User's Manual

Table Of Contents
507
Users Manual of CS-6306R
50.2.3 Configuring TTL Threshold
Run the command ip multicast ttl-threshold to configure the TTL threshold of the multicast message that is
allowed to pass the port. Run the command no ip multicast ttl-threshold to use the default threshold value
1.
Command Purpose
ip multicast ttl-thresholdttl-value
Configures the TTL threshold on the
port.
Example
The following example shows how the administrator configures the TTL threshold on a port:
interface ethernet 1/0
ip multicast ttl-threshold 200
50.2.4 Cancelling Rapid Multicast Forwarding
Run the command ip multicast mroute-cache to configure the rapid multicast forwarding function on a port.
Run the command no ip multicast mroute-cache to cancel the rapid multicast forwarding function.
Command Purpose
ip multicast mroute-cache
Enables the rapid multicast forwarding
function on a port.
Example
The following example shows how the administrator cancels the rapid multicast forwarding function on a port:
interface ethernet 1/0
no ip mroute-cache
50.2.5 Configuring Static Multicast Route
The static multicast route allows that the multicast forwarding path is different from the unicast path. RPF
check is performed when the multicast message is forwarded. The actual port receiving the message is the
expected receiving port. That is, the port is the next-hop port of the unicast route that reaches the sender. If
the unicast topology is same to the multicast topology, RPF check is reasonable. In some cases, the unicast
path requires to be different from the multicast path.
Take the tunnel technology as an example. When a router in a path does not support the multicast protocol,
the resolution is to configure the GRE tunnel between two routeres. In the following figure, each unicast router
supports only the unicast message; each multicast router supports only the multicast message. The source
host sends the multicast message to the destination host through MR1 and MR2. MR2 forwards the multicast
message only when it is received through the tunnel. When the destination host sends the unicast message to
the source host, the tunnel is also used. When the tunnel technology is adopted, the message transmission
speed is slower than that of the direct message transmission.