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Example: Configuring PIM Anycast with MSDP

When you configure anycast RP, you bypass the restriction of having one active RP per multicast group, and instead deploy multiple RPs for the same group range. The RP routers share one unicast IP address. Sources from one RP are known to other RPs that use Multicast Source Discovery Protocol (MSDP). Sources and receivers use the closest RP, as determined by the interior gateway protocol (IGP).

You can use anycast RP within a domain to provide redundancy and RP load sharing. When an RP goes down, sources and receivers are taken to a new RP by means of unicast routing.

You can configure anycast RP to use PIM and MSDP for IPv4, or PIM alone for both IPv4 and IPv6 scenarios. Both are covered in this section.

For information about standards supported for anycast RP, see IP Multicast Specifications.

We recommend a static RP mapping with anycast RP over a bootstrap router and auto-RP configuration because it provides all the benefits of a bootstrap router and auto-RP without the complexity of the BSR and auto-RP mechanisms.

The following example shows an anycast RP configuration for the RP routers, first with MSDP and then using PIM alone, and for non-RP routers.

  1. For an network using an RP with MSDP, configure the RP using the lo0 or loopback interface, which is always up. Include the address statement and specify the unique and routable router ID and the RP address at the [edit interfaces lo0 unit 0 family inet] hierarchy level. In this example, the router ID is 198.58.3.254/32 and the shared RP address is 198.58.3.253/32. Include the primary statement for the first address. Including the primary statement selects the router's primary address from all the preferred addresses on all interfaces.
    interfaces {lo0 {description "PIM RP";unit 0 {family inet {address 198.58.3.254/32;primary;address 198.58.3.253/32;}}}}
  2. Specify the RP address. Include the address statement at the [edit protocols pim rp local] hierarchy level (the same address as the secondary lo0).

    For all interfaces, include the mode statement to set the mode to sparse and the version statement to specify PIM version 2 at the [edit protocols pim rp local interface all] hierarchy level. When configuring all interfaces, exclude the fxp0.0 management interface by including the disable statement for that interface.

    protocols {pim {rp {local {family inet;address 198.58.3.253;}interface all {mode sparse;version 2;}interface fxp0.0 {disable;}}}}
  3. Configure MSDP peering. Include the peer statement to configure the address of the MSDP peer at the [edit protocols msdp] hierarchy level. For MSDP peering, use the unique, primary addresses instead of the anycast address. To specify the local address for MSDP peering, include the local-address statement at the [edit protocols msdp peer] hierarchy level.
    protocols {msdp {peer 198.58.3.250 {local-address address 198.58.3.254;}}}
  4. If you need to configure a PIM RP for both IPv4 and IPv6 scenarios, perform this step and the following one.

    Configure an RP using the lo0 or loopback interface, which is always up. Include the address statement to specify the unique and routable router address and the RP address at the [edit interfaces lo0 unit 0 family inet] hierarchy level. In this example, the router ID is 198.58.3.254/32 and the shared RP address is 198.58.3.253/32. Include the primary statement on the first address. Including the primary statement selects the router's primary address from all the preferred addresses on all interfaces.

    interfaces {lo0 {description "PIM RP";unit 0 {family inet {address 198.58.3.254/32 {primary;}address 198.58.3.253/32;}}}}
  5. Include the address statement at the [edit protocols pim rp local] hierarchy level to specify the RP address (the same address as the secondary lo0 interface).

    For all interfaces, include the mode statement to set the mode to sparse, and the version statement to specify PIM version 2 at the [edit protocols pim rp local interface all] hierarchy level. When configuring all interfaces, exclude the fxp0.0 management interface by Including the disable statement for that interface.

    Include the anycast-pim statement to configure anycast RP without MSDP (for example, if IPv6 is used for multicasting). The other RP routers that share the same IP address are configured using the rp-set statement. There is one entry for each RP, and the maximum that can be configured is 15. For each RP, specify the routable IP address of the router and whether MSDP source active (SA) messages are forwarded to the RP.

    MSDP configuration is not necessary for this type of IPv4 anycast RP configuration.

    protocols {pim {rp {local {family inet {address 198.58.3.253;anycast-pim {rp-set {address 198.58.3.240;address 198.58.3.241 forward-msdp-sa;}local-address 198.58.3.254; #If not configured, use lo0 primary}}}}interface all {mode sparse;version 2;}interface fxp0.0 {disable;}}}
  6. Configure the non-RP routers. Whether MSDP is used or not, the anycast RP configuration for a non-RP router is the same. Specify a static RP by adding the address at the [edit protocols pim rp static] hierarchy level. Include the version statement at the [edit protocols pim rp static address] hierarchy level to set PIM version 2.
    protocols {pim {rp {static {address 198.58.3.253 {version 2;}}}}}
  7. Include the mode statement at the [edit protocols pim rp interface all] hierarchy level to specify sparse mode on all interfaces. Then include the version statement at the [edit protocols pim rp interface all mode] to configure all interfaces for PIM version 2. When configuring all interfaces, exclude the fxp0.0 management interface by including the disable statement for that interface.
    protocols {pim {interface all {mode sparse;version 2;}interface fxp0.0 {disable;}}}

Published: 2010-04-16

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