1. Review Routing fundamental W.lilakiatsakun

2. Review Routing Fundamental VLSM VLSM Route Summarization Route Summarization Static & Dynamic Routing Static & Dynamic Routing Routing algorithm concept Routing algorithm concept RIP V2 RIP V2

3. VLSM Variable Length Subnet Mask Variable Length Subnet Mask VLSM allows an organization to use more than one subnet mask within the same network address space VLSM allows an organization to use more than one subnet mask within the same network address space VLSM implementation maximizes address efficiency, and is often referred to as subnetting a subnet VLSM implementation maximizes address efficiency, and is often referred to as subnetting a subnet Main reason – addressing crisis Main reason – addressing crisis

4. Supporting protocols for classless routing and VLSM OSPF OSPF Integrated IS-IS Integrated IS-IS EIGRP EIGRP RIP V2 RIP V2 Static Routing Static Routing Subnet information will be exchanged as well as routing information Subnet information will be exchanged as well as routing information –172.16.10.0 /255.255.255.0 –10.5.2.0 /255.255.255.0

5. VLSM - example

6. Calculating VLSM

7. Subnet Mask 255.255.255.252 - /30 255.255.255.252 - /30 255.255.255.248 - /29 255.255.255.248 - /29 255.255.255.240 - /28 255.255.255.240 - /28 255.255.255.224 - /27 255.255.255.224 - /27 255.255.255.192 - /26 255.255.255.192 - /26 255.255.255.128 - /25 255.255.255.128 - /25 255.255.255.0 - /24 255.255.255.0 - /24 255.255.254.0 - /23 255.255.254.0 - /23 255.255.252.0 - /22 255.255.252.0 - /22 255.255.248.0 - /21 255.255.248.0 - /21

8. Waste of Space (1/2) All one subnet and all zero subnet can be used to reduce the waste of space All one subnet and all zero subnet can be used to reduce the waste of space

9. Waste of space (2/2)

10. Sub-subnet (1/2)

11. Sub-subnet (2/2)

12. Calculating VLSM (1/6)

13. Calculating VLSM (2/6)

14. Calculating VLSM (3/6)

15. Calculating VLSM (4/6)

16. Calculating VLSM (5/6)

17. Calculating VLSM (6/6)

18. Problem 1- 192.168.10.0/24

19. Route Aggregation (Route Summarization) The use of classless interdomain routing (CIDR) and VLSM prevents address waste and promotes route aggregation, or summarization The use of classless interdomain routing (CIDR) and VLSM prevents address waste and promotes route aggregation, or summarization Aka. Route Summarization Aka. Route Summarization Save routing table space Save routing table space

20. Route summarization (1/3)

21. Route summarization (2/3)

22. Route summarization (3/3)

23. Static Routing VS Dynamic Routing

24. AS / IGP and EGP An autonomous system (AS) - otherwise known as a routing domain - is a collection of routers under a common administration. An autonomous system (AS) - otherwise known as a routing domain - is a collection of routers under a common administration. Interior Gateway Protocols (IGP) are used for intra-autonomous system routing - routing inside an autonomous system. 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. Exterior Gateway Protocols (EGP) are used for inter-autonomous system routing - routing between autonomous systems.

25. AS /IGP and EGP

26. Class of routing protocol Most routing algorithms can be classified into one of two categories: Most routing algorithms can be classified into one of two categories: –Distance vector –Link-state The distance vector routing approach determines the direction, or vector, and distance to any link in an internetwork. The distance vector routing approach determines the direction, or vector, and distance to any link in an internetwork. The link-state approach recreates the exact topology of an entire internetwork. The link-state approach recreates the exact topology of an entire internetwork.

27. Distance Vector Routing The distance vector routing algorithm passes periodic copies of a routing table from router to router. The distance vector routing algorithm passes periodic copies of a routing table from router to router. These regular updates between routers communicate topology changes. These regular updates between routers communicate topology changes. The distance vector routing algorithm is also known as the Bellman-Ford algorithm. The distance vector routing algorithm is also known as the Bellman-Ford algorithm.

28. Distance Vector Operation

29. Distance Vector Network Discovery

30. Routing Metric Component

31. Work best situation for Distance Vector Distance vector protocols work best in situations where: Distance vector protocols work best in situations where: –The network is simple and flat and does not require a special hierarchical design. –The administrators do not have enough knowledge to configure and troubleshoot link- state protocols. –Specific types of networks, such as hub-and- spoke networks, are being implemented. –Worst-case convergence times in a network are not a concern.

32. Link State Protocol The link-state algorithm is also known as Dijkstra's algorithm or as the shortest path first (SPF) algorithm. The link-state algorithm is also known as Dijkstra's algorithm or as the shortest path first (SPF) algorithm. The link-state routing algorithm maintains a complex database of topology information The link-state routing algorithm maintains a complex database of topology information It also maintain full knowledge of distant routers and how they interconnect It also maintain full knowledge of distant routers and how they interconnect

33. Link State Concept

34. Link state Network discovery

35. Link State Concern

36. Work best situation for Link state Link-state protocols work best in situations where: Link-state protocols work best in situations where: –The network design is hierarchical, usually occurring in large networks. –The administrators have a good knowledge of the implemented link-state routing protocol. –Fast convergence of the network is crucial.

37. Classful routing protocols (1/3) Classful routing protocols do not send subnet mask information in routing updates. Classful routing protocols do not send subnet mask information in routing updates. This was at a time when network addresses were allocated based on classes, class A, B, or C. This was at a time when network addresses were allocated based on classes, class A, B, or C. A routing protocol did not need to include the subnet mask in the routing update because the network mask could be determined based on the first octet of the network address. A routing protocol did not need to include the subnet mask in the routing update because the network mask could be determined based on the first octet of the network address.

38. Classful routing protocols(2/3) Classful routing protocols cannot be used when a network is subnetted using more than one subnet mask, Classful routing protocols cannot be used when a network is subnetted using more than one subnet mask, –do not support variable length subnet masks (VLSM). There are other limitations to classful routing protocols including their inability to support discontiguous networks. There are other limitations to classful routing protocols including their inability to support discontiguous networks. Classful routing protocols include RIPv1 and IGRP. Classful routing protocols include RIPv1 and IGRP.

39. Classful routing protocols(3/3)

40. Classless Routing Protocols (1/3) Classless routing protocols include the subnet mask with the network address in routing updates. Classless routing protocols include the subnet mask with the network address in routing updates. Today's networks are no longer allocated based on classes and the subnet mask cannot be determined by the value of the first octet. Today's networks are no longer allocated based on classes and the subnet mask cannot be determined by the value of the first octet. Classless routing protocols are required in most networks today because of their support for VLSM Classless routing protocols are required in most networks today because of their support for VLSM

41. Classless Routing Protocols (2/3) In the figure, notice that the classless version of the network is using both /30 and /27 subnet masks in the same topology. In the figure, notice that the classless version of the network is using both /30 and /27 subnet masks in the same topology. –Also notice that this topology is using a discontiguous design. Classless routing protocols are RIPv2, EIGRP, OSPF, IS-IS, BGP. Classless routing protocols are RIPv2, EIGRP, OSPF, IS-IS, BGP.

42. Classless Routing Protocols (3/3)

43. Convergence Convergence time is the time it takes routers to share information, calculate best paths, and update their routing tables. Convergence time is the time it takes routers to share information, calculate best paths, and update their routing tables. Most networks require short convergence times. Most networks require short convergence times. Generally, RIP and IGRP are slow to converge, whereas EIGRP and OSPF are faster to converge. Generally, RIP and IGRP are slow to converge, whereas EIGRP and OSPF are faster to converge.

44. Metrics (1/4) A metric is a value used by routing protocols to assign costs to reach remote networks. A metric is a value used by routing protocols to assign costs to reach remote networks. The metric is used to determine which path is most preferable when there are multiple paths to the same remote network. The metric is used to determine which path is most preferable when there are multiple paths to the same remote network.

45. Metrics (2/4)

46. Metrics (3/4) Metrics used in IP routing protocols include: Metrics used in IP routing protocols include: –Hop count - A simple metric that counts the number of routers a packet must traverse –Bandwidth - Influences path selection by preferring the path with the highest bandwidth –Load - Considers the traffic utilization of a certain link –Delay - Considers the time a packet takes to traverse a path –Reliability - Assesses the probability of a link failure, calculated from the interface error count or previous link failures –Cost - A value determined either by the IOS or by the network administrator to indicate preference for a route.

47. Metrics (4/4) The metric for each routing protocol is: The metric for each routing protocol is: –RIP: Hop count - Best path is chosen by the route with the lowest hop count. –IGRP and EIGRP: Bandwidth, Delay, Reliability, and Load - Best path is chosen by the route with the smallest composite metric value calculated from these multiple parameters. By default, only bandwidth and delay are used. –IS-IS and OSPF: Cost - Best path is chosen by the route with the lowest cost..

48. Metric in routing table

49. Load Balancing When two or more routes to the same destination have identical metric values When two or more routes to the same destination have identical metric values The router does not choose only one route. The router does not choose only one route. Instead, the router "load balances" between these equal cost paths. The packets are forwarded using all equal-cost paths. Instead, the router "load balances" between these equal cost paths. The packets are forwarded using all equal-cost paths. Note: Load balancing can be done either per packet or per destination. Note: Load balancing can be done either per packet or per destination.

50. Administrative Distance (AD)(1/3) Administrative distance (AD) defines the preference of a routing source. Administrative distance (AD) defines the preference of a routing source. Each routing source - including specific routing protocols, static routes, and even directly connected networks - is prioritized in order of most- to least-preferable using an administrative distance value. Each routing source - including specific routing protocols, static routes, and even directly connected networks - is prioritized in order of most- to least-preferable using an administrative distance value. Administrative distance is an integer value from 0 to 255. The lower the value the more preferred the route source. Administrative distance is an integer value from 0 to 255. The lower the value the more preferred the route source. An administrative distance of 0 is the most preferred. An administrative distance of 0 is the most preferred. –Only a directly connected network has an administrative distance of 0, which cannot be changed.

51. Administrative Distance (AD) (2/3)

52. Administrative Distance (AD) (3/3)

53. RIP V2 W.lilakiatsakun

54. RFC 2453 (obsoletes –RFC 1723 /1388) RFC 2453 (obsoletes –RFC 1723 /1388) Extension of RIP v1 (Classful routing protocol) Extension of RIP v1 (Classful routing protocol) Classless routing protocol Classless routing protocol –VLSM is supported Subnet mask included in the routing updates Subnet mask included in the routing updates Next-hop addresses included in the routing updates Next-hop addresses included in the routing updates Use of multicast addresses in sending updates Use of multicast addresses in sending updates Authentication option available Authentication option available

56. RIP V2 & V1 Use of holddown and other timers to help prevent routing loops. Use of holddown and other timers to help prevent routing loops. Use of split horizon or split horizon with poison reverse to also help prevent routing loops. Use of split horizon or split horizon with poison reverse to also help prevent routing loops. Use of triggered updates when there is a change in the topology for faster convergence. Use of triggered updates when there is a change in the topology for faster convergence. Maximum hop count limit of 15 hops, with the hop count of 16 signifying an unreachable network. Maximum hop count limit of 15 hops, with the hop count of 16 signifying an unreachable network.

57. RIP v1 Limitation (Discontiguous Address)

58. Addressing scheme

59. VLSM

60. Private IP

61. Problems R1 cannot ping to network 172.30.100.0 R1 cannot ping to network 172.30.100.0 R3 cannot ping to network 172.30.1.0 R3 cannot ping to network 172.30.1.0 R2 can partially ping to network 172.30.1.0 and 172.30.100.0 R2 can partially ping to network 172.30.1.0 and 172.30.100.0

62. R2 installs both paths in routing table

63. R2 routing table

64. NO VLSM supported RIPv1 either summarizes the subnets to the classful boundary or uses the subnet mask of the outgoing interface to determine which subnets to advertise. RIPv1 either summarizes the subnets to the classful boundary or uses the subnet mask of the outgoing interface to determine which subnets to advertise.

65. No CIDR supported

66. Static Routing configuration and Routing Table on R2

68. Because … RIPv1 and other classful routing protocols cannot support CIDR routes that are summarized routes with a smaller subnet mask than the classful mask of the route. RIPv1 and other classful routing protocols cannot support CIDR routes that are summarized routes with a smaller subnet mask than the classful mask of the route. RIPv1 ignores these supernets in the routing table and does not include them in updates to other routers. RIPv1 ignores these supernets in the routing table and does not include them in updates to other routers. This is because the receiving router would only be able to apply the larger classful mask to the update and not the shorter /16 mask. This is because the receiving router would only be able to apply the larger classful mask to the update and not the shorter /16 mask.

69. RIP V2 RFC 1723 RFC 1723 RIPv2 is encapsulated in a UDP segment using port 520 and can carry up to 25 routes. RIPv2 is encapsulated in a UDP segment using port 520 and can carry up to 25 routes. 3 extensions are added. 3 extensions are added. –The subnet mask field –The Next Hop address –The Route Tag

71. RIP V2 configuration

72. Auto-Summary and RIP V2 (1)

73. Auto-Summary and RIP V2 (2) Auto-summary

74. Auto summary Auto-Summary and RIP V2 (3)

75. Redistribute Static

76. Disabling Auto-summary

79. RIP V2 and VLSM

81. RIP V2 and CIDR

82. Verifying RIP

83. Authentication RIPv2, EIGRP, OSPF, IS-IS, and BGP can be configured to authenticate routing information. RIPv2, EIGRP, OSPF, IS-IS, and BGP can be configured to authenticate routing information. This practice ensures routers will only accept routing information from other routers that have been configured with the same password or authentication information. This practice ensures routers will only accept routing information from other routers that have been configured with the same password or authentication information. Note: Authentication does not encrypt the routing table. Note: Authentication does not encrypt the routing table.

84. RIPV2 Authentication The authentication scheme for RIP version 2 will use the space of an entire RIP entry. If the Address Family Identifier of the first (and only the first) entry in the message is 0xFFFF, then the remainder of the entry contains the authentication. This means that there can be at most, 24 RIP entries in the remainder of the message.

86. LAB – RIP V2 CCNA2 – LAB7.5.1 / 7.5.2 CCNA2 – LAB7.5.1 / 7.5.2