Multicast control plane traffic is always seen by every router on a LAN environment. The Stub IP Multicast is used to reduce and minimize the unnecessary multicast traffic that is seen on LAN in the access layer and save the bandwidth on the media to forward multicast traffic to the upstream distribution/core layer.
In the Catalyst 3750 and 3560 Series Switches, the PIM Stub Multicast feature supports multicast routing between the distribution layer and access layer. It supports two types of PIM interfaces: uplink PIM interfaces and PIM passive interfaces. In particular, a routed interface configured with the PIM Passive mode does not pass/forward PIM control plane traffic; it only passes/forwards IGMP traffic.
Ensure that you meet these requirements before you attempt this configuration:
The PIM stub router does not route the transit traffic between distribution routers. This behavior is enforced by unicast (EIGRP) stub routing. The proper unicast stub routing configuration is required to assist this PIM stub router behavior. The PIM stub feature does not prevent router administrator configuring RIP, static routes, or PIM RP to bypass this restriction.
Only direct-connected multicast (IGMP) receivers and sources are allowed in the layer 2 access domains. The PIM protocol is not supported in access domains.
The redundant PIM stub router topology is not supported.
The information in this document is based on output from the Catalyst 3750 Switch.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
This configuration can also be used with these switch types:
Catalyst 3750 and 3560 Series Switches
Cisco Catalyst 3750 and 3560 switches support PIM Stub Multicast Routing Code Version 12.2(37)SE and later.
Refer to the Cisco Technical Tips Conventions for more information on document conventions.
In this section, you are presented with the information to configure the features described in this document.
PIM SSM is used on the uplinks to communicate with the upstream router. Users can use any other PIM Mode (for example, Dense or Sparse).
For additional information about the configuration of Multicast Routing on the 3750 Series Switches, refer to Configuring IP Multicast Routing.
This document uses this network setup:
This document uses these configurations:
Complete these steps to configure PIM Stub Routing:
Issue this command to enable multicast routing globally on the switch or switch stack:
mix_stack(config)#ip multicast-routing distributed
Issue this command to define the SSM range of IP multicast address with default group range:
mix_stack(config)#ip pim ssm default
Issue this command to enable PIM SSM on the uplink:
mix_stack(config)#interface GigabitEthernet3/0/25 !--- By default switch configures the Layer 2 parameters. So in order to configure the Layer 3 parameter, use the next command. mix_stack(config-if)#no switchport mix_stack(config-if)#ip pim sparse-dense-mode
Issue this command to enable PIM Stub Routing on the VLAN interface:
mix_stack(config)#interface vlan100 mix_stack(config-if)#ip pim passive
mix_stack#show run Building configuration... Current configuration : 7810 bytes ! version 12.2 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname mix_stack ! ! switch 2 provision ws-c3750e-24pd switch 3 provision ws-c3750g-24ts switch 5 provision ws-c3750-24fs switch 9 provision ws-c3750e-24pd ! ip routing ! ! ip multicast-routing distributed ! !--- Output suppressed. ! ! vlan 100 ! ! interface GigabitEthernet2/0/1 switchport access vlan 100 no keepalive spanning-tree portfast ! interface GigabitEthernet2/0/2 switchport access vlan 100 no keepalive spanning-tree portfast ! ! !--- Output suppressed. ! ! interface GigabitEthernet3/0/25 no switchport ip address 126.96.36.199 255.255.255.248 ip pim sparse-dense-mode ! ! !--- Output suppressed. ! ! interface GigabitEthernet9/0/24 no switchport ip address 10.1.1.1 255.255.255.0 ip pim passive no keepalive ! ! !--- Output suppressed. ! ! interface Vlan1 no ip address ! interface Vlan100 ip address 188.8.131.52 255.255.255.0 ip pim passive ! ! !--- Output suppressed. ! ! ip pim ssm default ! ! !--- Output suppressed. ! ! control-plane ! ! line con 0 exec-timeout 0 0 speed 115200 line vty 0 4 login line vty 5 15 login ! end
Use this section to confirm that your configuration works properly.
Issue the show ip pim interface command in order to display the PIM Stub that is enable for each interface.
mix_stack#show ip pim interface Address Interface Ver/ Nbr Query DR DR Mode Count Intvl Prior 184.108.40.206 GigabitEthernet3/0/25 v2/SD 1 30 1 220.127.116.11 18.104.22.168 Vlan100 v2/P 0 30 1 22.214.171.124 10.1.1.1 GigabitEthernet9/0/24 v2/P 0 30 1 10.1.1.1
Issue the show ip igmp groups detail to display the interested client that has joined the specific Multicast source/group.
mix_stack#show ip igmp groups 126.96.36.199 det Flags: L - Local, U - User, SG - Static Group, VG - Virtual Group, SS - Static Source, VS - Virtual Source, Ac - Group accounted towards access control limit Interface: GigabitEthernet9/0/24 Group: 188.8.131.52 Flags: SSM Uptime: 00:00:10 Group mode: INCLUDE Last reporter: 10.1.1.2 CSR Grp Exp: 00:02:57 Group source list: (C - Cisco Src Report, U - URD, R - Remote, S - Static, V - Virtual, M - SSM Mapping, L - Local, Ac - Channel accounted towards access control limit) Source Address Uptime v3 Exp CSR Exp Fwd Flags 184.108.40.206 00:00:10 stopped 00:02:57 Yes CM Interface: Vlan100 Group: 220.127.116.11 Flags: SSM Uptime: 01:42:08 Group mode: INCLUDE Last reporter: 18.104.22.168 CSR Grp Exp: 00:02:00 Group source list: (C - Cisco Src Report, U - URD, R - Remote, S - Static, V - Virtual, M - SSM Mapping, L - Local, Ac - Channel accounted towards access control limit) Source Address Uptime v3 Exp CSR Exp Fwd Flags 22.214.171.124 01:42:12 stopped 00:02:00 Yes CM mix_stack#
Issue the show ip mroute to verify that the Multicast stream forwards from the source to the interested clients.
mix_stack#show ip mroute 126.96.36.199 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, 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 V - RD & Vector, v - Vector Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (188.8.131.52, 184.108.40.206), 01:44:23/00:02:52, flags: sTI Incoming interface: GigabitEthernet3/0/25, RPF nbr 220.127.116.11 Outgoing interface list: GigabitEthernet9/0/24, Forward/Sparse-Dense, 00:02:24/00:02:50 Vlan100, Forward/Sparse-Dense, 01:44:23/00:02:52
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Refer to Cisco Technical Tips Conventions for information on conventions used in this document.