# Internet Protocol Analysis/Routing

This lesson introduces routing and routing protocols. Activities include configuring routing on Windows workstations and using Wireshark to examine Routing Information Protocol (RIP), Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (EIGRP), and Border Gateway Protocol (BGP) network traffic.

## Readings

* Wikipedia: Routing
* Wikipedia: Distance-vector routing protocol
* Wikipedia: Link-state routing protocol
* Wikipedia: Routing Information Protocol
* Wikipedia: Open Shortest Path First
* Wikipedia: Enhanced Interior Gateway Routing Protocol
* Wikipedia: Border Gateway Protocol

## Multimedia

* YouTube: Routing Tables - CompTIA Network+ N10-005: 1.4
* YouTube: Using the Route Command - CompTIA Network+ N10-005: 4.3
* YouTube: Configuring Routing Tables - CompTIA Network+ N10-005: 2.1
* YouTube: Routing Protocols Overview (Distance Vector and Link-State) CCNA Part 1
* YouTube: Routing Protocols Overview (Cisco CCNA- RIP, RIPv2, EIGRP, OSPF) Part 2

## Activities

* Use the route command to display the local routing table.
* Use the route command to modify the local routing table.
* Review Wireshark: Routing Information Protocol (RIP).
* Review Wireshark: Open Shortest Path First (OSPF).
* Review Wireshark: Enhanced Interior Gateway Routing Protocol (EIGRP).
* Review Wireshark: Border Gateway Protocol (BGP).
* Consider situations in which a packet analyzer might be used to troubleshoot routing traffic.

## Lesson Summary

* Routing is the process of selecting paths in a network along which to send network traffic.
* Static routing involves manual updating of routing tables with fixed paths to destination networks.
* Dynamic or adaptive routing involves automatic updating of routing tables based on information carried by routing protocols.
* Routing protocols are divided into interior and exterior protocols. Interior protocols are further divided into distance-vector protocols and link-state protocols. Distance-vector routing protocols are simple and efficient in small networks. Larger networks use link-state routing protocols.
* Distance-vector routing protocols require that a router informs its neighbors of topology changes periodically. Each link is assigned a numeric distance or cost value, and information is shared among neighboring routers to accumulate a total cost to a given destination.
* Link-state protocols require that a router inform all the nodes in a network of topology changes. Each node shares information regarding the nodes it can connect to with the entire network so that each node can build its own network map and determine for itself the least cost path to any given node.
* Routing Information Protocol (RIP) is a distance-vector routing protocol which employs the hop count as a routing metric. RIP uses the User Datagram Protocol (UDP) as its transport protocol, and is assigned the reserved port number 520.
* Open Shortest Path First (OSPF) is a link-state routing protocol. OSPF does not use a TCP/IP transport protocol (UDP, TCP), but is encapsulated directly in IP datagrams with protocol number 89.
* Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary advanced distance-vector routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router.
* Border Gateway Protocol (BGP) is the protocol which makes core routing decisions on the Internet. BGP uses the Transmission Control Protocol (TCP) as its transport protocol, and is assigned the reserved port 179.

## Key Terms
### Autonomous System (AS)

    A collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet.

### convergence

    The state of a set of routers that have the same topological information about the internetwork in which they operate.

### convergence time

    A measure of how fast a group of routers reach the state of convergence.

### count-to-infinity problem

    An error in distance-vector routing protocols caused by the routers being unable to determine if routing loops exist in the information provided.

### exterior gateway protocol

    A routing protocol that is used to determine network reachability between autonomous systems and makes use of interior gateway protocols to resolve routes within an autonomous system.

### holddown timer

    A timer used by link-state routers that prevents invalid updates within a given period of time after they first receive information about a network that is unreachable.

### interior gateway protocol

    A routing protocol that is used to exchange routing information within an autonomous system (AS).

### route poisoning

    A link-state method of notifying a router that a previously available route has become invalid.

### split-horizon route advertisement

    A method of preventing routing loops in distance-vector routing protocols by prohibiting a router from advertising a route back onto the interface from which it was learned.

## Review Questions

Click on a question to see the answer.
* Routing is the process of _____. Routing is the process of selecting paths in a network along which to send network traffic.
* Static routing involves _____ updating of routing tables with _____ paths to destination networks. Static routing involves manual updating of routing tables with fixed paths to destination networks.
* Dynamic or adaptive routing involves _____ updating of routing tables based on _____. Dynamic or adaptive routing involves automatic updating of routing tables based on information carried by routing protocols.
* Routing protocols are divided into _____ and _____ protocols. _____ protocols are further divided into _____ protocols and _____ protocols. Routing protocols are divided into interior and exterior protocols. Interior protocols are further divided into distance-vector protocols and link-state protocols.
* _____ routing protocols are simple and efficient in small networks. Larger networks use _____ routing protocols. Distance-vector routing protocols are simple and efficient in small networks. Larger networks use link-state routing protocols.
* _____ routing protocols require that a router informs its neighbors of topology changes periodically. Each link is assigned a numeric distance or cost value, and information is shared among neighboring routers to accumulate a total cost to a given destination. Distance-vector routing protocols require that a router informs its neighbors of topology changes periodically. Each link is assigned a numeric distance or cost value, and information is shared among neighboring routers to accumulate a total cost to a given destination.
* _____ protocols require that a router inform all the nodes in a network of topology changes. Each node shares information regarding the nodes it can connect to with the entire network so that each node can build its own network map and determine for itself the least cost path to any given node. Link-state protocols require that a router inform all the nodes in a network of topology changes. Each node shares information regarding the nodes it can connect to with the entire network so that each node can build its own network map and determine for itself the least cost path to any given node.
* Routing Information Protocol (RIP) is a _____ routing protocol which employs the hop count as a routing metric. RIP uses _____ as its transport protocol, and is assigned the reserved port number _____. Routing Information Protocol (RIP) is a distance-vector routing protocol which employs the hop count as a routing metric. RIP uses the User Datagram Protocol (UDP) as its transport protocol, and is assigned the reserved port number 520.
* Open Shortest Path First (OSPF) is a _____ routing protocol. OSPF does not use a TCP/IP transport protocol (UDP, TCP), but is encapsulated directly in IP datagrams with protocol number _____. Open Shortest Path First (OSPF) is a link-state routing protocol. OSPF does not use a TCP/IP transport protocol (UDP, TCP), but is encapsulated directly in IP datagrams with protocol number 89.
* Enhanced Interior Gateway Routing Protocol (EIGRP) is a _____ routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router. Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary advanced distance-vector routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router.
* Border Gateway Protocol (BGP) is the protocol which makes core routing decisions on the Internet. BGP uses _____ as its transport protocol, and is assigned the reserved port _____. Border Gateway Protocol (BGP) is the protocol which makes core routing decisions on the Internet. BGP uses the Transmission Control Protocol (TCP) as its transport protocol, and is assigned the reserved port 179.

## Assessments

* Lesson Flashcards
* Terms Flashcards
* Quiz

## See Also

* Computer Networks - Routing