5. Multicast > Multicast Group Tables
111
Tsi578 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
3.
Write the
“RapidIO Multicast DestID Association Register” on page 266
, setting the LARGE field
to indicate whether the destination ID is an 8-bit or a 16-bit ID; and setting the CMD field to 11.
This associates the destination ID to the list of ports that must receive copies of the packet. Note
that there must be a 1:1 association between destination IDs and multicast masks.
Ports can be removed from a multicast mask by writing the Multicast Mask Configuration Register,
even when the mask is associated with a destination ID.
If a port that is powered down or detected as faulty is a part of a multicast mask, packets are still
replicated and sent to that port. However, the port silently drops the packets.
Multicast groups can be deleted by breaking the association between destination IDs and multicast
mask numbers through the
“RapidIO Multicast DestID Configuration Register” on page 265
and
“RapidIO Multicast DestID Association Register” on page 266
.
To execute either of the previous two operations (port removal or group deletion), the system software
must remember what port is associated to which multicast masks and to which multicast mask number
the destination ID is bound. If the software designer selects not to maintain a state table, it is possible to
determine what multicast mask a destination ID/TT value is associated with through the use of
Write-to-Verify commands.
It is possible that a multicast mask has no ports selected, or the only port selected is the ingress port the
original packet was received on. In this case, the multicast engine silently discards the packet.
The following figure is a representation of the relationship between the destination ID, multicast group
number, multicast vector, and egress port.
In alignment with the RapidIO multicast specification, if multiple destination ID association
operations occur for a multicast mask, the last association operation executed determines
which destination ID and TT value is associated with a multicast mask.