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Dynamic routing protocols (CCNA)


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This tutorial gives very good understanding on CCNA Dynamic Routing Protocols.After completing this tutorial,You will find yourself at a moderate level of expertise in knowing Advance Networking(CCNA)

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Dynamic routing protocols (CCNA)

  2. 2. DYNAMIC ROUTING PROTOCOLS  Dynamic routing protocols help the network administrator overcome the time-consuming and exacting process of configuring and maintaining static routes.  The purpose of a dynamic routing protocol is to:  Discover remote networks  Maintaining up-to-date routing information  Choosing the best path to destination networks  Ability to find a new best path if the current
  3. 3. CLASSIFYING ROUTING PROTOCOLS  Interior Gateway Routing Protocols (IGP) -Used for routing inside an autonomous system & used to route within the individual networks themselves. -Examples: RIP, EIGRP, OSPF  Exterior Routing Protocols (EGP) -Used for routing between autonomous systems -Example: BGPv4
  5. 5. CLASSIFYING ROUTING PROTOCOLS  Classful routing protocols Do NOT send subnet mask in routing updates  Classless routing protocols Do send subnet mask in routing updates.
  6. 6. ROUTING PROTOCOLS METRICS  Metric A value used by a routing protocol to determine which routes are better than others.  Metrics used in IP routing protocols: -Bandwidth -Cost -Delay -Hop count -Load -Reliability
  7. 7. AD VALUE FOR ROUTING PROTOCOLS it is a numeric value that specifies the preference of a particular route
  9. 9. ROUTING INFORMATION PROTOCOL  The Routing Information Protocol (RIP) is an intradomain routing protocol used inside an autonomous system. It is a very simple protocol based on distance vector routing.  A metric in RIP is called a hop count; distance; defined as the number of links (networks) that have to be used to reach the destination.  Distance vector algorithm. Included in BSD-UNIX Distribution in 1982
  10. 10. COMMAND USED  Router (config)# router rip  Router (config-router)# network_required network IP
  11. 11. RIP CHARACTERISTICS  Distance vector routing protocol.  Uses hop count as a path selection metric.  Three types of timers.  Multiple stability features.
  12. 12. Hop Count -- Fifteen Hop Limit - Hop count is the sum of all the legs in a route. -After 15 hops, the packet is discarded
  13. 13. RIP TIMERS  Timers in RIP  Periodic timer : controlling the advertisements of regular update messages  expiration timer : governing the validity of a route  the garbage collection timer : advertising the failure of a route
  14. 14. RIPv2  RIPv2 is an extends RIPv1:  Subnet masks are carried in the route information  Authentication of routing messages  Route information carries next-hop address  Exploites IP multicasting  Extensions of RIPv2 are carried in unused fields of RIPv1 messages
  15. 15. COMMAND USED  Router (config)# router rip  Router (config)# ver 2  Router (config-router)# network_required network IP
  16. 16. RIP ADVANTAGES  Advantages  Simplicity ; little to no configuration, just start routed up  Passive version for hosts If a host wants to just listen and update its routing table
  17. 17. RIP Problems  RIP takes a long time to stabilize  Even for a small network, it takes several minutes until the routing tables have settled after a change  RIP has all the problems of distance vector algorithms, e.g., count-to-Infinity  RIP uses split horizon to avoid count- to-infinity  The maximum path in RIP is 15 hops
  18. 18. OSPF (Open Shortest Path First)  The Open Shortest Path First (OSPF) protocol is an intradomain routing protocol based on link state routing. Its domain is also an autonomous system  Dividing an AS(autonomous system) into areas  to handle routing efficiently and in a timely manner
  19. 19. Functional Requirements of OSPF  Faster Convergence and less consumption of network resources  A more descriptive routing metric  configurable  value ranges between 1 and 65,535  no restriction on network diameters  Equal-cost multipath  a way to do load balancing
  20. 20. Functional Requirements(contd.)  Routing Hierarchy  support large routing domains  Separate internal and external routes  Support of flexible subnetting schemes  route to arbitrary [address,mask] combinations using VLSMs  Security  Type of Service Routing
  21. 21. OSPF (cont’d)  Areas  Is a collection of networks, hosts, and routers in AS  AS can be divided into many different areas.  All networks inside an area must be connected.  Routers inside an area flood the area with routing information.  Area Border Router  Summarizes the information about the area and sends it to other areas  Backbone  All of the areas inside an AS must be connected to the backbone  Serving as a primary area  Consisting of backbone routers  Back bone routers can be an area border router
  22. 22. OSPF (cont’d)  Metric  OSPF protocol allows the administrator to assign a cost, called the metricc, to each route  Based on a type of service (minimum delay, maximum throughput, and so on)  A router can have multiple routing tables, each based on a different type of service.  Link State Routing  OSPF uses Link State Routing to update the routing tables in an area  Each router shares its knowledge about its neighborhood with every router in the area.
  23. 23. OSPF (cont’d)  Types of Links  In OSPF terminology, a connection is called a link.
  24. 24. OSPF (cont’d)  Point-to-point Link  Routers are represented by nodes and the link is represented by a bidirectional edge connecting the nodes.  Each router has only one neighbor at the other side of the link.
  25. 25. OSPF (cont’d) • Tranisent network: is a network with several routers attached to transient Link . (network)
  26. 26. OSPF (cont’d)  Stub Link  is a network that is connected to only one router  is a special case of transient network  The link is only one-directional, from the router to the network.
  27. 27. OSPF (cont’d)  Virtual Link  When the link between two routers is broken, the administration may create a virtual link between them using a longer path  Graphical Representation  An internet with 7 networks and 6 routers
  28. 28. SYNTAX  Router (config )# router ospf_ PID(range 1-65535)  Router (config –router)# network_requires network IP_ wildcard mask_area_any value(range 0- 4294967295)
  29. 29. EIGRP  A classless version of IGRP.  EIGRP includes several features that are not commonly found in other distance vector routing protocols like RIP (RIPv1 and RIPv2) and IGRP.  These features include:  Reliable Transport Protocol (RTP)  Bounded Updates  Diffusing Update Algorithm (DUAL)  Establishing Adjacencies  Neighbor and Topology Tables  Although EIGRP may act like a link-state routing protocol, it is still a distance vector routing protocol.
  30. 30. Path Determination (1)  Traditional distance vector routing protocols such as RIP and IGRP keep track of only the preferred routes; the best path to a destination network.  If the route becomes unavailable, the router waits for another routing update with a path to this remote network.  EIGRP's DUAL maintains a topology table separate from the routing table.  including both the best path to a destination network and any backup paths that DUAL has determined to be loop-free.  Loop-free means that the neighbor does not have a route to the destination network that passes through this router.
  31. 31. Path Determination (2)  If a route becomes unavailable, DUAL will search its topology table for a valid backup path.  If one exists, that route is immediately entered into the routing table.  If one does not exist, DUAL performs a network discovery process to see if there happens to be a backup path that did not meet the requirement of the feasibility condition.
  32. 32. SYNTAX :  Router (config)# router eigrp_PROCESS ID ( )  Router (config-router)# network _ required network IP
  33. 33. EXTERIOR ROUTING PROTOCOL BORDER GATEWAY PROTOCOL  Routing protocols used to route information between multiple autonomous systems BGP (Border Gateway Protocol) is a protocol for exchanging routing information between gateway hosts (each with its own router) in a network of autonomous systems. BGP is often the protocol used between gateway hosts on the Internet. The routing table contains a list of known routers, the addresses they can reach, and a cost metric associated with the path to each router so that the best available route is chosen.
  34. 34. SYNTAX:  Router (config)#router bgp_PID1  Router (config)#Network directly connect  Router (config –router)# neighbor_ip of end point_remote-as_PID2  NOTE 1: Before applying this command apply Dynamic routing on each router  NOTE 2: Each router has different Process ID  NOTE 3:Do not write directly attached IP of network. All except directly attached IP will be treated as neighbor  NOTE 4: PID will be of current router only.