D-Link DES-3326, Руководство пользователя

Страница: 213 / 425

24-port NWay Ethernet Switch User’s Guide
Configuring the Switch Using the Console Interface 197
transmitting Hello messages to advertise its availability to
become the root router.
The default is
30
seconds.
The
Join/Prune Interval:[60 ]
field allows an entry of
between 1 and 65535 seconds and determines the interval
between transmitting (flooding to all interfaces) multicast
messages to downstream routers, and automatically ‘pruning’ a
branch from the multicast delivery tree. This interval also
determines the time interval the router uses to automatically
remove prune information from a branch of a multicast delivery
tree and begin to flood multicast messages to all branches of that
delivery tree. These two actions are equivalent.
The default is
60 seconds.
Note: The PIM-DM multicast routing protocol is
assumes that all downstream routers want to receive
multicast messages and relies upon explicit prune
messages from downstream routers to remove branches
from the multicast delivery tree that do not contain
multicast group members.
Note: PIM-DM has no explicit ‘join’ messages. It relies
upon periodic flooding of multicast messages to all
interfaces and then either waiting for a timer to expire
(the
Join/Prune Interval ) or for the downstream
routers to transmit explicit ‘prune’ messages indicating
that there are no multicast members on their respective
branches. PIM-DM then removes these branches (‘prunes’
them) from the multicast delivery tree.
Note:
Because a member of a pruned branch of a
multicast delivery tree may want to join a multicast
delivery group (at some point in the future), the protocol
periodically removes the ‘prune’ information from its
database and floods multicast messages to all interfaces
on that branch. The interval for removing ‘prune’
information is the
Join/Prune Interval.