Transition Networks
S4224 Web User Guide
33558 Rev. C
Page 187 of 669
MLD SSM Range
SSM (Source-Specific Multicast) Range allows the SSM-aware hosts and routers to run the SSM
service model for the groups in the address range. SSM destination addresses must be in the ranges
232.0.0.0/8 for IPv4 or FF3x::/96 for IPv6.
SSM Range allows the SSM-aware hosts and routers run the SSM service model for the groups in
the address range. SSM is a method of delivering multicast packets in which the only packets
delivered to a receiver are those originating from a specific source address requested by the receiver.
By so limiting the source, SSM reduces demands on the network and improves security. SSM
requires that the receiver specify the source address and explicitly excludes the use of the (*,G) join
for all multicast groups in
, which is possible only in IPv4's IGMPv3 and IPv6's MLDv2.
SSM is best viewed in contrast to ASM (Any-Source Multicast), where a receiver expresses interest in
traffic to a multicast address. The multicast network must 1) discover all multicast sources sending to
that address, and 2) route data from all sources to all interested receivers. ASM is particularly well
suited to groupware applications where 1) all participants in the group want to be aware of all other
participants, and 2) the list of participants is not known in advance. With ASM, the source discovery
burden on the network can become significant with a large number of sources.
With SSM, the receiver expresses interest in traffic to a multicast address, and also expresses
interest in receiving traffic from just one specific source sending to that multicast address. This keeps
the network from having to discover numerous multicast sources, and reduces the amount of
multicast routing information that the network must maintain. SSM requires support in last-hop routers
and in the receiver's operating system. SSM support is not required in other network components
(including routers and even the sending host). Interest in multicast traffic from a specific source is
conveyed from hosts to routers using IGMPv3 as specified in
In SSM, some types of
denial of service (DoS) attack cannot be made by simply sending traffic to a multicast group.
SSM destination addresses must be in the ranges 232.0.0.0/8 for IPv4 or FF3x::/96 for IPv6.
http://tools.ietf.org/html/rfc4607
for the full set of reserved addresses.
Leave Proxy Enabled
Check to enable MLD Leave Proxy. This feature can be used to avoid forwarding unnecessary Leave
messages to the router side. The default is unchecked.
Proxy Enabled
Check to enable MLD Proxy. This feature can be used to avoid forwarding unnecessary Join and
Leave messages to the router side. The default is unchecked.
Port
The S4224 logical port number. The * in the Port column acts as a ‘wild card’ character which causes
the selections in this row to be applied to all other Ports (rows) in the table for which this selection is
valid.
Router Port
Check to specify which ports act as router ports. A router port is a port on the S4224 that leads
towards the Layer 3 multicast device or MLD querier. If an aggregation member port is selected as a
router port, the whole aggregation will act as a router port. The default is unchecked.
