Table Of Contents

Multicast Service Reflection

Multicast Service Reflection Working Architecture

Restrictions for Multicast Service Reflection

Configuring Multicast Service Reflection

Multicast Service Reflection

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Multicast service reflection feature enables the users to translate externally received multicast destination addresses to addresses that conform to the organization's internal addressing policy. With this feature, users need not redistribute routes at the translation boundary into their network infrastructure for the Reverse Path Forwarding (RPF) to work properly. Also, users can receive identical feeds from two ingress points in the network and route them independently.

The multicast service reflection feature is configured on the virtual interface. When a packet is forwarded to a virtual interface (original IP), this feature maps the original IP address to an internal IP address and the traffic is directed to the internal IP address. Therefore, it enables an organization to logically separate the private and public multicast networks.

Multicast Service Reflection Working Architecture

For multicast service reflection, the virtual interface is configured to statically join the group that needs to be translated to build a multicast tree. The virtual interface maintains information about:

•Input interface

•Private-to-public multicast group mappings

•Mask length to define the pool range

•Source of translated packet

When a packet is forwarded to a virtual interface, it is reflected for translation. The source IP address is changed to the IP address of the virtual interface subnet, which prevents RPF failures. Finally, the destination IP address is translated to a new multicast group IP address.

Figure 74-1 shows the multicast service reflection working architecture.

Figure 74-1 Multicast Service Reflection Working Architecture

Restrictions for Multicast Service Reflection

Following restrictions apply for multicast service reflection feature:

•The virtual interface should be installed on the border router.

•Multicast service reflection does not support bidirectional multicast.

•Protocol Independent Multicast (PIM)/IGMP control packets are not translated.

•Multicast service reflection does not support P2P GRE tunnelling.

•Multicast service reflection does not support IPv6 multicasting.

•Only 1000 service reflection translations are supported.

•Multicast service reflection is not supported in the PIM-Dense mode.

Configuring Multicast Service Reflection

Complete these steps to configure multicast service reflection feature.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip multicast-routing [distributed]

4. interface loopback loopback_id

5. description description

6. ip address ip_address subnet_mask

7. ip pim sparse-mode

8. exit

9. interface gigabitEthernet slot/port

10. ip address ip_address subnet_mask

11. ip pim sparse-mode

12. exit

13. interface gigabitEthernet slot/port

14. ip address ip_address subnet_mask

15. ip pim sparse-mode

16. exit

17. interface vif_id

18. ip address ip_address subnet_mask

19. ip pim sparse-mode

20. ip service reflect interface_id destination destination_ip1 to destination_ip2 mask-len subnet_mask_length source source_ip

21. ip igmp static-group {* | group-address [source {source-address | ssm-map}]}

22. exit

23. ip pim rp-address rp_address

24. end

DETAILED STEPS

	Command	Purpose
Step 1	enable Example: R1> enable	Enables the privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: R1# configure terminal	Enters the global configuration mode.
Step 3	ip multicast-routing [distributed] Example: R1(config)# ip multicast-routing	Enables the IP multicast routing.
Step 4	interface loopback loopback_if_number Example: R1(config)# interface Loopback0	Enters the interface configuration mode.
Step 5	description description Example: R1(config-if)# description Rendezvous Point for Public Net	Describes the interface.
Step 6	ip address ip_address subnet_mask Example: R1(config-if)# ip address 22.22.22.22 255.255.255.255	Assigns the IP address and subnet mask to the interface.
Step 7	ip pim sparse-mode Example: R1(config-if)# ip pim sparse-mode	Enables the PIM sparse mode on the interface.
Step 8	exit Example: R1(config-if)# exit	Exits the interface configuration mode.
Step 9	interface gigabitethernet GigabitEthernet_interface_number Example: R1(config)# interface GigabitEthernet2/0/0	Enters the interface configuration mode.
Step 10	ip address ip_address subnet_mask Example: R1(config-if)# ip address 2.1.1.1 255.255.0.0	Assigns the IP address and subnet mask to the interface.
Step 11	ip pim sparse-mode Example: R1(config-if)# ip pim sparse-mode	Enables the PIM sparse mode on the interface.
Step 12	exit Example: R1(config-if)# exit	Exits the interface configuration mode.
Step 13	interface gigabitethernet GigabitEthernet_interface_number Example: R1(config)# interface GigabitEthernet4/13	Enters the interface configuration mode.
Step 14	ip address ip_address subnet_mask Example: R1(config-if)# ip address 23.1.1.2 255.255.0.0	Assigns the IP address and subnet mask to the interface.
Step 15	ip pim sparse-mode Example: R1(config-if)# ip pim sparse-mode	Enables the PIM sparse mode on the interface.
Step 16	exit Example: R1(config-if)# end	Exits the interface configuration mode.
Step 17	interface interface_name Example: R1(config)# interface Vif1	Enters the interface configuration mode.
Step 18	ip address ip_address subnet_mask Example: R1(config-if)# ip address 1.1.1.1 255.255.0.0	Assigns the IP address and subnet mask to the interface.
Step 19	ip pim sparse-mode Example: R1(config-if)# ip pim sparse-mode	Enables the PIM sparse mode on the interface.
Step 20	ip service reflect input-interface destination destination-address to new-destination-address mask-len number source new-source-address Example: R1(config-if)# ip service reflect GigabitEthernet2/0/0 destination 239.1.1.100 to 225.1.1.100 mask-len 32 source 1.1.1.2	Matches and rewrites the multicast packets routed onto the virtual interface. •The matched and rewritten packets are sent back into multicast packet routing (or unicast routing if the destination is unicast), where they are handled like any other packets arriving from an interface.
Step 21	ip igmp static-group {* | group-address [source {source-address | ssm-map}]} Example: R1(config-if)# ip igmp static-group 239.1.1.100	Configures the router to be a statically connected member of the specified group on the interface, and forwards traffic destined for the multicast group onto the interface. Note This step is only applicable for multicast-to-multicast and multicast-to-unicast scenarios.
Step 22	exit Example: R1(config-if)# end	Exits the interface configuration mode.
Step 23	ip pim rp-address rp-address Example: R1(config)# ip pim rp-address 22.22.22.22	Configures the address of a PIM RP for a particular group.
Step 24	end Example: R1(config-controller)# end	Ends the configuration session.

Configuration Example

This example describes how to configure multicast service reflection.

R11>enable

R11#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

R11(config)#ip multicast-routing

R11(config)#interface Loopback0

R11(config-if)#description Rendezvous Point for Public Net

R11(config-if)#ip address 22.22.22.22 255.255.255.255

R11(config-if)#ip pim sparse-mode

R11>exit

R11#interface GigabitEthernet2/0/0

R11(config)#ip address 2.1.1.1 255.255.0.0

R11(config-if)#ip pim sparse-mode

R11(config)#exit

R11(config)#interface GigabitEthernet4/13

R11(config-if)#ip address 23.1.1.2 255.255.0.0

R11(config-if)#ip pim sparse-mode

R11(config-if)#exit

R11(config)#interface Vif1

R11(config-if)#ip address 1.1.1.1 255.255.0.0

R11(config-if)#ip pim sparse-mode

R1(config-if)#ip service reflect GigabitEthernet2/0/0 destination 239.1.1.100 to 
225.1.1.100 mask-len 32 source 1.1.1.2

R1(config-if)#ip igmp static-group 239.1.1.100

R1(config-if)#exit

R1(config)#ip pim rp-address 22.22.22.22

R11(config-if)#exit

For more information on configuring multicast service reflection, see Configuring Multicast Service Reflection.