Chapter 14: Multicast Routing Configuration Guide

Configuring the DVMRP Routing Metric

You can configure the DVMRP routing metric associated with a set of destinations for DVMRP reports. The default metric is 1.

To configure the DVMRP routing metric, enter the following command in Configure mode:

Configure the DVMRP routing metric.

dvmrp set interface <ip-addr>metric <number>

Configuring DVMRP TTL & Scope

For control over internet traffic, per-interface control is allowed through Scopes and TTL thresholds.

The TTL value controls whether packets are forwarded from an interface. The following are conventional guidelines for assigning TTL values to a multicast application and their corresponding SSR setting for DVMRP threshold:

TTL = 1

Threshold = 1

Application restricted to subnet

TTL < 16

Threshold = 16

Application restricted to a site

TTL < 64

Threshold = 64

Application restricted to a region

TTL < 128

Threshold = 128

Application restricted to a continent

TTL = 255

 

Application not restricted

To configure the TTL Threshold, enter the following command in Configure mode:

Configure the TTL Threshold.

dvmrp set interface <ip-addr>threshold <number>

TTL thresholding is not always considered useful. There is another approach of a range of multicast addresses for “administrative” scoping. In other words, such addresses would be usable within a certain administrative scope, a corporate network, for instance, but would not be forwarded across the internet. The range from 239.0.0.0 through 239.255.255.255 is being reserved for administratively scoped applications. Any organization can currently assign this range of addresses and the packets will not be sent out of the organization. In addition, multiple scopes can be defined on per-interface basis.

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SmartSwitch Router User Reference Manual

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Cabletron Systems 9032578-05 manual Configuring the Dvmrp Routing Metric, Configuring Dvmrp TTL & Scope