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Configuring IP Multicast Routing
Configuring Optional Multicast Routing Features
DETAILED STEPS
To return to the default setting, use the no ip sap cache-timeout global configuration command. To delete the entire
cache, use the clear ip sap privileged EXEC command.
To display the session directory cache, use the show ip sap privileged EXEC command.
EXAMPLE
The following example causes SAP cache entries to remain in the cache for 30 minutes:
ip sap cache-timeout 30
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 cannot 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 91 on page 724 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
1. configure terminal Enter global configuration mode.
2. ip sap cache-timeout minutes Limit how long an SAP cache entry stays active in the cache.
By default, session announcements remain for 1440 minutes (24
hours) in the cache.
For minutes, the range is 1 to 4294967295.
3. end Return to privileged EXEC mode.
4. show running-config Verify your entries.
5. copy running-config
startup-config
(Optional) Save your entries in the configuration file.
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