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Configuring Static RP

 

Understanding Static RP

Protocol Independent Multicast (PIM) sparse mode is the most common multicast protocol used on the Internet. PIM sparse mode is the default mode whenever PIM is configured on any interface of the device. However, because PIM must not be configured on the network management interface, you must disable it on that interface.

Each any-source multicast (ASM) group has a shared tree through which receivers learn about new multicast sources and new receivers learn about all multicast sources. The rendezvous point (RP) router is the root of this shared tree and receives the multicast traffic from the source. To receive multicast traffic from the groups served by the RP, the device must determine the IP address of the RP for the source.

You can configure a static rendezvous point (RP) configuration that is similar to static routes. A static configuration has the benefit of operating in PIM version 1 or version 2. When you configure the static RP, the RP address that you select for a particular group must be consistent across all routers in a multicast domain.

Starting in Junos OS Release 15.2, the static configuration uses PIM version 2 by default, which is the only version supported in that release and beyond..

One common way for the device to locate RPs is by static configuration of the IP address of the RP. A static configuration is simple and convenient. However, if the statically defined RP router becomes unreachable, there is no automatic failover to another RP router. To remedy this problem, you can use anycast RP.

Configuring Local PIM RPs

Local RP configuration makes the routing device a statically defined RP. Consider statically defining an RP if the network does not have many different RPs defined or if the RP assignment does not change very often. The Junos IPv6 PIM implementation supports only static RP configuration. Automatic RP announcement and bootstrap routers are not available with IPv6.

You can configure a local RP globally or for a routing instance. This example shows how to configure a local RP in a routing instance for IPv4 or IPv6.

To configure the routing device’s RP properties:

  1. Configure the routing instance as the local RP.
  2. Configure the IP protocol family and IP address.

    IPv6 PIM hello messages are sent to every interface on which you configure family inet6, whether at the PIM level of the hierarchy or not. As a result, if you configure an interface with both family inet at the [edit interface interface-name] hierarchy level and family inet6 at the [edit protocols pim interface interface-name] hierarchy level, PIM sends both IPv4 and IPv6 hellos to that interface.

    By default, PIM operates in sparse mode on an interface. If you explicitly configure sparse mode, PIM uses this setting for all IPv6 multicast groups. However, if you configure sparse-dense mode, PIM does not accept IPv6 multicast groups as dense groups and operates in sparse mode over them.

  3. (IPv4 only) Configure the routing device’s RP priority.Note

    The priority statement is not supported for IPv6, but is included here for informational purposes. The routing device’s priority value for becoming the RP is included in the bootstrap messages that the routing device sends. Use a smaller number to increase the likelihood that the routing device becomes the RP for local multicast groups. Each PIM routing device uses the priority value and other factors to determine the candidate RPs for a particular group range. After the set of candidate RPs is distributed, each routing device determines algorithmically the RP from the candidate RP set using a hash function. By default, the priority value is set to 1. If this value is set to 0, the bootstrap router can override the group range being advertised by the candidate RP.

  4. Configure the groups for which the routing device is the RP.

    By default, a routing device running PIM is eligible to be the RP for all IPv4 or IPv6 groups (224.0.0.0/4 or FF70::/12 to FFF0::/12). The following example limits the groups for which this routing device can be the RP.

  5. (IPv4 only) Modify the local RP hold time.

    If the local routing device is configured as an RP, it is considered a candidate RP for its local multicast groups. For candidate RPs, the hold time is used by the bootstrap router to time out RPs, and applies to the bootstrap RP-set mechanism. The RP hold time is part of the candidate RP advertisement message sent by the local routing device to the bootstrap router. If the bootstrap router does not receive a candidate RP advertisement from an RP within the hold time, it removes that routing device from its list of candidate RPs. The default hold time is 150 seconds.

  6. (Optional) Override dynamic RP for the specified group address range.

    If you configure both static RP mapping and dynamic RP mapping (such as auto-RP) in a single routing instance, allow the static mapping to take precedence for the given static RP group range, and allow dynamic RP mapping for all other groups.

    If you exclude this statement from the configuration and you use both static and dynamic RP mechanisms for different group ranges within the same routing instance, the dynamic RP mapping takes precedence over the static RP mapping, even if static RP is defined for a specific group range.

  7. Monitor the operation of PIM by running the show pim commands. Run show pim ? to display the supported commands.

Example: Configuring PIM Sparse Mode and RP Static IP Addresses

This example shows how to configure PIM sparse mode and RP static IP addresses.

Requirements

Before you begin:

  1. Determine whether the router is directly attached to any multicast sources. Receivers must be able to locate these sources.

  2. Determine whether the router is directly attached to any multicast group receivers. If receivers are present, IGMP is needed.

  3. Determine whether to configure multicast to use sparse, dense, or sparse-dense mode. Each mode has different configuration considerations.

  4. Determine the address of the RP if sparse or sparse-dense mode is used.

  5. Determine whether to locate the RP with the static configuration, BSR, or auto-RP method.

  6. Determine whether to configure multicast to use its own RPF routing table when configuring PIM in sparse, dense, or sparse-dense mode.

  7. Configure the SAP and SDP protocols to listen for multicast session announcements.

  8. Configure IGMP.

Overview

In this example, you set the interface value to all and disable the ge-0/0/0 interface. Then you configure the IP address of the RP as 192.168.14.27.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level and then enter commit from configuration mode.

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure PIM sparse mode and the RP static IP address:

  1. Configure PIM.
  2. Set the interface value.
  3. Disable PIM on the network management interface.
  4. Configure RP.
  5. Configure the IP address of the RP.

Results

From configuration mode, confirm your configuration by entering the show protocols command. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

If you are done configuring the device, enter commit from configuration mode.

Verification

To confirm that the configuration is working properly, perform these tasks:

Verifying SAP and SDP Addresses and Ports

Purpose

Verify that SAP and SDP are configured to listen on the correct group addresses and ports.

Action

From operational mode, enter the show sap listen command.

Verifying the IGMP Version

Purpose

Verify that IGMP version 2 is configured on all applicable interfaces.

Action

From operational mode, enter the show igmp interface command.

Verifying the PIM Mode and Interface Configuration

Purpose

Verify that PIM sparse mode is configured on all applicable interfaces.

Action

From operational mode, enter the show pim interfaces command.

Configuring the Static PIM RP Address on the Non-RP Routing Device

Consider statically defining an RP if the network does not have many different RPs defined or if the RP assignment does not change very often. The Junos IPv6 PIM implementation supports only static RP configuration. Automatic RP announcement and bootstrap routers are not available with IPv6.

You configure a static RP address on the non-RP routing device. This enables the non-RP routing device to recognize the local statically defined RP. For example, if R0 is a non-RP router and R1 is the local RP router, you configure R0 with the static RP address of R1. The static IP address is the routable address assigned to the loopback interface on R1. In the following example, the loopback address of the RP is 2001:db8:85a3::8a2e:370:7334.

Starting in Junos OS Release 15.2, the default PIM version is version 2, and version 1 is not supported.

For Junsos OS Release 15.1 and earlier, the default PIM version can be version 1 or version 2, depending on the mode you are configuring. PIM version 1 is the default for RP mode ([edit pim rp static address address]). PIM version 2 is the default for interface mode ([edit pim interface interface-name]). An explicitly configured PIM version will override the default setting.

You can configure a static RP address globally or for a routing instance. This example shows how to configure a static RP address in a routing instance for IPv6.

To configure the static RP address:

  1. On a non-RP routing device, configure the routing instance to point to the routable address assigned to the loopback interface of the RP.
    Note

    Logical systems are also supported. You can configure a static RP address in a logical system only if the logical system is not directly connected to a source.

  2. (Optional) Set the PIM sparse mode version.

    For each static RP address, you can optionally specify the PIM version. For Junos OS Release 15.1 and earlier, the default PIM version is version 1.

  3. (Optional) Set the group address range.

    By default, a routing device running PIM is eligible to be the RP for all IPv4 or IPv6 groups (224.0.0.0/4 or FF70::/12 to FFF0::/12). The following example limits the groups for which the 2001:db8:85a3::8a2e:370:7334 address can be the RP.

    The RP that you select for a particular group must be consistent across all routers in a multicast domain.

  4. (Optional) Override dynamic RP for the specified group address range.

    If you configure both static RP mapping and dynamic RP mapping (such as auto-RP) in a single routing instance, allow the static mapping to take precedence for the given static RP group range, and allow dynamic RP mapping for all other groups.

    If you exclude this statement from the configuration and you use both static and dynamic RP mechanisms for different group ranges within the same routing instance, the dynamic RP mapping takes precedence over the static RP mapping, even if static RP is defined for a specific group range.

  5. Monitor the operation of PIM by running the show pim commands. Run show pim ? to display the supported commands.
Release History Table
Release
Description
Starting in Junos OS Release 15.2, the static configuration uses PIM version 2 by default, which is the only version supported in that release and beyond.
Starting in Junos OS Release 15.2, the default PIM version is version 2, and version 1 is not supported.
For Junsos OS Release 15.1 and earlier, the default PIM version can be version 1 or version 2, depending on the mode you are configuring. PIM version 1 is the default for RP mode ([edit pim rp static address address]). PIM version 2 is the default for interface mode ([edit pim interface interface-name]). An explicitly configured PIM version will override the default setting.