Routing

1. Routing Routing is the process of moving data from one network to another by forwarding packets via gateways.

2. Path Determination Graphic

4. EGP Exterior Gateway Protocols are used for routing between Autonomous Systems IGP Interior Gateway Protocols are used for routing decisions within an Autonomous System. Autonomous System An Autonomous System (AS) is a group of IP networks, which has a single and clearly defined external routing policy. AS 1000 AS 3000 AS 2000 Fig. 48 IGP and EGP (TI1332EU02TI_0004 The Network Layer, 67)

5. Exterior Gateway Protocol (EGP) EGP EGP EGP Interior Gateway Protocol (IGP) Interior Gateway Protocol (IGP) AS 1000 AS 3000 IGP AS 2000 Fig. 49 The use of IGP and EGP protocols (TI1332EU02TI_0004 The Network Layer, 67)

6. IGP and EGP An autonomous system is a network or set of networks under common administrative control, such as the cisco.com domain.

7. Types of Protocols • ROUTED PROTOCOLS are nothing more than data being transported across the networks. Routed protocols include: • Internet Protocol • Telnet • Remote Procedure Call (RPC) (Client is requesting for the services from the server) • SNMP (simple network management protocol) SNMP use, one or more administrative computers have the task of monitoring or managing a group of hosts or devices on a computer network • SMTP • Novell IPX NetWare is a network operating system (NOS) that provides transparent remote file access and numerous other distributed network services, including printer sharing and support for various applications such as electronic mail transfer and database access. • ROUTING PROTOCOLS are the software that allow routers to dynamically advertise and learn routes, determine which routes are available and which are the most efficient routes to a destination. Routing protocols used by the Internet Protocol suite include: • Routing Information Protocol (RIP and RIP II) • Open Shortest Path First (OSPF) • Intermediate System to Intermediate System (IS-IS) • Interior Gateway Routing Protocol (IGRP) • Cisco's Enhanced Interior Gateway Routing Protocol (EIGRP) • Border Gateway Protocol (BGP)

8. Appletalk AppleTalk is a proprietarysuite of protocols developed by Apple Inc. for networking computers • Banyan Vines (for Virtual Integrated NEtwork Service) was a computer network operating system and the set of computer network protocols it used to talk to client machines on the network. The Banyan company based the VINES operating system on Unix

9. Routing Protocol Router Switch Router Router Router Router Switch What is an optimal route ?

10. Routing Protocols Routing protocols includes the following: processes for sharing route information allows routers to communicate with other routers to update and maintain the routing tables Examples of routing protocols that support the IP routed protocol are: RIP, IGRP, OSPF, BGP, and EIGRP.

11. Routed Protocols Protocols used at the network layer that transfer data from one host to another across a router are called routed or routable protocols. The Internet Protocol (IP) and Novell's Internetwork Packet Exchange (IPX) are examples of routed protocols. Routers use routing protocols to exchange routing tables and share routing information. In other words, routing protocols enable routers to route routed protocols.

12. Types of Routing • Static Routing • Default Routing • Dynamic Routing

13. Static Routing • It is configured by Administrator manually. • Mandatory need of Destination Network ID • It is Secure & fast • Used for Small organizations with a network of 10-15 Routers. • Administrative distance for Static Route is 0 and 1. • It is the “trustworthiness” of the routing information. Lesser the Administrative distance, higher the preference.

14. Disadvantages of Static Routing • Administrative work is more. • Compulsory need of Destination Network ID’s • Used for only Small organizations • It cannot dynamically update topology changes.

15. Default Routing • A Default routing protocol is configured for unknown destinations. • Generally used in the internet where the destinations are unknown. • Example : The address of yahoo is unknown. • Configured at end points • It is the last preferred routing

16. HYD Default Routing - Real Time Example INTERNET E0 192.168.1.150/24 E0 202.54.30.150/24 LAN - 192.168.1.0/24 IP 202.54.30.1/24

17. Dynamic Routing • Advantages of Dynamic over static : • There is no need to know the destination networks. • Need to advertise the directly connected networks. • Updates the topology changes dynamically. • Administrative work is reduced • Used for large organizations.

18. Types of Dynamic Routing Protocols • Distance Vector Protocol • Link State Protocol • Hybrid Protocol

19. Distance Vector Protocol • Works with Bellman Ford algorithm • Periodic updates • Classful routing protocol • Full Routing tables are exchanged • Updates are through broadcast • Also known as “Routing By Rumor” • Example: RIP, IGRP

20. Link State Protocol • Works with Dijkstra algorithm • Link state updates • Classless routing protocol • Missing routes are exchanged • Updates are through multicast • Also known as “ Routing by Intelligence” • Example : OSPF, IS-IS

21. Hybrid Protocol • Works with DUAL algorithm • Link state updates • Classless routing protocol • Missing routes are exchanged • Updates are through multicast • Also known as “ Routing by Intelligence” • Example : EIGRP

22. Routing Information Protocol • Open Standard Protocol • Classful routing protocol • Updates are broadcasted via 255.255.255.255 • Administrative distance is 120 • Metric : Hop count • Max Hop counts : 15 Max routers : 16 • Load Balancing of 4 equal paths • Used for small organizations

23. Rip Timers • Update timer : 30 sec • Time between consecutive updates • Invalid timer : 180 sec • Time a router waits to hear updates • The route is marked unreachable if there is no update during this interval. • Flush timer : 240 sec • Time before the invalid route is purged from the routing table • Holddown timer : 180sec • Specifies the amount of time for which the information about poorer routes are ignored.

24. RIP Timers • Update Timer: 30 sec. • Time between consecutive updates. • Invalid Timer: 180 sec • It is a time a router waits to hear updates • The route is marked unreachable if there is no update during this interval • Flush Timer: 240 sec • Time before the invalid route is purged from the routing table. • Hold down Timer: 180 sec • Specifies the amount of time for which the information about poorer router is ignored.

25. Disadvantages of RIP • More bandwidth utilization since it sends updates for every 30 secs. • Doesn’t consider bandwidth, works only with hop count. • Slow convergence. • Formation of routing loops. • Note: The biggest disadvantage of RIP is, it sends updates every 30 sec i.e., bandwidth consumption.

26. RIP Version 2 Features and Concepts • Supported in IOS version 11.1 and later • Route updates include subnet masks • Supports Variable-Length Subnet Masks (VLSM) • Authentication of Routing Updates • Next hop address carried with each Routing Update • Multicast address used for Routing Updates • Same as RIP Version 1 • Exception is the Multicasting of Routing updates to a Multicast address of 224.0.0.9.

27. RIP Version 2 Features and Concepts • Supported in IOS version 11.1 and later • Route updates include subnet masks • Supports Variable-Length Subnet Masks (VLSM) • Authentication of Routing Updates • Next hop address carried with each Routing Update • Multicast address used for Routing Updates • Same as RIP Version 1 • Exception is the Multicasting of Routing updates to a Multicast address of 224.0.0.9.

28. Distance Vector • Uses Autonomous Systems • Update Timers = 90 sec • Default maximum hop Count = 100, configurable to a maximum of 255. • Holddown timers = 3 x 90 sec + 10 • Invalidation Timer = 3 x 90 sec = 270 sec • Random Jitter = 20% (72-90 sec) • Metrics used : BDRLM. By Default it only uses Bandwidth and Delay • Bandwidth = Default is 1544. • Delay = 10 Millisecond units. • Reliability = Can equal number of errors, a fraction of 255, 255 means 100% reliable. • Load = A fraction of 255, 0 means no load • MTU = The MTU value of the path.