Table Of Contents

Configuring Multicast Services

Understanding How Multicasting Works

Understanding Multicasting and Multicast Services Operation

Joining a Multicast Group

Leaving a Multicast Group

Understanding GMRP Operation

Configuring CGMP

CGMP Hardware and Software Requirements

Default CGMP Configuration

Enabling CGMP

Enabling CGMP Fast-Leave Processing

Displaying Multicast Router Information

Displaying Multicast Group Information

Checking CGMP Statistics

Disabling CGMP Fast-Leave Processing

Disabling CGMP

Configuring GMRP

GMRP Software Requirements

Default GMRP Configuration

Enabling GMRP Globally

Enabling GMRP on Individual Switch Ports

Disabling GMRP on Individual Switch Ports

Enabling GMRP Forward-All Option

Disabling GMRP Forward-All Option

Configuring GMRP Registration

Setting Normal Registration Mode

Setting Fixed Registration Mode

Setting Forbidden Registration Mode

Setting the GARP Timers

Displaying GMRP Statistics

Clearing GMRP Statistics

Disabling GMRP on the Switch

Configuring Multicast Router Ports and Group Entries

Specifying Multicast Router Ports

Configuring Multicast Groups

Clearing Multicast Router Ports

Clearing Multicast Group Entries

Configuring Multicast Services

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This chapter describes how to configure multicast services, including Cisco Group Management Protocol (CGMP), Internet Group Management Protocol (IGMP) snooping, and GARP Multicast Registration Protocol (GMRP) on the Catalyst enterprise LAN switches.

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Note For complete syntax and usage information for the commands used in this chapter, refer to the Command Reference—Catalyst 4000 Family, Catalyst 2948G, and Catalyst 2980G Switches.

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This chapter consists of these sections:

•Understanding How Multicasting Works

•Configuring CGMP

•Configuring GMRP

•Configuring Multicast Router Ports and Group Entries

Understanding How Multicasting Works

These sections describe how multicasting works on the Catalyst enterprise LAN switches:

•Understanding Multicasting and Multicast Services Operation

•Joining a Multicast Group

•Leaving a Multicast Group

•Understanding GMRP Operation

Understanding Multicasting and Multicast Services Operation

CGMP, IGMP snooping, and GMRP manage multicast traffic in switches by allowing directed switching of IP multicast traffic.

Switches can use CGMP, IGMP snooping, or GMRP to dynamically configure switch ports so that IP multicast traffic is forwarded only to those ports associated with IP multicast hosts.

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Note For more information on IP multicast and IGMP, refer to RFC 1112. GMRP is described in IEEE 802.1p.

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CGMP and IGMP software components run on both the Cisco router and the switch. A CGMP/IGMP-capable IP multicast router sees all IGMP packets and can inform the switch when specific hosts join or leave IP multicast groups.

When the CGMP/IGMP-capable router receives an IGMP control packet, it creates a CGMP or IGMP packet that contains the request type (either join or leave), the multicast group address, and the Media Access Control (MAC) address of the host. The router sends the packet to a well-known address to which all switches listen. When a switch receives the packet, the supervisor engine module interprets the packet and modifies the forwarding table automatically.

You can statically configure multicast groups using the set cam static command. Multicast groups learned through CGMP or IGMP snooping are dynamic. If you specify group membership for a multicast group address, your static setting supersedes any automatic manipulation by CGMP or IGMP. Multicast group membership lists can consist of both user-defined and CGMP/IGMP-learned settings.

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Note If a spanning tree virtual LAN (VLAN) topology changes, the CGMP/IGMP-learned multicast groups on the VLAN are purged and the CGMP/IGMP-capable router generates new multicast group information.

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If a CGMP/IGMP-learned port link is disabled for any reason, that port is removed from any multicast group memberships.

We recommend that you enable the spanning tree PortFast feature on ports to which hosts are directly connected if you are using CGMP. For information on configuring spanning tree PortFast, see "Configuring Spanning Tree PortFast, UplinkFast, and BackboneFast, and Loop Guard."

Joining a Multicast Group

When a host wants to join an IP multicast group, it sends an IGMP join message specifying its MAC address and the IP multicast group it wants to join. The CGMP/IGMP-capable router then builds a CGMP/IGMP join message and multicasts the join message to the well-known address to which the switches listen.

Upon receipt of the join message, each switch searches its Enhanced Address Recognition Logic (EARL) table to determine if it contains the MAC address of the host asking to join the multicast group. If a switch finds the MAC address of the host in its EARL table associating the MAC address with a nontrunking port, the switch creates a multicast forwarding entry in the EARL forwarding table. The host associated with that port receives multicast traffic for that multicast group. In this way, the EARL automatically learns the MAC addresses and port numbers of the IP multicast hosts.

Leaving a Multicast Group

The CGMP/IGMP-capable router sends periodic multicast group queries. If a host wants to remain in a multicast group, it responds to the query from the router. In this case, the router does nothing. If a host does not want to remain in the multicast group, it does not respond to the router query. After a number of queries, if the router receives no reports from any host in a multicast group, the router sends a CGMP/IGMP command to the switch and requests that the swich remove the multicast group from its forwarding tables.

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Note If there are other hosts in the same multicast group and they do respond to the multicast group query, the router does not request the switch to remove the group from its forwarding tables. The router does not remove a multicast group from the forwarding tables of the switch until all the hosts in the group ask to leave the group.

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CGMP fast-leave-processing allows the switch to detect IGMP version 2 leave messages sent to the all-routers multicast address by hosts on any of the supervisor engine module ports. When the supervisor engine module receives a leave message, it starts a query-response timer. If this timer expires before a CGMP join message is received, the port is pruned from the multicast tree for the multicast group specified in the original leave message. Fast-leave processing ensures optimal bandwidth management for all hosts on a switched network, even when multiple multicast groups are in use simultaneously.

Understanding GMRP Operation

GARP Multicast Registration Protocol (GMRP) is a Generic Attribute Registration Protocol (GARP) application that provides a constrained multicast flooding facility similar to IGMP snooping and CGMP. GMRP and GARP are industry-standard protocols defined by the IEEE. For detailed protocol operational information, refer to IEEE 802.1p.

GMRP can register and deregister multicast group addresses at the MAC layer throughout the Layer 2-connected network. GMRP is Layer 3-protocol independent, which allows it to support the multicast traffic of any Layer 3 protocol (such as IP, IPX, and so forth).

GMRP software components run on both the switch and on the host (Cisco is not a source for GMRP host software). On the host, GMRP is typically used with IGMP: the host GMRP software generates Layer 2 GMRP versions of the host's Layer 3 IGMP control packets. The switch receives both the Layer 2 GMRP and the Layer 3 IGMP traffic from the host. The switch uses the received GMRP traffic to constrain multicasts at Layer 2 in the host's VLAN.

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Note In all cases, you can use CGMP or IGMP snooping to constrain multicasts at Layer 2 without the need to install or configure software on hosts.

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When a host wants to join an IP multicast group, it sends an IGMP join message, which creates a corresponding GMRP join message.

When the switch receives the GMRP join message, it adds the port through which the join message was received to the appropriate multicast group. The switch propagates the GMRP join message to all other hosts in the VLAN, one of which is typically the multicast source. When the source is multicasting to the group, the switch forwards the multicast only to the ports from which it received join messages for the group.

The switch sends periodic GMRP queries. If a host wants to remain in a multicast group, it responds to the query. In this case, the switch does nothing. If a host does not want to remain in the multicast group, it can either send a leave message or not respond to the periodic queries from the switch. If the switch receives a leave message or receives no response from the host for the duration of the leaveall timer, the switch removes the host from the multicast group.

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Note To use GMRP in a routed environment, enable the GMRP forward-all option on all ports where routers are attached.

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Configuring CGMP

These sections describe how to configure CGMP:

•CGMP Hardware and Software Requirements

•Default CGMP Configuration

•Enabling CGMP

•Enabling CGMP Fast-Leave Processing

•Displaying Multicast Router Information

•Displaying Multicast Group Information

•Checking CGMP Statistics

•Disabling CGMP Fast-Leave Processing

•Disabling CGMP

CGMP Hardware and Software Requirements

CGMP requires these hardware and software versions:

•Supervisor engine software release 2.2 or later

•Router running CGMP

Default CGMP Configuration

Table 15-1 shows the default CGMP configuration.

Table 15-1 CGMP Default Configuration

Feature	Default Value
CGMP enable state	Disabled
Multicast routers	None configured

Enabling CGMP

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Note You cannot enable CGMP if IGMP snooping or GMRP is enabled.

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To enable CGMP, perform this task in privileged mode:

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

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

Console> (enable) set cgmp enable

CGMP support for IP multicast enabled.

Console> (enable) show cgmp statistics 1

CGMP enabled

CGMP statistics for vlan 1:

valid rx pkts received           211915

invalid rx pkts received         0

valid cgmp joins received        211729

valid cgmp leaves received       186

valid igmp leaves received       0

valid igmp queries received      3122

igmp gs queries transmitted      0

igmp leaves transmitted          0

failures to add GDA to EARL      0

topology notifications received  80

number of CGMP packets dropped   2032227

Console> (enable)

Enabling CGMP Fast-Leave Processing

To enable CGMP fast-leave processing, perform this task in privileged mode:

	Task	Command
Step 1	Enable CGMP fast-leave processing on the switch.	set cgmp leave enable
Step 2	Verify that CGMP fast-leave processing is enabled.	show cgmp leave

This example shows how to enable CGMP fast-leave processing and verify the configuration:

Console> (enable) set cgmp leave enable

CGMP leave processing enabled.

Console> (enable)

Console> (enable) show cgmp leave

CGMP:       enabled

CGMP leave: enabled

Console> (enable)

Displaying Multicast Router Information

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

To display the dynamically learned multicast router information, perform one of these tasks in privileged mode:

Task	Command
•Display information on dynamically learned and manually configured multicast router ports.	show multicast router [mod_num/port_num] [vlan_id]
•Display information only on those multicast router ports learned dynamically using CGMP.	show multicast router cgmp [mod_num/port_num] [vlan_id]

This example shows how to display information on all multicast router ports (the asterisk [*] next to the multicast router on port 3/1 indicates that the entry was configured manually):

Console> (enable) show multicast router

CGMP enabled

IGMP disabled

Port       Vlan

---------  ----------------

 2/1       99

 2/2       255

 3/1    *  1

Total Number of Entries = 4

'*' - Configured

Console> (enable)

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

Console> (enable) show multicast router cgmp

CGMP enabled

IGMP disabled

Port       Vlan

---------  ----------------

 2/1       99

 2/2       255

Total Number of Entries = 3

'*' - Configured

Console> (enable)

Displaying Multicast Group Information

To display information about multicast groups, perform one of these tasks in privileged mode:

Task	Command
•Display information about multicast groups.	show multicast group [mac_addr] [vlan_id]
•Display only information about multicast groups learned dynamically through CGMP.	show multicast group cgmp [mac_addr] [vlan_id]
•Display the total number of multicast addresses (groups) in each VLAN.	show multicast group count [vlan_id]
•Display the total number of multicast addresses (groups) in each VLAN that were learned dynamically through CGMP.	show multicast group count cgmp [vlan_id]

This example shows how to display information about all multicast groups on the switch:

Console> (enable) show multicast group

CGMP enabled

IGMP disabled

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)

Checking CGMP Statistics

To check CGMP statistics on the switch, perform this task:

Task	Command
Display CGMP statistics.	show cgmp statistics [vlan_id]

This example shows how to display CGMP statistics:

Console> (enable) show cgmp statistics

CGMP enabled

CGMP statistics for vlan 1:

valid rx pkts received           211915

invalid rx pkts received         0

valid cgmp joins received        211729

valid cgmp leaves received       186

valid igmp leaves received       0

valid igmp queries received      3122

igmp gs queries transmitted      0

igmp leaves transmitted          0

failures to add GDA to EARL      0

topology notifications received  80

number of CGMP packets dropped   2032227

Console> (enable)

Disabling CGMP Fast-Leave Processing

To disable CGMP fast-leave processing, perform this task in privileged mode:

Task	Command
Disable CGMP fast-leave processing on the switch.	set cgmp leave disable

This example shows how to disable CGMP fast-leave processing on the switch:

Console> (enable) set cgmp leave disable

CGMP leave processing disabled.

Console> (enable)

Disabling CGMP

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

Task	Command
Disable CGMP on the switch.	set cgmp disable

This example shows how to disable CGMP:

Console> (enable) set cgmp disable

CGMP support for IP multicast disabled.

Console> (enable)

Configuring GMRP

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

•GMRP Software Requirements

•Default GMRP Configuration

•Enabling GMRP Globally

•Enabling GMRP on Individual Switch Ports

•Disabling GMRP on Individual Switch Ports

•Enabling GMRP Forward-All Option

•Disabling GMRP Forward-All Option

•Configuring GMRP Registration

•Setting the GARP Timers

•Displaying GMRP Statistics

•Clearing GMRP Statistics

•Disabling GMRP on the Switch

GMRP Software Requirements

GMRP requires supervisor engine software release 5.1 or later.

Default GMRP Configuration

Table 15-2 shows the default GMRP configuration.

Table 15-2 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

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Note You cannot enable GMRP if CGMP is enabled.

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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

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                             Enabled     Normal       Disabled  

Console> (enable)

Enabling GMRP on Individual Switch Ports

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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.

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

	Task	Command
Step 1	Enable GMRP on an individual switch port.	set port gmrp enable mod_num/port_num
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 enable 6/12    

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                 Enabled     Normal       Disabled  

6/10-11,6/13-14                              Disabled    Normal       Disabled  

Console> (enable)

Disabling GMRP on Individual Switch Ports

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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.

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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 disable mod_num/port_num
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 disable 6/10-14

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                      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

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

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

•Setting Fixed Registration Mode

•Setting Forbidden Registration Mode

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

This example shows how to configure normal registration on port 2/10:

Console> (enable) set gmrp registration normal 2/10

GMRP Registration is set normal on port 2/10.

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

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   1/1-4

                                    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

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   1/1-4

                                    2/1-9,2/11-48

                                    3/1-24

                                    5/1

Enabled     Forbidden    Disabled   2/10

Console> (enable) 

Setting the GARP Timers

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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.

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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.)

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You can modify the default 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). The more registered attributes on the switch, the greater you should configure the difference between the leave value and the join value.

For better performance on switches with many registered multicast groups, increase the timer values to the order of seconds.

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.

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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.

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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

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

Console> (enable) set garp timer leaveall 12000

GMRP/GARP leaveAll timer value is set to 12000 milliseconds.

Console> (enable) set garp timer leave 650

GMRP/GARP leave timer value is set to 650 milliseconds.

Console> (enable) set garp timer join 300

GMRP/GARP join timer value is set to 300 milliseconds.

Console> (enable) show garp timer

Timer     Timer Value (milliseconds)

--------  --------------------------

Join      300                       

Leave     650                       

LeaveAll  12000                    

Console> (enable)

Displaying GMRP Statistics

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

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> (enable)

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}

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

Console> (enable) clear gmrp statistics all

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

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

Console> (enable) set gmrp disable

GMRP disabled.

Console> (enable)

Configuring Multicast Router Ports and Group Entries

These sections describe how to manually specify multicast router ports and configure multicast group entries:

•Specifying Multicast Router Ports

•Configuring Multicast Groups

•Clearing Multicast Router Ports

•Clearing Multicast Group Entries

Specifying Multicast Router Ports

When you enable CGMP or GMRP, the switch automatically learns to which ports a multicast router is connected. However, if desired, you can manually specify multicast router ports.

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

	Task	Command
Step 1	Manually specify a multicast router port.	set multicast router mod_num/port_num
Step 2	Verify the configuration.	show multicast router [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 3/1 indicates that the entry was configured manually):

Console> (enable) set multicast router 3/1

Port 3/1 added to multicast router port list.

Console> (enable) show multicast router

CGMP enabled

IGMP disabled

Port       Vlan

---------  ----------------

 2/1       99

 2/2       255

 3/1    *  1

Total Number of Entries = 4

'*' - Configured

Console> (enable)

Configuring Multicast Groups

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

	Task	Command
Step 1	Add one or more multicast MAC addresses to the CAM 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]

This example shows how to define multicast groups manually and verify the configuration (the asterisks indicate the entry was manually configured):

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 enabled

IGMP disabled

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)

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

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)

Clearing Multicast Group Entries

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]

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)