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Lectures notes for 2010 - KTH

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Reverse -Path Forwarding (RPF)<br />

RPF algorithm takes advantage of a routing table to “orientate” the network and<br />

to compute an implicit tree per network source.<br />

Procedure<br />

1.When a multicast packet is received, note source (S) and interface (I)<br />

2.If I belongs to the shortest path toward S, <strong>for</strong>ward to all interfaces except I.<br />

• Compute shortest path from the source to the node rather than from<br />

the node to the source.<br />

• Check whether the local router is on the shortest path between a<br />

neighbor and the source be<strong>for</strong>e <strong>for</strong>warding a packet to that neighbor.<br />

If this is not the case, then there is no point in <strong>for</strong>warding a packet that<br />

will be immediately dropped by the next router.<br />

Maguire Reverse -Path Forwarding (RPF) 8: 38 of 78<br />

maguire@kth.se <strong>2010</strong>.03.21 Internetworking/Internetteknik

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