Cisco Systems 3750E Controlling Route Exchanges, Limiting the Number of Dvmrp Routes Advertised

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-routinginterface configuration command).

Beginning in privileged EXEC mode, follow these steps to change the DVMRP route limit. This procedure is optional.

	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.

To configure no route limit, use the no ip dvmrp route-limitglobal 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.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		42-47