Cisco Systems 3750E Disabling Dvmrp Autosummarization, Ip dvmrp summary-address address, 42-50

Chapter 42 Configuring IP Multicast Routing

Configuring Advanced DVMRP Interoperability Features

Beginning in privileged EXEC mode, follow these steps to customize the summarization of DVMRP routes if the default classful autosummarization does not suit your needs. This procedure is optional.

Note At least one more-specific route must be present in the unicast routing table before a configured summary address is advertised.

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	interface interface-id	Specify the interface that is connected to the DVMRP router, and enter
		interface configuration command.
Step 3
	ip dvmrp summary-address address	Specify a DVMRP summary address.
	mask [metric value]	• For summary-addressaddress mask, specify the summary IP
		address and mask that is advertised instead of the more specific
		route.
		• (Optional) For metric value, specify the metric that is advertised
		with the summary address. The default is 1. The range is 1 to 32.
Step 4
	end	Return to privileged EXEC mode.
Step 5
	show running-config	Verify your entries.
Step 6
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

To remove the summary address, use the no ip dvmrp summary-addressaddress mask [metric value] interface configuration command.

Disabling DVMRP Autosummarization

By default, the software automatically performs some level of DVMRP summarization. Disable this function if you want to advertise all routes, not just a summary. In some special cases, you can use the neighboring DVMRP router with all subnet information to better control the flow of multicast traffic in the DVMRP network. One such case might occur if the PIM network is connected to the DVMRP cloud at several points and more specific (unsummarized) routes are being injected into the DVMRP network to advertise better paths to individual subnets inside the PIM cloud.

If you configure the ip dvmrp summary-addressinterface configuration command and did not configure no ip dvmrp auto-summary, you get both custom and autosummaries.

Beginning in privileged EXEC mode, follow these steps to disable DVMRP autosummarization. This procedure is optional.

	Command		Purpose
Step 1	configure terminal		Enter global configuration mode.
Step 2	interface interface-id		Specify the interface connected to the DVMRP router, and enter
			interface configuration mode.
Step 3	no ip dvmrp auto-summary		Disable DVMRP autosummarization.
Step 4	end		Return to privileged EXEC mode.
		Catalyst 3750-E and 3560-E Switch Software Configuration Guide
42-50			OL-9775-02