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04/11/23
Basic Training on Transmission NMS
Asim Kumar KunduTransmission Network Support
RPTS/ROMEmail: [email protected]
04/11/23
Basic of IP
Topics:OSI ModelLAN protocolNetwork devicesIP addressingSubnetRouting
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Application
Presentation
Session
Transport
Network
Data-Link
Physical
THE OSI MODEL
Where We’ve Been
Chapter 1—Review
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Table of Contents
Enterprise
Review the OSI Model
Encapsulation
LAN Devices & Technologies
Transport Layer
IP Addressing
Go There!
Go There!
Go There!
Go There!
Go There!
Go There!
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A New Word!—Enterprise
A corporation, agency, school, or other organization that works to tie together its data, communication, computing, and file servers.
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Your Job as a Network Guru Help Enterprises meet their needs by:
Interconnecting their LANs so that geographically remote services can be accessed
Ensuring users get high bandwidth access over their LANs (i.e. Replacing hubs with switches; 10Mbps NICs with 10/100 Mbps NICs)
Implementing new technologies as they emerge like e-commerce, video conferencing, voice over IP, and distance learning.
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Application
Presentation
Session
Transport
Network
Data-Link
Physical
THE OSI MODEL
Review The Model
Open Systems Interconnected Reference Model
Table of Contents
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Why A Layered Model? Reduces complexity Standardizes interfaces Facilitates modular
engineering Ensures interoperable
technology Accelerates evolution Simplifies teaching &
learning
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Host Layers vs. Media Layers
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Host Layers
Provides accurate data delivery
between computers
Application
Presentation
Session
Transport
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Host Layers vs. Media Layers
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Media Layers
Controls physical delivery of the
message over the network
Network
Data-Link
Physical
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Application Layer Provides network services
(processes) to applications. For example, a computer on
a LAN can save files to a server using a network redirector supplied by NOSs like Novell.
Network redirectors allow applications like Word and Excel to “see” the network.
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Presentation Layer Provides data
representation and code formatting.
Code formatting includes compression and encryption
Basically, the presentation layer is responsible for representing data so that the source and destination can communicate at the application layer.
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Session Layer Provides inter-host
communication by establishing, maintaining, and terminating sessions.
Session uses dialog control and dialog separation to manage the session
Some Session protocols: NFS (Network File System) SQL (Structured Query
Language) RCP (Remote Call Procedure) ASP (AppleTalk Session
Protocol) SCP (Session Control Protocol) X-window
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Transport Layer Provides reliability, flow control,
and error correction through the use of TCP.
TCP segments the data, adding a header with control information for sequencing and acknowledging packets received.
The segment header also includes source and destination ports for upper-layer applications
TCP is connection-oriented and uses windowing.
UDP is connectionless. UDP does not acknowledge the receipt of packets.
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Network Layer Responsible for logically
addressing the packet and path determination.
Addressing is done through routed protocols such as IP, IPX, AppleTalk, and DECnet.
Path Selection is done by using routing protocols such as RIP, IGRP, EIGRP, OSPF, and BGP.
Routers operate at the Network Layer
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Data-Link Layer Provides access to the media Handles error notification,
network topology issues, and physically addressing the frame.
Media Access Control through either... Deterministic—token
passing Non-deterministic—
broadcast topology (collision domains)
Important concept: CSMA/CD
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Physical Layer Provides electrical,
mechanical, procedural and functional means for activating and maintaining links between systems.
Includes the medium through which bits flow. Media can be... CAT 5 cable Coaxial cable Fiber Optics cable The atmosphere
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Application
Presentation
Session
Transport
Network
Data-Link
Physical
THE OSI MODEL
Encapsulation
Peer-to-Peer Communications
Table of Contents
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Peer-to-Peer Communications Peers communicate using the PDU of their
layer. For example, the network layers of the source and destination are peers and use packets to communicate with each other.
Application Application
Presentation Presentation
Session Session
Transport Transport
Network Network
Data-Link Data-Link
Physical Physical
Data
SegmentsPacketsFramesBits
DataData
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Encapsulation Example You type an email
message. SMTP takes the data and passes it to the Presentation Layer.
Presentation codes the data as ASCII.
Session establishes a connection with the destination for the purpose of transporting the data.
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Encapsulation Example Transport segments the
data using TCP and hands it to the Network Layer for addressing
Network addresses the packet using IP.
Data-Link then encaps. the packet in a frame and addresses it for local delivery (MACs)
The Physical layer sends the bits down the wire.
Application
Presentation
Session
Transport
Network
Data-Link
Physical
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Application
Presentation
Session
Transport
Network
Data-Link
Physical
THE OSI MODEL
LAN Devices & Technologies
The Data-Link & Physical Layers
Table of Contents
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Devices What does it do?
Connects LAN segments;
Filters traffic based on MAC addresses; and
Separates collision domains based upon MAC addresses.
What layer device?
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Devices What does it do?
Since it is a multi-port bridge, it can also Connect LAN
segments; Filter traffic based
on MAC addresses; and
Separate collision domains
However, switches also offer full-duplex, dedicated bandwidth to segments or desktops.
What layer device?
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Devices What does it do?
Concentrates LAN connections from multiple devices into one location
Repeats the signal (a hub is a multi-port repeater)
What layer device?
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Devices What does it do?
Interconnects networks and provides broadcast control
Determines the path using a routing protocol or static route
Re-encapsulates the packet in the appropriate frame format and switches it out the interface
Uses logical addressing (i.e. IP addresses) to determine the path
What layer device?
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Media Types
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LAN Technologies
Three Most Common
Used Today in
Networking
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Ethernet/802.3 Cable Specifications:
10Base2 Called Thinnet; uses coax Max. distance = 185 meters (almost 200)
10Base5 Called Thicknet; uses coax Max. distance = 500 meters
10BaseT Uses Twisted-pair Max. distance = 100 meters
10 means 10 Mbps
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Ethernet/802.3 Ethernet is broadcast topology.
What does that mean? Every devices on the Ethernet segment
sees every frame. Frames are addressed with source and
destination ______ addresses. When a source does not know the
destination or wants to communicate with every device, it encapsulates the frame with a broadcast MAC address: FFFF.FFFF.FFFF
What is the main network traffic problem caused by Ethernet broadcast topologies?
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Ethernet/802.3 Ethernet topologies are also shared
media. That means media access is controlled
on a “first come, first serve” basis. This results in collisions between the
data of two simultaneously transmitting devices.
Collisions are resolved using what method?
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Ethernet/802.3 CSMA/CD (Carrier Sense Multiple Access
with Collision Detection) Describe how CSMA/CD works:
A node needing to transmit listens for activity on the media. If there is none, it transmits.
The node continue to listen. A collision is detected by a spike in voltage (a bit can only be a 0 or a 1--it cannot be a 2)
The node generates a jam signal to tell all devices to stop transmitting for a random amount of time (back-off algorithm).
When media is clear of any transmissions, the node can attempt to retransmit.
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Address Resolution Protocol In broadcast topologies, we need a way to
resolve unknown destination MAC addresses. ARP is protocol where the sending device
sends out a broadcast ARP request which says, “What’s you MAC address?”
If the destination exists on the same LAN segment as the source, then the destination replies with its MAC address.
However, if the destination and source are separated by a router, the router will not forward the broadcast (an important function of routers). Instead the router replies with its own MAC address.
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Application
Presentation
Session
Transport
Network
Data-Link
Physical
THE OSI MODEL
Transport Layer
A Quick Review
Table of Contents
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Transport Layer Functions Synchronization of the connection
Three-way handshake Flow Control
“Slow down, you’re overloading my memory buffer!!”
Reliability & Error Recovery Windowing: “How much data can I send
before getting an acknowledgement?” Retransmission of lost or
unacknowledged segments
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Transport’s Two Protocols TCP
Transmission Control Protocol
Connection-oriented Acknowledgment &
Retransmission of segments
Windowing Applications:
Email File Transfer E-Commerce
UDP User Datagram
Protocol Connectionless No
Acknowledgements Applications:
Routing Protocols Streaming Audio Gaming Video
Conferencing
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Application
Presentation
Session
Transport
Network
Data-Link
Physical
THE OSI MODEL
IP Addressing
Subnetting Review
Table of Contents
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Logical Addressing At the network layer, we use logical,
hierarchical addressing. With Internet Protocol (IP), this address is a
32-bit addressing scheme divided into four octets.
Do you remember the classes 1st octet’s value? Class A: 1 - 126 Class B: 128 - 191 Class C: 192 - 223 Class D: 224 - 239 (multicasting) Class E: 240 - 255 (experimental)
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Network vs. Host
N H H H
Class A: 27 = 126 networks; 224 > 16 million hosts
N N H H
Class B : 214 = 16,384 networks; 216 > 65,534 hosts
N N N H
Class C : 221 > 2 million networks; 28 = 254 hosts
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Why Subnet? Remember: we are usually dealing
with a broadcast topology. Can you imagine what the network
traffic overhead would be like on a network with 254 hosts trying to discover each others MAC addresses?
Subnetting allows us to segment LANs into logical broadcast domains called subnets, thereby improving network performance.
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Stealing Bits In order to subnet, we must steal or “borrow” bits from the
host portion on the IP address. First, we must to determine how many subnets we need
and how many hosts per subnet. We do this through the power of 2
For example, I need 8 subnets from a Class C: 24 = 16 - 2 = 14 subnets Remember: we subtract 2 because these subnets
are not used How many host do we have?
It’s a Class C, so 4 bits are left: 24 = 16 - 2 = 14 hosts
Remember: we subtract 2 because one address is the subnet address and one is the broadcast address
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Subnet Mask We determine the subnet mask by adding up
the decimal value of the bits we borrowed. In the previous Class C example, we borrowed
4 bits. Below is the host octet showing the bits we borrowed and their decimal values.
128 64 32 16 8 4 2 1
1 1 1 1
We add up the decimal value of these bits and get 240. That’s the last non-zero octet of our subnet mask.So our subnet mask is 255.255.255.240
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Last Non-Zero Octet Memorize this table. You should be able to:
Quickly calculate the last non-zero octet when given the number of bits borrowed.
Determine the number of bits borrowed given the last non-zero octet.
Determine the amount of bits left over for hosts and the number of host addresses available.
Bits Borrowed
Non-Zero Octet Hosts
2 192 623 224 304 240 145 248 66 252 2
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CIDR Notation Classless Interdomain Routing is a method
of representing an IP address and its subnet mask with a prefix.
For example: 192.168.50.0/27 What do you think the 27 tells you?
27 is the number of 1 bits in the subnet mask. Therefore, 255.255.255.224
Also, you know 192 is a Class C, so we borrowed 3 bits!!
Finally, you know the magic number is 256 - 224 = 32, so the first useable subnet address is 197.168.50.32!!
Let’s see the power of CIDR notation.
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202.151.37.0/26 Subnet mask?
255.255.255.192 Bits borrowed?
Class C so 2 bits borrowed Magic Number?
256 - 192 = 64 First useable subnet address?
202.151.37.64 Third useable subnet address?
64 + 64 + 64 = 192, so 202.151.37.192
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198.53.67.0/30 Subnet mask?
255.255.255.252 Bits borrowed?
Class C so 6 bits borrowed Magic Number?
256 - 252 = 4 Third useable subnet address?
4 + 4 + 4 = 12, so 198.53.67.12 Second subnet’s broadcast address?
4 + 4 + 4 - 1 = 11, so 198.53.67.11
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200.39.89.0/28 What kind of address is 200.39.89.32?
Class C, so 4 bits borrowed Last non-zero octet is 240 Magic number is 256 - 240 = 16 32 is a multiple of 16 so 200.39.89.32 is
a subnet address--the second subnet address!!
What’s the broadcast address of 200.39.89.32? 32 + 16 -1 = 47, so 200.39.89.47
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194.53.45.0/29 What kind of address is 194.53.45.26?
Class C, so 5 bits borrowed Last non-zero octet is 248 Magic number is 256 - 248 = 8 Subnets are .8, .16, .24, .32, ect. So 194.53.45.26 belongs to the third subnet
address (194.53.45.24) and is a host address. What broadcast address would this host use
to communicate with other devices on the same subnet? It belongs to .24 and the next is .32, so 1 less
is .31 (194.53.45.31)
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No Worksheet Needed! After some practice, you should never need
a subnetting worksheet again. The only information you need is the IP
address and the CIDR notation. For example, the address 221.39.50/26 You can quickly determine that the first
subnet address is 221.39.50.64. How? Class C, 2 bits borrowed 256 - 192 = 64, so 221.39.50.64
For the rest of the addresses, just do multiples of 64 (.64, .128, .192).
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The Key!! MEMORIZE THIS TABLE!!!
Bits Borrowed
Non-Zero Octet Hosts
2 192 623 224 304 240 145 248 66 252 2
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Practice On Your Own Below are some practice problems. Take out a sheet of paper and calculate...
Bits borrowed Last non-zero octet Second subnet address and broadcast address
1. 192.168.15.0/262. 220.75.32.0/303. 200.39.79.0/294. 195.50.120.0/275. 202.139.67.0/286. Challenge: 132.59.0.0/197. Challenge: 64.0.0.0/16
Answers
