1. IP Routing
Chapter 6

2. Chapter Objectives
 Explain Protocols
 Explain Routing Metrics
 Discuss Routing Mechanisms
 Explain Routing Algorithms
 Set up routing
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3. Recall
 The router configuration files are located in:
 RAM
 NVRAM
 TFTP Server
 Protocol that gives the information about locally
attached and remote devices in the network is
termed as Cisco Discovery Protocol (CDP)
 CDP global parameters include:
 CDP timer
 CDP holdtime
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4. Goals of Routing
 Routing process ensures that appropriate packets
are routed from the source to the destination
 Goals of routing include:
 Stability
 Provides with a robust network
 Dynamic update of the network paths
 Information is safe while transmitting
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5. IP Routing with One Router
Chapter 6 5

6. IP Routing with Three Routers
Chapter 6 6

7. Process of Routing Packets within a
Router
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8. Routing Metrics
 Routing metrics are values that allow the routers
decide the best route for the data packet
 Different routing metrics include:
 Hops
 Bandwidth
 Load
 Cost
 Reliability
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9. Dynamic Routing
 The phenomena in which the routing protocols are
assigned the job of finding the path to route the
packets and update the routing tables
 Two types of dynamic routing protocols include:
 Interior routing protocols
 Exterior routing protocols
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10. Administrative Distance
 An integer assigned to every routing protocol, which
determines the reliability of the routing protocol is
termed as administrative distance (AD)
 The integer is in the range of 0 to 255
 Lower the AD, more reliable is the routing
information provided by the routing protocol
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11. AD of Routing Protocols
Routed Source Default AD
Connected Interface 0
Static Route 1
Enhanced Interior Gateway Routing Protocol 90
(EIGRP)
Interior Gateway Routing Protocol (IGRP) 100
Open Shortest Path First (OSPF) 110
Routing Information Protocol (RIP) 120
External EIGRP 170
Unknown 255 (This route will never be
used)
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12. Interior Routing Protocols
 The protocols used to route the packets inside an
autonomous system, are termed as Interior Routing
protocols
 Interior routing protocols include:
 Routing Information Protocol (RIP)
 Open Shortest Path First (OSPF)
 Interior Gateway Routing Protocol (IGRP)
 Enhanced Interior Gateway Routing Protocol
(EIGRP)
 Intermediate System to Intermediate System (IS – IS)
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13. Exterior Routing Protocols
 The routing protocols that communicate between
the two or more Autonomous Systems (AS) are
termed as Exterior routing protocols
 Exterior Routing Protocols include:
 Exterior Gateway Protocols (EGP)
 Border Gateway Protocol (BGP)
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14. Routing Tables
 The routing tables then decide the best path to the
route the packet, which also includes the next hop
address
 Information contained in the routing table include:
 Destination
 Next hop address
 Outgoing interface
 Routing Protocols
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15. Static Routing
 The phenomena of adding routes manually to the
routing table, is termed as static routing
 This is feasible in small networks, but not in large
networks
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16. Routing Information Protocol (RIP)
 RIP allows routers to exchange their routing tables
at a predefined interval
 Characteristics of RIP include:
 Uses hop count metric
 Supports 15 hop-count limit
 Supports six equal-cost paths
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17. Distance Vector concept
 The routers connected to the neighboring networks
update the list of networks and the hop counts in the
routing table
 The connected routers update the routing table with
the network information
 The routers connected to the distant networks
construct a new routing table
 The network information of the connected routers
combined with the new routing table entries is
passed to all the neighboring routing tables
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18. RIP Timers
 RIP timers are used to keep a track of the various
routes connected
 The different RIP timers include:
 Route update timer
 Route invalid timer
 Holddown timer
 Route Flush timer
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19. Enhancements in RIPv2
 RIPv2 was created to overcome the drawbacks of
RIPv1
 RIPv2 enhancements include:
 Multicasting
 Triggered updates
 Classless protocol
 Authentication
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20. Case Study
The Hyderabad branch of the Blue Diamond Steel
Company has 10 routers connected in the network.
Initially, the network administrator had configured the
network to use static routes to route the packets
containing the data and to communicate between the
networks. Now the company has decided employ
more than 100 employees for their operations in
Software Management, Human Resource, Detailing,
Business Development and Sales. This requires the
company to add five more networks to the existing
ones.
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21. Problem
The network administrator has to manually add
routes to all the networks connected and then
send the packets
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22. Solution
The network administrator decided to use RIP, which
is a dynamic routing protocol. It can add the routes
to the network automatically and uses hop count as
its metric to route the packets and can be used to
connect small networks
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23. Summary - I
 Routing occurs at the network layer of the OSI
model
 Protocols are a set of rules that define data transfer
 The routing protocols can be classified based on
their routing abilities as:
 Interior Routing Protocols
 Exterior Routing Protocols
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24. Summary - II
 Interior Routing protocols can be classified as:
 Routing Information Protocol (RIP)
 Open Shortest Path First (OSPF)
 Interior Gateway Routing Protocol (IGRP)
 Enhanced Intermediate System to Intermediate
System (EIGRP)
 Intermediate System to Intermediate System
 Exterior Routing protocols can be classified as:
 Exterior Gateway Protocol (EGP)
 Border Gateway Protocol (BGP)
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25. Summary - III
 Routing metrics are cost values that enable routers
decide the best route for the data packet
 When a router forwards a data packet to a network
segment, it is counted as a single hop
 Bandwidth measures the amount of data that can
travel over the network segment in a fixed amount of
time
 Delay specifies the amount of time that a router takes
to process and transfer a data packet to the next
device on the network
 The delay is represented with a µ symbol
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26. Summary - IV
 Load refers to the amount of traffic on a particular link
relative to the total capacity of the link
 The load value 255 indicates 100% traffic congestion
 Direct interfaces consist of routes that are local to the
router
 Routed protocols consist of protocols that define
routing and addressing
 Routing protocols are a set of rules that are
implemented on a router to determine the best path to
route the packets
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27. Summary - V
 Routing protocols can be classified into Interior
Routing Protocols and Exterior Routing Protocols
 Every router has a routing table based on which the
data packets are forwarded to the destinations
 Static routes are the routes that the administrator
manually enters in the routing table
 Static routes are used in temporary connections
such as dial-up networks
 The router automatically collects and stores
dynamic routes in the routing table
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28. Summary - VI
 Enhancements in RIPv2 include:
 Supports multicast updates against broadcast
updates
 Uses triggered updates to share its routing
information with the neighbors, when a change
occurs
 Supports Variable-Length Subnet Masking
(VSLM)
 Allows you to select the routers you want to
participate in RIPv2
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