OSI Network Layer

OSI Network Layer Network Fundamentals – Chapter 5

Network Layer Protocols and Internet Protocol (IP) • Define the basic role of the Network Layer in data networks Define services & applications Define hosts

Network Layer Protocols and Internet Protocol (IP) • Identify the basic characteristics and the role of the IPv4 protocol Attributes (characteristics) of IP

Network Layer Protocols and Internet Protocol (IP) • Describe the implications for the use of the IP protocol as it is connectionless Packets are sent before contacting destination

Network Layer Protocols and Internet Protocol (IP) • Describe the implications for the use of the IP protocol as it is considered an unreliable protocol

Network Layer Protocols and Internet Protocol (IP) • Describe the implications for the use of the IP as it is media independent

Network Layer Protocols and Internet Protocol (IP) • Describe the role of framing in the Transport Layer and explain that segments are encapsulated as packets

Network Layer Protocols and Internet Protocol (IP) • Identify the major header fields in the IPv4 protocol and describe each field's role in transporting packets TTL is used to prevent endless loop.

Grouping Devices into Networks and Hierarchical Addressing • List several different reasons for grouping devices into sub-networks and define several terms used to identify the sub-networks (managements, performance, security, control)

Grouping Devices into Networks and Hierarchical Addressing • List several ways in which dividing a large network can increase network performance

Grouping Devices into Networks and Hierarchical Addressing • List several ways in which dividing a large network can increase network security

Grouping Devices into Networks and Hierarchical Addressing • Explain the communication problems that emerge when very large numbers of devices are included in one large network

Grouping Devices into Networks and Hierarchical Addressing • Describe how hierarchical addressing solves the problem of devices communicating across networks of networks

Classes of IP Address The Two unused addresses are : • This Net (Zeros for Host ID) • Broad Cast (255 for Host ID)

ReservedIP Addresses • Loopback Address : 127.x.y.z for testing internal configuration. Packets send to loopback address are not put out onto the wire, they are processed locally & treated as incoming packets. • Broadcast Address : assigning 255 to host ID (sending packets • to all hosts in the Net). • 192.34.200.255 all hosts of 192.34.200.0 network • 130.50.255.255 all hosts of 130.50.0.0 network • This network : assigning 0 to host ID. • 192.34.200.0 ; 130.50.0.0 • Special Case Source Addresses • all internet addresses 0.0.0.0 • In DHCP net, IP address of each host is initially 0.0.0.0

PrivateIPAddresses Subnetting Advantages By subnetting, the 2 portions of IP become 3 portions : Net Portion , Subnet portion & Host portion, this can be done by borrowing bits from Host portion. IPv6vsIPv4 16 Bytes → 3.4 x 10 38 IP Addresses 4 Bytes → 4.3 x 10 9 IP Addresses

ARP vs RARP Static vs Dynamic IP Addresses BooTP Serve to distribute IP Address from a manually created data base (fixed IP for each computer). DHCP Installing DHCP service on Server computer (NOS). Configuration this DHCP Server. Configuration each client to obtain its IP from DHCP Server.

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Describe the role of an intermediary gateway device in allowing devices to communicate across sub-divided networks Router used Net ID to forward packets

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Trace the steps of an IP packet as it traverses unchanged via routers from sub network to sub-network

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Describe the role of a gateway and the use of a simple route table in directing packets toward their ultimate destinations

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Define a route and its three key parts

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Describe the purpose and use of the destination network in a route 172.16.0.0/12 A Fa0/0 2 What will happen if we add the 172.16.0.0/12 to the left of Router A?

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Describe the purpose and use of the next hop in a route 2 Incorrect configuration of GW on a host, will cause this host to be unable to communicate with remote networks

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Trace the steps of several IP packets as they are routed through several gateways from devices on one sub network to devices on other sub networks

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Describe the purpose of routing protocols and the need for both static and dynamic routes

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Explain how routes are manually configured to build routing table

Fundamentals of Routes, Next Hop Addresses and Packet Forwarding • Explain the role of routing protocols in building the routing table

Summary Routing Table of Router A Type Net ID Mask Next Hop metric C 150.10.0.0 255.255.0.0 150.10.0.2 R 80.0.0.0 255.0.0.0 210.2.2.2 30 C 210.2.2.0 255.255.255.0 210.2.2.2 C 30.0.0.0 255.0.0.0 30.0.0.2 C 192.168.1.0 255.255.255.0 Fa0/0 * 0.0.0.0 0.0.0.0 30.8.8.2 150.10.0.0 192.168.1.0 A 210.2.2.0 30..0.0.0 80.0.0.0 Internet

Words indicating Network Layer of IOS Model • Best Efforts • Connectionless • IP Addressing • Logical Addressing • Packets • Identifying Hosts • Routing Table (Routing Protocols) • Determination of Best Path

Encapsulation Steps

OSI Network Layer