# Configuring an RP Router for PIM Sparse Mode and PIM Sparse-Dense Mode

When you use the router for PIM sparse mode or PIM sparse-dense mode, some VRs must act as RP routers. You can configure static RP routers or configure the router to assign RP routers automatically.

To configure the router to assign RP routers automatically, you must define several VRs as RP routers and one VR as an RP mapping agent. RP routers send their announcement messages to the RP mapping agent, which assigns groups to RP routers and resolves any conflicts. The RP mapping agent notifies neighbors of the RP assigned to each group.

## Configuring a Static RP Router

If you want to control PIM more tightly, you can configure a static RP router. To do so:

1. Configure an access list that specifies the multicast groups that can use the static RP router.
   host1(config)#access-list boston permit 228.0.0.0 15.255.255.255
2. Specify a static RP router.
   host1(config)#ip pim rp-address 122.0.0.1 1 boston

## Configuring an Auto-RP Router for PIM Sparse Mode

Two multicast groups, 224.0.1.39 and 224.0.1.40, are reserved for forwarding auto-RP messages through the network. When you configure an auto-RP router for PIM sparse mode, you must assign a static RP router to these two groups. You can then specify an RP mapping agent for other multicast groups.

To configure an auto-RP router for PIM sparse mode:

1. Configure a static RP to have priority over the auto-RP for the groups that send auto-RP multicast messages.
   host1(config)#access-list 11 permit 224.0.1.39 0.0.0.0 host1(config)#access-list 11 permit 224.0.1.40 0.0.0.0 host1(config)#ip pim rp-address 192.48.1.22 11 override
2. Assign an RP mapping agent.
   host1(config)#ip pim send-rp-discovery scope 23 loopback 1
3. Configure routers to send auto-RP announcement messages to the mapping agent.
   host1(config)#ip pim send-rp-announce loopback 2 scope 16 group-list 1

## Configuring an Auto-RP Router for PIM Sparse-Dense Mode

In PIM sparse-dense mode, you must prevent routers from advertising auto-RP messages to the multicast groups 224.0.1.39 and 224.0.1.40, which are reserved for forwarding auto-RP messages through the network. To configure an auto-RP router for PIM sparse-dense mode:

1. Assign an RP mapping agent.
   host1(config)#ip pim send-rp-discovery scope 23 loopback 1
2. Configure an access list that details the multicast groups that can use the static RP router.
   host1(config)access-list boston permit 224.0.0.0 15.255.255.255
3. Prevent routers from advertising auto-RP messages to the multicast groups that are reserved for forwarding auto-RP messages through the network.
   host1(config)#access-list 1 deny 224.0.1.39 host1(config)#access-list 1 deny 224.0.1.40
4. Configure routers to send auto-RP announcement messages to the mapping agent.
   host1(config)#ip pim send-rp-announce loopback 2 scope 23 group-list boston interval 200

ip pim rp-address

- Use to specify a static PIM RP router.
- Specify a standard IP access list of multicast groups to control which multicast groups can use this RP router.
- Specify the override keyword if you want this static RP router to have priority over auto-RP routers.
- Example
  host1(config)#ip pim rp-address 192.48.1.22 11 override
- Use the no version to clear the filter from this interface.
- See ip pim rp-address.

ip pim send-rp-announce

- Use to send auto-RP announcement messages from a router you configured as an RP.
- Specify an interface type and specifier, such as atm 3/0. For details about interface types and specifiers, see Interface Types and Specifiers in JunosE Command Reference Guide.
- The auto-RP announcement messages contain the IP address for the interface that you specify.
- Specify the number of hops for which the announcement is valid; default value is 64.
- Specify an access list that details which multicast groups the RP can include in announcement messages.
- Specify a time interval in the range 1–65535 seconds to control how often the router sends announcements. The default is 60 seconds.
- Example
  host1(config)#ip pim send-rp-announce loopback 2 scope 23 group-list boston interval 200
- Use the no version to clear filters from this interface.
- See ip pim send-rp-announce.

ip pim send-rp-discovery scope

- Use to configure the router as an RP mapping agent, which records group-to-RP mappings and notifies PIM designated routers about the mappings.
- Specify the number of hops for which the RP discovery message is valid; default value is 64.
- To assign an interface from which the router sends auto-RP discovery messages, specify an interface type and specifier, such as atm 3/0. For details about interface types and specifiers, see Interface Types and Specifiers in JunosE Command Reference Guide.
- Example
  host1(config)#ip pim send-rp-discovery scope 23 loopback 1
- Use the no version to stop the router from acting as an RP mapping agent.
- See ip pim send-rp-discovery scope.