BGP: Difference between revisions
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*Origin - Prefer Internal(advertised by network cmd - 'i') over External(advertised by redistribe cmd -'?') |
*Origin - Prefer Internal(advertised by network cmd - 'i') over External(advertised by redistribe cmd -'?') |
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* Directions |
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'''Aspath prepend:''' Applied outwardly. |
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Impacts incoming path. |
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Shorter the as-path length higher the preference |
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As-path prepend is the way to add AS number to the list of subnet u want to advertise. |
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This is a way to route poisoning. |
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Tell the outside world not to follow the path. |
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'''Local preference:''' Applied while the traffic coming inside. |
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Impacts traffic while going out. |
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Non transitive. |
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Propagates within the same as-path. |
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Higher the local preference value higher the preference |
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'''MED:''' Multiexitdescriptor |
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When your router has connection with two other routers with same AS. |
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Let's say you have 2 subnets behind your router. |
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You can use MED value to mention which networks should be accessed through which links. |
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It is advertised outwards. |
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Impacts the incoming traffic. |
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Semi transitive. |
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Propagates to one AS. |
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Lower the MED value higher the preference. |
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MED should be used carefully as it reduces network resiliency. |
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=Filter with Route Maps= |
=Filter with Route Maps= |