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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter24 Configuring IP Multicast Routi ng Configuring Optional Multicast Routing Features
multicast packets with an initial TTL value set to 99. The engineering and marketing departments have
set a TTL threshold of 40 at the perimeter of their networks; therefore, multicast applications runni ng
on these networks can prevent their multicast transmissions from leaving their respective networks.
Figure24-11 TTL Boundaries
Beginning in privileged EXEC mode, follow these steps to change the defa ult TTL th reshol d val ue:
To return to the default TTL setting, use the no ip multicast ttl-threshold interface configuration
command.
45153
Company XYZ
TTL threshold = 40
Engineering
TTL threshold = 40
TTL threshold = 100
Marketing
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and specify the interface to be
configured.
Step3 ip multicast ttl-threshold ttl-value Configure the TTL threshold of packets being forwarded out an
interface.
The default TTL value is 0 hops, which means that all multicast packets
are forwarded out the interface. The range is 0 to 255.
Only multicast packets with a TTL value greater than the threshold are
forwarded out the interface.
You should configure the TTL threshold only on routed interfaces at the
perimeter of the network.
Step4 end Return to privileged EXEC mode.
Step5 show running-config Verify your entries.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.