Skip to main content

Protocol PIM-SM

Installation files

Caution

The Protocol PIM-SM Router App has been deprecated, and its functionality has been integrated into the FRR Router App. Installing the FRR Router App is strongly recommended, as Protocol PIM-SM will no longer be maintained or supported.

Caution

  • This Router App has been tested on a router with firmware version 6.3.10. After updating the router firmware to a higher version, check whether a newer version of the Router App has also been released and update it accordingly for compatibility.

Description

This Router App makes the PIM-SM (Protocol Independent Multicast — Sparse Mode) protocol available. PIM-SM is the most commonly used multicast routing protocol, designed on the assumption that receivers for any particular multicast group are sparsely distributed throughout the network. To receive multicast data, routers must explicitly inform their upstream neighbors of interest in specific groups and sources. PIM-SM uses shared trees by default — multicast distribution trees rooted at a selected node called the Rendezvous Point (RP), shared by all sources sending to the multicast group.

The Router App web interface is accessible by clicking the Router App name on the Router Apps page of the router's web interface. The left menu contains pages for Configuration, monitoring (Status), and Customization. Customization contains only Return, which switches back to the router's main interface.

The configuration page includes the following items:

  • Enable PIM-SM — Activates the Router App (runs the pimd daemon implementing the PIM-SM protocol).
  • Network Interfaces — List of network interfaces (ethX and greX) on which PIM-SM is activated. The allmulti flag is set for ethX interfaces (e.g., eth0) and the multicast flag for greX interfaces (e.g., gre1). TTL value is 64. Return path filtering is disabled for all listed interfaces by setting the appropriate rp_filter entry in the proc filesystem (e.g., echo 0 > /proc/sys/net/ipv4/conf/eth0/rp_filter). Example: eth0 gre1
  • Disable Vifs — Corresponds to -N / --disable-vifs in the pimd daemon. If checked, all network interfaces are inactive for PIM-SM and must be enabled selectively using the enable option of the phyint command in the Configuration section. If unchecked, all interfaces are active and those that should not have PIM-SM enabled (e.g., ppp0) must be explicitly disabled.
  • Timer Hello Period — Period at which PIM hello messages are sent on each PIM-enabled interface. Default: 30 seconds.
  • Timer Join/Prune Period — Interval at which the router sends PIM join/prune messages to the upstream RPF (Reverse Path Forwarding) neighbor. Default: 60 seconds.
  • Timer Bootstrap Period — Period at which bootstrap messages are sent. Default: 60 seconds.
  • pimd.conf — Configuration file for the pimd daemon.

Click Apply to apply all changes.

Configuration

The following commands can be used when editing the pimd.conf file (entered via the pimd.conf field in the web interface):

  • default_source_preference <preference> — Sets the preference value used when selecting a forwarder and upstream router for the LAN. A lower value increases the likelihood of this router being selected. For dedicated applications such as pimd, a somewhat higher value is recommended (e.g., 101).

  • default_source_metric <metric> — Sets the cost for sending data through this router. The recommended default value is 1024.

  • phyint <local-addr|ifname> [disable/enable] [altnet <network> masklen <masklen>] [scoped <network> masklen <masklen>] [threshold thr] [preference pref] [metric cost] — Specifies interfaces by IP address or name. Entering the command without additional options activates the interface with default values.

  • cand_rp [<local-addr>] [priority <number>] [time <number>] — The Rendezvous Point (RP) is the key element in PIM-SM networks, bringing together data from multicast sources and recipient requests. RP selection can be static or dynamic. For dynamic selection, the bootstrap mechanism selects one BSR from multiple Candidate Bootstrap Routers (CBSR), which then selects one RP from a set of Candidate Rendezvous Points (CRP). If cand_rp is used in pimd.conf, the router becomes a CRP. Parameters are: the network interface address used for CRP reporting, CRP priority (lower number = higher priority), and reporting period.

  • cand_bootstrap_router [<local-addr>] [priority <number>] — If used in pimd.conf, the router becomes a CBSR. Parameters are similar to those of cand_rp.

  • rp_address <rp-addr> [<group-addr> [masklen <masklen>] [priority <number>]] — Used for static RP selection. The required parameter is the unicast IP address of the RP or a multicast group. Additional parameters can restrict the use of this RP.

  • group_prefix <group-addr> [masklen <masklen>] [priority <number>] — Used for dynamic RP selection. Specifies the multicast group for which this router acts as RP if selected from the set of CRPs. Maximum 255 entries in pimd.conf.

  • switch_data_threshold [rate <number> interval <number>] — PIM-SM uses several forwarding topologies (shared tree / RPT, source-specific tree, source-specific shortest-path tree) ordered by increasing maintenance overhead and typically increasing throughput. This command sets the threshold for switching to a topology with higher throughput.

  • switch_register_threshold [rate <number> interval <number>] — Opposite of switch_data_threshold.

Configuration Example — Static Selection of RP

The following example configures PIM-SM with a static Rendezvous Point. Enter this in the pimd.conf field in the Router App web interface.

Static selection of RP
Static selection of RP

Configuration Example — Dynamic Selection of RP

The following example configures PIM-SM with dynamic Rendezvous Point selection. Enter this in the pimd.conf field in the Router App web interface.

Dynamic selection of RP
Dynamic selection of RP

System Log

In case of problems, the system log can be viewed by clicking the System Log menu item. It displays detailed reports from all applications running on the router, including messages related to the PIM-SM Router App.

Interoperability

pimd can interoperate with other software products that comply with the PIM-SM specification. An exception is some older versions of Cisco IOS that do not meet the specification regarding checksum calculation of PIM_REGISTER messages. This issue has been resolved in newer IOS versions.

Licenses

This section summarizes the Open-Source Software (OSS) licenses used by this Router App.

Licenses
Licenses