Pimv1 And Pimv2 Interoperability; Auto-Rp And Bsr Configuration Guidelines - Cisco WS-CBS3032-DEL Software Configuration Manual

Configuring IP Multicast Routing

PIMv1 and PIMv2 Interoperability

The Cisco PIMv2 implementation provides interoperability and transition between Version 1 and
Version 2, although there might be some minor problems.
You can upgrade to PIMv2 incrementally. PIM Versions 1 and 2 can be configured on different routers
and multilayer switches within one network. Internally, all routers and multilayer switches on a shared
media network must run the same PIM version. Therefore, if a PIMv2 device detects a PIMv1 device,
the Version 2 device downgrades itself to Version 1 until all Version 1 devices have been shut down or
upgraded.
PIMv2 uses the BSR to discover and announce RP-set information for each group prefix to all the routers
and multilayer switches in a PIM domain. PIMv1, together with the Auto-RP feature, can perform the
same tasks as the PIMv2 BSR. However, Auto-RP is a standalone protocol, separate from PIMv1, and is
a proprietary Cisco protocol. PIMv2 is a standards track protocol in the IETF. We recommend that you
use PIMv2. The BSR mechanism interoperates with Auto-RP on Cisco routers and multilayer switches.
For more information, see the
When PIMv2 devices interoperate with PIMv1 devices, Auto-RP should have already been deployed. A
PIMv2 BSR that is also an Auto-RP mapping agent automatically advertises the RP elected by Auto-RP.
That is, Auto-RP sets its single RP on every router or multilayer switch in the group. Not all routers and
switches in the domain use the PIMv2 hash function to select multiple RPs.
Dense-mode groups in a mixed PIMv1 and PIMv2 region need no special configuration; they
automatically interoperate.
Sparse-mode groups in a mixed PIMv1 and PIMv2 region are possible because the Auto-RP feature in
PIMv1 interoperates with the PIMv2 RP feature. Although all PIMv2 devices can also use PIMv1, we
recommend that the RPs be upgraded to PIMv2. To ease the transition to PIMv2, we have these
recommendations:
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If Auto-RP is not already configured in the PIMv1 regions, configure Auto-RP. For more information,
see the

Auto-RP and BSR Configuration Guidelines

There are two approaches to using PIMv2. You can use Version 2 exclusively in your network or migrate
to Version 2 by employing a mixed PIM version environment.
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Use Auto-RP throughout the region.
Configure sparse-dense mode throughout the region.
"Configuring Auto-RP" section on page
If your network is all Cisco routers and multilayer switches, you can use either Auto-RP or BSR.
If you have non-Cisco routers in your network, you must use BSR.
If you have Cisco PIMv1 and PIMv2 routers and multilayer switches and non-Cisco routers, you
must use both Auto-RP and BSR. If your network includes routers from other vendors, configure the
Auto-RP mapping agent and the BSR on a Cisco PIMv2 device. Ensure that no PIMv1 device is
located in the path a between the BSR and a non-Cisco PIMv2 device.
Because bootstrap messages are sent hop-by-hop, a PIMv1 device prevents these messages from
reaching all routers and multilayer switches in your network. Therefore, if your network has a
PIMv1 device in it and only Cisco routers and multilayer switches, it is best to use Auto-RP.
"Auto-RP and BSR Configuration Guidelines" section on page
45-30.
Chapter 45 Configuring IP Multicast Routing
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