4-17Configuring Multicast Source LifetimeInitially, some data is lost when multicast receivers receive multicast data from a multicast source. Thereason is that (S, G) entries in the PIM routing table and multicast routing table age out if no data streamis received within a configurable period of time, known as multicast source lifetime or (S, G) aging time.These entries need to be reestablished before the corresponding multicast data can be forwarded bythe multicast switch again. In the process of table entry reestablishment, some data may be lost.If the multicast source lifetime is appropriately lengthened when the data traffic has stopped, themulticast data, when arriving at the multicast switch again, can be forwarded by the switch without theneed of reestablishing the table entries. This helps avoid data loss.Follow these steps to configure multicast source lifetime:To do... Use the command... RemarksEnter system view system-view —Enter PIM view pim —Configure multicast source lifetime source-lifetime interval Optional210 seconds by defaultThe configured multicast source lifetime applies to all (S, G) entries in the PIM routing table and themulticast routing table rather than to a specific (S, G) entry, and the configuration changes the agingtime of all the existing (S, G) entries.Configuring PIM Prune DelayThe PIM prune delay function is applicable only to PIM-SM networks, but not to PIM-DM networks.Upon receiving a prune message from a downstream device, the upstream node removes the interfaceconnecting the downstream node from the outgoing interface list of the (S, G) entry. If the downstreamnode finds shortly after it has sent a prune message that a member for the multicast group is present onthe local subnet, it immediately sends a prune override message to the upstream to let the upstreamnode cancel the prune action.The S5600 series Ethernet switches support prune delay configuration. Upon receiving a prunemessage from a downstream node, the upstream node does not take a prune action immediately;instead, it maintains the forwarding state of the interface to the downstream. If the upstream nodereceives a prune override message from the downstream node within the prune delay interval, itcancels the prune action; otherwise, it prunes the interface to the downstream when the prune delaytimes out.
