Configure Multicast Forwarding with MLD Snooping in an EVPN-MPLS Environment
MLD snooping with multicast forwarding ensures that IPv6 multicast traffic reaches all subscribed receivers within and between bridge domains or VLANs, and preserves bandwidth on the access side by reducing the amount of multicast control and data traffic being forwarded.
You can configure multicast with MLD snooping on provider edge (PE) devices in an Ethernet VPN (EVPN) over MPLS environment. You must enable MLD snooping in this environment to support IPv6 multicast traffic for receivers that are multihomed to EVPN PE devices as follows:
Peer PE devices must be operating in all-active multihoming mode.
You enable MLD snooping in proxy mode.
You configure and commit the same configuration on each multihoming peer PE device.
PEs in this environment support processing MLDv1 and MLDv2 membership reports in any-source multicast (ASM) mode and MLDv2 membership reports in source-specific multicast (SSM) mode with a special configuration option. See IGMP or MLD Versions and Supported Group Membership Report Modes for details on how PEs process MLD reports.
In addition, to route multicast traffic between bridge domains or VLANs, PEs with hosts in multicast groups that span bridge domains or VLANs use PIM distributed designated router (PIM DDR) mode on IRB interfaces. With PIM DDR configured on the IRB interfaces, all the PE devices send the traffic locally through the IRB interfaces to their interested receivers on the corresponding bridge domains or VLANs even if an IRB is not the elected PIM designated router (DR) for that bridge domain or VLAN. See Configure Multicast Routing Across Bridge Domains or VLANs with PIM in EVPN-MPLS for details.
This topic describes configuration tasks to set up MLD snooping on PE devices in a multihoming EVPN-MPLS environment with either the default ASM group membership report processing (MLDv1 and MLDv2) or SSM-only group membership report processing (MLDv2). This topic also summarizes the CLI commands you can use to verify MLD snooping and multicast operation in this environment.
Configure MLD Snooping for Default Any-Source Multicast (ASM) Group Membership Processing with MLDv1 or MLDv2
By default, the EVPN-MPLS network processes only ASM (*,G) membership reports with MLDv1 and MLDv2.
On ACX Series routers, you can configure MLD snooping only on
one or more routing instances of type evpn. On other types
of devices, you can configure MLD snooping with ASM for routing instances
of type evpn or virtual-switch and for all bridge
domains or VLANs or only for a specific bridge domain or VLAN.
For example:
To configure MLD snooping in proxy mode on PE devices in an EVPN-MPLS network for the
default-switchrouting instance:user@device# set protocols mld-snooping proxy
To configure MLD snooping in proxy mode on a PE device for a particular routing instance configured as
instance-type evpnorinstance-type virtual-switchfor all bridge domains or VLANs in the instance:user@device# set routing-instances routing-instance-name protocols mld-snooping proxy
To configure MLD snooping on a PE device for a specific bridge domain or VLAN for an EVPN instance with
instance-type virtual-switch:user@device# set routing-instances routing-instance-name bridge-domain bridge-domain-name protocols mld-snooping proxy
PE devices can’t process both ASM (*,G) reports and SSM (S,G) reports at the same time, but you can alternatively configure PEs to process only SSM (S,G) membership reports. See Configure MLD Snooping with MLDv2 to Process Source-Specific Multicast Group Membership Reports Only.
In the following sample configuration, MLD snooping is enabled
in proxy mode (and the same for IGMP snooping) for an instance of
type evpn named EVPN-1:
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EVPN-1 {
instance-type evpn;
protocols {
evpn {
remote-ip-host-routes;
designated-forwarder-preference-least;
}
igmp-snooping {
proxy;
}
mld-snooping {
proxy;
}
}
vlan-id 100;
interface ae1.100;
l3-interface irb.100;
route-distinguisher 90.90.90.10:1;
vrf-target target:64510:1;
}
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.In following sample configuration, MLD snooping is enabled for
three bridge domains (V100, V200, V300) in a routing instance of type virtual-switch named CUST-2:
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CUST-2 {
instance-type virtual-switch;
route-distinguisher 10.255.255.1:100;
vrf-target target:64510:100;
protocols {
evpn {
extended-vlan-list [ 100 200 300 ];
}
}
bridge-domains {
V100 {
domain-type bridge;
vlan-id 100;
interface ae0.100;
routing-interface irb.100;
protocols {
igmp-snooping;
mld-snooping;
}
}
V200 {
domain-type bridge;
vlan-id 200;
interface ae0.200;
routing-interface irb.200;
protocols {
igmp-snooping;
mld-snooping;
}
}
V300 {
domain-type bridge;
vlan-id 300;
interface ge-0/0/5.300;
routing-interface irb.300;
protocols {
igmp-snooping;
mld-snooping;
}
}
}
}
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Configure MLD Snooping with MLDv2 to Process Source-Specific Multicast Group Membership Reports Only
By default, the EVPN-MPLS network processes only ASM (*,G) membership
reports with MLDv1 and MLDv2. You can alternatively configure PEs
to process only MLDv2 SSM (S,G) membership reports. To do this, use
the evpn-ssm-reports-only option in the [edit protocols mld-snooping] configuration statement hierarchy when you configure MLD snooping.
When you enable this option, the device doesn’t process ASM reports and drops those packets. See IGMP or MLD Versions and Supported Group Membership Report Modes for details on how PEs process MLD reports in this environment.
You can enable SSM-only processing when you configure MLD snooping for:
All bridge domains or VLANs in a routing instance of type
evpn.All bridge domains or a specific bridge domain or VLAN in a
virtual-switchinstance.
On ACX Series routers, you can configure MLD snooping
only on one or more routing instances of type evpn. On
other devices, you can configure MLD snooping for routing instances
of type evpn or virtual-switch.
For example:
To configure MLD snooping to process only SSM membership reports with MLDv2 for the
default-switchEVPN routing instance:user@device# set protocols mld-snooping evpn-ssm-reports-only
To configure MLD snooping with MLDv2 to process only SSM membership reports for all bridge domains or VLANs in a routing instance:
user@device# set routing-instances routing-instance-name protocols mld-snooping evpn-ssm-reports-only
To configure MLD snooping in proxy mode to process only SSM membership reports for a specific bridge domain or VLAN for an EVPN instance with
instance-type virtual-switch:user@device# set routing-instances routing-instance-name bridge-domain bridge-domain-name protocols mld-snooping evpn-ssm-reports-only proxy
In following sample configuration, MLD snooping is configured
to process only SSM membership reports for a routing instance of type evpn named EVPN-2:
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EVPN-2 {
instance-type evpn;
protocols {
evpn {
remote-ip-host-routes;
designated-forwarder-preference-least;
}
mld-snooping {
evpn-ssm-reports-only;
proxy;
}
}
vlan-id 200;
interface ae2.200;
l3-interface irb.200;
route-distinguisher 90.90.90.10:2;
vrf-target target:64510:1;
}
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.Viewing MLD Snooping Multicast Information for EVPN-MPLS in the CLI
The following EVPN commands are supported to view MLD snooping multicast information in an EVPN-MPLS environment. The output of these commands includes information learned from native MLD snooping on a PE device and learned from EVPN Type 7 Join Sync Route and Type 8 Leave Sync Route messages.
show evpn multicast-snooping next-hopsshow mld snooping evpn membership