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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter46 Configuring IP Multicast Routing
Configuring Advanced DVMRP Interoperability Features
Controlling Route Exchanges
These sections describe how to tune the Cisco device advertisements of DVMRP routes:
Limiting the Number of DVMRP Routes Advertised, page46-57 (optional)
Changing the DVMRP Route Threshold, page46-57 (optional)
Configuring a DVMRP Summary Address, page46-58 (optional)
Disabling DVMRP Autosummarization, page46-60 (optional)
Adding a Metric Offset to the DVMRP Route, page46-60 (optional)

Limiting the Number of DVMRP Routes Advertised

By default, only 7000 DVMRP routes are advertised over an interface enabled to run DVMRP (that is,
a DVMRP tunnel, an interface where a DVMRP neighbor has been discovered, or an interface configured
to run the ip dvmrp unicast-routing interface configuration command).
Beginning in privileged EXEC mode, follow these steps to change the DVMRP route limit. This
procedure is optional.
To configure no route limit, use the no ip dvmrp route-limit global configuration command.

Changing the DVMRP Route Threshold

By default, 10,000 DVMRP routes can be received per interface within a 1-minute interval. When that
rate is exceeded, a syslog message is issued, warning that there might be a route surge occurring. The
warning is typically used to quickly detect when devices have been misconfigured to inject a large
number of routes into the MBONE.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 ip dvmrp route-limit count Change the number of DVMRP routes advertised over an interface
enabled for DVMRP.
This command prevents misconfigured ip dvmrp metric interface
configuration commands from causing massive route injection into the
MBONE.
By default, 7000 routes are advertised. The range is 0 to 4294967295.
Step3 end Return to privileged EXEC mode.
Step4 show running-config Verify your entries.
Step5 copy running-config startup-config (Optional) Save your entries in the configuration file.