Juniper JUNOSE 11.0.X MULTICAST ROUTING Configuration Manual page 217

If you set limits for both a port and interfaces on that port, the router uses the lower
of the two limits when determining how many MLD groups an interface can accept.
For example, if you set a limit of 10 groups for the port and 15 groups for each
interface, the router allows only 10 groups to be accepted among the interfaces.
However, if you set a limit for a port and that limit is lower than the number of groups
currently accepted by the interfaces on that port, the router does not dissociate the
groups from the interfaces. The router enforces the new limit on the port when the
number of groups associated with the interfaces falls to that limit. For example, if
the interfaces on the port have accepted a total of 15 groups, and you set a limit of
10 groups on the port, the router does not disconnect any of the groups and does
not allow the interfaces to accept any more groups. Over time, some groups leave
the interfaces and, eventually, a maximum of ten groups remains connected.
ipv6 mld group limit
multicast group port limit
A specific MLD interface
Use to limit the number of MLD groups that an interface can accept.
Example
host1:boston(config-if)#ipv6 mld group limit 5
Use the no version to restore the default situation, in which there is no limit on
the number of MLD groups that an interface can accept.
See ipv6 mld group limit.
Use to limit the number of MLD groups that a port can accept.
Specify the identifier for the port in slot/port format (ERX routers) or in
slot/adapter/port format (E120 and E320 routers) and the maximum number of
MLD groups that interfaces can accept.
slot Number of the chassis slot in the range 0–6 (ERX7xx models), 0–13
(ERX14xx models), 0–5 (E120 router), or 0–16 (E320 router)
adapter Number of the bay in which the I/O adapter (IOA) resides. This
identifier applies to the E120 and E320 routers only. In the software, adapter
0 identifies the right IOA bay (E120 router) and the upper IOA bay (E320
router); adapter 1 identifies the left IOA bay (E120 router) and the lower IOA
bay (E320 router).
port Port number on the I/O module or IOA
Example 1 ERX models
host1(config)#multicast group port 3/0 limit 5
Example 2 E120 and E320 routers
host1(config)#multicast group port 3/1/0 limit 5
Chapter 6: Configuring Multicast Listener Discovery
Limiting the Number of Accepted MLD Groups
195