3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuration Task List 517
■ For a packet traveling along the shortest path tree (SPT) from the multicast
source to the receivers or the source-based tree from the multicast source to
the rendezvous point (RP), "packet source" means the multicast source.
■ For a packet traveling along the rendezvous point tree (RPT) from the RP to the
receivers, "packet source" means the RP.
■ For a bootstrap message from the bootstrap device (BSR), "packet source"
means the BSR.
For details about the concepts of SPT, RPT, RP and BSR, refer to “PIM
Configuration” on page 563.
Assume that IPv6 unicast routes exist in the network, and IPv6 multicast packets
travel along the SPT from the multicast source to the receivers, as shown in
Figure 165.
Figure 165 RPF check process
■ An IPv6 multicast packet from Source arrives on VLAN-interface 2 of Switch C,
and the IPv6 multicast forwarding table does not contain the corresponding
forwarding entry. Switch C performs an RPF check, and finds in its IPv6 unicast
routing table that the outgoing interface to the network subnet FF02::/16 is
VLAN-interface 1. This means that the interface on which the packet actually
arrived is not the RPF interface. The packet fails the FPR check and is discarded.
■ An IPv6 multicast packet from Source arrives on VLAN-interface 1 of Switch C,
and the IPv6 multicast forwarding table does not contain the corresponding
forwarding entry. Switch C performs an RPF check, and finds in its IPv6 unicast
routing table that the outgoing interface to the subnet FF02::/16 is the one on
which the IPv6 multicast packet actually arrived. The RPF check succeeds and
the packet is forwarded.
Configuration Task
List
Complete these tasks to configure IPv6 multicast routing and forwarding:
Receive
r
Receive
r
Source
FF02::101 /16
Switch A
Switch B
Switch C
Vlan-int1
Vlan-int2
Vlan-int2
Vlan-int1
IPv6 Multicast packets
Destination/Prefix
IPv6 Routing Table on Switch C
FF02::/16
Interface
Vlan-int1
Task Remarks
“Enabling IPv6 Multicast Routing” on page 518 Required
“Configuring IPv6 Multicast Load Splitting” on page 518 Optional