Asante Technologies 35516 - Manual (Page 64)

- 64 -
Configuring the TTL Threshold
The time-to-live (TTL) value controls whether packets are forwarded out of an interface. The TTL value is specified in
hops. Only multicast packets with a TTL value greater than the interface TTL threshold are forwarded on the
interface. The default value is 0, which means that all multicast packets are forwarded on the interface.
To change the default TTL threshold value, use the following command in interface configuration mode:
Command Purpose
ip multicast ttl-threshold <0-255> Configure the TTL threshold of packets being forwarded out
an interface.
5.5.3 DVMRP
Distance Vector Multicast Routing Protocol (DVMRP) is a routing protocol that provides packet delivery to a group of
hosts across an inter-network. DVMRP routers dynamically discover their neighbors by sending neighbor probe
messages periodically to an IP multicast group address that is reserved for all DVMRP routers. These mechanisms
allow the formation of shortest-path trees, which are used to forward packets to all group members from each
network source of multicast traffic. Multicast packets are initially flooded down a source tree. If redundant paths are
on the source tree, packets are not forwarded along those paths. Forwarding occurs until Prune messages are
received on those links, which further constrain the broadcast of multicast packets.
DVMRP is designed as an interior gateway protocol (IGP) within a multicast domain.
5.5.4 Configuring DVMRP
This section presents the commands for configuring DVMRP IP Multicast Routing Protocol. The following commands
are available from global configuration mode:
Router(config)# ip dvmrp ?
enable Enable DVMRP Multicast Routing Protocol
graft-retransmit-interval DVMRP graft message retransmitting interval
nbr-timeout DVMRP neighbor timeout value
probe-interval DVMRP Neighbor Probe message interval
prune-age DVMRP prune lifetime value in seconds
report-interval DVMRP report interval
route-discard-timeout DVMRP route discard timeout
route-expire-timeout DVMRP route expiration timeout
route-holddown-time DVMRP route holdown time
Router(config)# ip dvmrp
Important! Remember that a no command (such as no ip dvmrp enable) negates a previously entered command.
Enabling DVMRP
In order to enable DVMRP protocol, you must enter into the global configuration mode and then issue the following
global command.
Command Purpose
ip dvmrp enable Enable a DVMRP IP Multicast routing process, which places
you in router configuration mode.