Cisco IOS XE Catalyst SD-WAN overlay multicast supports PIM version 2 (defined in RFC 4601 ), with some restrictions.

On the service side, the Cisco IOS XE Catalyst SD-WAN software supports native multicast. A router appears as a native PIM router and establishes PIM neighborship with other PIM routers at a local site. A Cisco IOS XE SD-WAN router supports a directly connected local source, referred as a first hop router (FHR). Receivers residing downstream of a router can join multicast streams by exchanging IGMP membership reports directly with the device, and no other routers are required. Additionally, the Cisco Catalyst SD-WAN router can act as the PIM-RP for the local site.

On the transport side, PIM-enabled Cisco IOS XE Catalyst SD-WAN routers originate multicast service routes (called multicast autodiscover routes), sending them using OMP to the Cisco Catalyst SD-WAN Controllers. The multicast autodiscover routes indicate whether the router is a replicator and the local threshold. Each PIM router also conveys information learned from the PIM join messages sent by local-site multicast-enabled routers, including multicast group state, source information, and RPs. These routes assist Cisco IOS XE Catalyst SD-WAN routers in performing optimized joins across the overlay when joining existing multicast sources.

Cisco IOS XE Catalyst SD-WAN routers support both PIM source-specific mode (SSM) and ASM (Any Source Multicast) mode.

Rendezvous Points

The root of a PIM multicast shared tree resides on a router configured to be a rendezvous point (RP). In the Cisco Catalyst SD-WAN solution, RPs can be Cisco Catalyst SD-WAN routers or non-Cisco Catalyst SD-WAN routers that reside in the local site.

Cisco IOS XE Catalyst SD-WAN supports the following modes of RP discovery:

• Static RP

• Auto-RP

• Auto-RP Proxy

Dynamic RP-group mappings are propagated in the Cisco IOS XE Catalyst SD-WAN solution using Auto-RP. ACLs can be used to control or map certain group ranges to a specific RP. With this information, each PIM router has the ability to forward joins to the correct RP for the group that a downstream IGMP client is attempting to join. Auto-RP updates are propagated to downstream PIM routers if such routers are present in the local site and across the overlay to the remote sites that belong to the same VPN. While using Auto-RP, Replicator Node should be configured as the Auto-RP mapping agent.

Another RP selection model called bootstrap router (BSR) was introduced after Auto-RP in PIM-SM version 2. Auto-RP is a Cisco proprietary protocol, whereas PIM BSR is part of the PIM version 2 specification. BSR performs similarly to Auto-RP in that it uses candidate routers for the RP function and for relaying the RP information for a group.

Replicators

For efficient use of WAN bandwidth, strategic Cisco IOS XE Catalyst SD-WAN routers can be deployed and configured as replicators throughout the overlay network. Replicators mitigate the requirement for a Cisco Catalyst SD-WAN router with local sources or the PIM-RP to replicate a multicast stream once for each receiver. As discussed above, replicators advertise themselves, using OMP multicast-autodiscover routes, to the Cisco Catalyst SD-WAN Controllers in the overlay network. The controllers then forward the replicator location information to the PIM-enabled Cisco IOS XE Catalyst SD-WAN routers that are in the same VPN as the replicator.

A replicator Cisco IOS XE Catalyst SD-WAN router receives streams from multicast sources, replicates them, and forwards them to other Cisco Catalyst SD-WAN routers with multicast receivers in the same VPN. The details of the replication process are discussed below, in the section Multicast Traffic Flow through the Overlay Network. A replicator is typically a Cisco IOS XE Catalyst SD-WAN router located at a colo-site or another site with a higher-speed connection to the WAN transport network.

Multicast Service Routes

Cisco IOS XE Catalyst SD-WAN routers send multicast service routes to the Cisco Catalyst SD-WAN Controller using OMP. From these routes, the controller processes and forwards joins for requested multicast groups towards the source address or PIM-RP as specified in the original PIM join message that resulted in a Cisco Catalyst SD-WAN router advertising the OMP multicast service route. The source address can be either the IP address of an RP if the originating router is attempting to join the PIM shared tree or the IP address of the actual source of the multicast stream if the originating router is attempting to join the source tree.

Cisco IOS XE Catalyst SD-WAN routers support the Internet Group Management Protocol (IGMP) V2 and V3 protocol. IGMP is used by IPv4 hosts and routers to indicate their interest and in receiving multicast traffic for particular multicast groups. IGMP v3 report is used to indicate interest for a particular multicast group traffic from a specific source. From these membership reports, Cisco IOS XE Catalyst SD-WAN routers originate the corresponding PIM join or OMP service route advertisements.

1. From the Cisco SD-WAN Manager menu, choose Configuration > Templates.

2. Click Device Templates.

   Note	In Cisco vManage Release 20.7.x and earlier releases, Device Templates is titled Device.

3. Click Create Template.

4. From the Create Template drop-down list, choose From Feature Template.

5. From the Device Model drop-down list, choose the type of device for which you are creating the template.

6. Click Service VPN in the Service VPN section.

7. Click the Service VPN drop-down list.

8. Under Additional VPN Templates, click Multicast.

9. To enable Local Replicator on the device, choose On (otherwise keep it Off).

10. To configure replicator, choose the Threshold. (Optional, keep it default if you are not configuring replicator).

11. Save feature template.

12. Attach feature template to device template.

13. In the Template Description field, enter a description of the template. The description can be up to 2048 characters and can contain only alphanumeric characters.

When you first open a feature template, for each parameter that has a default value, the scope is set to Default (indicated by a check mark), and the default setting or value is shown. To change the default or to enter a value, click the scope drop-down list to the left of the parameter field and select the value.

Use the PIM template for all Cisco IOS XE Catalyst SD-WAN devices.

Configure the PIM Sparse Mode (PIM-SM) protocol using Cisco SD-WAN Manager templates so that a router can participate in the Cisco IOS XE Catalyst SD-WAN multicast overlay network:

1. Create a PIM feature template to configure PIM parameters.

2. Optionally, create an IGMP feature template to allow individual hosts on the service side to join multicast groups within a particular VPN. For more information, see Configure IGMP Using Cisco SD-WAN Manager Templates.

3. Optionally, create a multicast feature template to configure a Cisco IOS XE Catalyst SD-WAN to be a multicast replicator.

4. Create a VPN feature template to configure parameters for the VPN that is running PIM.

Create a PIM Feature Template

1. From the Cisco SD-WAN Manager menu, choose Configuration > Templates.

2. Click Device Templates.

   Note	In Cisco vManage Release 20.7.x and earlier releases, Device Templates is titled Device.

3. Click Create Template.

4. From the Create Template drop-down list, choose From Feature Template.

5. From the Device Model drop-down list, choose the type of device for which you are creating the template.

6. Click Service VPN located directly beneath the Description field, or scroll to the Service VPN section.

7. Click the Service VPN drop-down list.

8. Under Additional VPN Templates, click PIM.

9. From the PIM drop-down list, click Create Template. The PIM template form is displayed. The top of the form contains fields for naming the template, and the bottom contains fields for defining PIM parameters.

10. In the Template Name field, enter a name for the template. The name can be up to 128 characters and can contain only alphanumeric characters.

11. In the Template Description field, enter a description of the template. The description can be up to 2048 characters and can contain only alphanumeric characters.

12. Click Basic Configuration and configure SSM – On/Off.

13. Configure access list (if already defined).

14. Configure RP option – Auto-RP or static RP.

15. Configure RP Announce settings.

16. Configure the interface name on the service side.

17. Save feature template and attach feature template to a device template.

When you first open a feature template, for each parameter that has a default value, the scope is set to Default (indicated by a check mark), and the default setting or value is shown. To change the default or to enter a value, click the scope drop-down list to the left of the parameter field and select the value.

Configure Basic PIM

To configure PIM, click Basic Configuration and configure the following parameters. Parameters marked with an asterisk are required to configure PIM.

To save the feature template, click Save.

Configure PIM Interfaces

If the router is just a multicast replicator and is not part of a local network that contains either multicast sources or receivers, you do not need to configure any PIM interfaces. The replicator learns the locations of multicast sources and receivers from the OMP messages it exchanges with the Cisco Catalyst SD-WAN Controller. These control plane messages are exchanged in the transport VPN (VPN 0). Similarly, other Cisco IOS XE Catalyst SD-WAN devices discover replicators dynamically, through OMP messages from the Cisco Catalyst SD-WAN Controller.

To configure PIM interfaces, click Interface. Then click Add New Interface and configure the following parameters:

To edit an interface, click the pencil icon to the right of the entry.

To delete an interface, click the trash icon to the right of the entry.

To save the feature template, click Save.

Features and Benefits

• IPv4 support.

• Dynamic rather than static selection of an RP.

• Automatic failover if one RP is not available.

• RP discovery is handled by a BSR.

• Configuration of multiple RP candidates for the same group range.

• Selection of a Cisco IOS XE Catalyst SD-WAN device as the RP.

Restrictions for PIM BSR

• IPv6 is not supported.

• Bidirectional PIM is not supported for IPv4.

• BSR is not supported in a hub-and-spoke topology on Cisco IOS XE Catalyst SD-WAN devices.

Use the IGMP template for all Cisco IOS XE Catalyst SD-WAN devices. Internet Group Management Protocol (IGMP) allows routers to join multicast groups within a particular VPN.

To configure IGMP using Cisco SD-WAN Manager templates:

1. Create an IGMP feature template to configure IGMP parameters.

2. Create the interface in the VPN to use for IGMP. See the VPN-Interface-Ethernet help topic.

3. Create a VPN feature template to configure VPN parameters. See the VPN help topic.

Navigate to the Template Window and Name the Template

1. From the Cisco SD-WAN Manager menu, choose Configuration > Templates.

2. Click Device Templates.

   Note	In Cisco vManage Release 20.x.7 and earlier releases, Device Templates is titled Device.

3. Click Create Template.

4. From the Create Template drop-down list, choose From Feature Template.

5. From the Device Model drop-down list, choose the type of device for which you are creating the template.

6. Click Service VPN located directly beneath the Description field, or scroll to the Service VPN section.

7. Click the Service VPN drop-down list.

8. Under Additional VPN Templates, click IGMP.

9. From the IGMP drop-down list, click Create Template. The IGMP template form is displayed. The top of the form contains fields for naming the template, and the bottom contains fields for defining IGMP parameters.

10. Add interface name on the service side to enable IGMP.

11. (Optional) In the Join Group And Source Address field, click on Add Join Group and Source Address. The Join Group and Source Address window displays.

12. (Optional) Enter group address to join and source address.

13. In the Template Name field, enter a name for the template. The name can be up to 128 characters and can contain only alphanumeric characters.

14. In the Template Description field, enter a description of the template. The description can be up to 2048 characters and can contain only alphanumeric characters.

When you first open a feature template, for each parameter that has a default value, the scope is set to Default (indicated by a check mark), and the default setting or value is shown. To change the default or to enter a value, click the scope drop-down to the left of the parameter field and select the value.

Configure Basic IGMP Parameters

To configure IGMP, click Basic Configuration to enable IGMP. Then, click Interface, and click Add New Interface to configure IGMP interfaces. All parameters listed below are required to configure IGMP.

To save the feature template, click Save.

For a Cisco IOS XE Catalyst SD-WAN router located at a site that contains one or more multicast sources, enable PIM on the service-side interface or interfaces. These are the interfaces that connect to the service-side network. To enable PIM or IGMP per VPN, you must configure PIM or IGMP and its interfaces for all VPNs support multicast services. PIM configuration is not required in VPN 0 (the transport VPN facing the overlay network) or in VPN 512 (the management VPN).

If a source interface is specified in the send-rp-discovery container, ensure that the interface already has an IP address and PIM configured.

Sample configuration:

vrf definition 1
 rd 1:1
 address-family ipv4
  exit-address-family
 !
!
ip pim vrf 1 autorp listener
ip pim vrf 1 send-rp-announce Loopback1 scope 12 group-list 10
ip pim vrf 1 send-rp-discovery Loopback1 scope 12
ip pim vrf 1 ssm default
ip access-list standard 10
 10 permit 10.0.0.1 0.255.255.255
!
ip multicast-routing vrf 1 distributed
interface GigabitEthernet0/0/0.1
 no shutdown
 encapsulation dot1Q 1
 vrf forwarding 1
 ip address 172.16.0.0 255.255.255.0
 ip pim sparse-mode
 ip igmp version 3
 ip ospf 1 area 0
exit
interface GigabitEthernet0/0/2
 no shutdown
 vrf forwarding 1
 ip address 172.16.0.1 255.255.255.0
 ip pim sparse-mode
 ip ospf 1 area 0
exit
interface Loopback1
 no shutdown
 vrf forwarding 1
 ip address 192.0.2.255 255.255.255.255
 ip pim sparse-mode
 ip ospf 1 area 0
exit  
sdwan
 multicast
  address-family ipv4 vrf 1
   replicator threshold 7500
   
   exit

Before You Begin

Note	By enabling an MSDP peer, you implicitly enable MSDP.

• IP multicast routing must be enabled and PIM-SM must be configured. For more information, see Configure PIM.

Configure MSDP Using a CLI Template

For more information about using CLI templates, see CLI Add-On Feature Templates and CLI Templates.

Note	By default, CLI templates execute commands in global config mode.

This section provides example CLI configurations to configure MSDP.

1. Enable MSDP and configure an MSDP peer as specified by the DNS name or IP address.

   
   ip msdp peer peer ip address connect-source 
   

   If you specify the connect-source keyword, the primary address of the specified local interface type and number values are used as the source IP address for the TCP connection. The connect-source keyword is recommended, especially for MSDP peers on a border that peer with a device inside of a remote domain.

2. Configure an originating address.

   Perform this optional task to allow an MSDP speaker that originates an SA message to use the IP address of its interface as the RP address in the SA message.

   You can also change the originator ID for any one of the following reasons:

   • If you configure multiple devices in an MSDP mesh group for Anycast RP.

   • If you have a device that borders a PIM-SM domain and a PIM-DM domain. If a device borders a PIM-SM domain and a PIM-DM domain and you want to advertise active sources within the PIM-DM domain, configure the RP address in SA messages to be the address of the originating device’s interface.

   
   ip msdp originator-id type number 
   

3. Configure an MSDP Mesh Group.

   Configures an MSDP mesh group and indicates that an MSDP peer belongs to that mesh group.

   Note	You can configure multiple mesh groups per device.

   
   ip msdp mesh-group mesh name{peer-ip address | peer name} 
   

   Note	All MSDP peers on a device that participate in a mesh group must be fully meshed with all other MSDP peers in the group. Each MSDP peer on each device must be configured as a peer using the ip msdp peer command and also as a member of the mesh group using the ip msdp mesh-group command.

Single Homed Network

In the sample topology, MSDP interoperability is enabled on the Cisco IOS XE Catalyst SD-WAN device, R20, at site 2. R3 is configured as an RP for its PIM domain at the non-SD-WAN site. MSDP peering is established between R3 at the non-SD-WAN site and on R20 at site 2. When source H2 sends traffic to R4, R4 initiates a data registration with R3, and thereafter, R3 sends an MSDP SA message to R20. As MSDP interoperability is enabled in R20, R20 converts the received MSDP SA message to OMP SA routes, and then advertises them to all Cisco IOS XE Catalyst SD-WAN devices located at other sites through the Cisco SD-WAN Controller serving the Cisco IOS XE Catalyst SD-WAN devices. When the Cisco IOS XE Catalyst SD-WAN device R10 at site 1 receives this OMP SA route, R10 converts the OMP SA route into MSDP SA message and advertises the MSDP SA message to its MSDP peer R2 at the non-SD-WAN site. If R2 has any receivers interested in the group advertised in MSDP SA message, then R2 sends a (S,G) join towards the source. As a result, a inter-domain source tree is established across Cisco Catalyst SD-WAN. As multicast packets arrive at R2 (RP), they are then forwarded down its own shared tree to the group members in the RP’s domain. R20 withdraws the advertised OMP SA route only when the MSDP SA message expires.

Dual-Homed Network

A dual home network is where there are two Cisco IOS XE Catalyst SD-WAN devices configured for MSDP interoperability. In the dual-homed Cisco Catalyst SD-WAN site 3, MSDP peering must be established between the Cisco IOS XE Catalyst SD-WAN devices R30, R40, and the non-SDWAN device R5. When the source registers its traffic with the RP R5, R5 sends a MSDP SA message to both R30 and R40. When R30 receives the MSDP SA message, it converts the MSDP SA message into OMP SA routes and then advertises to all the Cisco IOS XE Catalyst SD-WAN devices located at other sites, and to R40 within the same, site 3. MSDP SA filter must be configured between R30 and R40 to drop the SA message received from other Cisco IOS XE Catalyst SD-WAN devices and sites through the Overlay Management Protocol (OMP). The Cisco IOS XE Catalyst SD-WAN device R10 at site 1 receives two OMP SA routes for the same Source Group (S, G) and caches them both. R10 then converts the OMP SA route into MSDP SA message and advertises to its MSDP peer R2 at the non-SD-WAN site. If R2 has any receivers interested in the group advertised in MSDP SA message, then R2 sends a (S,G) join towards the source. As a result, a inter-domain source tree is established across Cisco Catalyst SD-WAN.

MSDP supports the following scenarios where Cisco IOS XE Catalyst SD-WAN devices at the Cisco Catalyst SD-WAN sites are configured for MSDP interoperability with other devices located in the non-SD-WAN sites.

• Source devices located at the Cisco Catalyst SD-WAN sites, and receivers at the Cisco Catalyst SD-WAN and non-SD-WAN sites.

• Source devices located in the non-SD-WAN sites, and receivers at the Cisco Catalyst SD-WAN and non-SD-WAN sites.

• In Dual border sites, where two devices are configured for MSDP interoperability in Cisco Catalyst SD-WAN where sources and receivers are located in the Cisco Catalyst SD-WAN sites.

• In dual border sites, where two devices are configured for MSDP interoperability in non-SD-WAN, and where sources and receivers are located at the non-SD-WAN sites.

• A Replicator can be any Cisco IOS XE Catalyst SD-WAN device located in the Cisco Catalyst SD-WAN site. For more information about Replicators, see the Replicators section in PIM.

The following example shows the configuration of centralized control policy for hub-and-spoke deployment:

policy
 lists
  tloc-list Hub-TLOCs
   tloc 10.10.10.2 color biz-internet encap ipsec
   tloc 192.0.2.1 color biz-internet encap ipsec
  !
  site-list Branches
   site-id 140
   site-id 68
  !
  site-list DCs
   site-id 50
   site-id 67
  !
 !
 control-policy Hub-Control-Policy
  sequence 11
   match tloc
    site-list DCs
   !
   action accept
   !
  !
  sequence 31
   match route
    site-list DCs
   !
   action accept
   !
  !
  default-action reject
 !
 control-policy Spoke-Control-Policy
  sequence 1
   match tloc
    site-list Branches
   !
   action reject
   !
  !
  sequence 11
   match tloc
    site-list DCs
   !
   action accept
   !
  !
  default-action reject
 !
!
apply-policy
 site-list Branches
  control-policy Spoke-Control-Policy out
 !
 site-list DCs
  control-policy Hub-Control-Policy out
 !
!  

The following example shows the spoke configuration for hub-and-spoke multicast deployment:

sdwan
 multicast        
  address-family ipv4 vrf 1
   spoke
  !
 !
!

Verify Multicast Routing on Hub-and-Spoke

Use the command show platform software sdwan multicast active-sources vrf on spokes to verify multicast source active route next-hop pointing to the selected replicator.

Device# show platform software sdwan multicast active-sources vrf 1    

Multicast SDWAN Overlay Received Source-Active Routes:
  (10.0.0.0, 255.0.0.0) next-hop: 192.168.255.254
      src-orig-count: 1, rp-addr: 10.0.0.1