IPv6 Bidirectional PIM

Bidirectional PIM allows multicast devices to keep reduced state information, as compared with unidirectional shared trees in PIM-SM. Bidirectional shared trees convey data from sources to the rendezvous point address (RPA) and distribute it from the RPA to the receivers.

Restrictions for IPv6 Bidirectional PIM

When the bidirectional (bidir) range is used in a network, all devices in that network must be able to understand the bidirectional range in the bootstrap message (BSM).

Information About IPv6 Bidirectional PIM

Bidirectional PIM

Bidirectional PIM allows multicast devices to keep reduced state information, as compared with unidirectional shared trees in PIM-SM. Bidirectional shared trees convey data from sources to the RPA and distribute them from the RPA to the receivers. Unlike PIM-SM, bidirectional PIM does not switch over to the source tree, and there is no register encapsulation of data from the source to the RP.

A single designated forwarder (DF) exists for each RPA on every link within a bidirectional PIM domain (including multiaccess and point-to-point links). The only exception is the RPL on which no DF exists. The DF is the device on the link with the best route to the RPA, which is determined by comparing MRIB-provided metrics. A DF for a given RPA forwards downstream traffic onto its link and forwards upstream traffic from its link toward the rendezvous point link (RPL). The DF performs this function for all bidirectional groups that map to the RPA. The DF on a link is also responsible for processing Join messages from downstream devices on the link as well as ensuring that packets are forwarded to local receivers discovered through a local membership mechanism such as MLD.

Bidirectional PIM offers advantages when there are many moderate or low-rate sources. However, the bidirectional shared trees may have worse delay characteristics than do the source trees built in PIM-SM (depending on the topology).

Only static configuration of bidirectional RPs is supported in IPv6.

How to Configure IPv6 Bidirectional PIM

Configuring Bidirectional PIM and Displaying Bidirectional PIM Information

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. ipv6 pim [vrf vrf-name ] rp-address ipv6-address [group-access-list ] [bidir ]
  4. exit
  5. show ipv6 pim [vrf vrf-name ] df [interface-type interface-number ] [rp-address ]
  6. show ipv6 pim [vrf vrf-name ] df winner [interface-type interface-number ] [rp-address ]

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

ipv6 pim [vrf vrf-name ] rp-address ipv6-address [group-access-list ] [bidir ]

Example:


Device(config)# ipv6 pim rp-address 2001:DB8::01:800:200E:8C6C bidir

Configures the address of a PIM RP for a particular group range. Use of the bidir keyword means that the group range will be used for bidirectional shared-tree forwarding.

Step 4

exit

Example:


Device(config-if)# exit

Exits global configuration mode, and returns the device to privileged EXEC mode.

Step 5

show ipv6 pim [vrf vrf-name ] df [interface-type interface-number ] [rp-address ]

Example:


Device# show ipv6 pim df

Displays the designated forwarder (DF)-election state of each interface for RP.

Step 6

show ipv6 pim [vrf vrf-name ] df winner [interface-type interface-number ] [rp-address ]

Example:


Device# show ipv6 pim df winner ethernet 1/0 200::1

Displays the DF-election winner on each interface for each RP.

Configuration Examples for IPv6 Bidirectional PIM

Example: Configuring Bidirectional PIM and Displaying Bidirectional PIM Information

The following example displays the DF-election states: 

Device# show ipv6 pim df

Interface          DF State     Timer         Metrics
Ethernet0/0        Winner       4s 8ms        [120/2]
    RP :200::1
Ethernet1/0        Lose         0s 0ms        [inf/inf]
    RP :200::1

The following example displays information on the RP: 

Device# show ipv6 pim df

Interface          DF State     Timer         Metrics
Ethernet0/0        None:RP LAN 0s 0ms        [inf/inf]
    RP :200::1
Ethernet1/0        Winner       7s 600ms      [0/0]
    RP :200::1
Ethernet2/0        Winner       9s 8ms        [0/0]
    RP :200::1

Additional References

Related Documents

Related Topic

Document Title

IPv6 addressing and connectivity

IPv6 Configuration Guide

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IP multicast commands

Cisco IOS IP Multicast Command Reference

IPv6 commands

Cisco IOS IPv6 Command Reference

Cisco IOS IPv6 features

Cisco IOS IPv6 Feature Mapping

Standards and RFCs

Standard/RFC

Title

RFCs for IPv6

IPv6 RFCs

MIBs

MIB

MIBs Link

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for IPv6 Bidirectional PIM

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to https://cfnng.cisco.com/. An account on Cisco.com is not required.