Below are the brief notes of ICND Part 1 v3 (100-105)
Disclaimer : These are self made notes which can help in understanding the topic of the syllabus.
Interconnecting Cisco Networking Devices Part 1 (100-105)
Syllabus :
1.0 Network Fundamentals - 20%
2.0 LAN Switching Fundamentals - 26%
3.0 Routing Fundamentals - 25%
4.0 Infrastructure Services - 15%
5.0 Infrastructure Maintenance - 14%
Full syllabus pdf is available in the below URL :
https://learningcontent.cisco.com/cln_storage/text/cln/marketing/exam-topics/100-105-icnd1-v3.pdf
Notes :
1.1 OSI and TCP/IP Model
Open Systems Interconnection model (OSI) and Transmission Control Protocol/Internet Protocol (TCP/IP) models are the protocols which allow the flow of data from one computer to another.
Below is the pictorial representation of those
TCP/IP is the initial method followed and OSI model is used for much better understanding. Here OSI model helps us understand the concept much better when compared to TCP/IP.
Pictorial Representation of OSI and TCP/IP model
TCP/IP model have 4 sections which describe the flow of data from one PC to another where as OSI model have 7 sections which explain the same. As you see, layer 4, Application layer in TCP/IP is classified into three separate layers in OSI model and layer 1, Link and Physical layer in TCP/IP is classified into two separate layers in OSI model. This helps us understand the data transmission better in OSI compared to TCP/IP model.
TCP/IP model Explaination :
layer 4 : Application Layer
This layer acquires data from the user, i.e. user is interacted with the computer on this layer. This layer includes the protocols like HTTP, FTP, DHCP, Telnet, etc.
layer 3 : Transport Layer
This layer transports the data acquired from the application layer to the internetwork layer by using the protocols like Transmission Control Protocol(TCP) and User Datagram Protocol(UDP). This layer mainly works on port numbers.
layer 2 : Internetwork Layer
This layer works on the Internet Protocol(IP) address i.e. the sender or the destination IP address.
This layer works on the Media Access Control(MAC) address and the physical connectivity i.e. the cable connectivity(copper cable, fiber cable, etc) from one computer to another.
For more reference : https://en.wikipedia.org/wiki/Internet_protocol_suite
OSI model Explaination :
layer 7 : Application Layer
This is the layer, where the user interacts with the computer through a software like HTTP, Telnet, etc.
Layer 6 : Presentation Layer
This layer gentrifies the data given by the user. Data conversion happens through SSL or other encryption formats.
Layer 5 : Sessions Layer
This layer creates and maintains sessions which run through the computer. For example, if both applications like telnet and HTTP are running, then this layer maintains their sessions separately, i.e. if telnet session gets closed then HTTP session will still run.
After the three layers, DATA is generated
Layer 4 : Transport Layer
This layer breaks the data into segments and assigns TCP or UDP layer depending on the requirement of the application and assigns a port number so that it can forward the data through that port number to another computer. Here in this layer a segment is formed which consists of Data and port number.
DATA + Port Number = Segment
Layer 3 : Network Layer
This layer adds an IP address to the data. Here in this layer a packet is formed
Segment + IP Address = Packet
Layer 2 : Data Link Layer
This layer adds the MAC address to the data and is also responsible to check the CRC errors occurred in the transmission.
Packet + MAC Address + Error Check = Frame
Layer 1 : Physical Layer
This layer is the physical layer which consists of cables or the media which is used to connect two different computers. Data transfer from one computer to another happens in signals.
Frame + Bits = Signals
For more reference : https://en.wikipedia.org/wiki/OSI_model
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