# Limiting the Number of Accepted MLD Groups

By default, there is no limit on the number of MLD groups that an MLD interface can accept. However, you can manage multicast traffic on the router by restricting the number of MLD groups accepted by:

- A specific port on an I/O module
- A specific MLD interface

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

- 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.

multicast group port 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
- Use the no version to restore the default situation, in which there is no limit on the number of MLD groups that a port can accept.
- See multicast group port limit.