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42-47
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter 42 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, page 42-47 (optional)
• Changing the DVMRP Route Threshold, page 42-47 (optional)
• Configuring a DVMRP Summary Address, page 42-48 (optional)
• Disabling DVMRP Autosummarization, page 42-50 (optional)
• Adding a Metric Offset to the DVMRP Route, page 42-51 (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
Step 1
configure terminal Enter global configuration mode.
Step 2
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.
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.