HP A8800 Configuration Manual page 83

corresponding VLAN interface, you need to use the reset igmp group port-info command to clear
Layer 2 port information for all IGMP multicast groups in the VLAN and use the reset igmp group
command clear all IGMP multicast group information on the corresponding VLAN interface.
Otherwise this configuration cannot take effect.
• If the VLAN enabled with the multicast programs-on-demand function is not a multicast VLAN but
has IGMP snooping enabled, this configuration cannot take effect.
After you enable delivering the multicast packets that failed RPF check to the CPU,, use the reset multicast
forwarding-table command to clear all the forwarding entries in the multicast forwarding table;
otherwise this configuration cannot take effect.
Enabling forwarding packets in the VLAN
In practice, a multicast packet that failed RPF check on a VLAN interface might be expected by some
receivers in the VLAN. You can enable forwarding such multicast packets through multicast or flooding
in the VLAN so that the receivers can receive them.
With this feature enabled, the router searches its multicast forwarding table upon receiving a packet that
failed RPF check. If a match is found, it multicasts the packet according to the matching entry. Otherwise,
the router floods the packet in the VLAN.
To enable this feature, you also need to enable the multicast programs-on-demand function.
To enable flooding packets that have failed an RPF check in a VLAN or all VLANs:
Step
1. Enter system view.
2. Enable forwarding packets
that have failed an RPF check
in the VLAN or all VLANs.
3. Enter VLAN view.
4. Enable the multicast
programs-on-demand
function in the VLAN.
Delivering packets to the CPU
In the following two cases, a multicast packet that failed the RPF check needs to be delivered to the CPU:
When a multicast packet arrives on an outgoing interface of the corresponding multicast
•
forwarding entry, the packet will fail the RPF check and needs to be sent to the CPU in order to
trigger the assert mechanism to prune the unwanted branch.
If the SPT and RPT have different incoming interfaces on the receiver-side DR (the designated router),
•
the multicast traffic will fail the RPF check on the SPT incoming interface during an RPT-to-SPT
switchover before the RPF information is refreshed. If the RPT is pruned at this moment, the multicast
service will be instantaneously interrupted. By delivering packets that failed the RPF check on a
non-outgoing interface to the CPU, the router can determine whether the packets that have failed
the RPF check on the SPT interface are expected. If they are, the router initiates an RPT prune.
For more information about the assert mechanism, DR, and RPT-to-SPT switchover, see
PIM."
To enable delivering packets that have failed an RPF check to the CPU:
Command
system-view
multicast rpf-fail-pkt bridging
vlan vlan-id
multicast forwarding on-demand
71
Remarks
N/A
Disabled by default.
N/A
Disabled by default.
"Configuring