Cisco IE 4000, Руководство по настройке программного обеспечения

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Configuring IP Multicast Routing
Guidelines and Limitations
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Be familiar with the information in the Information About Cisco’s Implementation of IP Multicast Routing, page 675
and Guidelines and Limitations, page 686 .
Guidelines and Limitations
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
Auto-RP and BSR Configuration Guidelines,
page 686 .
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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Use Auto-RP throughout the region.
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Configure sparse-dense mode throughout the region.
If Auto-RP is not already configured in the PIMv1 regions, configure Auto-RP. For more information, see Configuring
Auto-RP, page 699 .
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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If your network is all Cisco routers and multilayer switches, you can use either Auto-RP or BSR.
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If you have non-Cisco routers in your network, you must use BSR.
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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.
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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.
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If you have a network that includes non-Cisco routers, configure the Auto-RP mapping agent and the BSR on a Cisco
PIMv2 router or multilayer switch. Ensure that no PIMv1 device is on the path between the BSR and a non-Cisco
PIMv2 router.