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CHAPTER 2.3 Describe Ethernet And ARP - Coggle Diagram
CHAPTER 2.3 Describe Ethernet And ARP
2.3.1 Describe the purpose of ARP
(ANDY)
The Address Resolution Protocol (ARP) is 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. This mapping is a critical function in the Internet protocol suite.
2.3.2 Explain why the IPv4 protocol requires other layers to provide reliability
(FAHIM)
The Network Layer
Which is resides at OSI Layer 3, provides services that allow end devices to exchange data across a network . The network layer uses four processes in order to provide end-to-end transport
1. Addressing of end devices
2. Encapsulation
3. Routing
4. De-encapsulation
There are several network layer protocols in existence however the most commonly implemented are
Internet Protocol version 4 (IPv4)
and
Internet Protocol version 6 (IPv6)
Characteristics of the IP Protocol
IP was designed as a protocol with low overhead - it provides only the function required to deliver a packet from the source to a destination. An IP packet is sent to the destination without prior establishment of a connection
1. IP - Connectionless
IP is a connectionless protocols with no dedicated end-to-end connection is created before data is sent.
Its very similar process as sending someone a letter through snail mail. Sender do not know wheather or not the destination is present, reachable or functional before sending packets.
2. IP- Best Effort Delivery
IP is a Best Effort Delivery protocol whicj is IP is considered "unreliable" because it does not gurantee that all packets that are sent will be recieved.
Unrealiable means that IP does not have the capability to manage and recover from undelivered, corrupt, or out of sequence packets
3.IP-Media Independent
Operates independently from the media that carries the data at lower layers of the protocol stack and it does not care if the media is copper cables, fiber optics or wirelss
IPv4 Packet Header
(NURUL)
consists of the fields containing binary numbers.
these numbers identify various settings of the IP packet which are examined by the Layer 3 process
significant fields include:
version
protocol
source IPv4 address
has been updated to address new challenges
IP address depletion
IPv4 has a limited number of unique public IPv4 addresses available.
Internet routing table expansion
A routing table contains the routes to different networks in order to make the best path determination.
Lack of end-to-end connectivity
Network Address Translation (NAT) cause problems for technologies that
require end-to-end connectivity
IPv6 Packet Header
(NURUL)
Introducing IPv6 :
The IETF started looking at a replacement for IPv4 - which led to IPv6
Advantages of IPv6
Increased address space
Improved packet handling
Eiminates the need for NAT
Encapsulating IPv6
Advantages of IPv6 over IPv4 using the simplified header
Hiearchical network architecture for routing efficiency
Simplified header format for efficient packet handling
Autoconfiguration for addresses
The IPv 6 is simpler than the IPv4 header
Version
- Consist a 4 bit binary value set to 0110 that identifies it as a IPv6 packet.
traffic class
- 8 bit field equavalent to the IPv4 Differentiated Services (DS) field.
flow label
- 20 bit field suggests that all packets with the same flow label receive the same type of handling by router
payload length
- 16 bit feild indicates the lenght of the data portion or playload of the packet
next header
- 8 bit field is equivalent to the IPv4 Protocol equivalent to the data payload type that the packet is carrying
hop limit
- 8 bit field replaces the IPv4 TTL field
source IPv6 address
- 128 bit field that identifies the IPv6 address of sending host
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2.2.3 Explain how network devices use routing tables to direct packets to a destination network
(BET & DAYANG)
Host Forwarding Decision
◦ An important role of the network layer is
to direct packets between hosts Ahost can send a packet to;
Itself – A host can ping itself for testing purposes using 127.0.0.1 which is referred to as the loopback interface
Local host – This is a host on the same local network as the sending host.The hosts share the same network address
Remote host – This is a host on a remove network.The hosts do not share the same network address.
Default Gateway
The default gateway is the network devices that can route traffic out to other networks.It is the router that routes traffic out of local network
The default gateway will know where to send the packet using its routing table.
A host’s routing table usually includes a default gateway address which is the router IP address for the network that the host is on.
configured creates a default route in the routing table of a host which is the route the computer will send a packet to when it needs to contact a remote network
Host Routing Tables
on the windows hosts can display the routing table using
route print
and
netstat -r
◦ Three sections will be
displayed
Interface List
IPv4 Route Table
IPv6 Route Table
