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Group 5 - Coggle Diagram
Group 5
Describe the purpose and function of the data link layer for transmission on specific media.
Message Segmentation
Large streams of data are
divided into smaller pieces
multiplexing.
Each piece must be labeled.
only the missing pieces need
to be retransmitted
Protocol Data Units
As application data is passed down
the protocol stack, information is
added at each level.
Data
Segment
Packet
Frame
Bits
encapsulation
Encapsulation Example
The encapsulation
process works from top
to bottom
De-encapsulation
The de-encapsulation
process works from
bottom to top.
the process used by a receiving device to remove one or more of the protocol headers.
Network Addresses
Responsible for delivering
the IP packet from the
original source to the final
destination.
Source IP address
Destination IP address
Data Link Addresses
to deliver the data link frame from one
network interface to another network
interface on the same network.
Devices on the Same Network
The network layer addresses, or IP
addresses
Network portion
Host portion
The data link frame which uses MAC
addressing, is sent directly to the receiving device.
Source MAC address
Destination MAC address
Devices on a Remote Network
The data link frame cannot be
sent directly to the remote
destination host.
Sending to a remote network -
the source and destination IP
addresses represent hosts on
different networks.
Explain how the ARP process in sending packet to a destination network.
At the network layer when the source wants to find out the MAC address of the destination device it first looks for the MAC address (Physical Address) in the ARP cache or ARP table. It present there then it will use the MAC address from there for communication. If you want to view your ARP cache in ( Windows Operating System) then open Command Prompt and type command-'arp -a' (without quotes)
If the MAC address is not present in the ARP table then the source device will generate an ARP Request message. In the request message the source puts its own MAC address.Its IP address, destination IP address and the destination MAC address is lets blank since the source is trying to find this.
The ARP reply message is unicast and it is not broadcasted because the source which is sending the ARP reply to the destination knows the MAC address of the source device. When the source receives the ARP reply it comes to know about the destination MAC address and it also updates its ARP cache. Now the packets can be sent as the source nows destination MAC address
If the MAC address is not present in the ARP table then the source device will generate an ARP Request message. In the request message the source puts its own MAC address, its IP address, destination IP address and the destination MAC address is left blank since the source is trying to find this.
The device whose IP address has matched with the destination IP address in the packet wit reply and send the ARP Reply message. This ARP Reply message contains the MAC address of this device. The destination device updates its ARP table and stores the MAC address of the source as it will need to contact the source soon. Now, the source becomes destination(target) for this device and the ARP Reply message is sent
Explain why the IPv4 protocol requires other layers to provide reliability.
IP address depletion
IPv4 has a limited number of
unique public IPv4 addresses available.
Although
there are about 4 billion IPv4 addresses, the
exponential growth of new IP- enabled devices has
increased the need.
Internet routing table expansion
A routing table
contains the routes to different networks in order to
make the best path determination.
As more devices
and servers are connected to the network, more
routes are created.
A large number of routes can slow
down a router
Lack of end-to-end connectivity
Network Address
Translation (NAT) was created for devices to share a
single IPv4 address.
Because they are
shared, this can cause problems for technologies that
require end-to-end connectivity.
Describe the purpose of ARP
-A communication protocol
-used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address
Describe the basic characteristics of media access control methods on WAN and LAN topologies.
Physical WAN Topologies
Point-to-Point
Permanent link
between two endpoints.
Hub and Spoke
A central site
interconnects branch sites using
point-to-point links
Mesh
Provides high availability, but
requires that every end system be
interconnected to every other
system.
Physical LAN Topologies
Star
End devices are connected to a central
intermediate device.
Use Ethernet switches.
Extended Star
Additional Ethernet switches
interconnect other star topologies.
Bus
Used in legacy networks.
Switches are not required to interconnect the
end devices.
using coax cables
were used in legacy Ethernet networks（inexpensive and easy to set up.）
Ring
The ring does not need to be
terminated
used in
legacy Fiber Distributed Data Interface (FDDI)
and Token Ring networks.
QUESTION3: Describe the characteristics and functions of the data link frame.
Characteristic
Frame Header: It contains the source and the destination addresses of the frame and the control bytes
Payload field: It contains the message to be delivered.
Trailer: It contains the error detection and error correction bits.
Functions
Addressing- Indicates the source and destination nodes
Frame start and stop indicator flags - Identifies the beginning and end limitsof the frame.
Type - Identifies the Layer 3 protocol in the data field.
Control - Identifies special flow control services such as QoS.
Data - Contains the frame
payload.
QUESTION 4:Differentiate the roles of the MAC address and the IP address.
When the destination IP address is on a remote network, the destination MAC address will be the address of the host’s default gateway.