# PIM

PIM -- Protocol Independent Multicast

pimd supports pim-sm as well as igmp v2 and v3. pim is vrf aware and can work within the context of vrf's in order to do S,G mrouting. Additionally PIM can be used in the EVPN underlay network for optimizing forwarding of overlay BUM traffic.

Note

On Linux for PIM-SM operation you must have kernel version 4.19 or greater. To use PIM for EVPN BUM forwarding, kernels 5.0 or greater are required. OpenBSD has no multicast support and FreeBSD, and NetBSD only have support for SSM.

## Starting and Stopping pimd

The default configuration file name of pimd's is `pimd.conf`. When invoked pimd searches directory /etc/frr. If `pimd.conf` is not there then next search current directory.

pimd requires zebra for proper operation. Additionally pimd depends on routing properly setup and working in the network that it is working on.

    # zebra -d
    # pimd -d

Please note that zebra must be invoked before pimd.

To stop pimd please use:

    kill `cat /var/run/frr/pimd.pid`

Certain signals have special meanings to pimd.

Signal | Meaning
--- | ---
SIGUSR1 | Rotate the pimd logfile
SIGINT SIGTERM | pimd sweeps all installed PIM mroutes then terminates gracefully.

pimd invocation options. Common options that can be specified (Common Invocation Options).

ip pim rp A.B.C.D A.B.C.D/M

  In order to use pim, it is necessary to configure a RP for join messages to be sent to. Currently the only methodology to do this is via static rp commands. All routers in the pim network must agree on these values. The first ip address is the RP's address and the second value is the matching prefix of group ranges covered. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim rp keep-alive-timer (1-65535)

  Modify the time out value for a S,G flow from 1-65535 seconds at RP. The normal keepalive period for the KAT(S,G) defaults to 210 seconds. However, at the RP, the keepalive period must be at least the Register_Suppression_Time, or the RP may time out the (S,G) state before the next Null-Register arrives. Thus, the KAT(S,G) is set to max(Keepalive_Period, RP_Keepalive_Period) when a Register-Stop is sent. If choosing a value below 31 seconds be aware that some hardware platforms cannot see data flowing in better than 30 second chunks. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim register-accept-list PLIST

  When pim receives a register packet the source of the packet will be compared to the prefix-list specified, PLIST, and if a permit is received normal processing continues. If a deny is returned for the source address of the register packet a register stop message is sent to the source.

ip pim spt-switchover infinity-and-beyond [prefix-list PLIST]

  On the last hop router if it is desired to not switch over to the SPT tree configure this command. Optional parameter prefix-list can be use to control which groups to switch or not switch. If a group is PERMIT as per the PLIST, then the SPT switchover does not happen for it and if it is DENY, then the SPT switchover happens. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim ecmp

  If pim has the a choice of ECMP nexthops for a particular RPF, pim will cause S,G flows to be spread out amongst the nexthops. If this command is not specified then the first nexthop found will be used. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim ecmp rebalance

  If pim is using ECMP and an interface goes down, cause pim to rebalance all S,G flows across the remaining nexthops. If this command is not configured pim only modifies those S,G flows that were using the interface that went down. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim join-prune-interval (1-65535)

  Modify the join/prune interval that pim uses to the new value. Time is specified in seconds. This command is vrf aware, to configure for a vrf, enter the vrf submode. The default time is 60 seconds. If you enter a value smaller than 60 seconds be aware that this can and will affect convergence at scale.

ip pim keep-alive-timer (1-65535)

  Modify the time out value for a S,G flow from 1-65535 seconds. If choosing a value below 31 seconds be aware that some hardware platforms cannot see data flowing in better than 30 second chunks. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim packets (1-255)

  When processing packets from a neighbor process the number of packets incoming at one time before moving on to the next task. The default value is 3 packets. This command is only useful at scale when you can possibly have a large number of pim control packets flowing. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim register-suppress-time (1-65535)

  Modify the time that pim will register suppress a FHR will send register notifications to the kernel. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim send-v6-secondary

  When sending pim hello packets tell pim to send any v6 secondary addresses on the interface. This information is used to allow pim to use v6 nexthops in it's decision for RPF lookup. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim ssm prefix-list WORD

  Specify a range of group addresses via a prefix-list that forces pim to never do SM over. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip multicast rpf-lookup-mode WORD

  Modify how PIM does RPF lookups in the zebra routing table. You can use these choices:

  longer-prefix

    Lookup the RPF in both tables using the longer prefix as a match

  lower-distance

    Lookup the RPF in both tables using the lower distance as a match

  mrib-only

    Lookup in the Multicast RIB only

  mrib-then-urib

    Lookup in the Multicast RIB then the Unicast Rib, returning first found. This is the default value for lookup if this command is not entered

  urib-only

    Lookup in the Unicast Rib only.

ip igmp generate-query-once [version (2-3)]

  Generate IGMP query (v2/v3) on user requirement. This will not depend on the existing IGMP general query timer.If no version is provided in the cli, the default will be the igmp version enabled on that interface.

ip igmp watermark-warn (1-65535)

  Configure watermark warning generation for an igmp group limit. Generates warning once the configured group limit is reached while adding new groups. 'no' form of the command disables the warning generation. This command is vrf aware. To configure per vrf, enter vrf submode.

## PIM Interface Configuration

PIM interface commands allow you to configure an interface as either a Receiver or a interface that you would like to form pim neighbors on. If the interface is in a vrf, enter the interface command with the vrf keyword at the end.

ip pim active-active

  Turn on pim active-active configuration for a Vxlan interface. This command will not do anything if you do not have the underlying ability of a mlag implementation.

ip pim bsm

  Tell pim that we would like to use this interface to process bootstrap messages. This is enabled by default. 'no' form of this command is used to restrict bsm messages on this interface.

ip pim unicast-bsm

  Tell pim that we would like to allow interface to process unicast bootstrap messages. This is enabled by default. 'no' form of this command is used to restrict processing of unicast bsm messages on this interface.

ip pim drpriority (1-4294967295)

  Set the DR Priority for the interface. This command is useful to allow the user to influence what node becomes the DR for a lan segment.

ip pim hello (1-65535) (1-65535)

  Set the pim hello and hold interval for a interface.

ip pim

  Tell pim that we would like to use this interface to form pim neighbors over. Please note that this command does not enable the reception of IGMP reports on the interface. Refer to the next ip igmp command for IGMP management.

ip pim use-source A.B.C.D

  If you have multiple addresses configured on a particular interface and would like pim to use a specific source address associated with that interface.

ip pim passive

  Disable sending and receiving pim control packets on the interface.

ip igmp

  Tell pim to receive IGMP reports and Query on this interface. The default version is v3. This command is useful on a LHR.

ip igmp join A.B.C.D [A.B.C.D]

  Join multicast group or source-group on an interface.

ip igmp query-interval (1-65535)

  Set the IGMP query interval that PIM will use.

ip igmp query-max-response-time (1-65535)

  Set the IGMP query response timeout value. If an report is not returned in the specified time we will assume the S,G or *,G has timed out.

ip igmp version (2-3)

  Set the IGMP version used on this interface. The default value is 3.

ip multicast boundary oil WORD

  Set a pim multicast boundary, based upon the WORD prefix-list. If a pim join or IGMP report is received on this interface and the Group is denied by the prefix-list, PIM will ignore the join or report.

ip igmp last-member-query-count (1-255)

  Set the IGMP last member query count. The default value is 2. 'no' form of this command is used to to configure back to the default value.

ip igmp last-member-query-interval (1-65535)

  Set the IGMP last member query interval in deciseconds. The default value is 10 deciseconds. 'no' form of this command is used to to configure back to the default value.

ip mroute INTERFACE A.B.C.D [A.B.C.D]

  Set a static multicast route for a traffic coming on the current interface to be forwarded on the given interface if the traffic matches the group address and optionally the source address.

See also

PIM BFD Configuration

## PIM Multicast RIB

In order to influence Multicast RPF lookup, it is possible to insert into zebra routes for the Multicast RIB. These routes are only used for RPF lookup and will not be used by zebra for insertion into the kernel or for normal rib processing. As such it is possible to create weird states with these commands. Use with caution. Most of the time this will not be necessary.

ip mroute A.B.C.D/M A.B.C.D (1-255)

  Insert into the Multicast Rib Route A.B.C.D/M with specified nexthop. The distance can be specified as well if desired.

ip mroute A.B.C.D/M INTERFACE (1-255)

  Insert into the Multicast Rib Route A.B.C.D/M using the specified INTERFACE. The distance can be specified as well if desired.

## Multicast Source Discovery Protocol (MSDP) Configuration

MSDP can be setup in different ways:

- MSDP meshed-group: where all peers are connected with each other creating a fully meshed network. SAs (source active) messages are not forwarded in this mode because the origin is able to send SAs to all members.

  This setup is commonly used with anycast.

- MSDP peering: when there is one or more peers that are not fully meshed. SAs may be forwarded depending on the result of filtering and RPF checks.

  This setup is commonly consistent with BGP peerings (for RPF checks).

- MSDP default peer: there is only one peer and all SAs will be forwarded there.

Note

MSDP default peer and SA filtering is not implemented.

Commands available for MSDP:

ip msdp timers (1-65535) (1-65535) [(1-65535)]

  Configure global MSDP timers.

  First value is the keep-alive interval. This configures the interval in seconds between keep-alive messages. The default value is 60 seconds. It should be less than the remote hold time.

  Second value is the hold-time. This configures the interval in seconds before closing a non responding connection. The default value is 75. This value should be greater than the remote keep alive time.

  Third value is the connection retry interval and it is optional. This configures the interval between connection attempts. The default value is 30 seconds.

ip msdp mesh-group WORD member A.B.C.D

  Create or update a mesh group to include the specified MSDP peer.

ip msdp mesh-group WORD source A.B.C.D

  Create or update a mesh group to set the source address used to connect to peers.

ip msdp peer A.B.C.D source A.B.C.D

  Create a regular MSDP session with peer using the specified source address.

## Show PIM Information

All PIM show commands are vrf aware and typically allow you to insert a specified vrf command if information is desired about a specific vrf. If no vrf is specified then the default vrf is assumed. Finally the special keyword 'all' allows you to look at all vrfs for the command. Naming a vrf 'all' will cause great confusion.

show ip igmp interface

  Display IGMP interface information.

show ip igmp [vrf NAME] join [json]

  Display IGMP static join information for a specific vrf.

show ip igmp [vrf NAME$vrf_name] groups [INTERFACE$ifname [GROUP$grp_str]] [detail] [json$json]

  Display IGMP static join information for all the vrfs present.

show ip igmp vrf all groups [GROUP$grp_str] [detail$detail] [json$json]

  Display IGMP groups information.

show ip igmp groups retransmissions

  Display IGMP group retransmission information.

show ip igmp [vrf NAME] sources [json]

  Display IGMP sources information.

show ip igmp sources retransmissions

  Display IGMP source retransmission information.

show ip igmp statistics

  Display IGMP statistics information.

show ip multicast

  Display various information about the interfaces used in this pim instance.

show ip mroute [vrf NAME] [A.B.C.D [A.B.C.D]] [fill] [json]

  Display information about installed into the kernel S,G mroutes. If one address is specified we assume it is the Group we are interested in displaying data on. If the second address is specified then it is Source Group. The keyword fill says to fill in all assumed data for test/data gathering purposes.

show ip mroute [vrf NAME] count [json]

  Display information about installed into the kernel S,G mroutes and in addition display data about packet flow for the mroutes for a specific vrf.

show ip mroute vrf all count [json]

  Display information about installed into the kernel S,G mroutes and in addition display data about packet flow for the mroutes for all vrfs.

show ip mroute [vrf NAME] summary [json]

  Display total number of S,G mroutes and number of S,G mroutes installed into the kernel for a specific vrf.

show ip mroute vrf all summary [json]

  Display total number of S,G mroutes and number of S,G mroutes installed into the kernel for all vrfs.

show ip msdp mesh-group

  Display the configured mesh-groups, the local address associated with each mesh-group, the peer members included in each mesh-group, and their status.

show ip msdp peer

  Display information about the MSDP peers. That includes the peer address, the local address used to establish the connection to the peer, the connection status, and the number of active sources.

show ip pim assert

  Display information about asserts in the PIM system for S,G mroutes. This command does not show S,G Channel states that in a NOINFO state.

show ip pim assert-internal

  Display internal assert state for S,G mroutes

show ip pim assert-metric

  Display metric information about assert state for S,G mroutes

show ip pim assert-winner-metric

  Display winner metric for assert state for S,G mroutes

show ip pim group-type

  Display SSM group ranges.

show ip pim interface

  Display information about interfaces PIM is using.

show ip pim mlag [vrf NAME|all] interface [detail|WORD] [json]

  Display mlag interface information.

show ip pim join

  Display information about PIM joins received. If one address is specified then we assume it is the Group we are interested in displaying data on. If the second address is specified then it is Source Group.

show ip pim local-membership

  Display information about PIM interface local-membership.

show ip pim mlag summary [json]

  Display mlag information state that PIM is keeping track of.

show ip pim neighbor

  Display information about PIM neighbors.

show ip pim nexthop

  Display information about pim nexthops that are being used.

show ip pim nexthop-lookup

  Display information about a S,G pair and how the RPF would be chosen. This is especially useful if there are ECMP's available from the RPF lookup.

show ip pim [vrf NAME] rp-info [A.B.C.D/M] [json]

  Display information about RP's that are configured on this router.

  You can filter the output by specifying an arbitrary group range.

      # show ip pim rp-info
      RP address       group/prefix-list   OIF               I am RP    Source   Group-Type
      192.168.10.123   225.0.0.0/24        eth2              yes        Static   ASM
      192.168.10.123   239.0.0.0/8         eth2              yes        Static   ASM
      192.168.10.123   239.4.0.0/24        eth2              yes        Static   SSM

      # show ip pim rp-info 239.4.0.0/25
      RP address       group/prefix-list   OIF               I am RP    Source   Group-Type
      192.168.10.123   239.0.0.0/8         eth2              yes        Static   ASM
      192.168.10.123   239.4.0.0/24        eth2              yes        Static   SSM

show ip pim rpf

  Display information about currently being used S,G's and their RPF lookup information. Additionally display some statistics about what has been happening on the router.

show ip pim secondary

  Display information about an interface and all the secondary addresses associated with it.

show ip pim state

  Display information about known S,G's and incoming interface as well as the OIL and how they were chosen.

show ip pim [vrf NAME] upstream [A.B.C.D [A.B.C.D]] [json]

  Display upstream information about a S,G mroute. Allow the user to specify sub Source and Groups that we are only interested in.

show ip pim upstream-join-desired

  Display upstream information for S,G's and if we desire to join the multicast tree

show ip pim upstream-rpf

  Display upstream information for S,G's and the RPF data associated with them.

show ip pim [vrf NAME] mlag upstream [A.B.C.D [A.B.C.D]] [json]

  Display upstream entries that are synced across MLAG switches. Allow the user to specify sub Source and Groups address filters.

show ip pim mlag summary

  Display PIM MLAG (multi-chassis link aggregation) session status and control message statistics.

show ip pim bsr

  Display current bsr, its uptime and last received bsm age.

show ip pim bsrp-info

  Display group-to-rp mappings received from E-BSR.

show ip pim bsm-database

  Display all fragments of stored bootstrap message in user readable format.

mtrace A.B.C.D [A.B.C.D]

  Display multicast traceroute towards source, optionally for particular group.

show ip multicast count [vrf NAME] [json]

  Display multicast data packets count per interface for a vrf.

show ip multicast count vrf all [json]

  Display multicast data packets count per interface for all vrf.

See also

Multicast RIB Commands

## PIM Debug Commands

The debugging subsystem for PIM behaves in accordance with how FRR handles debugging. You can specify debugging at the enable CLI mode as well as the configure CLI mode. If you specify debug commands in the configuration cli mode, the debug commands can be persistent across restarts of the FRR pimd if the config was written out.

debug igmp

  This turns on debugging for IGMP protocol activity.

debug mtrace

  This turns on debugging for mtrace protocol activity.

debug mroute

  This turns on debugging for PIM interaction with kernel MFC cache.

debug pim events

  This turns on debugging for PIM system events. Especially timers.

debug pim nht

  This turns on debugging for PIM nexthop tracking. It will display information about RPF lookups and information about when a nexthop changes.

debug pim nht detail

  This turns on debugging for PIM nexthop in detail. This is not enabled by default.

debug pim packet-dump

  This turns on an extraordinary amount of data. Each pim packet sent and received is dumped for debugging purposes. This should be considered a developer only command.

debug pim packets

  This turns on information about packet generation for sending and about packet handling from a received packet.

debug pim trace

  This traces pim code and how it is running.

debug pim bsm

  This turns on debugging for BSR message processing.

debug pim zebra

  This gathers data about events from zebra that come up through the ZAPI.

## PIM Clear Commands

Clear commands reset various variables.

clear ip interfaces

  Reset interfaces.

clear ip igmp interfaces

  Reset IGMP interfaces.

clear ip mroute

  Reset multicast routes.

clear ip mroute [vrf NAME] count

  When this command is issued, reset the counts of data shown for packet count, byte count and wrong interface to 0 and start count up from this spot.

clear ip pim interfaces

  Reset PIM interfaces.

clear ip pim oil

  Rescan PIM OIL (output interface list).

clear ip pim [vrf NAME] bsr-data

  This command will clear the BSM scope data struct. This command also removes the next hop tracking for the bsr and resets the upstreams for the dynamically learnt RPs.

## PIM EVPN configuration

To use PIM in the underlay for overlay BUM forwarding associate a multicast group with the L2 VNI. The actual configuration is based on your distribution. Here is an ifupdown2 example:

    auto vx-10100
    iface vx-10100
        vxlan-id 10100
        bridge-access 100
        vxlan-local-tunnelip 27.0.0.11
        vxlan-mcastgrp 239.1.1.100

Note

PIM will see the `vxlan-mcastgrp` configuration and auto configure state to properly forward BUM traffic.

PIM also needs to be configured in the underlay to allow the BUM MDT to be setup. This is existing PIM configuration:

- Enable pim on the underlay L3 interface via the "ip pim" command.

- Configure RPs for the BUM multicast group range.

- Ensure the PIM is enabled on the lo of the VTEPs and the RP.

## Sample configuration

    debug igmp
    debug pim
    debug pim zebra

    ! You may want to enable ssmpingd for troubleshooting
    ! See http://www.venaas.no/multicast/ssmping/
    !
    ip ssmpingd 1.1.1.1
    ip ssmpingd 2.2.2.2

    ! HINTS:
    !  - Enable "ip pim ssm" on the interface directly attached to the
    !    multicast source host (if this is the first-hop router)
    !  - Enable "ip pim ssm" on pim-routers-facing interfaces
    !  - Enable "ip igmp" on IGMPv3-hosts-facing interfaces
    !  - In order to inject IGMPv3 local membership information in the
    !    PIM protocol state, enable both "ip pim ssm" and "ip igmp" on
    !    the same interface; otherwise PIM won't advertise
    !    IGMPv3-learned membership to other PIM routers

    interface eth0
     ip pim ssm
     ip igmp