Topic5-Part II Module6.pdf

Part II Routing Protocols and Concepts 1 Part II Module 6: Routing and Routing Protocols 6.1 Routing 3 6.1.1 Introduction to routing 4 5 6 6.1.3 Configuring static routes Using outgoing interface 7 6.1.3 Configuring static routes -How many networks here? -What is the configuration for Waycross? Usin...

Part II Routing Protocols and Concepts 1 Part II Module 6: Routing and Routing Protocols 6.1 Routing 3 6.1.1 Introduction to routing 4 5 6 6.1.3 Configuring static routes Using outgoing interface 7 6.1.3 Configuring static routes -How many networks here? -What is the configuration for Waycross? Using a next-hop 8 Administrative Distance (AD) waycross(config)#ip route 172.16.3.0 255.255.255.0 s1 130 Administrative distance (AD) (static route=1, directly connect=0, 255 max) A route with a lower administrative distance will be installed before a similar route with a higher administrative distance. "show ip route" to verify AD If an interface is down, the route will not be placed in the routing table. Sometimes, a static route are used for backup purposes (when the dynamically learned route has failed). It should has a higher AD than the dynamic routing protocol. 9 6.1.2 -e-Lab Activity: Static Route Operation Description: step 3 The 255 will make this route the least desirable so that it will only be used when all other routes are unavailable. This type of route is called a floating static route. It floats in the router memory, but is not added to the routing table until all other rotes are unavailable. -e-Lab Activity: Static Routes Step by step, ask students why. 10 6.1.4 Configuring default route forwarding Default routes are used to route packets with destinations that do not match any of the other routes in the routing table. Using outgoing interface Waycross(config)#ip route 0.0.0.0 0.0.0.0 172.16.4.1 Using next hop Using outgoing interface Sterling(config)#ip route 0.0.0.0 0.0.0.0 s0 11 Sterling(config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2 Using next hop 6.1.5 Verifying static route configuration - show ip route - show running-config You need to check both. Why? (some paths with lower AD is not shown in the routing table, but their configurations are shown in running-config. 12 6.2 Dynamic Routing Overview 13 6.2.1 Introduction to routing protocols A routing protocol is the communication used between routers. Routers use this information to build and maintain routing tables. A routed protocol provides enough information in its network layer address to allow a packet to be forwarded from one host to another based on the addressing scheme. 14 6.2.2 Autonomous systems An AS is a collection of networks under a common administration that share a common routing strategy. To the outside world, an AS is viewed as a single entity. The American Registry of Internet Numbers (ARIN), a service provider, or an administrator assigns a 16-bit identification number to each AS. Routing protocols, such as Cisco IGRP, require the assignment of a unique, AS number. 15 Routing protocols RIP - a distance vector IGRP - the Cisco distance vector EIGRP - the advanced Cisco distance vector OSPF - a link-state 16 BGP - a distance vector 6.2.3 Purpose of a routing protocol and autonomous systems Converged Whenever the topology of a network changes, the network knowledgebase must also change. When all routers in an internetwork operate with the same knowledge, the internetwork is said to have converged. Fast convergence is desirable because it reduces the period of time in which routers would continue to make incorrect routing decisions. Dynamic Routing Operations 17 6.2.4 Identifying the classes of routing protocols Distance vector It determines the direction, or vector, and distance to any link in an internetwork. Link-state It recreates the exact topology of an entire internetwork. 18 6.2.5 Distance vector routing protocol features Distance vector concept 19 6.2.5 Distance vector routing protocol features Distance vector network discovery 20 Routing metric components 21 6.2.6 Link-state routing protocol features Link-state concepts 22 Link-state topology changes 23 Link-state concerns 24 6.3 Routing Protocols Overview 25 6.3.1 Path determination Network layer: path determination 26 27 6.3.1 Path determination 28 6.3.1 Path determination Routing with network addressing 29 6.3.2 Routing configuration IP routing configuration task steps 30 6.3.2 Routing configuration GAD(config)#router rip GAD(config-router)#network 172.16.0.0 31 32 6.3.2 e-Lab Activity: Routing Configuration 33