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JUNOS Cookbook by Aviva Garrett

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16.3. Using Auto-RP to Dynamically Map RPs

Problem

Instead of manually configuring the RP, you want the routers to decide among themselves which one should be the RP.

Solution

With auto-RP, the PIM routers determine which one should be the RP, thereby automating the distribution of the group-to-RP mappings. There are three steps for configuring auto-RP. First, configure PIM in sparse-dense mode on all routers in the PIM domain:

	[edit protocols pim]
	aviva@RouterA# set interface all mode sparse-dense

Then, configure the two multicast dense-mode groups 224.0.1.39/32 and 224.0.1.40/32 on all routers:

	[edit protocols pim]
	aviva@RouterA# set dense-groups 224.0.1.39/32
	aviva@RouterA# set dense-groups 224.0.1.40/32

Finally, configure auto-RP on each router. One router in the PIM domain must announce auto-RP messages and another must map them. You can also configure the local router to perform both functions:

	[edit protocols pim]
	aviva@RouterA# set rp local address 192.168.13.1
	aviva@RouterA# set rp auto-rp mapping

On the remaining routers in the PIM domain, configure sparse-dense mode and configure them to discover the RP:

	[edit protocols pim]
	aviva@RouterG# set interface all mode sparse-dense
	aviva@RouterG# set rp auto-rp discovery

Discussion

Auto-RP dynamically maps groups to RPs, and PIM routers in the network automatically learn the addresses of the RPs. The auto-RP mechanism is not defined in an IETF RFC but is a proprietary mechanism developed by Cisco Systems for IOS routers and is ...

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