comnet2 Flashcards
that’s connected using a hub, which is basically just an antiquated
device that connects wires together.
Local Area Network
is breaking up a massive network into a number to smaller one.
Network Segmentation
3 networking Devices
Routers
Switches
Bridges
Causes of LAN traffic Congestion
• Too many hosts in a collision or broadcast domain
• Broadcast storms
• Too much multicast traffic
• Low bandwidth
• Adding hubs for connectivity to the network
• A bunch of ARP broadcasts
are basically employed to efficiently break up a broadcast domain
Routers
are allowed to “hear” all broadcasts sent out on that specific segment.
Routers
provide connections to wide area network (WAN) services as well via a
serial interface for WAN connections
Routers
the set of all devices on a network segment
Broadcast Domain
Router functions in the network:
Router functions in the network:
• Packet switching
• Packet filtering
• Internetwork communication
• Path selection
it forwards or filter frames using logical addressing and provide an
important capacity.
Packet Switching
is connect two or more networks together and use logical addressing
(IPv4 or IPv6)
Internetwork
is an Ethernet term used to describe a network scenario in which one
device sends a packet out on a network segment and every other
device on that same segment is forced to pay attention no matter
what.
Collision Domain
- basically do the same thing—break up collision domains on a LAN
Bridged and Switches
These devices connect wireless devices such as computers, printers, and tablets to the network. Since pretty much every device
manufactured today has a wireless NIC, you just need to configure a
basic access point (AP) to connect to a traditional wired network.
WLAN devices
These devices allow wireless devices to connect to a wired network
and extend a collision domain from a switch, and are typically in their
own broadcast domain or what we’ll refer to as a Virtual LAN (VLAN).
Access Points or APS
Can be a simple standalone device, but today they are usually
managed by wireless controllers either in house or through the
intern
Access Points
These devices are network security systems that monitor and control
the incoming and outgoing network traffic based on predetermined
security rules, and is usually an Intrusion Protection System (IPS).
Firewalls
OSI meaning
Open systems interconnection
ISO meaning
International Organization for Standardization
In the late 1970s, the Open Systems Interconnection (OSI) reference model
was created by the International Organization for Standardization (ISO) to
break through this barrier.
Internetworking Models
model was meant to help vendors create interoperable network
devices and software in the form of protocols so that different vendor
networks could work in peaceable accord with each other.
OPEN SYSTEMS INTERCONNECTION
the primary architectural model for networks. It describes
how data and network information are communicated from an application
on one computer through the network media to an application on another
computer. The OSI reference model breaks this approach into lay
OSI model
is a conceptual blueprint of how communications should take place.
Reference Model
processes required for effective communication and divides them into logical groupings hierarchical or layered architecture a
communication system is design.
Layers
is a logical model, not a physical one.
OSI model
It’s essentially a set of guidelines that developers can use to create
and implement applications to run on a network.
OSI model
It also provides a framework for creating and implementing
networking standards, devices, and internetworking scheme
OSI model
Layer that define how the applications within the end
stations will communicate with each other as well as with users.
Three top layers ( Layer 7(Application) ,6 (presentation) ,5(session))
Layer that define how data is transmitted end to end.
Bottom four layer (layer 4(transport) ,3(network) ,2(Data Link),1 (Physical)
The OSI reference model has the following seven layers:
• Application layer (layer 7)
• Presentation layer (layer 6)
• Session layer (layer 5)
• Transport layer (layer 4)
• Network layer (layer 3)
• Data Link layer (layer 2)
• Physical layer (layer 1)
The layer that provides the user interface
Layer 7 ( Application )
Layer that presents data snd handles processing such as encryption
Presentation layer
Layer that keeps different applications data separate
Session layer
Layer that provides reliable or unreliable delivery and performs error correction before retransmit
Transport layer
Layer that provides logical addressing, which routers use for path determination
Network layer
Layer that combines packets into bytes, bytes into frames. It also provide access to media using MAC address. Perfroms error detection
Data link Layer
Layer that moves bits into devices. It also specifies voltage, wire speed, and pinout of cables
Physical layer
Its function is to file, print, message, databaseand application services
Application layer( layer 7)
Its function is to Data encryption, compression and translation services
Presentation layer( layer6)
Its function is to dialog control
Session layer (layer 5)
Its function is to provide end to end connection
Transport layer (layer 4)
It’s function is tl route
Network layer (layer 3)
It’s function is framing
Data link layer (layer 2)
Its function is to provide physical topology
Physical layer (layer 1)
the OSI model marks the spot where users
actually communicate to the computer and comes into play only
when it’s clear that access to the network will be needed soon.
Application layer
Here are a few good examples of these kinds of events:
• File transfers
• Email
• Enabling remote access
• Network management activities
• Client/server processes
• Information location
Application Layer
layer gets its name from its purpose: It presents
data to the Application layer and is responsible for data translation
and code formatting. Think of it as the OSI model’s translator,
providing coding and conversion services. One very effective way of
ensuring a successful data transfer is to convert the data into a
standard format before transmission.
Presentation layer
responsible for setting up, managing, and
dismantling sessions between Presentation layer entities and keeping
user data separate. Dialog control between devices also occurs at this
layer.
Session layer
Three Different Modes: (session layer)
• Simplex
• Half-duplex
• Full-duplex
simple one-way communication, kind of like saying
something and not getting a reply.
Simplex
is actual two-way communication, but it can take place in
only one direction at a time, preventing the interruption of the
transmitting device..
Half Duplex
is exactly like a real conversation where devices can
transmit and receive at the same time, much like two people arguing or
interrupting each other during a telephone conversation.
Full duplex
layer segments and reassembles data into a single data
stream
Transport layer
responsible for providing mechanisms for
multiplexing upper layer
Transport layer
device that transmit and
establish a connection-oriented communication session with a
remote device
Call set up or three way handshake
First segment in Three way handshake
Synchronization
Second segment in three way handshake
acknowledge (ACK) the request and establish
connection parameters—
The final segment in three way handshake
Acknowledgement
Its job is to ensure data integrity at the Transport layer
by allowing applications to request reliable data transport between
systems.
Flow control
is the quantity of data segments, measured in bytes, that the
transmitting machine is allowed to send without receiving an
acknowledgmen
Windowing
Reliable data delivery ensures the integrity of a
stream of data sent from one machine to the other through a fully
functional data link
Acknowledgement
technique that
requires a receiving machine to communicate with the transmitting
source by sending an acknowledgment message back to the sender
when it receives data.
CCNA Routing a
Positive acknowledgement
manages device addressing, tracks the
location of devices on the network, and determines the best way to move
data.
Network layer
layer to transport traffic between devices that aren’t locally
attached.
Network layer
these are used to transport user data through the
internetwork.
Data packets
these packets are used to update neighboring
routers about the networks connected to all routers within the internetwork.
Route update packet
send route update packets.
Routing protocols
specific network addresses.
NAP ( network access protocol)
The exit interface a packet will take when destined for a
specific network.
Interface
The distance to the remote network. Different routing
protocols use different ways of computing this distance.
Metric
What is the layer 2 of a router
bridging functions
What is the function of the layer 3 in router
provide connections between
virtual LANs (VLANs)
provides for the physical transmission of data and
handles error notification, network topology, and flow control.
Data Link
layer will ensure that messages are delivered to the proper
device on a LAN using hardware addresses and will translate
messages from the Network layer into bits for the Physical layer to
transmit.
Data link Layer
The Data Link layer formats the messages, each called
Data frame
Defines how packets are placed on the
media. Contention for media access is “first come/first served” access
where everyone shares the same bandwidth— hence the name.
Media Access Protocol
it’s the signal path through a physical topology.
Logical topology
Responsible for identifying Network layer
protocols and then encapsulating them
Logical link control (LLC)
tells the Data Link layer what to do with a packet once
a frame is received.
LLC Header
can also provide flow control and sequencing of control bits.
LLC
is considered hardware-based bridging because it
uses specialized hardware called an application-specific integrated
circuit (ASIC).
- ASICs can run up to
Layer 2 switching
does two things: it sends bits and receives bits. Bits come only in
values of 1 or 0 - a Morse code with numerical values.
Physical Layer
communicates directly with the various types of actual
communication media. Different kinds of media represent these bit values in
different ways.
Physical Layer
really a multiple-port repeater
Hub
receives a digital signal, reamplifies or regenerates that signal, then
forwards the signal out the other port without looking at any data.
Repeater
a network refers to the physical layout of the
devices, but mostly the cabling and cabling layout.
Physical topology
defines the logical path on which the signal will travel
on the physical topology.
Logical topology
every workstation is connected to a single cable,
meaning every
host is directly connected to every other workstation in the network.
Bus topology
computers and other network devices are cabled
together in a
way that the last device is connected to the first to form a circle or ring.
Ring topology
The most common physical topology is a star topology, which is
your Ethernet switching physical layout. A central cabling device
(switch) connects the computers and other network devices together.
This category includes star and extended star topologies. Physical
connection is commonly made using twisted-pair wiring.
Star topology
