Transcript Introduction to CCNA

CCNA
Tími 1
Network Icons
SOHO network
• SOHO network (small office/home office)
Overview of the TCP/IP Networking
Model
Transport Layer Protocols
• TCP is considered connection oriented
protocol and it has a build in error correction
and sequencing
• Similar to making a phone call, example:
Transport Layer Protocols
• UDP is considered connection less protocal, it
has no error connection so the application
must have using the it must have it.
• Similar to posting a letter, exchample:
Internet layer Protocols
• IP defines logical addresses used to
communicate over networks
• Each TCP/IP host—needs a unique address so
that it can be identified in the network
• Example of IP addresses:
• 1.1.1.1 , 2.2.2.2 , 192.168.10.1 ………….
• This format is called dotted-decimal notation
(DDN)
Example of a routed IP network
IP Routing Basic
Network Access Layer
• The TCP/IP model’s network access layer
defines the protocols and hardware required
to deliver data across some physical network.
Network Access Versus Data Link and
Physical Layers
TCP/IP model step by step
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Step 1 Create and encapsulate the application data
with any required application
layer headers. For example, the HTTP OK message
can be returned in an HTTP
header, followed by part of the contents of a web
page.
Step 2 Encapsulate the data supplied by the
application layer inside a
transport layer header. For end-user applications, a
TCP or UDP
header is typically used.
Step 3 Encapsulate the data supplied by the
transport layer inside an
Internet layer (IP) header. IP defines the IP addresses
that uniquely
identify each computer.
Step 4 Encapsulate the data supplied by the Internet
layer inside a data link
layer header and trailer. This is the only layer that
uses both a header
and a trailer.
Step 5 Transmit the bits. The physical layer encodes a
signal onto the medium
to transmit the frame.
Names of TCP/IP Messages
You must know this!!!!!!!
Transport layer
Network layer
Data link layer
Network layer
SEGMENT
PACET
FRAME
BITS
Comparing OSI and TCP/IP
OSI Layers and Their Functions
Layer
Functional Description
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Layer 7 provides an interface between the communications software and
any applications that need to communicate outside the computer on which
the application resides. It also defines processes for user authentication.
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This layer’s main purpose is to define and negotiate data formats, such as
ASCII text, EBCDIC text, binary, BCD, and JPEG. Encryption is also defined by
OSI as a presentation layer service.
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The session layer defines how to start, control, and end conversations
(called sessions). This includes the control and management of multiple
bidirectional messages so that the application can be notified if only some
of a series of messages are completed. This allows the presentation layer to
have a seamless view of an incoming stream of data.
OSI Layers and Their Functions
Layer
Functional Description
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Layer 4 protocols provide a large number of services, as described in
Chapter 6, “Fundamentals of TCP/IP Transport, Applications, and Security.”
Although OSI Layers 5 through 7 focus on issues related to the application,
Layer 4 focuses on issues related to data delivery to another computer (for
instance, error recovery and flow control).
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The network layer defines three main features: logical addressing, routing
(forwarding), and path determination. Routing defines how devices
(typically routers) forward packets to their final destination. Logical
addressing defines how each device can have an address that can be used
by the routing process. Path determination refers to the work done by
routing protocols to learn all possible routes, and choose the best route.
OSI Layers and Their Functions
Layer
Functional Description
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The data link layer defines the rules that determine when a device can send
data over a particular medium. Data link protocols also define the format of
a header and trailer that allows devices attached to the medium to
successfully send and receive data.
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This layer typically refers to standards from other organizations. These
standards deal with the physical characteristics of the transmission medium,
including connectors, pins, use of pins, electrical currents, encoding, light
modulation, and the rules for how to activate and deactivate the use of the
physical medium.
OSI Layering Benefits
• Less complex: Compared to not using a
layered model, network models break the
concepts into smaller parts.
• Standard interfaces: The standard interface
definitions between each layer allow for
multiple vendors to create products that fill a
particular role, with all the benefits of open
competition.
OSI Layering Benefits
• Easier to learn: Humans can more easily
discuss and learn about the many details of a
protocol specification.
• Easier to develop: Reduced complexity allows
easier program changes and faster product
development.
OSI Layering Benefits
• Multivendor interoperability: Creating products
to meet the same networking standards means
that computers and networking gear from
multiple vendors can work in the same network.
• Modular engineering: One vendor can write
software that implements higher layers—for
example, a web browser—and another vendor
can write software thatimplements the lower
layers—for example, Microsoft’s built-in TCP/IP
software in its OSs.
OSI Encapsulation and Protocol Data
Units
SEGMENT
PACKED
FRAM
PDU = Protocol Data Unit
BITS
Fundamentals of LANs
• The term Ethernet refers to a family of
standards that together define the physical
and data link layers of the world’s most
popular type of LAN.
• speeds of 10 megabits per second (Mbps), 100
Mbps, 1000 Mbps (1 gigabit per second, or
Gbps) or even 10Gbps being common today
Fundamentals of LANs
• The most commonly used Ethernet standards
allow the use of inexpensive unshielded
twisted-pair (UTP) cables.
• Fiber-optic cabling might be worth the cost in
some cases, because the cabling is more
secure and allows for much longer distances
between devices
The Data Link Layer
• The data link layer is divided into two sub layers
– The 802.3 Media Access Control (MAC) sub layer
– The 802.2 Logical Link Control (LLC) sub layer
• Each new physical layer standard from the IEEE
requires many differences at the physical layer.
However, each of these physical layer standards
uses the exact same 802.3 header, and each uses
the upper LLC sublayer as well. Table 3-2 lists the
most commonly used IEEE Ethernet physical layer
standards.
Common Types of Ethernet
Typical Small Modern LAN
This diagram applies to all the common types of Ethernet. The
same basic design and topology are used regardless of speed or
cabling type. The term LAN = Local Aria Network
Functions of Local Aria Networks
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File sharing
Printer sharing
File transfers
Gaming
Connection to the Web
And many more …………………….
Ethernet in the early days
• The two first Ethernet standard where:
– 10BASE2 also known as cheapernet, thin
Ethernet, thinnet, and thinwire. The caballing
used is coaxical connected in a bus. Maximum
length 185 meters with impedance of 50 Ω
– 10BASE5 also known as thick ethernet or
thicknet. The caballing used is coaxical connected
in a bus. Maximum length 500 meters with
impedance of 50 Ω
Ethernet 10BASE2 Network
Because the network uses a single bus, if two or more
electrical signals were sent at the same time, they would
overlap and collide, making both signals unintelligible.
The CSMA/CD algorithm
• A device that wants to send a frame waits
until the LAN is silent—in other words, no
frames are currently being sent—before
attempting to send an electrical signal.
• If a collision still occurs, the devices that
caused the collision wait a random amount of
time and then try again.
10BASE-T LAN Network With a Hub
Hubs are essentially repeaters with multiple physical ports. That
means that the hub simply regenerates the electrical signal that
comes in one port and sends the same signal out every other
port. Al ports on a Hub are in a single collision domain.
Using Hubs solved a lot of the reliability problems that exists in
bus networks.
UTP RJ-45 Connectors and Ports
Gigabit Interface Converters (GBIC)
• Cisco manufactures a wide range of GBICs and SFPs, for every
Ethernet standard, the switch can use a variety of cable
connectors and types of cabling and support different cable
lengths
• 1000BASE-T GBIC with an RJ-45 Connector
TIA Standard Ethernet Cabling Pinouts
• The Telecommunications Industry Association (TIA) defines
standards for UTP cabling, color coding for wires, and standard
pinouts on the cables
• The picture shows two pinout standards from the TIA, with the
color coding and pair numbers listed
Ethernet Straight-Through Cable
Concept
A straight-through cable is used when the devices on the ends of the
cable use opposite pins when they transmit data.
Ethernet Crossover Cable
• Because both switches send on the pair at pins 3,6, and receive on
the pair at pins 1,2, the cable must swap or cross the pairs
• For the exam, you should be well prepared to choose which type of
cable (straight-through or crossover) is needed in each part of the
network
Straight-Through and Crossover
Ethernet Cables
Ethernet Addressing
• Ethernet LAN addressing identifies either individual
devices or groups of devices on a LAN. Each address
is 6 bytes long.
• Example:
– D0-67-E5-3C-46-A0 or D0:67:E5:3C:46:A0
Ethernet Addressing
• Unicast Ethernet addresses identify a single LAN
card.
• Broadcast addresses: The most often used of the
IEEE group MAC addresses, the broadcast
address, has a value of FFFF.FFFF.FFFF
(hexadecimal notation).
• Multicast addresses: Multicast addresses are
used to allow a group of devices on a LAN to
communicate. When using IP multicasts over an
Ethernet, the multicast MAC addresses used
follow this format: 0100.5exx.xxxx,
Ethernet Framing
Framing defines how a string of binary numbers is
interpreted. Framing defines the meaning behind the bits
that are transmitted across a network. The physical layer
helps you get a string of bits from one device to another
Each frame must have a way to identify the upper layer
protocol to hand the data do.
To do that , most data-link protocol headers, including
Ethernet, have a field with a code that defines the type of
protocol header that follows. Generically speaking, these
fields in data-link headers are called Type fields.
Sending IP packets
when sending IP packets, the Ethernet frame has two
additional headers:
■ An IEEE 802.2 Logical Link Control (LLC) header
■ An IEEE Subnetwork Access Protocol (SNAP) header
Ethernet Header and Trailer Fields
Fundamentals of WANs
• Point-to-point WAN links provide basic
connectivity between two points.
Components and Terminology
Serial Cabling Options
WAN Speed Summary
OSI Layer 2 for Point-to-Point WANs
• Wan serial interface uses HDLC to encapsulate
data.
• HDLC needs to determine if the data passed
the link without any errors;
• HDLC discards the frame if errors occurred
• HDLC needs to identify the type of packet
inside the HDLC frame so the receiving device
knows the packet type
HDLC Framing
Point-to-Point Protocol
• PPP behaves much like HDLC. The framing looks
identical to the Cisco proprietary HDLC framing.
There is an Address field, but the a
• PPP has many additional features that had not
been seen in WAN data link layer (security,
passwords)
• PPP has become the most popular and featurerich of WAN data link layer protocols
• Can be used to connect CISCO and third party
devises
Frame Relay
• Frame Relay networks provide more features and
benefits than simple point-to-point WAN Links
• Frame Relay networks are multi-access networks,
which means that more than two devices can attach
to the network
• The access links run at the same speed and use the
same signaling standards as do point-to-point leased
lines. However, instead of extending from one router
to the other, each leased line runs from one router
to a Frame Relay switch.
Frame Relay Components
Frame Relay VC Concepts
• The logical path that a frame travels between each
pair of routers is called a Frame Relay VC.
• VCs are called permanent virtual circuits (PVC)
Fundamentals of IPv4
Addressing and Routing
Foundation Topics
• Routing: The process of forwarding packets (Layer 3 PDUs).
• Logical addressing: Addresses that can be used regardless of the
type of physical networks used, providing each device (at least) one
address. Logical addressing enables the routing process to identify a
packet’s source and destination.
• Routing protocol: A protocol that aids routers by dynamically
learning about the groups of addresses in the network, which in
turn allows the routing (forwarding) process to work well.
• Other utilities: The network layer also relies on other utilities. For
TCP/IP, these utilities include Domain Name System (DNS), Dynamic
Host Configuration Protocol (DHCP), Address Resolution Protocol
(ARP), and ping.
OSI layer 3 protocols
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Internet Protocol (IP) IPv4/IPv6
Novell Internetwork Packet Exchange (IPX)
AppleTalk Datagram Delivery Protocol (DDP)
Internet Control Message Protocol (ICMP)
Internet Group Multicast Protocol (IGMP)
Routing Information Protocol (RIP)
Address Resolution Protocol (ARP)
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IP Routing
IP Header
IPv4 Header Fields
Classes of Networks
All Possible Valid Network Numbers
A B C
• All A IP addresses start with 0
• All B IP addresses start with 10
• All C IP addresses start with 110
ARP