Configuring Multicast Services

Note For complete syntax and usage information for the commands used in this chapter, refer to the Catalyst 6000 and 6500 Series Command Reference publication.

This chapter consists of the following sections:

Understanding Multicasting and Multicast Services

Multicasting uses a multiple-recipient address, called a multicast address, to send the same data stream to the recipients while using the least bandwidth. Without multicasting, multiple unicast-addressed copies of the data stream would have to be sent to individual recipients.

Multicasts flood like broadcasts unless multicast services are used. A multicast service functions only with hosts that support the service. Hosts that do not support a multicast service generate uncontrolled multicasts. Multicast services can control the distribution of multicasts by determining which switch ports need to participate in multicasts.

Catalyst 6000 and 6500 series switches support the following Layer 2 multicast services:

Generic Attribute Registration Protocol (GARP; see IEEE 802.1P) and GARP Multicast Registration Protocol (GMRP; see IEEE 802.1P)---GMRP maintains Layer 2 multicast groups that determine which switch ports need to participate in multicasts.
Internet Group Management Protocol (IGMP) snooping---IGMP (see RFC 1112) is a Layer 3 multicast service for routers that can determine which router ports need to participate in multicasts. IGMP snooping looks at Layer 3 IGMP data to determine which switch ports need to participate in multicasts.

Note

Configuring GMRP

These sections describe how to configure the GARP Multicast Registration Protocol (GMRP):

GMRP Software Requirements

GMRP requires supervisor engine software release 5.2 or later.

Default GMRP Configuration

Table 12-1 shows the default GMRP configuration.

Table 12-1: GMRP Default Configuration
Feature Default Value

GMRP enable state

Disabled

GMRP per-port enable state

Disabled

GMRP forward all

Disabled on all ports

GMRP registration

Normal on all ports

GARP/GMRP timers

Join time: 200 ms

Leave time: 600 ms

Leaveall time: 10,000 ms

Table 12-1: **GMRP Default Configuration**
Feature	Default Value
GMRP enable state	Disabled
GMRP per-port enable state	Disabled
GMRP forward all	Disabled on all ports
GMRP registration	Normal on all ports
GARP/GMRP timers	Join time: 200 ms Leave time: 600 ms Leaveall time: 10,000 ms

Enabling GMRP Globally

Note You cannot enable GMRP if IGMP snooping is enabled (see the "Configuring IGMP Snooping" section ).

To enable GMRP globally, perform this task in privileged mode:

Task Command

Step 1 Enable GMRP on the switch.

set gmrp enable

Step 2 Verify the configuration.

show gmrp configuration

Task	Command
Step 1 Enable GMRP on the switch.	set gmrp enable
Step 2 Verify the configuration.	show gmrp configuration

This example shows how to enable GMRP and verify the configuration:

Console> (enable) set gmrp enable
GMRP enabled.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
Port                                         GMRP Status Registration ForwardAll
-------------------------------------------- ----------- ------------ ----------
1/1-2,3/1,6/1-48,7/1-24                      Enabled     Normal       Disabled  
Console> (enable)

Enabling GMRP on Individual Switch Ports

Note You can change the per-port GMRP configuration regardless of whether GMRP is enabled globally. However, GMRP will not function on any ports until you enable it globally. For information on configuring GMRP globally on the switch, see the "Enabling GMRP Globally" section.

To enable GMRP on individual switch ports, perform this task in privileged mode:

Task Command

Step 1 Enable GMRP on the port.

set port gmrp mod_num/port_num enable

Step 2 Verify the configuration.

show gmrp configuration

Task	Command
Step 1 Enable GMRP on the port.	set port gmrp mod_num/port_num enable
Step 2 Verify the configuration.	show gmrp configuration

This example shows how to enable GMRP on port 6/12 and verify the configuration:

Console> (enable) set port gmrp 6/12 enable 
GMRP enabled on port 6/12.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
Port                                         GMRP Status Registration ForwardAll
-------------------------------------------- ----------- ------------ ----------
1/1-2,3/1,6/1-9,6/12,6/15-48,7/1-24          Enabled     Normal       Disabled  
6/10-11,6/13-14                              Disabled    Normal       Disabled  
Console> (enable)

Disabling GMRP on Individual Switch Ports

To disable GMRP on individual switch ports, perform this task in privileged mode:

Task Command

Step 1 Disable GMRP on individual switch ports.

set port gmrp mod_num/port_num disable

Step 2 Verify the configuration.

show gmrp configuration

Task	Command
Step 1 Disable GMRP on individual switch ports.	set port gmrp mod_num/port_num disable
Step 2 Verify the configuration.	show gmrp configuration

This example shows how to disable GMRP on ports 6/10-14 and verify the configuration:

Console> (enable) set port gmrp 6/10-14 disable
GMRP disabled on ports 6/10-14.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
Port                                         GMRP Status Registration ForwardAll
-------------------------------------------- ----------- ------------ ----------
1/1-2,3/1,6/1-9,6/15-48,7/1-24               Enabled     Normal       Disabled  
6/10-14                                      Disabled    Normal       Disabled  
Console> (enable)

Enabling GMRP Forward-All Option

When you enable the GMRP forward-all option on a port, a copy of all multicast traffic registered on the switch is forwarded to that port. We recommend enabling the forward-all option on any port connected to a router. The forward-all option can also be used to forward all registered multicast traffic to a port with a network analyzer or probe attached.

To forward a copy of all GMRP multicast packets registered on the switch to a port, perform this task in privileged mode:

Task Command

Enable the GMRP forward-all option on a switch port.

set gmrp fwdall enable mod_num/port_num

Task	Command
Enable the GMRP forward-all option on a switch port.	set gmrp fwdall enable mod_num/port_num

This example shows how to enable the GMRP forward-all option on port 1/1:

Console> (enable) set gmrp fwdall enable 1/1
GMRP Forward All groups option enabled on port 1/1.
Console> (enable)

Disabling GMRP Forward-All Option

To disable the GMRP forward-all option on a port, perform this task in privileged mode:

Task Command

Disable the GMRP forward-all option on a port.

set gmrp fwdall disable mod_num/port_num

Task	Command
Disable the GMRP forward-all option on a port.	set gmrp fwdall disable mod_num/port_num

This example shows how to disable the GMRP forward-all option on port 1/1:

Console> (enable) set gmrp fwdall disable 1/1
GMRP Forward All groups option disabled on port 1/1.
Console> (enable)

Configuring GMRP Registration

These sections describe how to configure GMRP registration modes on switch ports:

Setting Normal Registration Mode

Configuring a port in normal registration mode allows dynamic GMRP multicast registration and deregistration on the port. Normal mode is the default on all switch ports.

To configure GMRP normal registration on a port, perform this task in privileged mode:

Task Command

Step 1 Configure normal registration on a port.

set gmrp registration normal mod_num/port_num

Step 2 Verify the configuration.

show gmrp configuration

Task	Command
Step 1 Configure normal registration on a port.	set gmrp registration normal mod_num/port_num
Step 2 Verify the configuration.	show gmrp configuration

This example shows how to configure normal registration on port 2/10 and verify the configuration:

Console> (enable) set gmrp registration normal 2/10
GMRP Registration is set normal on port 2/10.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
GMRP-Status Registration ForwardAll Port(s)
----------- ------------ ---------- --------------------------------------------
Enabled     Normal       Disabled   1/1-2
                                    2/1-48
                                    3/1-24
                                    5/1
Console> (enable)

Setting Fixed Registration Mode

When you configure a port in fixed registration mode, all the multicast groups currently registered on all ports are registered on the port, but the port ignores any subsequent registrations or deregistrations on other ports. A port in fixed registration mode continues to register multicast groups that are specific to the port. You must return the port to normal registration mode to deregister multicast groups on the port.

To configure GMRP fixed registration on a port, perform this task in privileged mode:

Task Command

Step 1 Configure fixed registration on a port.

set gmrp registration fixed mod_num/port_num

Step 2 Verify the configuration.

show gmrp configuration

Task	Command
Step 1 Configure fixed registration on a port.	set gmrp registration fixed mod_num/port_num
Step 2 Verify the configuration.	show gmrp configuration

This example shows how to configure fixed registration on port 2/10 and verify the configuration:

Console> (enable) set gmrp registration fixed 2/10 
GMRP Registration is set fixed on port 2/10.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
GMRP-Status Registration ForwardAll Port(s)
----------- ------------ ---------- --------------------------------------------
Enabled     Normal       Disabled   1/1-2
                                    2/1-9,2/11-48
                                    3/1-24
                                    5/1
Enabled     Fixed        Disabled   2/10
Console> (enable)

Setting Forbidden Registration Mode

Configuring a port in forbidden registration mode deregisters all GMRP multicasts and prevents any further GMRP multicast registration on the port.

To configure GMRP forbidden registration on a port, perform this task in privileged mode:

Task Command

Step 1 Configure forbidden registration on a port.

set gmrp registration forbidden mod_num/port_num

Step 2 Verify the configuration.

show gmrp configuration

Task	Command
Step 1 Configure forbidden registration on a port.	set gmrp registration forbidden mod_num/port_num
Step 2 Verify the configuration.	show gmrp configuration

This example shows how to configure forbidden registration on port 2/10 and verify the configuration:

Console> (enable) set gmrp registration forbidden 2/10
GMRP Registration is set forbidden on port 2/10.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
GMRP-Status Registration ForwardAll Port(s)
----------- ------------ ---------- --------------------------------------------
Enabled     Normal       Disabled   1/1-2
                                    2/1-9,2/11-48
                                    3/1-24
                                    5/1
Enabled     Forbidden    Disabled   2/10
Console> (enable)

Setting the GARP Timers

Note The commands set gmrp timer and show gmrp timer are aliases for set garp timer and show garp timer. The aliases may be used if desired.

Note Modifying the GARP timer values affects the behavior of all GARP applications running on the switch, not just GMRP. (For example, GVRP uses the same timers.)

You can modify the default Generic Attribute Registration Protocol (GARP) timer values on the switch.

When setting the timer values, the value for leave must be equal to or greater than three times the join value (leave >= join * 3). The value for leaveall must be greater than the value for leave (leaveall > leave).

If you attempt to set a timer value that does not adhere to these rules, an error is returned. For example, if you set the leave timer to 600 ms and you attempt to configure the join timer to 350 ms, an error is returned. Set the leave timer to at least 1050 ms and then set the join timer to 350 ms.

Caution
Set the same GARP timer values on all Layer 2-connected devices. If the GARP timers are set differently on the Layer 2-connected devices, GARP applications (for example, GMRP and GVRP) do not operate successfully.

To adjust the GARP timer values, perform this task in privileged mode:

Task Command

Step 1 Set the GARP timer values.

set garp timer {join | leave | leaveall} timer_value

Step 2 Verify the configuration.

show garp timer

Task	Command
Step 1 Set the GARP timer values.	set garp timer {join \| leave \| leaveall} timer_value
Step 2 Verify the configuration.	show garp timer

This example shows how to set GARP timers and verify the configuration:

Console> (enable) set garp timer leaveall 10000 
GMRP/GARP leaveAll timer value is set to 10000 milliseconds.
Console> (enable) set garp timer leave 600
GMRP/GARP leave timer value is set to 600 milliseconds.
Console> (enable) set garp timer join 200
GMRP/GARP join timer value is set to 200 milliseconds.
Console> (enable) show garp timer
Timer     Timer Value (milliseconds)
--------  --------------------------
Join      200 
Leave     600 
LeaveAll  10000 
Console> (enable)

Displaying GMRP Statistics

To display GMRP statistics on the switch, perform this task:

Task Command

Display GMRP statistics.

show gmrp statistics [vlan_id]

Task	Command
Display GMRP statistics.	show gmrp statistics [vlan_id]

This example shows how to display GMRP statistics for VLAN 23:

Console> show gmrp statistics 23
GMRP Statistics for vlan <23>:
Total valid GMRP Packets Received:500
Join Empties:200
Join INs:250
Leaves:10
Leave Alls:35
Empties:5
Fwd Alls:0
Fwd Unregistered:0
Total valid GMRP Packets Transmitted:600
Join Empties:200
Join INs:150
Leaves:45
Leave Alls:200
Empties:5
Fwd Alls:0
Fwd Unregistered:0
Total valid GMRP Packets Received:0
Total GMRP packets dropped:0
Total GMRP Registrations Failed:0
Console>

Clearing GMRP Statistics

To clear all GMRP statistics on the switch, perform this task in privileged mode:

Task Command

Clear GMRP statistics.

clear gmrp statistics {vlan_id | all}

Task	Command
Clear GMRP statistics.	clear gmrp statistics {vlan_id \| all}

This example shows how to clear the GMRP statistics for all VLANs:

Console> (enable) clear gmrp statistics all
GMRP statistics cleared.
Console> (enable)

Disabling GMRP on the Switch

To disable GMRP globally on the switch, perform this task in privileged mode:

Task Command

Disable GMRP globally on the switch.

set gmrp disable

Task	Command
Disable GMRP globally on the switch.	set gmrp disable

This example shows how to disable GMRP globally on the switch:

Console> (enable) set gmrp disable
GMRP disabled.
Console> (enable)

Configuring IGMP Snooping

These sections describe how to configure IGMP on the Catalyst 6000 and 6500 series switches:

IGMP Snooping Guidelines

These guidelines apply when you are configuring IGMP snooping on the Catalyst 6000 and 6500 series switches:

IGMP snooping requires a network connection from the switch to a router running IGMP.
By default, IGMP snooping is disabled, and no multicast routers are configured.
IGMP snooping cannot be enabled if GMRP is enabled.

Enabling IGMP Snooping

To enable IGMP snooping, perform this task in privileged mode:

Task Command

Step 1 Enable IGMP snooping on the switch.

set igmp enable

Step 2 Verify that IGMP snooping is enabled.

show igmp statistics [vlan_num]

Task	Command
Step 1 Enable IGMP snooping on the switch.	set igmp enable
Step 2 Verify that IGMP snooping is enabled.	show igmp statistics [vlan_num]

This example shows how to enable IGMP snooping and verify the configuration (shown by the arrow):

Console> (enable) set igmp enable
IGMP Snooping is enabled.
CGMP is disabled.
Console> (enable) show igmp statistics


 
  IGMP enabled
 
IGMP statistics for vlan 1:
Total valid pkts rcvd:           18951
Total invalid pkts recvd         0
General Queries recvd            377
Group Specific Queries recvd     0
MAC-Based General Queries recvd  0
Leaves recvd                     14
Reports recvd                    16741
Queries  Xmitted                 0
GS Queries Xmitted               16
Reports Xmitted                  0
Leaves Xmitted                   0
Failures to add GDA to EARL      0
Topology Notifications rcvd      10
IGMP packets dropped             0
Console> (enable)

Specifying Multicast Router Ports

When you enable IGMP snooping, the switch automatically learns to which ports a multicast router is connected.

To statically define multicast router ports, perform this task in privileged mode:

Task Command

Step 1 Configure multicast router ports.

set multicast router mod_num/port_num

Step 2 Verify the multicast router configuration.

show multicast router [mod_num/port_num] [vlan_id]

Step 3 Verify the multicast router information that was learned dynamically through IGMP.

show multicast router igmp [mod_num/port_num] [vlan_id]

Task	Command
Step 1 Configure multicast router ports.	set multicast router mod_num/port_num
Step 2 Verify the multicast router configuration.	show multicast router [mod_num/port_num] [vlan_id]
Step 3 Verify the multicast router information that was learned dynamically through IGMP.	show multicast router igmp [mod_num/port_num] [vlan_id]

This example shows how to define a multicast router port manually and verify the configuration (the asterisk [*] next to the multicast router on port 5/7 indicates that the entry was configured manually):

Console> (enable) set multicast router 5/7
Port 5/7 added to multicast router port list.
Console> (enable) show multicast router
CGMP disabled
IGMP enabled
Port       Vlan
---------  ----------------
 1/1       1
 2/1       2,99,255
 5/7    *  99
Total Number of Entries = 3
'*' - Configured
Console> (enable)

This example shows how to display only those multicast router ports that were learned dynamically through IGMP snooping:

Console> (enable) show multicast router igmp
CGMP disabled
IGMP enabled
Port       Vlan
---------  ----------------
 1/1       1
 2/1       2,99,255
Total Number of Entries = 2
'*' - Configured
Console> (enable)

Checking IGMP Snooping Statistics

To check IGMP snooping statistics on the switch, perform this task:

Task Command

Display IGMP snooping statistics.

show igmp statistics [vlan_id]

Task	Command
Display IGMP snooping statistics.	show igmp statistics [vlan_id]

This example shows how to display IGMP snooping statistics:

Console> (enable) show igmp statistics
IGMP enabled
 
IGMP statistics for vlan 1:
Total valid pkts rcvd:           18951
Total invalid pkts recvd         0
General Queries recvd            377
Group Specific Queries recvd     0
MAC-Based General Queries recvd  0
Leaves recvd                     14
Reports recvd                    16741
Queries  Xmitted                 0
GS Queries Xmitted               16
Reports Xmitted                  0
Leaves Xmitted                   0
Failures to add GDA to EARL      0
Topology Notifications rcvd      10
IGMP packets dropped             0
Console> (enable)

Clearing Multicast Router Ports

To clear manually configured multicast router ports, perform one of these tasks in privileged mode:

Task Command

Disable specific, manually configured multicast router ports.

clear multicast router mod_num/port_num

Disable all manually configured multicast router ports.

clear multicast router all

Task	Command
Disable specific, manually configured multicast router ports.	clear multicast router mod_num/port_num
Disable all manually configured multicast router ports.	clear multicast router all

This example shows how to clear a manually configured multicast router port entry:

Console> (enable) clear multicast router 2/12
Port 2/12 cleared from multicast router port list.
Console> (enable)

Disabling IGMP Snooping

To disable IGMP snooping on the switch, perform this task in privileged mode:

Task Command

Disable IGMP snooping on the switch.

set igmp disable

Task	Command
Disable IGMP snooping on the switch.	set igmp disable

This example shows how to disable IGMP snooping:

Console> (enable) set igmp disable
IGMP feature for IP multicast disabled
Console> (enable)

Using Multicast Group Commands

These sections describe how to use the multicast group commands on the Catalyst 6000 and 6500 series switches:

Showing Multicast Groups

To display the multicast groups on the switch, perform this task:

Task Command

Display multicast groups.

show multicast group [mac_addr] [vlan_id]

Task	Command
Display multicast groups.	show multicast group [mac_addr] [vlan_id]

This example shows how to display the multicast groups for VLAN 1:

Console> show multicast group 1
IGMP enabled
VLAN  Dest MAC/Route Des   Destination Ports or VCs / [Protocol Type]
----  ------------------  ----------------------------------------------------
1     01-00-5e-00-01-28*  3/1,12/9
1     01-00-5e-63-7f-6f*  3/1,12/5,12/9
Total Number of Entries = 2
Console>

Displaying the Multicast Group Count

To display the number of multicast groups on the switch, perform this task:

Task Command

Display the number of multicast groups.

show multicast group count [mac_addr] [vlan_id]

Task	Command
Display the number of multicast groups.	show multicast group count [mac_addr] [vlan_id]

This example shows how to display the number of multicast groups for VLAN 1:

Console> show multicast group count 1
GMRP disabled
IGMP enabled
Total Number of Entries = 2
Console> (enable)

Configuring Static Multicast Groups

To statically configure a multicast group, perform this task in privileged mode:

Task Command

Step 1 Add one or more multicast MAC addresses to the CAM¹ table.

set cam {static | permanent} multicast_mac mod_num/port_num [vlan]

Step 2 Verify the multicast group configuration.

show multicast group [mac_addr] [vlan_id]

Step 3 Verify the multicast group information that was learned dynamically through IGMP snooping.

show multicast group igmp [mac_addr] [vlan_id]

Step 4 If desired, show the total number of multicast addresses (groups) in a VLAN.

show multicast group count [igmp] [vlan_id]

¹CAM=content addressable memory.

Task	Command
Step 1 Add one or more multicast MAC addresses to the CAM¹ table.	set cam {static \| permanent} multicast_mac mod_num/port_num [vlan]
Step 2 Verify the multicast group configuration.	show multicast group [mac_addr] [vlan_id]
Step 3 Verify the multicast group information that was learned dynamically through IGMP snooping.	show multicast group igmp [mac_addr] [vlan_id]
Step 4 If desired, show the total number of multicast addresses (groups) in a VLAN.	show multicast group count [igmp] [vlan_id]

This example shows how to define multicast groups manually and verify the configuration:

Console> (enable) set cam static 01-00-11-22-33-44 2/6-12
Static multicast entry added to CAM table.
Console> (enable) set cam static 01-11-22-33-44-55 2/6-12
Static multicast entry added to CAM table.
Console> (enable) set cam static 01-22-33-44-55-66 2/6-12
Static multicast entry added to CAM table.
Console> (enable) set cam static 01-33-44-55-66-77 2/6-12
Static multicast entry added to CAM table.
Console> (enable) show multicast group
CGMP disabled
IGMP enabled
 
VLAN  Dest MAC/Route Des  Destination Ports or VCs / [Protocol Type]
----  ------------------  ----------------------------------------------------
1     01-00-11-22-33-44*  2/6-12
1     01-11-22-33-44-55*  2/6-12
1     01-22-33-44-55-66*  2/6-12
1     01-33-44-55-66-77*  2/6-12
 
Total Number of Entries = 4
Console> (enable)

To disable manually configured multicast group entries, perform this task in privileged mode:

Task Command

Clear a multicast group entry from the CAM table.

clear cam mac_addr [vlan]

Task	Command
Clear a multicast group entry from the CAM table.	clear cam mac_addr [vlan]

This example shows how to clear a multicast group entry from the CAM table:

Console> (enable) clear cam 01-11-22-33-44-55 1
CAM entry cleared.
Console> (enable)

Table of Contents

Configuring Multicast Services