Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

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Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

PIM sparse mode

Updated: April 10, 2026

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Explains how PIM sparse modes operate as multicast routing protocols, their reliance on explicit group membership, and the role of the Rendezvous Point (RP) in managing group traffic.

A PIM sparse mode is a multicast routing protocol that

  • assumes recipients for multicast groups are sparsely distributed throughout the network

  • builds multicast distribution trees rooted at a selected Rendezvous Point (RP) node by default, and

  • requires routers to explicitly signal interest in specific multicast groups or sources.

Protocol Independent Multicast (PIM) includes multicast routing protocols for various environments.

For information about PIM-SM, see https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/15-sy/imc-pim-15-sy-book/ip6-mcast-pim-sm.html.

PIM-SM

Most network subnets do not require every multicast packet. Routers explicitly inform upstream neighbors of their interest in specific multicast groups and sources to receive multicast data.

A key requirement of PIM-SM is discovering the RP address for a multicast group through a shared tree.

Enable multicast traffic without VRF (GUI)

Enable multicast routing and required protocols to support multicast traffic delivery in VLANs without VRF using the GUI.

Procedure

1.

Choose Configuration > Services > Multicast.
2.

In the PIM and Multicast Routing section, configure multicast routing globally by enabling Distributed Multicast-Routing.
3.

Configure PIM RP-Address in the PIM Configuration sub-section. This configuration is required so that receivers can find the multicast source in the network. Choose the configuration options from these options:

  • Enter the address to statically configure the RP Address.

  • Enable Auto RP Listener to dynamically discover RP in a PIM-SM network.
4.

Click Save & Apply to Device.
5.

Designate the interface on which multicast traffic should be sent. To do so, go to Configuration > Layer 2 > VLAN and select the SVI interface.
6.

Enable the PIM Sparse Mode protocol so that the SVI interface can participate in sparse mode multicast traffic transmission and join the multicast shared tree. This ensures that clients in that VLAN can receive multicast traffic from multiple multicast groups or sources.
7.

Select the desired IGMP version from the drop-down list to improve multicast packet direction. When this feature is enabled, the controller gathers IGMP reports from the clients and processes them. It creates unique multicast group IDs (MGIDs) from the IGMP reports by selecting the Layer 3 multicast address and the VLAN number, then sends the IGMP reports to the infrastructure switch.
8.

Select IPv4 checkbox and enter the details.
9.

Click Save & Apply to Device.

Enable multicast traffic without VRF (CLI)

Enable multicast routing capabilities on a device in a flat (non-VRF) environment and ensure proper configuration for multicast traffic propagation using commands.

Procedure

1.

Enter the global configuration mode and enable IP multicast routing.

Example:

Device# configure terminal
Device(config)# ip multicast-routing distributed

The distributed keyword enables multicast globally.
2.

Enable multicast traffic and configure the address of a PIM Rendezvous Point (RP).

Example:

Device(config)# wireless multicast ip-address
Device(config)# ip pim rp-address ip-address
3.

Select an interface connected to hosts on which PIM can be enabled.

Example:

Device(config)# interface interface-type-number
4.

Add a description for the VLAN.

Example:

Device(config-if)# description description
5.

Enable IP address on an interface and disable proxy ARP.

Example:

Device(config-if)# ip address ip-address mask-address
Device(config-if)# no ip proxy-arp
6.

Enable PIM-SM mode and enable OSPF authentication for a specific interface.

Example:

Device(config-if)# ip pim sparse-mode
Device(config-if)# ip ospf authentication message-digest
7.

Enable message digest key for the OSPF.

Example:

Device(config-if)# ip ospf authentication message-digest-key key-number md5 password
8.

Disable the maintenance operation protocol (MOP) for an interface.

Example:

Device(config-if)# no mop enabled
9.

Disable the task of sending MOP periodic system ID messages and return to the privileged EXEC mode.

Example:

Device(config-if)# no mop sysid
Device(config-if)# end

Enable multicast traffic with PIM-SSM (CLI)

Enable efficient multicast traffic routing for applications that require directed streaming to specific receivers using commands.

Procedure

1.

Enter the global configuration mode and enable IP multicast routing.

Example:

Device# configure terminal
Device(config)# ip multicast-routing distributed

The distributed keyword enables MDS globally.

2.

Enable multicast traffic.

Example:

Device(config)# wireless multicast ip address

For information about the multicast traffic, see Wireless Multicast.
3.

Configure PIM-SSM on all network devices.

Example:

Device(config)# ip pim ssm default
Note

The default SSM range is 232.0.0.0/8 . So, if you do not configure different range, the default SSM range is used.
4.

Define SSM range of IP multicast addresses.

Example:

Device(config)# ip pim ssm range access-list
5.

Select an interface connected to hosts on which PIM can be enabled.

Example:

Device(config)# interface interface-type-number
6.

Add a description for the VLAN.

Example:

Device(config-if)# description description
7.

Enable IP address on an interface.

Example:

Device(config-if)# ip address ip address mask-address
8.

Disable proxy ARP.

Example:

Device(config-if)# no ip proxy-arp
9.

Enable PIM-SM on an interface and return to privileged EXEC mode.

Example:

Device(config-if)# ip pim sparse-mode
Device(config-if)# end

Verify multicast traffic details

To verify if a multicast group supports SSM or not, use this command:


Device# show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group,
       G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
       N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
       Q - Received BGP S-A Route, q - Sent BGP S-A Route,
       V - RD & Vector, v - Vector, p - PIM Joins on route,
       x - VxLAN group, c - PFP-SA cache created entry,
       * - determined by Assert, # - iif-starg configured on rpf intf,
       e - encap-helper tunnel flag, l - LISP decap ref count contributor
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
                          t - LISP transit group
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.0.0.158), 00:00:07/stopped, RP 15.1.1.2, flags: SJC
  Incoming interface: GigabitEthernet3, RPF nbr 13.1.1.2
  Outgoing interface list:
    Vlan12, Forward/Sparse, 00:00:07/00:02:52, flags:
(17.1.1.1, 239.0.0.158), 00:00:06/00:02:53, flags: JT
  Incoming interface: GigabitEthernet3, RPF nbr 13.1.1.2
  Outgoing interface list:
    Vlan12, Forward/Sparse, 00:00:06/00:02:53, flags:
(*, 231.1.1.1), 02:32:08/stopped, RP 15.1.1.2, flags: SJCF
  Incoming interface: GigabitEthernet3, RPF nbr 13.1.1.2
  Outgoing interface list:
    Vlan12, Forward/Sparse, 00:01:31/00:01:28, flags:
(12.1.0.198, 231.1.1.1), 02:32:08/00:02:53, flags: PFT
  Incoming interface: Vlan12, RPF nbr 0.0.0.0
  Outgoing interface list: Null
(*, 224.0.1.40), 02:32:14/00:02:47, RP 15.1.1.2, flags: SJPL
  Incoming interface: GigabitEthernet3, RPF nbr 13.1.1.2
  Outgoing interface list: Null

To verify the IGMP membership details, use this command:


Device# show ip igmp membership
Flags: A  - aggregate, T - tracked
       L  - Local, S - static, V - virtual, R - Reported through v3
       I - v3lite, U - Urd, M - SSM (S,G) channel
       1,2,3 - The version of IGMP, the group is in
Channel/Group-Flags:
       / - Filtering entry (Exclude mode (S,G), Include mode (G))
Reporter:
       <mac-or-ip-address> - last reporter if group is not explicitly tracked
       <n>/<m>      - <n> reporter in include mode, <m> reporter in exclude
 Channel/Group                  Reporter        Uptime   Exp.  Flags  Interface
 *,239.255.255.250              11.1.1.4        00:01:38 02:57 2A     Vl12
 *,239.0.0.158                  11.1.1.3        00:00:05 02:54 2A     Vl12
 *,231.1.1.1                    12.1.0.8        00:00:07 02:52 2A     Vl12
 *,224.0.1.40                   13.1.1.1        02:34:15 02:45 2LA    Gi3

To verify the IGMP snooping details, use this command:


Device# show ip igmp snooping igmpv2-tracking
Client to SGV mappings
----------------------
Client: 11.1.1.3 Port: Ca2
    Group: 239.0.0.158 Vlan: 12 Source: 0.0.0.0 blacklisted: no
Client: 11.1.1.4 Port: Ca2
    Group: 239.255.255.250 Vlan: 12 Source: 0.0.0.0 blacklisted: no
SGV to Client mappings
----------------------
Group: 239.0.0.158 Source: 0.0.0.0 Vlan: 12
    Client: 11.1.1.3 Port: Ca2 Blacklisted: no
Group: 239.255.255.250 Source: 0.0.0.0 Vlan: 12
    Client: 11.1.1.4 Port: Ca2 Blacklisted: no

To verify the multicast group summary details, use this command:


Device# show wireless multicast group summary
IPv4 groups
-------------
MGID        Group              Vlan     
-----------------------------------------
4160        239.255.255.250    12       
4161        239.255.255.250    12       
 IPv6 groups
-------------
MGID        Group                         Vlan     
----------------------------------------------------

To verify the IGMP snooping groups, use this command:


Device# show ip igmp snooping groups
Vlan      Group                    Type        Version     Port List
-----------------------------------------------------------------------
12        239.0.0.158              igmp        v2          Ca2
12        239.255.255.250          igmp        v2          Ca2

To verify the IGMP snooping, use this command:


Device# show ip igmp snooping
Global IGMP Snooping configuration:
-------------------------------------------
IGMP snooping                : Enabled
Global PIM Snooping          : Disabled
IGMPv3 snooping (minimal)    : Enabled
Report suppression           : Enabled
TCN solicit query            : Disabled
TCN flood query count        : 2
Robustness variable          : 2
Last member query count      : 2
Last member query interval   : 1000
.
.
.
Vlan 11:
-------- 
IGMP snooping                       : Enabled
Pim Snooping                        : Disabled
IGMPv2 immediate leave              : Disabled
Multicast router learning mode      : pim-dvmrp
CGMP interoperability mode          : IGMP_ONLY
Robustness variable                 : 2
Last member query count             : 2
Last member query interval          : 1000
Vlan 12:
--------
IGMP snooping                       : Enabled
Pim Snooping                        : Disabled
IGMPv2 immediate leave              : Disabled
Multicast router learning mode      : pim-dvmrp
CGMP interoperability mode          : IGMP_ONLY
Robustness variable                 : 2
Last member query count             : 2
Last member query interval          : 1000

To verify the active streams from any sources, use this command:

Device# show ip mroute active
Active IP Multicast Sources - sending >= 4 kbps
Group: 239.255.0.1, (?)
   Source: 192.168.33.32 (?)
   Rate: 10 pps/115 kbps(1sec), 235 kbps(last 23 secs), 87 kbps(life avg)

To verify the TTL related issues in the path for the given stream, use this command:

Device# show ip traffic | include bad hop count
0 format errors, 0 checksum errors, 1529 bad hop count

To verify the RPF failures, use this command:


                Device# show ip mroute count | inc RPF failed|Other
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)
  RP-tree: Forwarding: 0/0/0/0, Other: 2/2/0
  RP-tree: Forwarding: 3/0/74/0, Other: 3/0/0
  Source: 32.32.32.32/32, Forwarding: 218747/2/74/1, Other: 218747/0/0
  RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
  Source: 9.4.168.10/32, Forwarding: 31/0/146/0, Other: 3841861/0/3841830