Lecture (03) RIP. By: Dr. Ahmed ElShafee. Dr. Ahmed ElShafee, ACU : Fall 2016, Practical App. Networks II

Transcription

1 Lecture (03) RIP By: Dr. Ahmed ElShafee ١ Dr. Ahmed ElShafee, ACU : Fall 2016, Practical App. Networks II Dynamic Routing Protocol Overview Routing protocols are used between routers to determine paths and maintain routing tables. After the path is determined, a router can route a routed protocol ٢

2 A routing protocol : defines the rules that are used by a router when it communicates with neighboring routers. Dynamic routing relies on a routing protocol to disseminate knowledge. In contrast, static routing defines the format and use of the fields within a packet. Packets generally are conveyed from end system to end system. ٣ Autonomous Systems: Interior or Exterior Routing Protocols An autonomous system is a collection of networks under a common administrative domain. ٤

3 The two types of routing protocols are as follows: Interior Gateway Protocols (IGPs): These routing protocols are used to exchange routing information within an autonomous system. RlPv1, R1Pv2, IGRP, EIGRP, and OSPF are examples of IGPs. ٥ Exterior Gateway Protocols (EGPs): These routing protocols are used to connect between autonomous systems. An autonomous system is a collection of networks under a common administration and sharing a common routing strategy. Border Gateway Protocol (BGP) is an example of an EGP. ٦

4 Classes of Routing Protocols Within an autonomous system, most IGP routing algorithms can be classified as conforming to one of the following algorithms: Distance vector: The distance vector routing approach determines the direction (vector) and distance (hops) to any link in the internetwork. ٧ Link state: The link state approach, also known as the shortest path first algorithm (SPF), creates an abstraction of the exact topology of the entire internetwork, or at least of the partition in which the router is situated. Balanced hybrid: The balanced hybrid approach combines aspects of the link state and distance vector algorithms. ٨

5 There is no single best routing algorithm for all internetworks. All routing protocols provide the information differently. ٩ Ranking Routes ١٠

6 Multiple routing protocols and static routes may be used at the same time. If there are several sources for routing information, an administrative distance value is used to rate the trustworthiness of each routing information source. By specifying administrative distance values, Cisco los software can discriminate between sources of routing information. ١١ Administrative Distance An administrative distance is an integer from 0 to 255. A routing protocol with a lower administrative distance is more trustworthy than one with a higher administrative distance.. ١٢

7 shown in the figure, if router A receives a route to network E from IGRP and RlP at the same time and because RlP and IGRP use incompatible routing metrics, router A would use the administrative distance to determine that IGRP is more trustworthy. Router A would then add the IGRP route to the routing table ١٣ ١٤

8 introduction RIP is one of the most popular of all routing protocols. RIP is a relatively old, but still commonly used, interior gateway protocol created for use in small, homogeneous networks. RIP is a classic distance vector routing protocol. ١٥ RIP Overview RIP is a distance vector routing protocol. It uses hop count as the metric for route selection and broadcasts routing updates every 30 seconds. ١٦

9 The maximum allowable hop count is 15. RIP is capable of load balancing over as many as six equal cost paths. (Four paths is the default.) ١٧ Defining the maximum number of parallel paths allowed in a routing table enables RIP load balancing. With RIP, the paths must be equal cost paths. If the maximum number of paths is set to one, load balancing is disabled. ١٨

10 RIPv1 and RIPv2 Comparison Route summarization, also called route aggregation, is a method of minimizing the number of routing tables in an IP (Internet Protocol) network. It works by consolidating selected multiple routes into a single route advertisement, in contrast to flat routing in which every routing table contains a unique entry for each route. ١٩ IP Routing Configuration Tasks Step 1 Select a routing protocol: RIP Step 2 Assign IP network numbers without specifying subnet values ٢٠

11 Defines an IP routing protocol Router (config) #router protocol [keyword] ٢١ Identification the physically connected network to which routing updates are forwarded Router (config router)#network networknumber ٢٢

12 ٢٣ Example The router A interfaces that are connected to networks and I , or their subnets, will send and ٢٤ receive RIP updates.

13 Routers B and C have similar RIP configurations but with different network numbers specified ٢٥ RIP Configuration Verification ٢٦

14 Verifying the RIP Configuration In the example, router A is configured with RIP and sends updated routing table information every 30 seconds. (This interval is configurable.) If a router running RIP does not receive an update from another router for 180 seconds or more, it marks the routes that are served by that router as being invalid. In the figure, the holddown timer is set to 180 seconds. As a result, an update to a route that was down and is now up will stay in the hold down (possibly down) state until 180 seconds have passed. Lf there is still no update after 240 seconds (flush timer), the router removes the routing table entries from the router. ٢٧ The router is injecting routes for the networks that are listed following the "Routing for Networks" line. The router is receiving routes from the neighboring RIP routers that are listed following the "Routing Information Sources" line. The distance default of 120 refers to the administrative distance for an RIP route. ٢٨

15 The router is injecting routes for the networks that are listed following the "Routing for Networks line. The router is receiving routes from the neighboring RIP routers that are listed following the "Routing Information Sources" line. The distance default of 120 refers to the administrative distance for an RIP route. You can also use the show ip interface brief command to get a summary of the IP information and status of all interfaces. ٢٩ Displaying the IP Routing Table ٣٠

16 ٣١ RIP Configuration Troubleshooting Use the debug ip rip command to display RIP routing updates as they are sent and received. ٣٢ The no debug all command turns off all debugging.

17 Thanks,.. See you next week (ISA), ٣٣ Dr. Ahmed ElShafee, ACU : Fall 2016, Practical App. Networks II Example PCS configuration ***************** PC fa0/1 PC fa0/1 ٣٤

18 **************** router A ********************* en ٣٥ config t interface fa0/0 ip address no sh interface serial0/0/0 ip address no sh end copy running config startup config exit **************** router B ********************* en config t interface serial0/0/0 ip address no sh interface serial0/0/1 ip address clock rate no sh end copy running config startup config ٣٦ exit *****************************************

19 **************** router C ********************* en ٣٧ config t interface serial0/0/1 ip address no sh interface fa0/0 ip address no sh end copy running config startup config exit ***************************************** PC1 >> ping PC2>> ping ٣٨

20 **************** router A ********************* en config t router rip network network end copy running config startup config exit ٣٩ **************** router B ********************* en config t router rip network network end copy running config startup config exit ***************************************** ٤٠