Dynamic routing protocols are used to automatically discover remote networks, maintain up-to-date routing information, and choose the best path to destination networks. There are two main types - interior gateway protocols (IGPs) like RIP, OSPF, and EIGRP that are used within an autonomous system, and exterior protocols like BGP that route between autonomous systems. IGPs use metrics like hop count or bandwidth to determine the best path. OSPF is a link-state protocol that floods link information, while EIGRP uses DUAL algorithm and maintains topology tables for fast convergence.

1. DYNAMIC ROUTING
PROTOCOLS
PRESENTED BY-:
VARINDER SINGH WALIA

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. 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

4. DYNAMIC ROUTING
PROTOCOLS

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. 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. AD VALUE FOR ROUTING PROTOCOLS
it is a numeric value that specifies the preference of a particular route

8. INTERIOR ROUTING PROTOCOLS
 RIP
 OSPF
 EIGRP

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. COMMAND USED
 Router (config)# router rip
 Router (config-router)# network_required network
IP

11. RIP CHARACTERISTICS
 Distance vector routing protocol.
 Uses hop count as a path selection metric.
 Three types of timers.
 Multiple stability features.

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. 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. 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. COMMAND USED
 Router (config)# router rip
 Router (config)# ver 2
 Router (config-router)# network_required network
IP

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. 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. 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. 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. 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. 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. 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. OSPF (cont’d)
 Types of Links
 In OSPF terminology, a connection is called a
link.

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. OSPF (cont’d)
• Tranisent network:
is a network with several routers attached to
transient Link .
(network)

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. 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. 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. 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. 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. 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. SYNTAX :
 Router (config)# router eigrp_PROCESS ID ( )
 Router (config-router)# network _ required
network IP

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. 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.