# Defining Permanent IPv6 Multicast Forwarding Entries

An mroute is a multicast traffic flow, a (Source, Group) entry used for forwarding multicast traffic). By default, forwarding mroutes (with a valid RPF incoming interface) are timed out if data for them is not received for 210 seconds. However, you can specify an mroute as permanent by using the ipv6 multicast-routing permanent-mroute command.

ipv6 multicast-routing permanent-mroute

- Use to specify that any newly created mroutes that match the specified access-list do not time out.
- Using this command does not change existing mroutes.
- Permanent mroutes are removed if a topology change occurs that affects the mroute.
- Permanent mroutes may be removed due to certain protocol actions (for example, PIM sparse mode switching from shared to shortest path tree).
- Outgoing interface lists of permanent mroutes may change due to protocol actions.
- Example
  host1(config)#ipv6 multicast-routing permanent-mroute routesv61
- Use the no version to prevent any new mroutes from becoming permanent. To remove existing permanent mroutes, use the clear ipv6 mroute command.
- See ipv6 multicast-routing permanent-mroute