Transcript NET 101 CISCO Semester 1 Chapter 2 – Networking Fundamentals

NET 101
CISCO Semester 1
Chapter 2 – Networking Fundamentals
Karl Wick - SUNY Ulster
Network Terminology
Network Terminology
 Network: An interconnected system of
objects
 Bandwidth: The amount of data that can be
sent along a path in a given amount of time
 LAN: Local Area Network
 MAN: Municipal Area Network
 WAN: Wide Area network
Digital Bandwidth
 How much information can flow from one
place to another in a given time
 Bits per second
 kilo, mega or giga bits per second
 More Bandwidth = Better Performance
Bandwidth
 Is limited by hardware and physics
 Has a cost. (Sometimes Substantial)
 Is critical to good performance
 Demand is growing
 Pipe Analogy
Throughput
 Throughput <= Bandwidth
 Highway Analogy
Typical LAN Throughput
 Category 5 Twisted Pair Cable
– 10Mbps
– 100Mbps
– 1000Mbps
 Optical Fiber: 1000Mbps
 Coaxial Cable: 10Mbps
Typical WAN Throughput
 ISDN: 128kbps
 DSL: Variable – 128kbps to 6.1Mbps
 Frame Relay: Variable – 128k to 44.7Mbps
 T1: 1.544 Mbps
 T3: 44.7 Mbps
 OC3: 155.25 Mbps
 OC48: 2.488 Gbps
E1: 2.048 Mbps
E3: 34.4Mbps
Throughput
 Try to answer the following question, using the
formula Throughput = FileSize /Bandwidth.
 Be sure to convert units of measurement as
necessary.
 Would it take less time to send the contents of a
floppy disk full of data (1.44 MB) over an ISDN
line, or to send the contents of a ten GB hard drive
full of data over an OC-48 line?
Solution to Exercise
 1440 kbytes / 128k bytes per second =
11.25 seconds for the file.
 10,000,000 kbytes / 2,488,000 kbytes per
second = 4.02 seconds
Models
The Seven Layer OSI Model
 7 Application
 6 Presentation
 5 Session
 Reduces Complexity
 Standardizes Interfaces
 Facilitates Modularity
 4 Transport
 Ensures Interoperability
 3 Network
 Accelerates Evolution
 2 Data Link
 Simplifies Learning
 1 Physical
The Seven Layer OSI Model
 7 Application
 6 Presentation
 5 Session
 4 Transport
 3 Network
 2 Data Link
 1 Physical
Data Transport Rules
Logical Addresses
Fixed Addresses
Wires and Hardware
Network Devices
Host Devices
PC
MAC
The symbols are
NOT standard
throughout the
industry.
Printer
Server
Most are easy to
figure out.
Host Devices
 Devices that connect directly to a network
segment are referred to as hosts.
 These hosts include computers, both clients
and servers, printers, scanners, and many
other user devices.
 These devices provide the users with
connection to the network.
 The users share, create, and obtain
information across the network.
NICs
NICs adapt the host device
to the network medium.
NICs are considered Layer
2 devices
This address is used to
control data
Each individual NIC throughout communication for the
the world carries a unique code, host on the network.
called a Media Access Control
(MAC) address.
Media
 The basic functions of media
are to carry a flow of
information, in the form of bits
and bytes, through a LAN.
 Coaxial cable, optical fiber,
and even free space can carry
network signals, however, the
principal medium we will
study is called Category 5
unshielded twisted-pair cable
(CAT 5 UTP).
Media
 Patch cables, patch panels, and other
interconnection components are considered
passive Layer 1 components because they
simply provide some sort of conducting path.
 Passive components do not require a power
source.
Repeaters
The purpose of a
repeater is regenerate
and retime network
signals at the bit level
to allow them to travel
a longer distance on
the media.
Repeaters
 Repeaters are single-port "in" and single-
port "out" devices.
 Repeaters are classified as Layer 1 devices,
in the OSI model, because they act only on
the bit level and look at no other
information.
 They are active devices because they
require power to work.
The 5-4-3 Rule
 This rule states that you can connect five
network segments end-to-end using four
repeaters but only three segments can have
hosts (computers) on them.
Hubs
 A hub is a repeater with
multiple ports.
 Any input signal gets
sent to all output ports.
 Allow concentration of
signals at a central
point
Bridges
 A bridge is a layer 2 device
designed to connect two LAN
segments.
 The purpose of a bridge is to
filter traffic on a LAN, to keep
local traffic local, yet allow
connectivity to other parts
(segments) of the LAN for
traffic that has been directed
there.
Bridges
 The bridge keeps track of which MAC
addresses are on each side of the bridge and
makes its forwarding decisions based on
this MAC address list.
Switches
Switches
 A Switch is a device like a bridge with many
ports.
 In fact a switch is called a multi-port bridge, just
like a hub is called a multi-port repeater.
 They are used to segment networks into smaller
parts as well as to provide connectivity.
 The difference between the hub and switch is
that switches make decisions based on MAC
addresses and hubs don't make decisions at all.
Switches
 Because of the decisions that switches make, they
make a LAN much more efficient.
 They do this by "switching" data only out the port
to which the proper host is connected. In contrast,
a hub will send the data out all of its ports so that
all of the hosts have to see and process (accept or
reject) all of the data on the LAN.
Routers
 Inter-network data
flow.
 Best path
determination
 Switching to
proper port
 Translation
 Regeneration
 Security
Routers
 Routers make decisions based on groups of network
addresses (Classes) as opposed to the individual MAC
addresses like bridges and switches do.
 Routers can also connect different media technologies, such
as Ethernet, Token-ring, and FDDI.
 Routers have become the backbone of the Internet, running
the IP protocol.
 The purpose of a router is to examine incoming packets
(layer 3 data), choose the best path for them through the
network, and then switch them to the best outgoing port.
Clouds
The purpose of the cloud is
to represent a large group of
details that are not pertinent
to a situation, or
description, at a given time.
Network Topology
The structure of the Network
Physical and Logical
Topology
 There are two parts to the topology
definition:
– The physical topology, which is the actual
layout of the wire (media), and
– The logical topology, which defines how the
media is accessed by the hosts.
Physical Topologies
Logical Topology
 The logical topology of a network is how
the hosts communicate across the medium.
 The two most common types of logical
topologies are Broadcast and Tokenpassing.
Broadcast Topology
 Broadcast topology simply means that each host
sends its data to all other hosts on the network
medium.
 There is no order the stations follow to use the
network, it is first come, first serve.
 Controlled Chaos!
 This is the way that Ethernet works and you will
learn much more about this later in the semester.
Token Passing Topology
 Token-passing controls network access by
passing an electronic token sequentially to
each host.
 When a host receives the token, only that
host can send data on the network.
 If the host has no data to send, it passes the
token to the next host and the process
repeats itself.
Network Protocols
Rules of the Road
Protocols
 How the physical network is built
 How computers connect to the network
 How the data is formatted for transmission
 How that data is sent
 How to deal with errors
The LAN
The LAN
The WAN
WAN Technologies
 Dial-up Modems
 Integrated Services Digital Network (ISDN)
 Digital Subscriber Line (DSL)
 Frame Relay
 US (T) and Europe (E) Carrier Series – T1, E1,
T3, E3
 Synchronous Optical Network (SONET)
 Cable Modem
The MAN
The SAN
 A SAN is a dedicated, high-performance
network used to move data between servers
and storage resources.
 Because it is a separate, dedicated network,
it avoids any traffic conflict between clients
and servers.
The SAN
 Storage Area Network
 Performance – SANs enable
concurrent access of disk or
tape arrays by two or more
servers at high speeds,
enhanced system performance.
 Availability –data can be
mirrored using a SAN up to 10
kilometers (km) or 6.2 miles
away.
 Scalability
VPN
The VPN
 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.
The VPN
 A VPN is a service that offers secure,
reliable connectivity over a shared public
network infrastructure such as the Internet.
 VPNs maintain the same security and
management policies as a private network.
 They are the most cost-effective method of
establishing a point-to-point connection
between remote users and an enterprise
customer's network.
Intranet / Extranet
Layered Models
OSI Model released in 1981 by the ISO
(Not to be confused with the IOS)
The Seven Layer OSI Model
 7 Application
 6 Presentation
 5 Session
 Reduces Complexity
 Standardizes Interfaces
 Facilitates Modularity
 4 Transport
 Ensures Interoperability
 3 Network
 Accelerates Evolution
 2 Data Link
 Simplifies Learning
 1 Physical
Layers in an Abstract Model
 What is flowing?
 In What forms does it exist?
 What rules govern the flow?
 Where does the flow occur?
Peer to Peer Networking and PDUs
The OSI Model
See 2.3.4 Drag and Drop Exercise
OSI model vs TCP/IP Model
 Application
 Application
 Presentation
 Session
 Transport
 Transport
 Network
 Internet
 Data Link
 Network Access
 Physical
Some TCP/IP Protocols
Application
Transport
Internet
Network
Access
Data Encapsulation
Layers and Hardware
 Layer 1-7 :
Workstations
 Layer 3: Router
– IP (Logical Addresses)
 Layer 2: Bridge, Switch
– Hardware (MAC) Addresses
 Layer 1: Media, Repeater, Hub, Transceiver
Summary
 Bandwidth
 LAN, MAN, WAN, SAN “can you eat
Green Eggs and Ham?”
 Models
 Protocol Data Units / Encapsulation
 VPN
 Terminology and Symbology