in the same broadcast domain.
Data-Link
OR
1
2
3
1
2
Switches
Each segment is its own collision domain.
Broadcasts are forwarded to all segments.
Memory
Switch
Layer 3 : Network Layer

Defines logical source and destination addresses associated with a specific protocol
Defines paths through network
Network
IP, IPX
Data-Link
Physical
EIA/TIA-232
V.35
Ethernet
Frame Relay
HDLC
802.2
802.3
Layer 3 : (cont.)
Data
Source
Address
Destination
Address
IP
Header
172.15.1.1
Node
Network
Logical Address
Network Layer End-Station Packet
Route determination occurs at this layer, so a packet must include a source and destination address.
Network-layer addresses have two components: a network component for internetwork routing, and a node number for a device-specific address. The example in the figure is an example of an IP packet and address.
Layer 3 (cont.)
11111111
11111111
00000000
00000000
10101100
00010000
01111010
11001100
Binary
Mask
Binary
Address
172.16.122.204 255.255.0.0
172
16
122
204
255
Address
Mask
255
0
0
Network
Host
Device On Layer 3
Router
Broadcast control
Multicast control
Optimal path determination
Traffic management
Logical addressing
Connects to WAN services

Layer 4 : Transport Layer
Distinguishes between upper-layer applications
Establishes end-to-end connectivity between applications
Defines flow control
Provides reliable or unreliable services for data transfer

Network
IPX
IP
Transport
SPX
TCP
UDP
Reliable Service
Synchronize
Acknowledge, Synchronize
Acknowledge
Data Transfer
(Send Segments)
Sender
Receiver
Connection Established
How They Operate
Hub
Bridge
Switch
Router
Collision Domains:
1 4 4 4
Broadcast Domains:
1 1 1 4
Why Another Model?
Although the OSI reference model is universally recognized, the historical and technical open standard of the Internet is Transmission Control Protocol / Internet Protocol (TCP/IP).
The TCP/IP reference model and the TCP/IP protocol stack make data communication possible between any two computers, anywhere in the world, at nearly the speed of light.
The U.S. Department of Defense (DoD) created the TCP/IP reference model because it wanted a network that could survive any conditions, even a nuclear war.
TCP/IP Protocol Stack
7
6
5
4
3
2
5
4
3
2
Application
Presentation
Session
Transport
Network
Data-Link
Physical
1
Application
Transport
Internet
Data-Link
Physical
1
Application Layer Overview
*Used by the Router
Application
Transport
Internet
Data-Link
Physical
File Transfer
- TFTP*
- FTP*
- NFS
E-Mail
- SMTP
Remote Login
- Telnet*
- rlogin*
Network Management
- SNMP*
Name Management
- DNS*
Transport Layer Overview
Transmission Control
Protocol (TCP)

User Datagram
Protocol (UDP)
Application
Transport
Internet
Data-Link
Physical
Connection-Oriented

Connectionless

TCP Segment Format
Source Port (16)
Destination Port (16)
Sequence Number (32)
Header
Length (4)
Acknowledgment Number (32)
Reserved (6)
Code Bits (6)
Window (16)
Checksum (16)
Urgent (16)
Options (0 or 32 if Any)
Data (Varies)
20
Bytes
Bit 0
Bit 15
Bit 16
Bit 31
Port Numbers
TCP
Port
Numbers
F
T
P
Transport
Layer
T
E
L
N
E
T
D
N
S
S
N
M
P
T
F
T
P
S
M
T
P
UDP
Application
Layer
21
23
25
53
69
161
R
I
P
520
TCP Port Numbers
Source
Port
Destination
Port
…
Host A
1028
23
…
SP
DP
Host Z
Telnet Z
Destination port = 23.
Send packet to my
Telnet
application.
TCP Port Numbers
Send SYN
(seq = 100 ctl = SYN)
SYN Received
Send SYN, ACK
(seq = 300 ack = 101
ctl = syn,ack)
Established
(seq = 101 ack = 301
ctl = ack)
Host A
Host B
SYN Received
TCP Three-Way Handshake/Open Connection
Opening & Closing Connection
Windowing
Windowing in networking means the quantity of data segments which is measured in bytes that a machine can transmit/send on the network without receiving an acknowledgement
Window Size = 1
Sender
Receiver
Send 1
Receive 1
Receive ACK 2
Send ACK 2
Send 2
Receive 2
Receive ACK 3
Send ACK 3
Send 3
Receive 3
Receive ACK 4
Send ACK 4
TCP Simple Acknowledgment
TCP Sequence and
Acknowledgment Numbers
Source
Port
Destination
Port
…
Sequence

Acknowledgment

1028
23
Source
Dest.
11
Seq.
101
Ack.
1028
23
Source
Dest.
10
Seq.
100
Ack.
1028
23
Source
Dest.
11
Seq.
100
Ack.
1028
23
Source
Dest.
12
Seq.
101
Ack.
I just got number
11, now I need
number 12.
I just
sent number
11.
Windowing

There are two window sizes—one set to 1 and one set to 3.
When you’ve configured a window size of 1, the sending machine waits for an acknowledgment for each data segment it transmits before transmitting another
If you’ve configured a window size of 3, it’s allowed to transmit three data segments before an acknowledgment is received.
Windowing
Transport Layer Reliable Delivery
Flow Control
Another function of the transport layer is to provide optional flow control.

Flow control is used to ensure that networking devices don’t send too much information to the destination, overflowing its receiving buffer space, and causing it to drop the sent information

The purpose of flow control is to ensure the destination doesn`t get overrun by too much information sent by the source
Flow Control
SEQ 1024
SEQ 2048
SEQ 3072
A
B
3072
3
Ack 3073 Win 0
Ack 3073 Win 3072
User Datagram Protocol (UDP)
User Datagram Protocol (UDP) is the connectionless transport protocol in the TCP/IP protocol stack.

UDP is a simple protocol that exchanges datagrams, without acknowledgments or guaranteed delivery. Error processing and retransmission must be handled by higher layer protocols.

UDP is designed for applications that do not need to put sequences of segments together.

The protocols that use UDP include:
TFTP (Trivial File Transfer Protocol)
SNMP (Simple Network Management Protocol)
DHCP (Dynamic Host Control Protocol)
DNS (Domain Name System)
No sequence or acknowledgment fields
UDP Segment Format
Source Port (16)
Destination Port (16)
Length (16)
Data (if Any)
1
Bit 0
Bit 15
Bit 16
Bit 31
Checksum (16)
8
Bytes
TCP vs UDP
Internet Layer Overview
In the OSI reference model, the network layer corresponds to the TCP/IP Internet layer.
Internet Protocol (IP)

Internet Control Message
Protocol (ICMP)

Address Resolution
Protocol (ARP)

Reverse Address
Resolution Protocol (RARP)
Application
Transport
Internet
Data-Link
Physical
IP Datagram
Version
(4)
Destination IP Address (32)
Options (0 or 32 if Any)
Data (Varies if Any)
1
Bit 0
Bit 15
Bit 16
Bit 31
Header
Length (4)
Priority &Type
of Service (8)
Total Length (16)
Identification (16)
Flags
(3)
Fragment Offset (13)
Time-to-Live (8)
Protocol (8)
Header Checksum (16)
Source IP Address (32)
20
Bytes
Determines destination upper-layer protocol
Protocol Field
Transport
Layer
Internet
Layer
TCP
UDP
Protocol
Numbers
IP
17
6
Internet Control Message
Protocol
Application
Transport
Internet
Data-Link
Physical
Destination
Unreachable

Echo (Ping)

Other
ICMP
1
Address Resolution Protocol
Map IP MAC
Local ARP
172.16.3.1
IP: 172.16.3.2
Ethernet: 0800.0020.1111
172.16.3.2
IP: 172.16.3.2 = ???
Reverse ARP
Map MAC IP

Ethernet: 0800.0020.1111
IP: 172.16.3.25
Ethernet: 0800.0020.1111 IP = ???
What is my IP address?
I heard that broadcast. Your IP address is 172.16.3.25.
Found by Xerox Palo Alto Research Center (PARC) in 1975
Original designed as a 2.94 Mbps system to connect 100 computers on a 1 km cable
Later, Xerox, Intel and DEC drew up a standard support 10 Mbps – Ethernet II
Basis for the IEEE’s 802.3 specification
Most widely used LAN technology in the world
Origin of Ethernet
10 Mbps IEEE Standards - 10BaseT
10BaseT  10 Mbps, baseband, over Twisted-pair cable
Running Ethernet over twisted-pair wiring as specified by IEEE 802.3
Configure in a star pattern
Twisting the wires reduces EMI
Fiber Optic has no EMI
Unshielded twisted-pair
RJ-45 Plug and Socket
Unshielded Twisted Pair Cable (UTP)
most popular
maximum length 100 m
prone to noise
Twisted Pair Cables
Baseband Transmission
Entire channel is used to transmit a single digital signal
Complete bandwidth of the cable is used by a single signal
The transmission distance is shorter
The electrical interference is lower

Broadband Transmission
Use analog signaling and a range of frequencies
Continuous signals flow in the form of waves
Support multiple analog transmission (channels)
Modem
Broadband Transmission
Network Card
Baseband Transmission
Baseband VS Broadband
Straight-through cable
Straight-through cable pinout
Crossover cable
Crossover cable
Rollover cable
Rollover cable pinout
Straight-Thru or Crossover
Use straight-through cables for the following cabling:
Switch to router
Switch to PC or server
Hub to PC or server

Use crossover cables for the following cabling:
Switch to switch
Switch to hub
Hub to hub
Router to router
PC to PC
Router to PC
Decimal to Binary
100 = 1
101 = 10
102 = 100
103 = 1000
1
10
100
1000
172 – Base 10
1
2
4
8
16
32
64
128
10101100– Base 2
20 = 1
21 = 2
22 = 4
23 = 8
24 = 16
25 = 32
26 = 64
27 = 128
10101100
172
2
70
100

172
0
0
4
8
0
32
0
128

172
Base 2 Number System
101102 = (1 x 24 = 16) + (0 x 23 = 0) + (1 x 22 = 4) +
(1 x 21 = 2) + (0 x 20 = 0) = 22
Converting Decimal to Binary
Convert 20110 to binary:
201 / 2 = 100 remainder 1
100 / 2 = 50 remainder 0
50 / 2 = 25 remainder 0
25 / 2 = 12 remainder 1
12 / 2 = 6 remainder 0
6 / 2 = 3 remainder 0
3 / 2 = 1 remainder 1
1 / 2 = 0 remainder 1
When the quotient is 0, take all the remainders in reverse order for your answer: 20110 = 110010012
Binary to Decimal Chart
Hex to Binary to Decimal Chart
Unique addressing allows communication
between end stations.
Path choice is based on destination address.
Location is represented by an address
Introduction to TCP/IP Addresses
172.18.0.2
172.18.0.1
172.17.0.2
172.17.0.1
172.16.0.2
172.16.0.1
SA
DA
HDR
DATA
10.13.0.0
192.168.1.0
10.13.0.1
192.168.1.1
IP Addressing
255
255
255
255
Dotted
Decimal
Maximum
Network
Host
128
64
32
16
8
4
2
1

11111111
11111111
11111111
11111111
10101100
00010000
01111010
11001100
Binary
32 Bits
172
16
122
204
Example
Decimal
Example
Binary
1
8
9
16
17
24
25
32
128
64
32
16
8
4
2
1

128
64
32
16
8
4
2
1

128
64
32
16
8
4
2
1

Class A:
Class B:
Class C:
Class D: Multicast
Class E: Research
IP Address Classes
8 Bits
8 Bits
8 Bits
8 Bits
IP Address Classes
1
Class A:
Bits:
0NNNNNNN
Host
Host
Host
8
9
16
17
24
25
32
Range (1-126)
1
Class B:
Bits:
10NNNNNN
Network
Host
Host
8
9
16
17
24
25
32
Range (128-191)
1
Class C:
Bits:
110NNNNN
Network
Network
Host
8
9
16
17
24
25
32
Range (192-223)
1
Class D:
Bits:
1110MMMM
Multicast Group
Multicast Group
Multicast Group
8
9
16
17
24
25
32
Range (224-239)
Host Addresses
172.16.2.2
172.16.3.10
172.16.12.12
10.1.1.1
10.250.8.11
10.180.30.118
E1
172.16
12
12
Network
Host
.
.
Network
Interface
172.16.0.0
10.0.0.0
E0
E1
Routing Table
172.16.2.1
10.6.24.2
E0
Classless Inter-Domain Routing (CIDR)
Basically the method that ISPs (Internet Service Providers) use to allocate an amount of addresses to a company, a home
Ex : 192.168.10.32/28
The slash notation (/) means how many bits are turned on (1s)
CIDR Values
11111111
Determining Available Host Addresses
172 16 0 0
10101100
00010000
00000000
00000000
16
15
14
13
12
11
10
9


8
7
6
5
4
3
2
1


Network
Host
00000000
00000001
11111111
11111111
11111111
11111110
...
...
00000000
00000011
11111101
1
2
3
65534
65535
65536
–
...
2
65534
N
2N – 2 = 216 – 2 = 65534
IP Address Classes Exercise
Address
Class
Network
Host
10.2.1.1
128.63.2.100
201.222.5.64
192.6.141.2
130.113.64.16
256.241.201.10
IP Address Classes Exercise Answers
Address
Class
Network
Host
10.2.1.1
128.63.2.100
201.222.5.64
192.6.141.2
130.113.64.16
256.241.201.10
A
B
C
C
B
Nonexistent
10.0.0.0
128.63.0.0
201.222.5.0
192.6.141.0
130.113.0.0
0.2.1.1
0.0.2.100
0.0.0.64
0.0.0.2
0.0.64.16
Subnetting
Subnetting is logically dividing the network by extending the 1’s used in SNM
Advantage
Can divide network in smaller parts
Restrict Broadcast traffic
Security
Simplified Administration


Formula
Number of subnets – 2x-2
Where X = number of bits borrowed

Number of Hosts – 2y-2
Where y = number of 0’s

Block Size = Total number of Address
Block Size = 256-Mask
Subnetting
Classful IP Addressing SNM are a set of 255’s and 0’s.
In Binary it’s contiguous 1’s and 0’s.
SNM cannot be any value as it won’t follow the rule of contiguous 1’s and 0’s.
Possible subnet mask values
0
128
192
224
240
248
252
254
255
Network 172.16.0.0
172.16.0.0
Addressing Without Subnets
172.16.0.1
172.16.0.2
172.16.0.3
…...
172.16.255.253
172.16.255.254
Network 172.16.0.0
Addressing with Subnets
172.16.1.0
172.16.2.0
172.16.3.0
172.16.4.0
Subnet Addressing
172.16.2.200
172.16.2.2
172.16.2.160
172.16.2.1
172.16.3.5
172.16.3.100
172.16.3.150
E0
172.16
Network
Network
Interface
172.16.0.0
172.16.0.0
E0
E1
New Routing Table
2
160
Host
.
.
172.16.3.1
E1
Subnet Addressing
172.16.2.200
172.16.2.2
172.16.2.160
172.16.2.1
172.16.3.5
172.16.3.100
172.16.3.150
172.16.3.1
E0
E1
172.16
2
160
Network
Host
.
.
Network
Interface
172.16.2.0
172.16.3.0
E0
E1
New Routing Table
Subnet
Subnet Mask
255
255
0
0
IP
Address
Default
Subnet
Mask
8-Bit
Subnet
Mask
Network
Host
Network
Host
Network
Subnet
Host
Also written as “/16,” where 16 represents the number of 1s in the mask
Also written as “/24,” where 24 represents the number of 1s in the mask

11111111
11111111
00000000
00000000
Decimal Equivalents of Bit Patterns
0 0 0 0 0 0 0 0 = 0
1 0 0 0 0 0 0 0 = 128
1 1 0 0 0 0 0 0 = 192
1 1 1 0 0 0 0 0 = 224
1 1 1 1 0 0 0 0 = 240
1 1 1 1 1 0 0 0 = 248
1 1 1 1 1 1 0 0 = 252
1 1 1 1 1 1 1 0 = 254
1 1 1 1 1 1 1 1 = 255
128 64 32 16 8 4 2 1
16
Network
Host
172
0
0
10101100
11111111
10101100
00010000
11111111
00010000
00000000
00000000
10100000
00000000
00000000
Subnets not in use—the default
00000010
Subnet Mask Without Subnets
172.16.2.160
255.255.0.0
Network
Number
Network number extended by eight bits
Subnet Mask with Subnets
16
Network
Host
172.16.2.160
255.255.255.0
172
2
0
10101100
11111111
10101100
00010000
11111111
00010000
11111111
00000010
10100000
00000000
00000000
00000010
Subnet
Network
Number
128
192
224
240
248
252
254
255
Subnet Mask with Subnets (cont.)
Network
Host
172.16.2.160
255.255.255.192
10101100
11111111
10101100
00010000
11111111
00010000
11111111
00000010
10100000
11000000
10000000
00000010
Subnet
Network number extended by ten bits
16
172
2
128
Network
Number
128
192
224
240
248
252
254
255
128
192
224
240
248
252
254
255
Subnet Mask Exercise
Address
Subnet Mask
Class
Subnet
172.16.2.10
10.6.24.20
10.30.36.12
255.255.255.0
255.255.240.0
255.255.255.0
Subnet Mask Exercise Answers
Address
Subnet Mask
Class
Subnet
172.16.2.10
10.6.24.20
10.30.36.12
255.255.255.0
255.255.240.0
255.255.255.0
B
A
A
172.16.2.0
10.6.16.0
10.30.36.0
Broadcast Addresses
172.16.1.0
172.16.2.0
172.16.3.0
172.16.4.0
172.16.3.255
(Directed Broadcast)
255.255.255.255
(Local Network Broadcast)
X
172.16.255.255
(All Subnets Broadcast)
Addressing Summary Example
10101100
11111111
10101100
00010000
11111111
00010000
11111111
00000010
10100000
11000000
10000000
00000010
10101100
00010000
00000010
10111111
10101100
00010000
00000010
10000001
10101100
00010000
00000010
10111110
Host
Mask
Subnet
Broadcast
Last
First
172.16.2.160
255.255.255.192
172.16.2.128
172.16.2.191
172.16.2.129
172.16.2.190
1
2
3
4
5
6
7
8
9
16
172
2
160
IP Host Address: 172.16.2.121
Subnet Mask: 255.255.255.0
Subnet Address = 172.16.2.0
Host Addresses = 172.16.2.1–172.16.2.254
Broadcast Address = 172.16.2.255
Eight Bits of Subnetting
Network
Subnet
Host
10101100
00010000
00000010
11111111
172.16.2.121:
255.255.255.0:
10101100
11111111
Subnet:
10101100
00010000
00010000
11111111
00000010
00000010
11111111
01111001
00000000
00000000
Class B Subnet Example
Broadcast:
Network
Subnet Planning
Other
Subnets
192.168.5.16
192.168.5.32
192.168.5.48
20 Subnets
5 Hosts per Subnet
Class C Address:
192.168.5.0
11111000
IP Host Address: 192.168.5.121
Subnet Mask: 255.255.255.248
Network
Subnet
Host
192.168.5.121:
11000000
11111111
Subnet:
11000000
10101000
10101000
11111111
00000101
00000101
11111111
01111001
01111000
255.255.255.248:
Class C Subnet Planning Example
Subnet Address = 192.168.5.120
Host Addresses = 192.168.5.121–192.168.5.126
Broadcast Address = 192.168.5.127
Five Bits of Subnetting
Broadcast:
Network
Network
11000000
10101000
00000101
01111111
Exercise
192.168.10.0
/27

? – SNM
? – Block Size
?- Subnets

Exercise
/27

? – SNM – 224
? – Block Size = 256-224 = 32
?- Subnets

Exercise
192.168.10.0
/30

? – SNM
? – Block Size
?- Subnets

Exercise
/30

? – SNM – 252
? – Block Size = 256-252 = 4
?- Subnets

Exercise
Exercise
Exam Question
Find Subnet and Broadcast address
192.168.0.100/27
Exercise
192.168.10.54 /29
Mask ?
Subnet ?
Broadcast ?
Exercise
192.168.10.130 /28
Mask ?
Subnet ?
Broadcast ?
Exercise
192.168.10.193 /30
Mask ?
Subnet ?
Broadcast ?
Exercise
192.168.1.100 /26
Mask ?
Subnet ?
Broadcast ?
Exercise
192.168.20.158 /27
Mask ?
Subnet ?
Broadcast ?
Class B
172.16.0.0 /19
Subnets ?
Hosts ?
Block Size ?


Class B
172.16.0.0 /19
Subnets 23 -2 = 6
Hosts 213 -2 = 8190
Block Size 256-224 = 32


Class B
172.16.0.0 /27
Subnets ?
Hosts ?
Block Size ?


Class B
172.16.0.0 /27
Subnets 211 -2 = 2046
Hosts 25 -2 = 30
Block Size 256-224 = 32


Class B
172.16.0.0 /23
Subnets ?
Hosts ?
Block Size ?


Class B
172.16.0.0 /23
Subnets 27 -2 = 126
Hosts 29 -2 = 510
Block Size 256-254 = 2


Class B
172.16.0.0 /24
Subnets ?
Hosts ?
Block Size ?


Class B
172.16.0.0 /24
Subnets 28 -2 = 254
Hosts 28 -2 = 254
Block Size 256-255 = 1


Class B
172.16.0.0 /25
Subnets ?
Hosts ?
Block Size ?


Class B
172.16.0.0 /25
Subnets 29 -2 = 510
Hosts 27 -2 = 126
Block Size 256-128 = 128


Find out Subnet and Broadcast Address
172.16.85.30/20
Find out Subnet and Broadcast Address
172.16.85.30/29
Find out Subnet and Broadcast Address
172.30.101.62/23
Find out Subnet and Broadcast Address
172.20.210.80/24
Exercise
Find out the mask which gives 100 subnets for class B
Exercise
Find out the Mask which gives 100 hosts for Class B
Class A
10.0.0.0 /10
Subnets ?
Hosts ?
Block Size ?


Class A
10.0.0.0 /10
Subnets 22 -2 = 2
Hosts 222 -2 = 4194302
Block Size 256-192 = 64


Class A
10.0.0.0 /18
Subnets ?
Hosts ?
Block Size ?


Class A
10.0.0.0 /18
Subnets 210 -2 = 1022
Hosts 214 -2 = 16382
Block Size 256-192 = 64


Broadcast Addresses Exercise
Address
Class
Subnet
Broadcast
201.222.10.60
255.255.255.248
Subnet Mask
15.16.193.6
255.255.248.0
128.16.32.13
255.255.255.252
153.50.6.27
255.255.255.128
Broadcast Addresses Exercise Answers
153.50.6.127
Address
Class
Subnet
Broadcast
201.222.10.60
255.255.255.248
C
201.222.10.63
201.222.10.56
Subnet Mask
15.16.193.6
255.255.248.0
A
15.16.199.255
15.16.192.0
128.16.32.13
255.255.255.252
B
128.16.32.15
128.16.32.12
153.50.6.27
255.255.255.128
B
153.50.6.0
VLSM
VLSM is a method of designating a different subnet mask for the same network number on different subnets

Can use a long mask on networks with few hosts and a shorter mask on subnets with many hosts

With VLSMs we can have different subnet masks for different subnets.

Variable Length Subnetting
VLSM allows us to use one class C address to design a networking scheme to meet the following requirements:
Bangalore 60 Hosts
Mumbai 28 Hosts
Sydney 12 Hosts
Singapore 12 Hosts
WAN 1 2 Hosts
WAN 2 2 Hosts
WAN 3 2 Hosts
Networking Requirements
Bangalore 60
Mumbai 60
Sydney 60
Singapore 60
WAN 1
WAN 2
WAN 3
In the example above, a /26 was used to provide the 60 addresses for Bangalore and the other LANs. There are no addresses left for WAN links
Networking Scheme
Mumbai 192.168.10.64/27
Bangalore 192.168.10.0/26
Sydney 192.168.10.96/28
Singapore 192.168.10.112/28
WAN 192.168.10.129 and 130
WAN 192.198.10.133 and 134
WAN 192.198.10.137 and 138
60
12
12
28
2
2
2
192.168.10.128/30
192.168.10.136/30
192.168.10.132/30
VLSM Exercise
2
2
2
40
25
12
192.168.1.0
VLSM Exercise
2
2
2
40
25
12
192.168.1.0
192.168.1.4/30
192.168.1.8/30
192.168.1.12/30
192.168.1.16/28
192.168.1.32/27
192.168.1.64/26
VLSM Exercise
2
2
8
15
5
192.168.1.0
2
2
35
Summarization
Summarization, also called route aggregation, allows routing protocols to advertise many networks as one address.
The purpose of this is to reduce the size of routing tables on routers to save memory
Route summarization (also called route aggregation or supernetting) can reduce the number of routes that a router must maintain
Route summarization is possible only when a proper addressing plan is in place
Route summarization is most effective within a subnetted environment when the network addresses are in contiguous blocks
Summarization
Supernetting
Network
Subnet
172.16.12.0
11000000
11111111
10101000
11111111
00001100
11111111
255.255.255.0
Network
Network
00000000
00000000
16 8 4 2 1
172.16.13.0
11000000
10101000
00001101
00000000
172.16.14.0
11000000
10101000
00001110
00000000
172.16.15.0
11000000
10101000
00001111
00000000
Supernetting
Network
Subnet
172.16.12.0
11000000
11111111
10101000
11111111
00001100
11111100
255.255.252.0
Network
Network
00000000
00000000
16 8 4 2 1
172.16.13.0
11000000
10101000
00001101
00000000
172.16.14.0
11000000
10101000
00001110
00000000
172.16.15.0
11000000
10101000
00001111
00000000
172.16.12.0/24
172.16.13.0/24
172.16.14.0/24
172.16.15.0/24

172.16.12.0/22
Supernetting Question
172.1.7.0/24
172.1.6.0/24
172.1.5.0/24
172.1.4.128/25
172.1.4.128/25
What is the most efficient summarization that TK1 can use to advertise its networks to TK2?

A. 172.1.4.0/24172.1.5.0/24172.1.6.0/24172.1.7.0/24
B. 172.1.0.0/22
C. 172.1.4.0/25172.1.4.128/25172.1.5.0/24172.1.6.0/24172.1.7.0/24
D. 172.1.0.0/21
E. 172.1.4.0/22