Transcript Introduction to Networking ITT Version

NT1210 Introduction to Networking
Unit 3:
Chapter 3, TCP/IP Networks
1
Objectives
 Compare and contrast the OSI and TCP/IP models and
their applications to actual networks.
 Explain the functionality and use of typical network
protocols.
 Analyze network components and their primary
functions in a typical data network from both logical and
physical perspectives.
 Differentiate among major types of LAN and WAN
technologies and specifications and determine how
each is used in a data network.
2
Objectives
 Differentiate between proprietary and nonproprietary
protocols.
 Explain the use of IP addressing in data networks.
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Defining the Rules for a TCP/IP Network:
Product Standards and Rules
 Transmission Control Protocol (TCP) / Internet Protocol
(IP).
 Requests for Comment (RFC): Documents created by
network stakeholders to comment and improve ideas for
standards.
 Define how products work.
 Used by network designers.
 Open source.
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Defining the Rules for a TCP/IP Network
 Hardware and software work together to create usable
network.
 Protocols (network software): Hypertext Transfer
Protocol (HTTP), Simple Mail Transfer Protocol
(SMTP), Post Office Protocol (POP), etc.
 Used on networked devices (hardware): Phones, game
systems, televisions, tablets, computers, software,
networking devices, cables, etc.
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Defining the Rules for a TCP/IP Network
 TCP/IP identifies both stuff and how it works together:
 Defines protocols.
 Defines concepts of Local Area Networks (LANs) and Wide
Area Networks (WANs).
 Defines concept of links and nodes the functions of each.
 Definition of TCP/IP network: Network built using
TCP/IP standards and rules.
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Defining the Rules for a TCP/IP Network:
Standards
 Record details of exactly what new technologies do and
how they do it.
 Help everyone agree to how something works so that it
works well within network.
 Important feature: Documentation of ideas that matter to
anyone creating networking products or designing
networks.
 Example: Brief history of Web browsers and servers as
envisioned by Web creator Tim Berners-Lee.
http://bit.ly/vd0pWE
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Defining the Rules for a TCP/IP Network:
HTTP Example
 HTTP began life as idea and details of how it was to work
had to be determined:
 What byte values does browser use to send HTTP GET?
 What byte value does server use to send HTTP REPLY?
 Is // required before name of server in web address?
 How does server tell browser when it can’t find requested
object?
 How does server tell browser where object’s bytes begin and
end?
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Defining the Rules for a TCP/IP Network:
Hardware
 Standards apply to both hardware and software.
 Example: NICs connectors.
 Without standards, not all cables would fit NIC’s port
(proprietary configurations).
 Fixes size and shape standards for connectors and other
networking gear set.
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Defining the Rules for a TCP/IP Network:
Hardware
Example: This cable has an RJ45 connector. (RJ-45 is the
name of the standard for the
connector).
The NIC has an RJ-45 port of
the same size.
The RJ-45 has 8 pins and looks
much like the RJ-11 which is
commonly know as a “Phone
Connector,” but is half the size of
the RJ-45.
Example of Physical Standard: RJ-45 Connector (on Cable) and Socket (on NIC)
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Figure 3-1
Defining the Rules for a TCP/IP Network:
Types of Standards, Part 1
 National: Standard approved by a national government
which then appoints an organization to oversee it.
 Example: Electrical power outlets’ size, shape, electrical current,
voltage.
 International: Standard approved by a group of nations
that typically relates to functions that benefit from
consistency among the participating nations.
 Vendor (proprietary): Standard approved by a single
vendor which allows the vendor to keep control yet
allows other vendors to use them so they are
interoperable.
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Defining the Rules for a TCP/IP Network:
Types of Standards, Part 2
 Vendor Group: Standard approved by a group of
vendors (vendor consortium, vendor alliance, vendor
forum).
 Wants their standards to become national/international
standards.
 Can move quicker than national/international standards groups.
 Works to get compatible products to market quicker, while
working with formal standards groups.
 De Facto: Standard that exists because it is what is
currently in use, usually not written down.
 Example: MS-Word has become de facto standard of most
offices.
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Defining the Rules for a TCP/IP Network
Not all protocols and hardware specs are standardized;
however, most used today happen to be standards.
Networking Standards Compared to Protocols and Hardware Specs
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Figure 3-2
Defining the Rules for a TCP/IP Network:
TCP/IP Model
 Defines large set of standards implemented together to
create safe and useful network.
 Model name has many variations but all refer to same
idea.
 TCP/IP network architecture, TCP/IP networking model, TCP/IP
networking blueprint.
 Organizes standards into layers so…
 Humans can understand what networks do.
 Easier to divide work among different products.
 Devices can be interoperable.
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Defining the Rules for a TCP/IP Network:
TCP/IP Model
 Commonly-used version of
TCP/IP model has five layers.
 Original TCP/IP model had four
layers:
 Bottom two layers of model
combined into Network Interface
layer (or Network Access layer).
TCP/IP Model
Figure 3-3
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Defining the Rules for a TCP/IP Network:
TCP/IP Model
 Includes standards created for TCP/IP, as well as some
created by other standards groups.
 Each standards-setting group follows some kind of process:
 Repeated experimentation
 Documentation
 Review
 Comments, etc.
 Example: Internet Engineering Task Force (IETF) acts as
primary standards group for TCP/IP model, so model
includes standards created by both IETF and other
standards groups.
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Defining the Rules for a TCP/IP Network:
Organizations Useful to TCP/IP
Sources of Standards in the TCP/IP Model
Figure 3-4
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Defining the Rules for a TCP/IP Network:
IETF (www.ietf.org)
 Works as standard-setting group for TCP/IP.
 Decides:
 What needs to be updated
 What new standards need to be added
 Organized around working groups made up of volunteers
who work on new standards (create “internet drafts”).
 Experiments, changes details, improves how new technology
works, then shares changes.
 Submits findings into standards process.
 Document created by group can become informational or
experimental RFC if draft not submitted.
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Defining the Rules for a TCP/IP Network:
IETF Working Groups Process
Standard and Non-Standard TCP/IP RFCs
Figure 3-5
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Defining the Rules for a TCP/IP Network:
IEEE (www.ieee.org)
 Institute of Electrical and Electronics Engineers (IEEE).
 Plays huge role in networking and for TCP/IP in general.
 World’s largest professional organization.
 IEEE standards for TCP/IP define LANs (including Ethernet,
most commonly used wired and wireless LAN technology).
 Not agency of any particular government or agency.
 US government appoints ANSI to manage US standards
across industries.
 ANSI certifies standards by certifying other standards groups.
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Defining the Rules for a TCP/IP Network:
ITU
 International Telecommunications Union.
 International standards body that focuses on standards for
telecom and WAN networking technologies.
 Example: ITU standards define country codes for international
phone calls.
 Enables worldwide digital voice communications by
standardizing voice codecs.
 TCP/IP model uses ITU standards for same reasons it
uses IEEE standards.
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Defining the Rules for a TCP/IP Network:
Vendor Consortia & Other Groups
 Vendor Group/Consortium: Vendors team up to get quick
and broad acceptance in marketplace.
 Group agrees on standardized version of new technology
BEFORE formal standards group sets standards.
 Example: Wi-Fi Alliance (www.wi-fi.org) helped get new wireless
technology to market quicker than formal IEEE standards process
would have.
 Tested products to certify (confirm) they worked together.
 Created pre-standard rules.
 Allowed vendors to brand products as “Wi-Fi certified”.
 Worked with IEEE to help overall standards process.
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Defining the Rules for a TCP/IP Network
Overall process: No matter whether a person with good ideas works
through the Wi-fi Alliance or IEEE, when those two groups cooperate,
products get to market sooner, and the standards happen.
Vendor Groups Impact on Speed to Market
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Figure 3-6
Defining the Rules for a TCP/IP Network:
LAN/WAN Standards
TCP/IP Using Other Standards for LAN and WAN
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Figure 3-7
Comparing TCP/IP to Other Networking
Models: Standards
While a single standard typically
focuses on one protocol or
hardware spec, the TCP/IP
model collects all the standards
needed to do everything
required to make a complete
modern network into one handy
model.
Each device in the network and
each component follows a
subset of the TCP/IP standards,
depending on its role.
Conceptual View of TCP/IP Model
Figure 3-8
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Comparing TCP/IP to Other Networking
Models: History of Networking Models
 First commercial computers hit market in 1950s and
became more common in larger companies by 1960s.
 Personal computers hit market in late 1970s and
became common in 1980s.
 Networks didn’t exist yet.
 Eventually computer vendors saw need to create
network between computers.
 Individual vendors created their own proprietary
networking products and networking models.
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Comparing TCP/IP to Other Networking
Models: History of Networking Models
Typical enterprise network from the 1980s—used 3 different
models to operate:
 IBM networking model.
 DEC networking model.
 Other vendor that could connect them together.
Typical Mix of Corporate Networks over Three Decades
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Figure 3-9
Comparing TCP/IP to Other Networking
Models: History of Networking Models
What happened in typical enterprise networks from the 1980s into the
early 21st century? Enter TCP/IP…
Typical Migration of Enterprise Networks from Vendor Models to TCP/IP
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Figure 3-10
Comparing TCP/IP to Other Networking
Models: OSI Model
 Open Systems Interconnection (OSI)
model.
 ISO began work on OSI model following
timeline that was close to TCP/IP’s:
 Started in 1970s.
 Progressed on individual standards in 1980s.
 Allowed standards-based vendor products to
start appearing by early 1990s.
The OSI Model
Figure 3-11
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Comparing TCP/IP to Other Networking
Models: OSI Model
The biggest differences
between the TCP/IP and OSI
models exist at the top.
The TCP/IP model defines
many functions as part of the
application layer, while the OSI
model split those functions into
multiple layers.
Mapping the Layers of the TCP/IP and OSI Models
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Figure 3-12
Comparing TCP/IP to Other Networking
Models: OSI Model
Three Example Standards, and the Phrases to Use
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Figure 3-13
Understanding How a TCP/IP Network
Works: LANs vs. WANs
When defining LANs and
WANs, always consider
the Data Link and
Physical layers as local
versus remote—or owned
versus leased.
The Terms LAN and WAN in the TCP/IP Model
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Figure 3-14
Understanding How a TCP/IP Network
Works: LAN Physical Links
Both the sender and receiver must agree on the rules of how to use the
electrical circuit. The sending NIC sends the bits over the loop to create
the electrical signal. Signal varies over time to encode different bits.
The receiving NIC must know what rules the sender uses so it can
interpret the circuit changes into the correct 0s and 1s (bits).
NICs on Both Ends of a Cable Creating a Loop
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Figure 3-15
Understanding How a TCP/IP Network
Works: LAN Switches
Every Ethernet LAN device connects to the LAN using a cable. The
cable installers run a cable from each device to a central place on that
floor, usually to a switch that sits in a locked room called a wiring
room. By connecting all the cables to the switch, all are connect to the
LAN—and each other.
Using a LAN Switch to Physically Connect Devices to a LAN
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Figure 3-16
Break
Take 15
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Defining the Rules for a TCP/IP Network:
Data Link Layer
The Ethernet Data Link layer/standards define the rules (protocols) that
tells the devices how and when to use the Ethernet Physical layer.
Using an Address to Send Data to the Right LAN Device
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Figure 3-17
Defining the Rules for a TCP/IP Network:
Data Communication over Layers 1 & 2
1. The server sends the data over the physical link, but only after the
sever adds the destination MAC (physical) address of
1111.1111.1111 to the data.
2. The switch sees the destination address and switches the data to
PC1—and PC1 only.
3. The data arrives at PC1, and PC1 knows the data is meant for it
because of the MAC address.
Using an Address to Send Data to the Right LAN Device
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Figure 3-17
Defining the Rules for a TCP/IP Network:
Data Link Layer
 Many protocols use headers and/or trailers to store
bytes of info that control data flow through network.
 Data Link protocols typically add both header and
trailer.
Data Link Header and Trailer, Like a Couple of Sticky Notes
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Figure 3-18
Defining the Rules for a TCP/IP Network:
WANs
 WAN physical links created by service provider (usually
Telco) used by customer company in its corporate network.
 Example: Fred
buys house
three miles from
Barney’s house.
Instead of building
private road
between their
houses, Barney
and Fred use public road already built.
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Defining the Rules for a TCP/IP Network:
WANs
 WANs create link between sites of corporate network
when company could not physically cable between sites
itself.
 Example: Company has two sites 3 miles apart; although
Ethernet LAN standards allow for 3-mile-long cables to
connect LAN switches at both sites, company can’t
legally lay cable over other people’s land between sites.
 Solution: Contract with 3rd party company that has right to run
cables near existing roads.
 Links are leased (rented) from 3rd party company by customers.
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Defining the Rules for a TCP/IP Network:
WAN Examples




Telco has phone line into most houses.
Electric company has power lines into most buildings.
Cable TV company has cable lines into most buildings.
Government lets
utility companies
dig up road to
install cables or
hang cables from
poles above
ground.
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Defining the Rules for a TCP/IP Network:
Leased Lines
 Creates equivalent of cable directly between two remote
sites.
 Enterprises lease lines to connect remote sites.
 Leased lines create 2-way path to transmit data at predetermined speed (for pre-determined price!).
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Defining the Rules for a TCP/IP Network:
Leased Lines
Enterprises use Layer 3 devices called routers to connect to the WAN
leased line at each site.
The Telco connects the ends of the leased line directly into the enterprise’s
routers in their WAN interfaces (ports) on each end of the link.
Physical Cabling of a Leased Line, from Each Customer Site to Central Office (CO)
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Figure 3-21
Defining the Rules for a TCP/IP Network:
Leased Lines
Two leased lines:
 One connecting
Miami to Atlanta.
 One connecting
Miami to Boston.
The length of the leased
line could literally run
across the street in a
city or thousands of
miles across a country.
(WAN lines that look like lightning bolts represent leased lines.)
Leased Line, Cabling View, with Routers Connecting LAN and WAN
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Figure 3-22
Defining the Rules for a TCP/IP Network:
Data Link Protocols for Leased Lines
 High-level Data Link Control (HDLC—standardized by
ISO).
 Point-to-Point Protocol (PPP—defined by TCP/IP in RFC
1661).
 Both define address in header to identify devices on
physical link
 When router sends data over leased line, data can only go
to router on other end of link.
 Every Data Link protocol focuses on particular Physical
layer technology.
 Routers typically sit at border between different data links.
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Defining the Rules for a TCP/IP Network:
Data Link Protocol Encapsulation
Routers strip off old Data Link headers no longer needed and
replace them with new Data Link headers needed for next leg (hop)
of the data’s journey to its destination.
Encapsulation and De-encapsulation
Figure 3-23
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Defining the Rules for a TCP/IP Network:
Encapsulation Example
1. Sending device adds Ethernet Data Link header/trailer to data before
sending across LAN.
2, 3. Border router removes Ethernet header/trailer and adds new WAN
one (e.g., PPP) then sends data over WAN link.
4, 5. Destination border
router discards
PPP header/
trailer and adds
new Ethernet
header/trailer for
destination device
and sends data
over LAN.
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Defining the Rules for a TCP/IP Network:
Header/Trailer Encapsulation Example
Similar to steps you take when you take a long trip:
1.Start by taking subway train to airport.
2.Take plane to
another city.
3.Rent car at
destination.
4.Drive car to final destination.
None of above vehicles accomplished entire trip from start to finish;
takes planes, trains, and automobiles!
Routers Separate a Network into Separate Data Links
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Figure 3-24
Defining the Rules for a TCP/IP Network:
IP Addressing
 Identifies device in TCP/IP network.
 Every device must have unique IP address.
 IP address has 32 bits written in dotted decimal
notation (DDN) of four sets of eight bits each with dot
(period) between each number.
 Networking devices see decimal numbers as binary.
Binary IP Address
00000001
01010101
00001010
01111110
00100001
00001000
10101010
00000101
10000001
01000001
00010000
00001111
00011010
01010101
10000001
00100000
11110000
00010101
11111000
00010001
Example IP Addresses, Binary and DDN Formats
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Equivalent Decimal
IP Address
1.8.16.32
85.170.15.240
10.5.26.21
126.129.85.248
33.65.129.17
Table 3-1
Defining the Rules for a TCP/IP Network:
IP Addressing
Each PC with a connection into the TCP/IP network has a
unique IP address.
IP Addresses in a Network Diagram
Figure 3-25
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Defining the Rules for a TCP/IP Network:
IP Addressing
Routers play a big role with the IP protocol in that they route (forward)
data based on the destination IP address. To do that, a router must
connect using multiple interfaces to multiple data links.
Example: Each router has 2 interfaces:
One for WAN link and one for LAN.
Routers: Multiple Interfaces, Multiple IP Addresses
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Figure 3-26
Defining the Rules for a TCP/IP Network:
IP Addressing Grouping
 To make IP routing work, addresses grouped using rules.
 IP groups addresses in different ways: Classful networks
and subnetting .
 Rules give network engineers
flexibility in how
they assign
addresses, but
still allow IP routing
to work efficiently.
Five Classful IP Networks
Figure 3-27
52
Defining the Rules for a TCP/IP Network:
IP Addressing Grouping
IP Classful Networks
Class
IP Range
Designed for
A
1.0.0.0 – 126.255.255.255
Large enterprises, government
agencies, etc.
B
128.0.0.0 – 191.255.255.255
Medium-sized businesses,
organizations, etc.
C
192.0.0.0 – 223.255.255.255
For small entities and home
networks
D
224.0.0.0 – 239.255.255.255
Multicast
E
240.0.0.0 – 255.255.255.255
Experimental, research
Five Classful IP Networks
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Defining the Rules for a TCP/IP Network:
IP Addressing Update—IPv6
 IP version 4 addresses no longer issued out (all used).
 Based on 32-bit addresses 192.168.3.5, dotted decimal.
 IP version 6 is new IP addressing scheme.
 Based on 128-bit address.
 Expressed in 8 sets of 4 hexadecimal numbers, for example:
2001:0db8:85a3:0000:0000:8a2e:0370:7334.
 Creates billions and billions of IP addresses: 2128, or
approximately 3.4×1038 (a number with 37 zeros).
 For all practical purposes, eliminates classful networks
and need for subnetting.
 World IPv6 Launch took place on 6 June 2012.
Five Classful IP Networks
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Defining the Rules for a TCP/IP Network:
IP Routing
 IP routing defines exactly how routers forward data in
network.
 Each router connects to multiple physical links so has
multiple physical interfaces (ports).
 Router has rules that tell it how to make routing
decisions.
 IP routing relies on two ideas:
 Sender addresses data.
 Routers forward data based on destination IP address.
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Defining the Rules for a TCP/IP Network:
IP Routing
 Moving data on network relies on routers to forward
data to correct destination host.
 Routers talk to each other (using protocols) to learn
about IP addresses in network.
 Routers keep routing information in their RAM in IP
routing tables.
Routing Tables on R1 and R2, for Network 12.0.0.0
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Figure 3-29
Defining the Rules for a TCP/IP Network:
IP Routing
PC11 sends an IPv4 packet to PC21 by adding an IP header that includes
its address and the destination’s IPv4 address to the data (payload).
Web Client Host PC11 Puts 12.1.1.21 into the IP Header Destination IP Address Field
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Figure 3-28
Defining the Rules for a TCP/IP Network:
IP Routing
1. PC11 sends data with destination IPv4 address 12.1.1.21 (PC21) to R1.
2. R1 compares destination
IP address listed in header
with its routing table. R1 finds
matching table entry that tells
R1 to send data14.1.1.2
(R2).
3. R21sends packet to
router R2.
4, 5. R2’s routing table says
that network IPv4 12.0.0.0 is local so R2 forwards
data over LAN directly to PC21.
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Defining the Rules for a TCP/IP Network:
Forwarding Packets
 IP creates and adds IP header to payload.
 Sending host adds IP header (Network Layer address)
and Data Link layer header/trailer before sending data
onto network.
 IP header follows Data Link header in frame.
Encapsulation on the Sending Host: Frame and Packet
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Figure 3-30
Defining the Rules for a TCP/IP Network:
Forwarding Packets
 Frame: Encapsulated data that includes Data Link
header and trailer—plus everything in between (including
IP header).
 Packet: What sits between Data Link header and trailer.
 Router discards Data Link header and trailer when it
receives frame, leaving IP packet.
 Router then encapsulates packet into new Data Link
header and trailer (with next hop Data Link address)
when it forwards IP packet.
 Encapsulation/de-encapsulation process continues until
IP packet delivered to destination.
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Defining the Rules for a TCP/IP Network:
Routing IP Packets
Routers: Remove Packet from Frame, Send Packet inside a New Frame
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Figure 3-31
Defining the Rules for a TCP/IP Network:
Routing IP Packets
1. Sending host sends Ethernet frame to router.
2. Router:
a. Removes IP packet from inside frame and discards old Data Link
header/trailer.
b. Decides where to route IP packet (to next router across WAN link).
c. Encapsulates packet in new PPP frame and sends across link.
3. PPP frame holds original IP packet as it crosses WAN link
to destination router.
4. Destination router repeats same three steps as sending
router.
5. Ethernet frame (with original IP packet) crosses LAN and
arrives at destination device.
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Defining the Rules for a TCP/IP Network:
Transport Protocols
Transport layer protocols provide the connection to network
applications (apps).
Widening Scope of Higher TCP/IP Layers
Figure 3-32
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Defining the Rules for a TCP/IP Network:
Transport Protocols TCP and UDP
 Transport layer connects source and destination
applications.
 Port number: Used by transport protocol to identify
each destination app.
 Transmission Control Protocol (TCP) – Connectionoriented.
 User Datagram Protocol (UDP) – Connectionless.
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Defining the Rules for a TCP/IP Network:
TCP/IP Roles Summary, Part 1
 TCP/IP network delivers bits from one device to another
and from one application to another.
 Applications run on various devices.
 Application vendors use protocols that let apps
communicate through network.
 Application layer protocols rely on Transport layer
protocols to connect sending app to destination app.
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Defining the Rules for a TCP/IP Network:
TCP/IP Roles Summary, Part 2
 Each application’s writer chooses to use TCP, UDP, or
some other less common Transport protocol.
 TCP and UDP use port numbers (specified in header)
that identify destination app.
 Transport layer protocols rely on IP to deliver packets
from sending host to destination host.
 Sending host adds IP header which includes destination
IP address.
 Each router reacts to destination IP address to make
routing choice.
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Defining the Rules for a TCP/IP Network:
TCP/IP Roles Summary, Part 3
 IP defines details to make network communication
possible, including logical IP addressing and routing.
 IP relies on Data Link and Physical layers to deliver
frames across LANs and WANs.
 Data Link layer defines how to best use physical link,
and adds Data Link headers/trailers that contain
delivery information (MAC addresses).
 Physical layer defines how to encode bits over cable or
wirelessly.
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Defining the Rules for a TCP/IP Network:
TCP/IP Roles Summary, Part 4
Host or
Network
Layer Name Key Functions
Physical parts that communicate, and energy
Physical
Network
over those parts (electricity, light, radio).
Data Link
Rules about when to use physical links;
Addressing specific to the physical links.
Network
Internetwork Logical addressing (addressing independent
Network
(Network)
of the physical links); routing.
Communications functions useful to apps,
Transport
Host
but likely useful to many apps.
Communication functions specific to a
Application
Host
particular app.
TCP/IP Model Summary
Device Focus
Cables, radio
LAN Switch
Router
Any endpoint
device
Any endpoint
device
Table 3-2
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Summary: This chapter…
 Distinguished between the key terms related to
networking standards, including standard, protocol, and
model.
 Listed the layers of the TCP/IP model and explained
the purpose of the TCP/IP model.
 Named standards organizations on which the TCP/IP
model relies.
 Briefly compared the history of the OSI and TCP/IP
models and classified the layers of each in comparison
to each other.
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Summary: This chapter…
 Summarized the key functions of Ethernet LANs.
 Summarized the key functions of leased line WANs.
 Explained how IP addressing and IP routing work
together.
 Defined how different headers help move data through
a network.
 Listed two Transport layer protocols: TCP and UDP.
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Questions? Comments?
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