# Limiting the Number of Accepted IGMP Groups

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

- A specific port on an I/O module
- A specific IGMP 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 IGMP groups an interface can accept. For example, if you set a limit of 10 groups for the port and 15 groups for each interface, only 10 groups can 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 prevents the interfaces from accepting any more groups. Over time, some groups leave the interfaces and, eventually, a maximum of ten groups remain connected.

ip igmp group limit

- Use to limit the number of IGMP groups that an interface can accept.

  | Note: This command is deprecated and might be removed completely in a future release. The function provided by this command has been replaced by the updated by limiting bandwidth of multicast streams using the ip multicast admission-bandwidth-limit command.

- Example
  host1:boston(config-if)#ip igmp group limit 5
- Use the no version to restore the default behavior, in which there is no limit on the number of IGMP groups that an interface can accept.
- See ip igmp group limit.

multicast group port limit

- Use to limit the number of IGMP groups that a port can accept.

  | Note: This command is deprecated and might be removed completely in a future release. The function provided by this command has been replaced by the updated by limiting bandwidth of multicast streams using the mroute port admission-bandwidth-limit command.

- Specify the identifier for the port in slot/port format (ERX routers) or in slot/adapter/port format (E320 router).
  - slot—Number of the chassis slot in the range 0–6 (ERX7xx models), 0–13 (ERX14xx models), or 0–16 (E320)
  - adapter—Adapter number on the E320 IOA module
  - port—Port number on the I/O or IOA module
- Specify the maximum number of IGMP groups that interfaces can accept.
- Example 1—ERX models
  host1(config)#multicast group port 3/0 limit 5
- Example 2—E320 router
  host1(config)#multicast group port 3/1/0 limit 5
- Use the no version to restore the default behavior, in which there is no limit on the number of IGMP groups that a port can accept.
- See multicast group port limit.