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Layered Architecture
CSC358 - Introduction to Computer Networks
Review
Shortest Path Routing AlgorithmsBellman-Ford algorithm (Distance Vector Routing)Dijkstra’s algorithm (Link State Routing)
CSC358 - Introduction to Computer Networks
Routing Algorithms
Distance Vector RoutingDistributed algorithmEach node uses local information
Link State RoutingDistributed algorithmEach node needs global information
CSC358 - Introduction to Computer Networks
Routing in Practice
Large Network (of Networks)Autonomous SystemsAddressing
CSC358 - Introduction to Computer Networks
Goal
Understand network layer issues that are important inpracticeUnderstand components of the Internet network layer
CSC358 - Introduction to Computer Networks
Boxes in a Network
CSC358 - Introduction to Computer Networks
Network Topology
CSC358 - Introduction to Computer Networks
Network Topology seen by Network Layer
CSC358 - Introduction to Computer Networks
Hierarchical Routing
CSC358 - Introduction to Computer Networks
Hierarchical Routing
Intra-Autonomous System (Intra-AS) Routing ProtocolInter-Autonomous System (Inter-AS) Routing Protocol
CSC358 - Introduction to Computer Networks
Internet Network Layer
Datagram (Connectionless) ServiceInternet Protocol (IP)
AddressingDefinition of Datagram
Routing ProtocolIntra-AS: RIP (Routing Information Protocol), OSPF (OpenShortest Path First), EIGRP (Enhanced Interior GatewayRouting Protocol) by Cisco.Inter-AS: BGP (Border Gateway Protocol)
ICMP (Internet Control Message Protocol)
CSC358 - Introduction to Computer Networks
IPv4 Addressing
32 bits long (4 bytes)232 possible addressesdotted-decimal notation: each byte of the address iswritten in its decimal form and is separated by a period(“dot”) from other bytes in the address.
193.32.216.9
CSC358 - Introduction to Computer Networks
IPv4 Addressing: Interface Addresses
CSC358 - Introduction to Computer Networks
IPv4 Addressing: Network Addresses
CSC358 - Introduction to Computer Networks
IPv4 Addressing: Network Addresses
CSC358 - Introduction to Computer Networks
IPv4 Addressing and Routing
CSC358 - Introduction to Computer Networks
IPv4 Addressing and Routing
Routing Table in A:Dest. Network Next router Nhops
223.1.1.0/24 1223.1.2.0/24 223.1.1.4 2223.1.3.0/24 223.1.1.4 2
CSC358 - Introduction to Computer Networks
IPv4 Addressing and Routing
Routing Table in Router:Dest. Network Next router Nhops Interface
223.1.1.0/24 1 223.1.1.4223.1.2.0/24 1 223.1.2.9223.1.3.0/24 1 223.1.3.27
CSC358 - Introduction to Computer Networks
IP Fragmentation and Reassembly
IPv4 Datagrams can be up to 65,353 bytes longEthernet frames can carry up to 1,500 bytes of data
CSC358 - Introduction to Computer Networks
Routing in the Internet
Intra-AS Routing:RIP: Routing Information Protocol
Distance Vector ProtocolMin-Hop Routing
OSPF: Open Shortest Path FirstLink State ProtocolSupports Several Cost Metrics
EIGRP: Enhanced Interior Gateway Routing ProtocolDistance Vector ProtocolSupports Several Cost Metrics
CSC358 - Introduction to Computer Networks
Routing in the Internet
Inter-AS Routing:BGP: Border Gateway Protocol
Distance Vector ProtocolNo Cost MetricIndicates Path VectorDe Facto Standard in public InternetAllows to Define Routing Policies
Example: To get from a node in AS X to a destination inAS Z , use AS’s
X1,X2, orX1,X3,X4
CSC358 - Introduction to Computer Networks
Network Layer
IntroductionRouting Algorithms
Bellman-FordDijkstra’s
Hierarchical RoutingInternet Network Layer
IPRouting Protocols
CSC358 - Introduction to Computer Networks
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