QLogic OFED+ Host Software User Guide, Rev. B

C–VirtualNIC Interface Configuration and Administration
VirtualNIC Interface Configuration and Administration
IB Host 1
IB Host 2
IB Switch
EVIC
IB Host 3
Single packet to
IB_multicast group
traffic
Packet forwarded to
host (UD)
Figure C-2. With IB_Multicast
Figure C-2 is showing that the EVIC sends a multicast packet ONCE to the
InfiniBand switch while posting to a specific InfiniBand multicast group. The switch
then forwards the packet to all hosts who have joined the same multicast group
that the host has joined. Since the EVIC only has to post the packet once instead
of once for each host, there is a substantial savings. Additionally, the packets are
delivered by an unreliable datagram (UD) queue pair, which means there is less
overhead per packet, per host.
For each IOC, the EVIC creates a unique multicast group. When the VNIC driver
provides multicast addresses for a virtual port (i.e., viport) to the EVIC, the EVIC
returns the multicast group for the IOC used by the viport. The VNIC driver then
joins the specified multicast group. When a viport connection is taken down, the
host leaves the multicast group. If an EVIC has two IOCs and the VNIC driver on a
host is configured to create viports using both IOCs, a join is issued by each
viport to join the corresponding IOC it is using.
D000046-005 B C-11