doc/user/pim.rst

   1 .. _pim:
   2
   3 ***
   4 PIM
   5 ***
   6
   7 PIM -- Protocol Independent Multicast
   8
   9 *pimd* supports pim-sm as well as igmp v2 and v3. pim is
  10 vrf aware and can work within the context of vrf's in order to
  11 do S,G mrouting.  Additionally PIM can be used in the EVPN underlay
  12 network for optimizing forwarding of overlay BUM traffic.
  13
  14 .. note::
  15
  16    On Linux for PIM-SM operation you *must* have kernel version 4.18 or greater.
  17    To use PIM for EVPN BUM forwarding, kernels 5.0 or greater are required.
  18    OpenBSD has no multicast support and FreeBSD, and NetBSD only
  19    have support for SSM.
  20
  21 .. _starting-and-stopping-pimd:
  22
  23 Starting and Stopping pimd
  24 ==========================
  25
  26 The default configuration file name of *pimd*'s is :file:`pimd.conf`. When
  27 invoked *pimd* searches directory |INSTALL_PREFIX_ETC|. If
  28 :file:`pimd.conf` is not there then next search current directory.
  29
  30 *pimd* requires zebra for proper operation. Additionally *pimd* depends on
  31 routing properly setup and working in the network that it is working on.
  32
  33 ::
  34
  35    # zebra -d
  36    # pimd -d
  37
  38
  39 Please note that *zebra* must be invoked before *pimd*.
  40
  41 To stop *pimd* please use::
  42
  43    kill `cat /var/run/pimd.pid`
  44
  45 Certain signals have special meanings to *pimd*.
  46
  47 +---------+---------------------------------------------------------------------+
  48 | Signal  | Meaning                                                             |
  49 +=========+=====================================================================+
  50 | SIGUSR1 | Rotate the *pimd* logfile                                           |
  51 +---------+---------------------------------------------------------------------+
  52 | SIGINT  | *pimd* sweeps all installed PIM mroutes then terminates gracefully. |
  53 | SIGTERM |                                                                     |
  54 +---------+---------------------------------------------------------------------+
  55
  56 *pimd* invocation options. Common options that can be specified
  57 (:ref:`common-invocation-options`).
  58
  59 .. clicmd:: ip pim rp A.B.C.D A.B.C.D/M
  60
  61    In order to use pim, it is necessary to configure a RP for join messages to
  62    be sent to. Currently the only methodology to do this is via static rp
  63    commands. All routers in the pim network must agree on these values. The
  64    first ip address is the RP's address and the second value is the matching
  65    prefix of group ranges covered. This command is vrf aware, to configure for
  66    a vrf, enter the vrf submode.
  67
  68 .. clicmd:: ip pim register-accept-list PLIST
  69
  70    When pim receives a register packet the source of the packet will be compared
  71    to the prefix-list specified, PLIST, and if a permit is received normal
  72    processing continues.  If a deny is returned for the source address of the
  73    register packet a register stop message is sent to the source.
  74
  75 .. clicmd:: ip pim spt-switchover infinity-and-beyond
  76
  77    On the last hop router if it is desired to not switch over to the SPT tree.
  78    Configure this command. This command is vrf aware, to configure for a vrf,
  79    enter the vrf submode.
  80
  81 .. clicmd:: ip pim ecmp
  82
  83    If pim has the a choice of ECMP nexthops for a particular RPF, pim will
  84    cause S,G flows to be spread out amongst the nexthops. If this command is
  85    not specified then the first nexthop found will be used. This command is vrf
  86    aware, to configure for a vrf, enter the vrf submode.
  87
  88 .. clicmd:: ip pim ecmp rebalance
  89
  90    If pim is using ECMP and an interface goes down, cause pim to rebalance all
  91    S,G flows across the remaining nexthops. If this command is not configured
  92    pim only modifies those S,G flows that were using the interface that went
  93    down. This command is vrf aware, to configure for a vrf, enter the vrf
  94    submode.
  95
  96 .. clicmd:: ip pim join-prune-interval (5-600)
  97
  98    Modify the join/prune interval that pim uses to the new value. Time is
  99    specified in seconds. This command is vrf aware, to configure for a vrf,
 100    enter the vrf submode.  The default time is 60 seconds.  If you enter
 101    a value smaller than 60 seconds be aware that this can and will affect
 102    convergence at scale.
 103
 104 .. clicmd:: ip pim keep-alive-timer (31-60000)
 105
 106    Modify the time out value for a S,G flow from 31-60000 seconds. 31 seconds
 107    is chosen for a lower bound because some hardware platforms cannot see data
 108    flowing in better than 30 second chunks. This command is vrf aware, to
 109    configure for a vrf, enter the vrf submode.
 110
 111 .. clicmd:: ip pim packets (1-100)
 112
 113    When processing packets from a neighbor process the number of packets
 114    incoming at one time before moving on to the next task. The default value is
 115    3 packets.  This command is only useful at scale when you can possibly have
 116    a large number of pim control packets flowing. This command is vrf aware, to
 117    configure for a vrf, enter the vrf submode.
 118
 119 .. clicmd:: ip pim register-suppress-time (5-60000)
 120
 121    Modify the time that pim will register suppress a FHR will send register
 122    notifications to the kernel. This command is vrf aware, to configure for a
 123    vrf, enter the vrf submode.
 124
 125 .. clicmd:: ip pim send-v6-secondary
 126
 127    When sending pim hello packets tell pim to send any v6 secondary addresses
 128    on the interface. This information is used to allow pim to use v6 nexthops
 129    in it's decision for RPF lookup. This command is vrf aware, to configure for
 130    a vrf, enter the vrf submode.
 131
 132 .. clicmd:: ip pim ssm prefix-list WORD
 133
 134    Specify a range of group addresses via a prefix-list that forces pim to
 135    never do SM over. This command is vrf aware, to configure for a vrf, enter
 136    the vrf submode.
 137
 138 .. clicmd:: ip multicast rpf-lookup-mode WORD
 139
 140    Modify how PIM does RPF lookups in the zebra routing table.  You can use
 141    these choices:
 142
 143    longer-prefix
 144       Lookup the RPF in both tables using the longer prefix as a match
 145
 146    lower-distance
 147       Lookup the RPF in both tables using the lower distance as a match
 148
 149    mrib-only
 150       Lookup in the Multicast RIB only
 151
 152    mrib-then-urib
 153       Lookup in the Multicast RIB then the Unicast Rib, returning first found.
 154       This is the default value for lookup if this command is not entered
 155
 156    urib-only
 157       Lookup in the Unicast Rib only.
 158
 159 .. clicmd:: ip igmp generate-query-once [version (2-3)]
 160
 161    Generate IGMP query (v2/v3) on user requirement. This will not depend on
 162    the existing IGMP general query timer.If no version is provided in the cli,
 163    it will be considered as default v2 query.This is a hidden command.
 164
 165 .. clicmd:: ip igmp watermark-warn (10-60000)
 166
 167    Configure watermark warning generation for an igmp group limit. Generates
 168    warning once the configured group limit is reached while adding new groups.
 169    'no' form of the command disables the warning generation. This command is
 170    vrf aware. To configure per vrf, enter vrf submode.
 171
 172 .. _pim-interface-configuration:
 173
 174 PIM Interface Configuration
 175 ===========================
 176
 177 PIM interface commands allow you to configure an interface as either a Receiver
 178 or a interface that you would like to form pim neighbors on. If the interface
 179 is in a vrf, enter the interface command with the vrf keyword at the end.
 180
 181 .. clicmd:: ip pim active-active
 182
 183    Turn on pim active-active configuration for a Vxlan interface.  This
 184    command will not do anything if you do not have the underlying ability
 185    of a mlag implementation.
 186
 187 .. clicmd:: ip pim bsm
 188
 189    Tell pim that we would like to use this interface to process bootstrap
 190    messages. This is enabled by default. 'no' form of this command is used to
 191    restrict bsm messages on this interface.
 192
 193 .. clicmd:: ip pim unicast-bsm
 194
 195    Tell pim that we would like to allow interface to process unicast bootstrap
 196    messages. This is enabled by default. 'no' form of this command is used to
 197    restrict processing of unicast bsm messages on this interface.
 198
 199 .. clicmd:: ip pim drpriority (1-4294967295)
 200
 201    Set the DR Priority for the interface. This command is useful to allow the
 202    user to influence what node becomes the DR for a lan segment.
 203
 204 .. clicmd:: ip pim hello (1-180) (1-630)
 205
 206    Set the pim hello and hold interval for a interface.
 207
 208 .. clicmd:: ip pim
 209
 210    Tell pim that we would like to use this interface to form pim neighbors
 211    over. Please note that this command does not enable the reception of IGMP
 212    reports on the interface. Refer to the next `ip igmp` command for IGMP
 213    management.
 214
 215 .. clicmd:: ip pim use-source A.B.C.D
 216
 217    If you have multiple addresses configured on a particular interface
 218    and would like pim to use a specific source address associated with
 219    that interface.
 220
 221 .. clicmd:: ip igmp
 222
 223    Tell pim to receive IGMP reports and Query on this interface. The default
 224    version is v3. This command is useful on a LHR.
 225
 226 .. clicmd:: ip igmp join A.B.C.D [A.B.C.D]
 227
 228    Join multicast group or source-group on an interface.
 229
 230 .. clicmd:: ip igmp query-interval (1-1800)
 231
 232    Set the IGMP query interval that PIM will use.
 233
 234 .. clicmd:: ip igmp query-max-response-time (10-250)
 235
 236    Set the IGMP query response timeout value. If an report is not returned in
 237    the specified time we will assume the S,G or \*,G has timed out.
 238
 239 .. clicmd:: ip igmp version (2-3)
 240
 241    Set the IGMP version used on this interface. The default value is 3.
 242
 243 .. clicmd:: ip multicast boundary oil WORD
 244
 245    Set a pim multicast boundary, based upon the WORD prefix-list. If a pim join
 246    or IGMP report is received on this interface and the Group is denied by the
 247    prefix-list, PIM will ignore the join or report.
 248
 249 .. clicmd:: ip igmp last-member-query-count (1-7)
 250
 251    Set the IGMP last member query count. The default value is 2. 'no' form of
 252    this command is used to to configure back to the default value.
 253
 254 .. clicmd:: ip igmp last-member-query-interval (1-255)
 255
 256    Set the IGMP last member query interval in deciseconds. The default value is
 257    10 deciseconds. 'no' form of this command is used to to configure back to the
 258    default value.
 259
 260 .. clicmd:: ip mroute INTERFACE A.B.C.D [A.B.C.D]
 261
 262    Set a static multicast route for a traffic coming on the current interface to
 263    be forwarded on the given interface if the traffic matches the group address
 264    and optionally the source address.
 265
 266
 267 .. seealso::
 268
 269    :ref:`bfd-pim-peer-config`
 270
 271
 272 .. _pim-multicast-rib:
 273
 274 PIM Multicast RIB
 275 =================
 276
 277 In order to influence Multicast RPF lookup, it is possible to insert
 278 into zebra routes for the Multicast RIB. These routes are only
 279 used for RPF lookup and will not be used by zebra for insertion
 280 into the kernel *or* for normal rib processing. As such it is
 281 possible to create weird states with these commands. Use with
 282 caution. Most of the time this will not be necessary.
 283
 284 .. clicmd:: ip mroute A.B.C.D/M A.B.C.D (1-255)
 285
 286    Insert into the Multicast Rib Route A.B.C.D/M with specified nexthop. The
 287    distance can be specified as well if desired.
 288
 289 .. clicmd:: ip mroute A.B.C.D/M INTERFACE (1-255)
 290
 291    Insert into the Multicast Rib Route A.B.C.D/M using the specified INTERFACE.
 292    The distance can be specified as well if desired.
 293
 294 .. _msdp-configuration:
 295
 296 Multicast Source Discovery Protocol (MSDP) Configuration
 297 ========================================================
 298
 299 MSDP can be setup in different ways:
 300
 301 * MSDP meshed-group: where all peers are connected with each other creating
 302   a fully meshed network. SAs (source active) messages are not forwarded in
 303   this mode because the origin is able to send SAs to all members.
 304
 305   This setup is commonly used with anycast.
 306
 307 * MSDP peering: when there is one or more peers that are not fully meshed. SAs
 308   may be forwarded depending on the result of filtering and RPF checks.
 309
 310   This setup is commonly consistent with BGP peerings (for RPF checks).
 311
 312 * MSDP default peer: there is only one peer and all SAs will be forwarded
 313   there.
 314
 315 .. note::
 316
 317    MSDP default peer and SA filtering is not implemented.
 318
 319
 320 Commands available for MSDP:
 321
 322 .. clicmd:: ip msdp timers (2-600) (3-600) [(1-600)]
 323
 324    Configure global MSDP timers.
 325
 326    First value is the keep-alive interval and it must be less than the
 327    second value which is hold-time. This configures the interval in
 328    seconds between keep-alive messages. The default value is 60 seconds.
 329
 330    Second value is the hold-time and it must be greater than the keep-alive
 331    interval. This configures the interval in seconds before closing a non
 332    responding connection. The default value is 75.
 333
 334    Third value is the connection retry interval and it is optional. This
 335    configures the interval between connection attempts. The default value
 336    is 30 seconds.
 337
 338 .. clicmd:: ip msdp mesh-group WORD member A.B.C.D
 339
 340    Create or update a mesh group to include the specified MSDP peer.
 341
 342 .. clicmd:: ip msdp mesh-group WORD source A.B.C.D
 343
 344    Create or update a mesh group to set the source address used to connect to
 345    peers.
 346
 347 .. clicmd:: ip msdp peer A.B.C.D source A.B.C.D
 348
 349    Create a regular MSDP session with peer using the specified source address.
 350
 351
 352 .. _show-pim-information:
 353
 354 Show PIM Information
 355 ====================
 356
 357 All PIM show commands are vrf aware and typically allow you to insert a
 358 specified vrf command if information is desired about a specific vrf. If no
 359 vrf is specified then the default vrf is assumed. Finally the special keyword
 360 'all' allows you to look at all vrfs for the command. Naming a vrf 'all' will
 361 cause great confusion.
 362
 363 .. clicmd:: show ip igmp interface
 364
 365    Display IGMP interface information.
 366
 367 .. clicmd:: show ip igmp [vrf NAME] join [json]
 368
 369    Display IGMP static join information for a specific vrf.
 370    If "vrf all" is provided, it displays information for all the vrfs present.
 371
 372 .. clicmd:: show ip igmp groups
 373
 374    Display IGMP groups information.
 375
 376 .. clicmd:: show ip igmp groups retransmissions
 377
 378    Display IGMP group retransmission information.
 379
 380 .. clicmd:: show ip igmp sources
 381
 382    Display IGMP sources information.
 383
 384 .. clicmd:: show ip igmp sources retransmissions
 385
 386    Display IGMP source retransmission information.
 387
 388 .. clicmd:: show ip igmp statistics
 389
 390    Display IGMP statistics information.
 391
 392 .. clicmd:: show ip multicast
 393
 394    Display various information about the interfaces used in this pim instance.
 395
 396 .. clicmd:: show ip mroute [vrf NAME] [A.B.C.D [A.B.C.D]] [fill] [json]
 397
 398    Display information about installed into the kernel S,G mroutes.  If
 399    one address is specified we assume it is the Group we are interested
 400    in displaying data on.  If the second address is specified then it is
 401    Source Group.  The keyword `fill` says to fill in all assumed data
 402    for test/data gathering purposes.
 403
 404 .. clicmd:: show ip mroute [vrf NAME] count [json]
 405
 406    Display information about installed into the kernel S,G mroutes and in
 407    addition display data about packet flow for the mroutes for a specific
 408    vrf.
 409
 410 .. clicmd:: show ip mroute vrf all count [json]
 411
 412    Display information about installed into the kernel S,G mroutes and in
 413    addition display data about packet flow for the mroutes for all vrfs.
 414
 415 .. clicmd:: show ip mroute [vrf NAME] summary [json]
 416
 417    Display total number of S,G mroutes and number of S,G mroutes installed
 418    into the kernel for a specific vrf.
 419
 420 .. clicmd:: show ip mroute vrf all summary [json]
 421
 422    Display total number of S,G mroutes and number of S,G mroutes
 423    installed into the kernel for all vrfs.
 424
 425 .. clicmd:: show ip msdp mesh-group
 426
 427    Display the configured mesh-groups, the local address associated with each
 428    mesh-group, the peer members included in each mesh-group, and their status.
 429
 430 .. clicmd:: show ip msdp peer
 431
 432    Display information about the MSDP peers. That includes the peer address,
 433    the local address used to establish the connection to the peer, the
 434    connection status, and the number of active sources.
 435
 436 .. clicmd:: show ip pim assert
 437
 438    Display information about asserts in the PIM system for S,G mroutes.
 439
 440 .. clicmd:: show ip pim assert-internal
 441
 442    Display internal assert state for S,G mroutes
 443
 444 .. clicmd:: show ip pim assert-metric
 445
 446    Display metric information about assert state for S,G mroutes
 447
 448 .. clicmd:: show ip pim assert-winner-metric
 449
 450    Display winner metric for assert state for S,G mroutes
 451
 452 .. clicmd:: show ip pim group-type
 453
 454    Display SSM group ranges.
 455
 456 .. clicmd:: show ip pim interface
 457
 458    Display information about interfaces PIM is using.
 459
 460 .. clicmd:: show ip pim mlag [vrf NAME|all] interface [detail|WORD] [json]
 461
 462    Display mlag interface information.
 463
 464 .. clicmd:: show ip pim join
 465
 466    Display information about PIM joins received.  If one address is specified
 467    then we assume it is the Group we are interested in displaying data on.
 468    If the second address is specified then it is Source Group.
 469
 470 .. clicmd:: show ip pim local-membership
 471
 472    Display information about PIM interface local-membership.
 473
 474 .. clicmd:: show ip pim mlag summary [json]
 475
 476    Display mlag information state that PIM is keeping track of.
 477
 478 .. clicmd:: show ip pim neighbor
 479
 480    Display information about PIM neighbors.
 481
 482 .. clicmd:: show ip pim nexthop
 483
 484    Display information about pim nexthops that are being used.
 485
 486 .. clicmd:: show ip pim nexthop-lookup
 487
 488    Display information about a S,G pair and how the RPF would be chosen. This
 489    is especially useful if there are ECMP's available from the RPF lookup.
 490
 491 .. clicmd:: show ip pim rp-info
 492
 493    Display information about RP's that are configured on this router.
 494
 495 .. clicmd:: show ip pim rpf
 496
 497    Display information about currently being used S,G's and their RPF lookup
 498    information. Additionally display some statistics about what has been
 499    happening on the router.
 500
 501 .. clicmd:: show ip pim secondary
 502
 503    Display information about an interface and all the secondary addresses
 504    associated with it.
 505
 506 .. clicmd:: show ip pim state
 507
 508    Display information about known S,G's and incoming interface as well as the
 509    OIL and how they were chosen.
 510
 511 .. clicmd:: show ip pim [vrf NAME] upstream [A.B.C.D [A.B.C.D]] [json]
 512
 513    Display upstream information about a S,G mroute.  Allow the user to
 514    specify sub Source and Groups that we are only interested in.
 515
 516 .. clicmd:: show ip pim upstream-join-desired
 517
 518    Display upstream information for S,G's and if we desire to
 519    join the multicast tree
 520
 521 .. clicmd:: show ip pim upstream-rpf
 522
 523    Display upstream information for S,G's and the RPF data associated with them.
 524
 525 .. clicmd:: show ip pim [vrf NAME] mlag upstream [A.B.C.D [A.B.C.D]] [json]
 526
 527    Display upstream entries that are synced across MLAG switches.
 528    Allow the user to specify sub Source and Groups address filters.
 529
 530 .. clicmd:: show ip pim mlag summary
 531
 532    Display PIM MLAG (multi-chassis link aggregation) session status and
 533    control message statistics.
 534
 535 .. clicmd:: show ip pim bsr
 536
 537    Display current bsr, its uptime and last received bsm age.
 538
 539 .. clicmd:: show ip pim bsrp-info
 540
 541    Display group-to-rp mappings received from E-BSR.
 542
 543 .. clicmd:: show ip pim bsm-database
 544
 545    Display all fragments ofstored bootstrap message in user readable format.
 546
 547 .. clicmd:: mtrace A.B.C.D [A.B.C.D]
 548
 549    Display multicast traceroute towards source, optionally for particular group.
 550
 551 .. clicmd:: show ip multicast count [vrf NAME] [json]
 552
 553    Display multicast data packets count per interface for a vrf.
 554
 555 .. clicmd:: show ip multicast count vrf all [json]
 556
 557    Display multicast data packets count per interface for all vrf.
 558
 559
 560 .. seealso::
 561
 562    :ref:`multicast-rib-commands`
 563
 564
 565 PIM Debug Commands
 566 ==================
 567
 568 The debugging subsystem for PIM behaves in accordance with how FRR handles
 569 debugging. You can specify debugging at the enable CLI mode as well as the
 570 configure CLI mode. If you specify debug commands in the configuration cli
 571 mode, the debug commands can be persistent across restarts of the FRR pimd if
 572 the config was written out.
 573
 574 .. clicmd:: debug igmp
 575
 576    This turns on debugging for IGMP protocol activity.
 577
 578 .. clicmd:: debug mtrace
 579
 580    This turns on debugging for mtrace protocol activity.
 581
 582 .. clicmd:: debug mroute
 583
 584    This turns on debugging for PIM interaction with kernel MFC cache.
 585
 586 .. clicmd:: debug pim events
 587
 588    This turns on debugging for PIM system events. Especially timers.
 589
 590 .. clicmd:: debug pim nht
 591
 592    This turns on debugging for PIM nexthop tracking. It will display
 593    information about RPF lookups and information about when a nexthop changes.
 594
 595 .. clicmd:: debug pim packet-dump
 596
 597    This turns on an extraordinary amount of data. Each pim packet sent and
 598    received is dumped for debugging purposes. This should be considered a
 599    developer only command.
 600
 601 .. clicmd:: debug pim packets
 602
 603    This turns on information about packet generation for sending and about
 604    packet handling from a received packet.
 605
 606 .. clicmd:: debug pim trace
 607
 608    This traces pim code and how it is running.
 609
 610 .. clicmd:: debug pim bsm
 611
 612    This turns on debugging for BSR message processing.
 613
 614 .. clicmd:: debug pim zebra
 615
 616    This gathers data about events from zebra that come up through the ZAPI.
 617
 618 PIM Clear Commands
 619 ==================
 620 Clear commands reset various variables.
 621
 622 .. clicmd:: clear ip interfaces
 623
 624    Reset interfaces.
 625
 626 .. clicmd:: clear ip igmp interfaces
 627
 628    Reset IGMP interfaces.
 629
 630 .. clicmd:: clear ip mroute
 631
 632    Reset multicast routes.
 633
 634 .. clicmd:: clear ip mroute [vrf NAME] count
 635
 636    When this command is issued, reset the counts of data shown for
 637    packet count, byte count and wrong interface to 0 and start count
 638    up from this spot.
 639
 640 .. clicmd:: clear ip pim interfaces
 641
 642    Reset PIM interfaces.
 643
 644 .. clicmd:: clear ip pim oil
 645
 646    Rescan PIM OIL (output interface list).
 647
 648 .. clicmd:: clear ip pim [vrf NAME] bsr-data
 649
 650    This command will clear the BSM scope data struct. This command also
 651    removes the next hop tracking for the bsr and resets the upstreams
 652    for the dynamically learnt RPs.
 653
 654 PIM EVPN configuration
 655 ======================
 656 To use PIM in the underlay for overlay BUM forwarding associate a multicast
 657 group with the L2 VNI. The actual configuration is based on your distribution.
 658 Here is an ifupdown2 example::
 659
 660    auto vx-10100
 661    iface vx-10100
 662        vxlan-id 10100
 663        bridge-access 100
 664        vxlan-local-tunnelip 27.0.0.11
 665        vxlan-mcastgrp 239.1.1.100
 666
 667 .. note::
 668
 669    PIM will see the ``vxlan-mcastgrp`` configuration and auto configure state
 670    to properly forward BUM traffic.
 671
 672 PIM also needs to be configured in the underlay to allow the BUM MDT to be
 673 setup. This is existing PIM configuration:
 674
 675 - Enable pim on the underlay L3 interface via the "ip pim" command.
 676 - Configure RPs for the BUM multicast group range.
 677 - Ensure the PIM is enabled on the lo of the VTEPs and the RP.
 678
 679
 680 Sample configuration
 681 ====================
 682
 683 .. code-block:: frr
 684
 685    debug igmp
 686    debug pim
 687    debug pim zebra
 688
 689    ! You may want to enable ssmpingd for troubleshooting
 690    ! See http://www.venaas.no/multicast/ssmping/
 691    !
 692    ip ssmpingd 1.1.1.1
 693    ip ssmpingd 2.2.2.2
 694
 695    ! HINTS:
 696    !  - Enable "ip pim ssm" on the interface directly attached to the
 697    !    multicast source host (if this is the first-hop router)
 698    !  - Enable "ip pim ssm" on pim-routers-facing interfaces
 699    !  - Enable "ip igmp" on IGMPv3-hosts-facing interfaces
 700    !  - In order to inject IGMPv3 local membership information in the
 701    !    PIM protocol state, enable both "ip pim ssm" and "ip igmp" on
 702    !    the same interface; otherwise PIM won't advertise
 703    !    IGMPv3-learned membership to other PIM routers
 704
 705    interface eth0
 706     ip pim ssm
 707     ip igmp
 708