Chapter 14: Multicast Routing Configuration Guide202 SmartSwitch Router User Reference ManualConfiguring the DVMRP Routing MetricYou can configure the DVMRP routing metric associated with a set of destinations forDVMRP reports. The default metric is 1.To configure the DVMRP routing metric, enter the following command in Configuremode:Configuring DVMRP TTL & ScopeFor control over internet traffic, per-interface control is allowed through Scopes and TTLthresholds.The TTL value controls whether packets are forwarded from an interface. The followingare conventional guidelines for assigning TTL values to a multicast application and theircorresponding SSR setting for DVMRP threshold:TTL = 1 Threshold = 1 Application restricted to subnetTTL < 16 Threshold = 16 Application restricted to a siteTTL < 64 Threshold = 64 Application restricted to a regionTTL < 128 Threshold = 128 Application restricted to a continentTTL = 255 Application not restrictedTo 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 ofmulticast addresses for “administrative” scoping. In other words, such addresses wouldbe usable within a certain administrative scope, a corporate network, for instance, butwould not be forwarded across the internet. The range from 239.0.0.0 through239.255.255.255 is being reserved for administratively scoped applications. Anyorganization can currently assign this range of addresses and the packets will not be sentout of the organization. In addition, multiple scopes can be defined on per-interface basis.Configure the DVMRP routingmetric.dvmrp set interface metric Configure the TTL Threshold. dvmrp set interface threshold
