elec2 - lecture 1

Elective 2 – Windows Server Management

By: Aaron Angeles

OSI Layers Network Terms Subnets

Topics

Multimedia – OSI Layers

media\2276_1_A_OSI.htm

OSI

1978

to define a unifying standard for the architecture of networking systems

International Telegraph and Telephone Consultative Committee and International Organization for Standardization (ISO)

Officially rolled out by ISO as Open Systems Interconnection model by 1984.

OSI Layers

OSI Layers7 Layers:7 - Application6 - Presentation5 - Session4 - Transport3 - Network2 - Data-Link1 - Physical

“All People Seem To Need Data Processing”

Each layer defines networking tasks

Each layer communicates with the layers above and below it

Layer 7 provides services for programs to gain access to the network

Layers 1 & 2 define the network’s physical media and related tasks

OSI

Application Layer ( Layer 7)

Provides an entrance point for programs (e.g. web browsers, e-mail system) to gain network services

Represent application programming interfaces (APIs) that developers can use to perform network functions when building applications

OSI

Presentation (Layer 6)

◦ Translates data between computing systems on a network

◦ Performs:

– data encryption

– data compression

– data conversion

OSI

Session (Layer 5)

◦ Enables two application to create a persisten communication connections.

◦ Ensures that both sender and receiver are ready to communicate

OSI

Transport (Layer 4)

◦ Ensures packets are delivered in order in which they are sent without loss or duplication.

◦ On the sending side, this layer is responsible for braking down larger messages into smaller packets for transmission

◦ On the receiving end, this layer is responsible for reassembling the packets into a single message to pass up to the upper layer

OSI

Network (Layer 3)

◦ Determines the physical path of the data to be transmitted based on the network conditions, priority of server and other factors.

◦ The only layer that uses logical networking and can move packets between different networks.

OSI

Data-link (Layer 2)

◦ Provides error free transfer of data frames from one computer to another over the physical layer. The Media Access Control (MAC) address of the network card exists at this layer that is added to the packet to create a frame.

OSI

Physical Layer (Layer 1)

◦ Establishes the physical interface and mechanisms for placing a raw stream of data bits on the network cabling.

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OSI

TCP/IP in Relation with OSI

Video

OSI

TCP/IP Protocol Suite

◦ Is an industry standard suite of protocols that provides communication in a heterogeneous environment.

◦ Only has four layers: Application Transport Internet Network Interface

OSI

OSI

TCP/IP in Relation to OSI Model

OSI

Network Terms

Hubs – operate at the physical layer of the OSI model.- Can only perform tasks with the

electrical signal on the network - regenerate 1s and 0s on network

cabling- unable to make decisions about where the regenerated signal should be sent.- synonymous to a “Repeater” - sometimes called as a “Multiport Repeater”

Network Terms

Bridge- is a network device that are able to control network traffic based on MAC addresses.

Switches- has the same functionality of a bridge- creates a table that lists port location of each computer and direct packets to the destination computer.

Network Terms

Routers- operate at the network layer of the OSI model.- moves packets from one logical networks to another

Gateway- is a device that converts one protocol to another.- can operate at any layer of the OSI Model, depending on which protocol is being converted. (e.g. SNA gateway)

Network Terms

HTTP – Hypertext Transfer Protocol (80) - specifies the client/server interaction

processes between web browsers and servers

FTP – File Transfer Protocol (21)- Performs file transfer and basic file

management task on remote computers

Network Terms

SMTP – Simple Mail Transfer Protocol (25)- carries email messages between

servers and from client to servers

DNS – Domain Name System (53)- Resolves internet host names to IP

addresses for network communications.

Network Terms

POP3 – Post Office Protocol Version 3 (110)- used by mail clients for reading

emails

SNMP – Simple Network Management Protocol (161)

- enables to collect information about network devices such as hubs, routers and bridge.

Network Terms

TCP – Transmission Control Protocol- provides connection-oriented reliable

communications for applications

UDP – User Datagram Protocol- provides connectionless and

unreliable communication.

Network Terms

IP – Internet Protocols- addresses and routes packets between hosts and networks.

ARP – Address Resolution Protocol.- obtains hardware address of hosts

located on the same physical network

Network Terms

IGMP – Internet Group Management Protocol- manages host membership in IP

multicast groups

ICMP – Internet Control Message Protocol- Sends messages and reports errors

regarding the delivery of a packets.

Network Terms

Subnet Mask

Subnet Mask- defines the part of an IP address that is the network ID and the part of an IP address that is the host id.- composed of four octets, similar to an IP address

Subnet Mask

Video

Subnetting