HP MSR ASM Configuration Manual page 151

Figure 45 Network diagram
IP network
Proxy & Querier
Switch A
Host A
Receiver
As shown in Figure 45, Switch A works as an IGMP snooping proxy. As a host from the perspective of
the querier Router A, Switch A represents its attached hosts to send membership reports and leave
messages to Router A.
Table 13 IGMP message processing on an IGMP snooping proxy
IGMP message Actions
When receiving an IGMP general query, the proxy forwards it to all ports except the port
General query that receive the query. In addition, the proxy generates a report according to the group
membership that it maintains and sends the report out of all router ports.
In response to the IGMP group-specific query for a certain multicast group, the proxy
Group-specific
sends the report to the group out of all router ports if the forwarding entry for the group still
query
contains a member port.
After receiving a report for a multicast group, the proxy looks up the multicast forwarding
table for the forwarding entry for the multicast group.
•
•
Report
•
In response to an IGMP leave message for a multicast group, the proxy sends a
group-specific query out of the receiving port. After making sure that no member port is
Leave
contained in the forwarding entry for the multicast group, the proxy sends a leave
message to the group out of all router ports.
IGMP Querier
Router A
Host C
Receiver
Host B
If a forwarding entry matches the multicast group and contains the receiving port as a
dynamic member port, the proxy restarts the aging timer for the port.
If a forwarding entry matches the multicast group but does not contain the receiving
port, the proxy adds the port to the forwarding entry as a dynamic member port and
starts an aging timer for the port.
If no forwarding entry matches the multicast group, the proxy creates a forwarding
entry for the multicast group, adds the receiving port to the forwarding entry as a
dynamic member port, and starts an aging timer for the port.
139
Query from Router A
Report from Switch A
Query from Switch A
Report from Host