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Catalyst 3750 Switch Software Configuration Guide
OL-8550-02
Chapter 40 Configuring IP Multicast Routing
Configuring Optional Multicast Routing Features
To return to the default setting, use the no ip sdr cache-timeout global configuration command. To
delete the entire cache, use the clear ip sdr privileged EXEC command.
To display the session directory cache, use the show ip sdr privileged EXEC command.
Configuring an IP Multicast Boundary
Administratively-scoped boundaries can be used to limit the forwarding of multicast traffic outside of a
domain or subdomain. This approach uses a special range of multicast addresses, called
administratively-scoped addresses, as the boundary mechanism. If you configure an
administratively-scoped boundary on a routed interface, multicast traffic whose multicast group
addresses fall in this range can not enter or exit this interface, thereby providing a firewall for multicast
traffic in this address range.
Note Multicast boundaries and TTL thresholds control the scoping of multicast domains; however, TTL
thresholds are not supported by the switch. You should use multicast boundaries instead of TTL
thresholds to limit the forwarding of multicast traffic outside of a domain or a subdomain.
Figure 40-5 shows that Company XYZ has an administratively-scoped boundary set for the multicast
address range 239.0.0.0/8 on all routed interfaces at the perimeter of its network. This boundary prevents
any multicast traffic in the range 239.0.0.0 through 239.255.255.255 from entering or leaving the
network. Similarly, the engineering and marketing departments have an administratively-scoped
boundary of 239.128.0.0/16 around the perimeter of their networks. This boundary prevents multicast
traffic in the range of 239.128.0.0 through 239.128.255.255 from entering or leaving their respective
networks.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
ip sdr cache-timeout minutes Limit how long an sdr cache entry stays active in the cache.
By default, entries are never deleted from the cache.
For minutes, the range is 1 to 4294967295.
Step 3
end Return to privileged EXEC mode.
Step 4
show running-config Verify your entries.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.
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