Network protocols and architecture

Week 1-Introduction

• Three elements to communication: Sender, receiver and transmission medium.
• Protocols-rules that govern communication/computers have protocols too.
• Ethernet-governs network interface card to nic within same network
• IP- governs comm from original source all the way to final communication (routers know where packets are goin)
• TCP-makes sure info gets there reliably and in sequential order
• HTTP-governs exchange or transfer of html (hyper text markup lang)
• Devices on a local network must share a common protocol
• Protocols-Timing(speed of transmission of bits)
• -Message size,Message format,Message patterns
• -Encapsulation-header message in addition to data that contains the source and destination addresses
• -Encoding-message converted to bits and these bits are encoded into light waves,sounds or electrical pulses and then received
• and then decoded by the destination.

Internet standards

• ISO, IEEE, ICANN, IANA, IETF-develop, publish and maintain these protocols
• Makes it possible for different types of devices to work together
• RFC-request for comments- each stage of development and approval of a new standard is stored
• IETF-Internet Engineering Task Force- manage and publish the RFC.

How protocols work-STACKING

• Stacking protocols-The protocols are stacked in increasing hierarchical order with the higher ones depending on the lower ones. also
• the protocols are implemented in both the hardware and software of the hosts. there is an intercomm. required between the protocols for co-ordination.
• WEB SERVER CONNECTED TO (Decreasing order of hierarchy)
• 1) HTTP
• 2) TCP
• 3) IP
• 4)ETHERNET
• The sep of functions enables each layer of the stack to operate independently.

How protocols work-LAYERED

• Layered model is nothing but a framework to understand how the different levels work together. These levels are all independent of each other however, the lower levels provide an interface to the higher levels.
• Each layer has protocols with defined info that they act upon and also a defined interface to the layers above and below it. so consider it to be a structure with two fields-information and interface.
• BENEFITS- 1) Assists in protocol design
• 2) Products from different vendors can work together because there is a common standard so it fosters competition-quality inc.
• 3) Technology changes in one level dont affect the other levels.
• INTERNET MODEL-early 1970s-first layered model-TCP/IP MODEL.
• 4 categories of functions- APPLICATION-data to user and encoding and dialogue control-http
• TRANSPORT-supports comm. between diverse devices among diverse networks.-tcp
• INTERNET-best path to take thru the network is determined-ip
• NETWORK ACCESS-controls the hardware devices and media that make up the network-ethernet

2 types of network models

• 1) PROTOCOL MODEL- DEFINES THE FUNCTIONS THAT EACH PROTOCOL AT EACH LEVEL IMPLEMENTS EG-tcp model.
• 2) REF MODEL-ONLY PROVIDES A FRAMEWORK BECAUSE IT SAYS WHAT FUNCTION IS TO BE COMPLETED AT EACH LEVEL BY THE PROTOCOL BUT IT DOESNT SAY HOW THE FUNCTION IS COMPLETED.
• EG: OPEN SYSTEMS INTERCONNECTION MODEL was created by the osi project at ISO.
• Its is used for network design, operation specification and troubleshooting.
• Division of tasks-vehicle manufacturing example.
• 7 layers
• Transport layer has common functionality between the two models.

PROTOCOLS FOR WIRED NETWORKS

• Why ethernet?
• Standards developed.
• ADVANTAGES-competition, vendor choices, product development, facilitate design, consistent interconnections.
• Ethernet has become the most standard protocol for wired local networks. IEEE 802.3.
• Ethernet specifies standards for layer 1 and 2 of OSI- physical and data link.
• Also the ethernet is constantly evolving- speed of data transfer.
• IEEE is responsible for maintaining its standards.
• ETHERNET ADDRESSING- each ethernet network interface comes with a mac address(media access control) that is used to identify the source and destination hosts. When the message is sent by the source host, its received by all the other hosts but only opened by the one whose address matches the encapsulated address of the destination. The other hosts will ignore this message since it isnt addressed to them.
• Ethernet switches can filter frames to send the message only to the destination.
• The mac address is burned onto the network interface card.

LAB

• organizationally unique identifier and unique id for interface make up the 6 byte mac address. the vendor must be registered with ieee to make the NICs. the mac address can hence be used to identify the vendor .
• Relearn.
• A device can have more than one mac address.
• It represents the physical address of the device.
• Command prompter- ipconfig /all
• Each mac address has 12 hexadecimal digits-6 sets of 2 hexadecimal digits each-the entire address is 6 bytes long.
• Email softwares have the same protocols and standards that they follow which allows for compatibility between devices like pc and phones. etc.

Slide 8