OSI Network Layer : OSI Network Layer Network Fundamentals – Chapter 5
Objectives : Objectives 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
Key Terms : Key Terms Source/Destination IP TTL MTU Hop Routing Subnetwork Broadcast Domain Octets Default Gateway Default Route Static Route Dynamic Routing
Network Layer Protocols and Internet Protocol : Network Layer Protocols and Internet Protocol Layer 3 is responsible for data delivery Provides for Source/Destination addressing Determines best (most efficient) path to deliver data Layer 3 PDU = Packet Network layer protocols include: IP v4 and v6 Novel IPX AppleTalk Connectionless Network Service (telecom net)
Internet Protocol (IPv4) : Internet Protocol (IPv4) IP header added to Transport layer segment Includes source and destination IP adress
IP Header Fields : IP Header Fields Source/Destination TTL – Time to Live Type of Service (TOS) Protocol Flag/Fragment Offset Version Packet Length Min = 20 bytes Max= 65,535 bytes
IP is a “Best Effort” Protocol : IP is a “Best Effort” Protocol
IP is Media Independent : IP is Media Independent Packet does not change, framing does Maximum Transmission Unit (MTU) varies with media Fragmentation may occur Offset value in IP header
Grouping Devices into Networks : Grouping Devices into Networks Location (geography) Function (purpose) Ownership Terms related to grouping: Workgroup Subnetwork or just Subnet VLAN
Grouping Devices into Networks : Grouping Devices into Networks Dividing a large network gains: Performance Security Address management Requires a router (default gateway to communicate) Broadcast domain Group of devices connected by hubs or switches and bordered by a router
IP Hierarchical Addressing : IP Hierarchical Addressing IP addresses contain both network and host numbers (or bits) Read from general to specific info (network to host) Hierarchy of networks determines pathway
Routers and Packet Forwarding : Routers and Packet Forwarding Routing occurs when a packet is destined for a network outside the local subnet Next hop – new network reached or traversed
Forwarding Requires Routing Table Entries : Forwarding Requires Routing Table Entries Routing table entry contains several parts: Destination network Next-hop Metric (cost) Future reference: routing protocol, admin distance, and aging
Learning Routes : Learning Routes Routes are stored in tables and are learned: Statically – administrator assigned Dynamically – distributed by routing protocols
Fundamentals of Routing : Fundamentals of Routing Dynamic Route Example (learned via routing protocols) Routing Protocols: RIP EIGRP OSPF
L2 and L3 Status During Routing : L2 and L3 Status During Routing As a packet is routed (forwarded), the following occurs: Layer 3 (Network) addresses remain the same Layer 2 (Datalink) addresses change with each hop
Summary : Summary
PowerPoint Presentation :