IE2052-ANT-Lecture-03-Routing.pdf

IE2052 - Advanced Networking Technologies Lecture 3 Routing Concepts Ms.Hansika Mahaadikara IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara What Is Routing? 10.120.2.0 172.16.1.0 T...

IE2052 - Advanced Networking Technologies Lecture 3 Routing Concepts Ms.Hansika Mahaadikara IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara What Is Routing? 10.120.2.0 172.16.1.0 To route, a router needs to do the following: – Know the destination address. – Identify the sources it can learn from. – Discover possible routes. – Select the best route. – Maintain and verify routing information. IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara What Is Routing? (cont.) 10.120.2.0 172.16.1.0 E0 S0 Network Destination Exit Protocol Network Interface Connected 10.120.2.0 E0 Routed Protocol: IP Learned 172.16.1.0 S0 Routers must learn destinations that are not directly connected. IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Static and Dynamic Routes Static Route Dynamic Route Uses a route that a Uses a route that a network network routing administrator enters protocol adjusts into the router automatically for manually topology or traffic changes IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Direct Delivery Send a message to a machine in the SAME LAN IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  Indirect Delivery IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Indirect Delivery cont. To send a packet from source to destination, need to go to the network ( packet should go from router to router ) All routers should maintain a routing table IP packet is analyzed at the router and correct path is selected form the routing table The packet is sent though that path Indirect delivery is done using the routing strategies IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Routing Table IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Adaptive Routing Each router maintains a routing table Also it can be changed according to the network changes (Adaptive) Advantages - Network traffic is minimized - Low latency - The best route will be selected most Disadvantages - Router memory need to keep routing tables IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  Routing Methods used in Adaptive Routing Next hop routing Host specific Network specific IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Host Specific Routing Each router keeps a table entry for each host (one record for one host) Table entry has Host IP and the Interface Host Address Interface A E0 B S0 C S1 Disadvantages Large number of records Table updating is difficult and complex as it should be done for each and every host IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Network Specific Routing Each router keeps a table entry for each network (one record for one network) Table entry has Network address and Interface Network Address Interface A E0 B S0 C S1 Advantages Number of records are limited (Entryfor each for a network) Update is easy IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  Routing Table update Methods Basic methods to update routing tables - Connected - Static - Dynamic IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Connected Once the router is connected to the network ,router automatically identifies the network addresses to which it connected IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Connected cont. R1#show ip route Codes: C - connected, S - static, Gateway of last resort is not set 172.16.0.0/24 is subnetted, 2 subnets C 172.16.2.0 is directly connected, Serial0/0/0 C 172.16.3.0 is directly connected, FastEthernet0/0 IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  Static Administrator manually give routing table records Router(config)#ip route IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Static cont. R1(config)# R1(config)#ip route 172.16.1.0 255.255.255.0 172.16.2.2 R1(config)#ip route 192.168.1.0 255.255.255.0 172.16.2.2 R1(config)#ip route 192.168.2.0 255.255.255.0 172.16.2.2 R1(config)# R1#show ip route Codes: C - connected, S - static Gateway of last resort is not set 172.16.0.0/24 is subnetted, 3 subnets S 172.16.1.0 [1/0] via 172.16.2.2 C 172.16.2.0 is directly connected, Serial0/0/0 C 172.16.3.0 is directly connected, FastEthernet0/0 S 192.168.1.0/24 [1/0] via 172.16.2.2 S 192.168.2.0/24 [1/0] via 172.16.2.2 IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Static cont. Advantages: Minimal CPU processing Easier for administrator to understand and configure Disadvantages: Configuration and maintenance is time-consuming Configuration is error-prone Administrator should maintain changing route information Does not scale well with growing networks; maintenance becomes complex Requires complete knowledge of the whole network for proper implementation IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Default Routing Last record in the routing table Indicates the route/path to be taken, if any of the records does not match with the IP packet destination IP address Stub networks only use default routing , Stub networks have only one exit port out of the network R(config)#ip route 0.0.0.0 0.0.0.0 IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Default Routing cont. B(config)# B(config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2 B(config)# B#show ip route Codes: C - connected, S - static Gateway of last resort is 172.16.2.2 to network 0.0.0.0 172.16.0.0/24 is subnetted, 2 subnets C 172.16.1.0 is directly connected, FastEthernet0/0 C 172.16.2.0 is directly connected, Serial2/0 S* 0.0.0.0/0 [1/0] via 172.16.2.2 B# IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Dynamic Routing tables are updated automatically by using routing protocols Routing tables have Initially only connected records Then add static’ records Then automatic dynamic updates IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Dynamic cont. Advantages: Administrator has less work maintaining the configuration when adding or deleting networks Protocols automatically update, according to the topology changes. Configuration is less error-prone Suitable for More scalable, growing networks Disadvantages: Router resources are used (CPU cycles, memory and bandwidth) More administrator knowledge is required for configuration, verification, and troubleshooting IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Routing Protocols IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Features of routing protocols Network changes (addition or removal or fault) are automatically updated in routing tables of all routers When there are many routes to a destination, the best route should be selected Share the traffic through different routes IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara What Is a Routing Protocol? Routing Protocols allow routers to 10.120.2.0 dynamically 172.16.1.0 advertise and E0 learn routes, S0 determine which routes are available and which are the Network Destination Exit 172.17.3.0 Protocol Network Interface most efficient Connected 10.120.2.0 E0 routes to a RIP 172.16.2.0 S0 destination EIGRP 172.17.3.0 S1 Routing Protocol: RIP, EIGRP,OSPF IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Routing Protocols IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Routing Protocols cont. An autonomous system (AS) is a collection of routers under a common administration ex : a company's internal network Interior Gateway Protocols (IGP) are used for intra-autonomous system routing (routing inside an autonomous system) Exterior Gateway Protocols (EGP) are used for inter-autonomous system routing (routing between autonomous systems) IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Routing Protocols cont. IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Interior Gateway Protocols (IGP) IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Distance Vector Routing Protocols Routes are advertised as vectors of distance and direction Distance is defined in terms of a metric such as hop count and direction is simply the next-hop router or exit interface Send periodic updates of their routing information Use the Bellman-Ford algorithm for best path selection Work best in situations where: - Network is simple - Administrators do not have enough knowledge to configure Ex : RIP, IGRP, EIGRP IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Link State Routing Protocols Routers running a link-state routing protocol send information about the state of its links to other routers in the routing domain The state of the links includes information about the type of network and any neighboring routers on the networks A link-state update only sent when there is a change in the topology Use the Dijkstra algorithm for best path/ route selection Work best in situations where: - Network design is complex (large networks) - Administrators have a good knowledge of network Ex : OSPF, IS-IS IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  RIP (Routing Information Protocol) IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara RIP (Routing Information Protocol) A Distance-vector routing protocol Sends the complete routing table out to all active interfaces in every 30 seconds Only uses hop count to select best path to a remote network RIP works well in small networks, but it is inefficient on large networks There are two versions RIP v1, RIP v2 IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara RIP Configuration Router(config)#router rip Router(config-router)#network < network-address> Directly connected network addresses IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  RIP Configuration Example – Version 1 E0 S0 S1 S0 S1 E0 172.16.0.0 A 192.168.1.0 B C 172.16.0.1 10.0.0.1 10.0.0.2 11.0.0.1 11.0.0.2 192.168.1.1 router rip 2.3.0.0 router rip 2.3.0.0 network 172.16.0.0 network 192.168.1.0 network 10.0.0.0 network 11.0.0.0 router rip network 10.0.0.0 Network 11.0.0.0 IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara Configure RIP V2 Classless Sub-networks Router(config)#router rip Router(config)#version 2 Router(config-router)#network < network-address> : Directly connected sub-network addresses IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara  RIP Configuration Example – Version 2 E0 S0 S1 S0 S1 E0 172.16.64.0 A 192.168.1.128 B C 172.16.64.1 10.0.1.1 10.0.1.2 10.0.2.1 10.0.2.2 192.168.1.129 router rip router rip Version 2 Version 2 No auto-summary No auto-summary network 172.16.64.0 network 192.168.1.0 network 10.0.1.0 router rip network 10.0.2.0 Version 2 No auto-summary network 10.0.1.0 Network 10.0.2.0 IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara IE2052| Adv Networing Tech| Routing| Hansika Mahaadikara