Configuration Guide User guide
1582 FastIron Configuration Guide
53-1002494-02
DVMRP configuration on the Layer 3 switch and interface
Grafts to a multicast tree
A DVMRP router restores pruned branches to a multicast tree by sending graft messages towards
the upstream switch. Graft messages start at the leaf node and travel up the tree, first sending the
message to its neighbor upstream switch.
In the example above, if a new 229.255.0.1 group member joins on switch S6, which had been
pruned previously, a graft will be sent upstream to S4. Since the forwarding state for this entry is in
a prune state, S4 sends a graft to S1. Once S4 has joined the tree, it and S6 will once again
receive multicast packets.
You do not need to perform any configuration to maintain the multicast delivery tree. The prune
and graft messages automatically maintain the tree.
DVMRP configuration on the Layer 3 switch
and interface
Suppose you want to initiate the use of desktop video for fellow users on a sprawling campus
network. All destination workstations have the appropriate hardware and software but the Layer 3
switches that connect the various buildings need to be configured to support Distance Vector
Multicast Protocol (DVMRP) multicasts from the designated video conference server as seen in
Figure 178.
...
...
...
229.225.0.1
Group
Member
Group
Member
Video Conferencing
Server
(207.95.5.1, 229.225.0.1)
(Source, Group)
229.225.0.1
Group
Member
Group
Member
Group
Member
Group
Member
Group
Member
Group
Member
229.225.0.1
Leaf Node
(No Group Members)
Intermediate Node
(No Group Members)
R2
R1
R3
R4
R5
R6
Prune Message
sent to upstream router (R4)