Planet Networking & Communication WGS3-2820 User Manual page 290

4.7.3.5 DVMRP Prune Summary
Non-Configurable Data
Group IP - The group address which has been pruned.
o
Source IP - The address of the source or source network which has been pruned.
o
Source Mask - The subnet mask to be combined with the source IP address to identify the source or source network
o
which has been pruned.
Expiry Time - The amount of time remaining before this prune should expire at the upstream neighbor. If no prune
o
messages have been received from downstream neighbors, this is set to value of the default prune lifetime timer,
otherwise it is set to the smallest received value or the default timer, whichever is less.
Command Buttons
Refresh - Refresh the screen with the new data
o
Notice
Purning
Pruning is the mechanism with which DVMRP is cutting unneeded routers out from the Truncated Broadcast Tree
(TBT) in order to minimize the network resources used in carrying the multicast traffic.
Infinity the multicast packet (S, G) is broadcasted thru all TBT.
Each leaf router that has no subsequent receivers for that traffic, sends up-stream a Prune message in order to be left
out of the TBT for that traffic.
Pruned branches of the TBT will time out (typically after 2 minutes) and traffic will once again flood down all branches
of the TBT.
Figure 4-6-66 DVMRP Prune Summary
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User's Manual of WGS3-2820/WGS3-5220