Network Router User Manual

Chapter 14: Multicast Routing Configuration Guide
202 SmartSwitch Router User Reference Manual
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:
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:
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.
Configure the DVMRP routing
metric.
dvmrp set interface
<ip-addr>
metric
<number>
Configure the TTL Threshold. dvmrp set interface <ip-addr> threshold
<number>