View source for CCNA Explorer 2 Introduction to Dynamic Routing Protocols

=Introduction and Advantages=
==Perspective and Background==
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|[[Image:ScreenShot740.jpg|800px|left|thumb|History]]
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==Network discovery and routing table maintenance==
'''The purpose of a routing protocol includes:'''
*Discovery of 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 path is no longer available
==Advantages==
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|[[Image:ScreenShot741.jpg|800px|left|thumb|Dynamic vs Static Routing]]
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==Overview==
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*RIP - A distance vector interior routing protocol 
*IGRP - The distance vector interior routing developed by Cisco (deprecated from 12.2 IOS and later)
*OSPF - A link-state interior routing protocol 
*IS-IS - A link-state interior routing protocol
*EIGRP - The advanced distance vector interior routing protocol developed by Cisco
*BGP - A path vector exterior routing protocol 
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=Classifying Dynamic Routing Protocols=
==IGP and EGP==
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|[[Image:ScreenShot743.jpg|800px|left|thumb|IGP vs. EGP Routing Protocols]]
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==Distance Vector and Link State==

Distance Vector bruger for det meste Bellman-Ford algoritmen.<br/>
'''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.

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|[[Image:ScreenShot745.jpg|800px|left|thumb|Distance vector]]
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'''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.

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|[[Image:ScreenShot746.jpg|800px|left|thumb|Link-State]]
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==Classful and Classless==
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|[[Image:ScreenShot747.jpg|800px|left|thumb|Classful vs. Classless]]
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==Convergence==
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|[[Image:ScreenShot748.jpg|800px|left|thumb|Convergence]]
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=Metrics=
==Purpose of a Metric==
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|[[Image:ScreenShot749.jpg|800px|left|thumb|Metric]]
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==Metrics and Routing Protocols==
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. . Cisco's implementation of OSPF uses bandwidth. IS-IS is discussed in CCNP.
Metric used in IP routing protocols:
*'''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. Cost can represent a metric, a combination of metrics or a policy. 
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|[[Image:ScreenShot750.jpg|800px|left|thumb|Show ip Route]]
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==Load Balancing==
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|[[Image:ScreenShot751.jpg|800px|left|thumb|Equal Cost Load Balancing]]
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|[[Image:ScreenShot918.jpg|800px|left|thumb|Equal Cost Load Balancing Topology]]
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=Administrativ Distance=
==Purpose of Administrative Distance==
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|[[Image:ScreenShot752.jpg|800px|left|thumb|Administrativ Distance]]
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|[[Image:ScreenShot753.jpg|800px|left|thumb|Administrativ Distance]]
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{{:Administrative_distance}}
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==Static Routes==
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|[[Image:ScreenShot754.jpg|800px|left|thumb|Static Routes]]
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