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Suleyman Demirel University, 2011 EXPLORATION 1 Chapter 5 OSI Network Layer By Zhamanov Azamat Suleyman Demirel University, 2011 EXPLORATION 1 Chapter 5 OSI Network Layer By Zhamanov Azamat

Suleyman Demirel University, 2011 Upon completion of this chapter, you will be able to: Suleyman Demirel University, 2011 Upon completion of this chapter, you will be able to: • Identify the role of the Network layer as it describes communication from one end device to another end device. • Examine the most common Network layer protocol, Internet Protocol (IP), and its features for providing connectionless and best-effort service. • Understand the principles used to guide the division, or grouping, of devices into networks. • Understand the hierarchical addressing of devices and how this allows communication between networks. • Understand the fundamentals of routes, next-hop addresses, and packet forwarding to a destination network.

Suleyman Demirel University, 2011 The Network Layer Suleyman Demirel University, 2011 The Network Layer

Suleyman Demirel University, 2011 NETWORK LAYER – COMMUNICATION FROM HOST TO HOST Suleyman Demirel University, 2011 NETWORK LAYER – COMMUNICATION FROM HOST TO HOST

Suleyman Demirel University, 2011 Four Basic Processes of Network Layer Processes Addressing Encapsulating Routing Suleyman Demirel University, 2011 Four Basic Processes of Network Layer Processes Addressing Encapsulating Routing Decapsulation

Suleyman Demirel University, 2011 Addressing • First, the Network layer must provide a mechanism Suleyman Demirel University, 2011 Addressing • First, the Network layer must provide a mechanism for addressing these end devices. If individual pieces of data are to be directed to an end device, that device must have a unique address. In an IPv 4 network, when this address is added to a device, the device is then referred to as a host.

Suleyman Demirel University, 2011 Encapsulation • Encapsulation? Suleyman Demirel University, 2011 Encapsulation • Encapsulation?

Suleyman Demirel University, 2011 Encapsulation • Encapsulation Packet Header Segment Suleyman Demirel University, 2011 Encapsulation • Encapsulation Packet Header Segment

Suleyman Demirel University, 2011 Encapsulation • After the Network layer completes its encapsulation process, Suleyman Demirel University, 2011 Encapsulation • After the Network layer completes its encapsulation process, the packet is sent down to the Data Link layer to be prepared for transportation over the media.

Suleyman Demirel University, 2011 Routing • Giving the path for destination Suleyman Demirel University, 2011 Routing • Giving the path for destination

Suleyman Demirel University, 2011 Decapsulation • Decapsulation? Suleyman Demirel University, 2011 Decapsulation • Decapsulation?

Suleyman Demirel University, 2011 Decapsulation • Decapsulation Packet Header Segment Suleyman Demirel University, 2011 Decapsulation • Decapsulation Packet Header Segment

Suleyman Demirel University, 2011 In Other Words Suleyman Demirel University, 2011 In Other Words

Suleyman Demirel University, 2011 Network Layer Protocols IPv 4 IPv 6 IPX (Nowell Internetwork Suleyman Demirel University, 2011 Network Layer Protocols IPv 4 IPv 6 IPX (Nowell Internetwork Packet Exchange Apple Talk (CLNS/DECN et)

Suleyman Demirel University, 2011 Network Layer Protocols Suleyman Demirel University, 2011 Network Layer Protocols

Suleyman Demirel University, 2011 Question • Which Layer 3 protocol is most popular? Suleyman Demirel University, 2011 Question • Which Layer 3 protocol is most popular?

Suleyman Demirel University, 2011 Answer • Currently IP version 4 (IPv 4) • In Suleyman Demirel University, 2011 Answer • Currently IP version 4 (IPv 4) • In future expected IP version 6 (IPv 6)

Suleyman Demirel University, 2011 IPv 4 Four Basic Characteristics IPv 4 Functionality Connectionless Best Suleyman Demirel University, 2011 IPv 4 Four Basic Characteristics IPv 4 Functionality Connectionless Best Effort(unreliable) Media Independent

Suleyman Demirel University, 2011 Connectionless Communication Suleyman Demirel University, 2011 Connectionless Communication

Suleyman Demirel University, 2011 Connectionless Communication Suleyman Demirel University, 2011 Connectionless Communication

Suleyman Demirel University, 2011 Best Effort • Unreliable? Suleyman Demirel University, 2011 Best Effort • Unreliable?

Suleyman Demirel University, 2011 Unreliable Suleyman Demirel University, 2011 Unreliable

Suleyman Demirel University, 2011 Best Effort (Unreliable) Suleyman Demirel University, 2011 Best Effort (Unreliable)

Suleyman Demirel University, 2011 Media Independence Suleyman Demirel University, 2011 Media Independence

Suleyman Demirel University, 2011 MTU – Maximum Transmission Unit • Different types of Media Suleyman Demirel University, 2011 MTU – Maximum Transmission Unit • Different types of Media have their own limitations of packet size which can be send. 802. 3 1492 bytes 802. 11 2272 bytes 802. 5 Tok en ring 4464 bytes FDDI 4500 bytes

Suleyman Demirel University, 2011 Fragmentation • Network layer makes fragmentation to enable transportation of Suleyman Demirel University, 2011 Fragmentation • Network layer makes fragmentation to enable transportation of data from media with bigger MTU to lower MTU

Suleyman Demirel University, 2011 Fragmentation MTU = 1492 bytes Fragment, Size 780 bytes MTU Suleyman Demirel University, 2011 Fragmentation MTU = 1492 bytes Fragment, Size 780 bytes MTU = 1492 bytes Packet, size 2272 bytes Fragment, Size 1492 bytes Fragment, Size 780 bytes Fragment, Size 1492 bytes MTU = 4500 bytes Fragment, Size 780 bytes

Suleyman Demirel University, 2011 Packet is… Suleyman Demirel University, 2011 Packet is…

Suleyman Demirel University, 2011 Packet is… • Packet Header Segment Suleyman Demirel University, 2011 Packet is… • Packet Header Segment

Suleyman Demirel University, 2011 Consists of two Flags: 1. MF(More Fragment) = 1 bit Suleyman Demirel University, 2011 Consists of two Flags: 1. MF(More Fragment) = 1 bit 2. DF(Don’t Fragment) = 1 bit Packet Header Defines Packet Header + Data Length, Specifies Priority of Packet, used for Qo. S If MF statement is 0 means that this is last fragment Sequence number of Fragment Uniquely identifies fragments of an original Defines Version of IP Protocol Defines Size of Packet Header, Needed because Minimum size is 20 bytes = 20 bytes of of packet, if statement is 1 means that there is one IP Packet size can be changed Packet Header + 0 bytes of Data, and more fragment is coming. Maximums size is 65, 535 bytes If DF statement is 0 it means that packet can be fragmented, is statement is 1 it means that fragment can not be fragmented Maximum Number of Hops that packet can do Defines upper Layer Protocol, like: TCP or UDP Responsible for Check header state at each Hop Sender’s IP address Receiver’s IP address

Suleyman Demirel University, 2011 Example of Packet Header Suleyman Demirel University, 2011 Example of Packet Header

Suleyman Demirel University, 2011 Packet Header • IP destination address • IP source address Suleyman Demirel University, 2011 Packet Header • IP destination address • IP source address • Time-to-live • 8 bit value, indicates remaining “life” of packet • Decreased by at least one each time the packet is processed by a router(hop). • Protocol (8 bits) • Identifies upper layer protocol • Type-of-service (8 bits) • Enables Quality-of-Service(Qo. S)

Suleyman Demirel University, 2011 Packet Header • Fragment offset • Identifies the order of Suleyman Demirel University, 2011 Packet Header • Fragment offset • Identifies the order of fragment • More fragments flag • MF(1 bit) if value is 1 it means that it is not last fragment, 0 vice-versa • Don’t fragment flag • DF(1 bit) if value is 1 it means that packet can’t be fragmented, if router needs to fragment packet and value of DF is 1, router will discard packet

Suleyman Demirel University, 2011 Packet Header • Version(4 bits) • Identifies version of protocol Suleyman Demirel University, 2011 Packet Header • Version(4 bits) • Identifies version of protocol • Header length(IHL) • Header size • Packet length • Between 20 bytes to 65, 535 • Identification • Uniquely identify fragments of an original IP packet • Header checksum • Error checking (compares packet header with this number) • Options

Suleyman Demirel University, 2011 DIVIDING NETWORK INTO SUB-NETWORKS Suleyman Demirel University, 2011 DIVIDING NETWORK INTO SUB-NETWORKS

Suleyman Demirel University, 2011 Question • Why? Suleyman Demirel University, 2011 Question • Why?

Suleyman Demirel University, 2011 Answer • Large network difficult to Manage • Small network Suleyman Demirel University, 2011 Answer • Large network difficult to Manage • Small network easy to Manage

Suleyman Demirel University, 2011 Dividing Networks Network Division Factors Geographic Location Purpose Ownership Suleyman Demirel University, 2011 Dividing Networks Network Division Factors Geographic Location Purpose Ownership

Suleyman Demirel University, 2011 Large Network Suleyman Demirel University, 2011 Large Network

Suleyman Demirel University, 2011 Division – Geographical Location Suleyman Demirel University, 2011 Division – Geographical Location

Suleyman Demirel University, 2011 Division - Purpose Suleyman Demirel University, 2011 Division - Purpose

Suleyman Demirel University, 2011 Division - Ownership Suleyman Demirel University, 2011 Division - Ownership

Suleyman Demirel University, 2011 OPTIMIZATION OF NETWORK Suleyman Demirel University, 2011 OPTIMIZATION OF NETWORK

Suleyman Demirel University, 2011 Question • What Optimization is? Suleyman Demirel University, 2011 Question • What Optimization is?

Suleyman Demirel University, 2011 Answer • Optimization, change something to increase functionality Suleyman Demirel University, 2011 Answer • Optimization, change something to increase functionality

Suleyman Demirel University, 2011 Optimization of Network Suleyman Demirel University, 2011 Optimization of Network

Suleyman Demirel University, 2011 Common issues with large networks are: • Performance degradation • Suleyman Demirel University, 2011 Common issues with large networks are: • Performance degradation • Security issues • Address Management

Suleyman Demirel University, 2011 Network Optimization Suleyman Demirel University, 2011 Network Optimization

Suleyman Demirel University, 2011 Broadcast Suleyman Demirel University, 2011 Broadcast

Suleyman Demirel University, 2011 What is Gateway in Computer Network? Suleyman Demirel University, 2011 What is Gateway in Computer Network?

Suleyman Demirel University, 2011 Gateway Suleyman Demirel University, 2011 Gateway

Suleyman Demirel University, 2011 Hierarchical Addressing • Letter to: • Kazakhstan, Almaty, Kaskelen, SDU, Suleyman Demirel University, 2011 Hierarchical Addressing • Letter to: • Kazakhstan, Almaty, Kaskelen, SDU, Engineering Faculty, Zhamanov Azamat

Suleyman Demirel University, 2011 Hierarchical addressing in IPv 4 Suleyman Demirel University, 2011 Hierarchical addressing in IPv 4

Suleyman Demirel University, 2011 Gateways Enable Communications between Networks Suleyman Demirel University, 2011 Gateways Enable Communications between Networks

Suleyman Demirel University, 2011 TCP/IP Gateway Configuration Suleyman Demirel University, 2011 TCP/IP Gateway Configuration

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 Routing IP Packets Suleyman Demirel University, 2011 Routing IP Packets

Suleyman Demirel University, 2011 How router finds the best path? • Router look at Suleyman Demirel University, 2011 How router finds the best path? • Router look at routing table to find best path.

Suleyman Demirel University, 2011 Routing Table Suleyman Demirel University, 2011 Routing Table

Suleyman Demirel University, 2011 Verifying Routing Table by “show ip route” command Suleyman Demirel University, 2011 Verifying Routing Table by “show ip route” command

Suleyman Demirel University, 2011 Useful Commands • ipconfig/all • Netstat –r • Route print Suleyman Demirel University, 2011 Useful Commands • ipconfig/all • Netstat –r • Route print

Suleyman Demirel University, 2011 Routing Process Suleyman Demirel University, 2011 Routing Process

Suleyman Demirel University, 2011 If no Route Entry and No Default Route Suleyman Demirel University, 2011 If no Route Entry and No Default Route

Suleyman Demirel University, 2011 Routing Types Static Dynamic Suleyman Demirel University, 2011 Routing Types Static Dynamic

Suleyman Demirel University, 2011 Static Routing Suleyman Demirel University, 2011 Static Routing

Suleyman Demirel University, 2011 Dynamic Routing Suleyman Demirel University, 2011 Dynamic Routing

Suleyman Demirel University, 2011 Q/A Suleyman Demirel University, 2011 Q/A