HP 3500YL - Manual (Page 80)

PIM-DM (Dense Mode)
Configuring PIM-DM
Syntax: ip pim-dense [ propagation-delay < 250-2000 >]
vlan < vid > ip pim-dense [ propagation-delay < 250-2000 >]
ip pim-dense [ override-interval < 500 - 6000 >]
vlan < vid > ip pim-dense [ override-interval < 500 - 6000 >]
A routing switch sharing a VLAN with other multicast
routers uses these two values to compute the
lan-prune-delay
setting (above) for how long to wait for a PIM-DM join after
receiving a prune packet from downstream for a particular
multicast group. For example, a network may have multiple
routing switches sharing VLAN “X”. When an upstream
routing switch initially floods traffic from multicast group
“X” to VLAN “Y”, if one of the routing switches on VLAN “Y”
does not want this traffic it issues a prune response to the
upstream neighbor. The upstream neighbor then goes into a
“prune pending” state for group “X” on VLAN “Y”. (During
this period, the upstream neighbor continues to forward the
traffic.) During the “pending” period, another routing
switch on VLAN “Y” can send a group “X” Join to the
upstream neighbor. If this happens, the upstream neighbor
drops the “prune pending” state and continues forwarding
the traffic. But if no routers on the VLAN send a Join, then
the upstream router prunes group “X” from VLAN “Y” when
the
lan-prune-delay timer expires. (Defaults: propagation-
delay = 500 milliseconds; override-interval = 2500
milliseconds.)
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