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Internet Group Management Protocol (IGMP) snooping restricts multicast flows at Layer 2 to only those segments with at least one interested receiver. This module describes how to implement IGMP snooping.
 Note |
Multicast traffic without Spanning-Tree protocol is supported at Layer 2 for multicast traffic without snooping enabled. |
Before implementing IGMP snooping, make sure that the network is configured with a Layer 2 VPN (L2VPN).
EVPN dual-homed Active Active (AA) IGMP State Sync using IGMP snooping profile is supported.
BVI under bridge domain is supported.
IGMP snooping is supported only under L2VPN bridge domains.
Explicit host tracking (an IGMPv3 snooping feature) is not supported.
IPv6 Multicast Listener Discovery (MLD) snooping is not supported.
IGMPv1 is not supported.
IGMP snooping with VPLS on bridge domain is not supported.
IGMP snooping over access and core Pseudo-wire is not supported.
ISSU is not supported on Layer 2 Multicast.
IGMPv3-exclude is not supported in EVPN multi-homing or proxy scenarios.
For EVPN AA, IGMPv2 and IGMPv3 joins for same groups are not supported.
router-alert-check disable configuration command is not supported.
EVPN configuration must have the control-word-disable configuration.
PIM control packets (join and hello) processing is not supported when snooping is enabled, so a multicast router selection based on PIM packets won't occur.
In an EVPN dual-home AA scenario:
If the multicast source and receiver are in the same bridge domain (BD), the receiver might receive permanent traffic duplication.
In an EVPN dual-home receiver AA scenario, transient traffic duplication is expected when the DH node role changes from DF to nDF and vice versa.
Source=ESI1=BE-X.A, Receiver=ESI1=BE-X.B under the same BD is not supported (where X.A and X.B represent two AC ports for the bundle interface BE).
Source=ESI1=BE-X.A (for NCS 5700 line cards), Receiver=ESI2=BE-Y.A (for NCS 5500 line cards) under the same BD is not supported (where X.A and Y.A represent two AC ports for the bundle interface BE).
Note |
IPv4 multicast is supported for a multicast source that is behind the BVI interface. For example, the below configuration shows how to configure source behind BVI for IPv4 multicast: IGMP snooping for bridge domains without Bridged Virtual Interface (BVI) is supported with the following design consideration: You must configure the multicast-source ipv4 command in the source switch where bridge domain and IGMP snooping are enabled. |
IGMP snooping provides a way to constrain multicast traffic at Layer 2. By snooping the IGMP membership reports sent by hosts in the bridge domain, the IGMP snooping application can set up Layer 2 multicast forwarding tables to deliver traffic only to ports with at least one interested member, significantly reducing the volume of multicast traffic.
Configured at Layer 3, IGMP provides a means for hosts in an IPv4 multicast network to indicate which multicast traffic they are interested in and for routers to control and limit the flow of multicast traffic in the network at Layer 3.
IGMP snooping uses the information in IGMP membership report messages to build corresponding information in the forwarding tables to restrict IP multicast traffic at Layer 2. The forwarding table entries are in the form <Route, OIF List>, where:
Route is a <*, G> route or <S, G> route, where * is any source, G is group and S is the source.
OIF List comprises all bridge ports that have sent IGMP membership reports for the specified route plus all multicast router (mrouter) ports in the bridge domain.
Implemented in a multicast network, IGMP snooping has the following attributes:
In its basic form, it reduces bandwidth consumption by reducing multicast traffic that would otherwise flood an entire VPLS bridge domain.
With the use of some optional configurations, it provides security between bridge domains by filtering the IGMP reports received from hosts on one bridge port and preventing leakage towards the hosts on other bridge ports.
Using optional configurations, reduces the traffic impact on upstream IP multicast routers by suppressing IGMP membership reports (IGMPv2) or by acting as an IGMP proxy reporter (IGMPv3) to the upstream IP multicast router.
All high availability features apply to the IGMP snooping processes with no additional configuration beyond enabling IGMP snooping. The following high availability features are supported:
Process restarts
RP Failover
Stateful Switch-Over (SSO)
Non-Stop Forwarding (NSF)—Forwarding continues unaffected while the control plane is restored following a process restart or route processor (RP) failover.
Line card online insertion and removal (OIR)
IGMP snooping operates at the bridge domain level. When IGMP snooping is enabled on a bridge domain, the snooping functionality applies to all ports under the bridge domain, including:
Physical ports under the bridge domain.
Ethernet flow points (EFPs)—An EFP can be a VLAN, VLAN range, list of VLANs, or an entire interface port.
Ethernet bundles—Ethernet bundles include IEEE 802.3ad link bundles and Cisco EtherChannel bundles. From the perspective of the IGMP snooping application, an Ethernet bundle is just another EFP. The forwarding application in the randomly nominates a single port from the bundle to carry the multicast traffic.
Note |
The efp-visibility configuration is required when a bridge has attachment circuits as VLAN sub-interfaces from the same bundle-ether or physical interface. |
IGMP snooping for bridge domains without Bridged Virtual Interface (BVI) is supported with the following design consideration:
You must configure the multicast-source ipv4 command in the source switch where IGMP snooping is enabled as seen in the following example:
l2vpn
bridge group 1
bridge-domain 1
multicast-source ipv4
igmp snooping profile grp1
!
interface TenGigE0/0/0/3.31 //Source
!
interface TenGigE0/0/0/3.32
!
routed interface BVI1 IGMP snooping classifies each port (for example, EFPs, PWs, physical ports, or EFP bundles) as one of the following:
Multicast router ports (mrouter ports)—These are ports to which a multicast-enabled router is connected. Mrouter ports are usually dynamically discovered, but may also be statically configured. Multicast traffic is always forwarded to all mrouter ports, except when an mrouter port is the ingress port.
Host ports—Any port that is not an mrouter port is a host port.
The following tables describe traffic handling behaviors by IGMP snooping mrouter and host ports. Table 1 describes traffic handling for an IGMPv2 querier. Table 2 applies to an IGMPv3 querier.
By default, IGMP snooping supports IGMPv2 and IGMPv3. The version of the IGMP querier discovered in the bridge domain determines the operational version of the snooping processes. If you change the default, configuring IGMP snooping to support a minimum version of IGMPv3, IGMP snooping ignores any IGMPv2 queriers.
|
Traffic Type |
Received on MRouter Ports |
Received on Host Ports |
|---|---|---|
|
IP multicast source traffic |
Forwards to all mrouter ports and to host ports that indicate interest. |
Forwards to all mrouter ports and to host ports that indicate interest. |
|
IGMP general queries |
Forwards to all ports. |
— |
|
IGMP group-specific queries |
Forwards to all other mrouter ports. |
Dropped |
|
IGMPv2 joins |
Examines (snoops) the reports.
|
Examines (snoops) the reports.
|
|
IGMPv3 reports |
Ignores |
Ignores |
|
IGMPv2 leaves |
Invokes last member query processing. |
Invokes last member query processing. |
|
Traffic Type |
Received on MRouter Ports |
Received on Host Ports |
|---|---|---|
|
IP multicast source traffic |
Forwards to all mrouter ports and to host ports that indicate interest. |
Forwards to all mrouter ports and to host ports that indicate interest. |
|
IGMP general queries |
Forwards to all ports. |
— |
|
IGMP group-specific queries |
If received on the querier port floods on all ports. |
— |
|
IGMPv2 joins |
Handles as IGMPv3 IS_EX{} reports. |
Handles as IGMPv3 IS_EX{} reports. |
|
IGMPv3 reports |
|
|
|
IGMPv2 leaves |
Handles as IGMPv3 IS_IN{} reports. |
Handles as IGMPv3 IS_IN{} reports. |
To enable IGMP snooping on a bridge domain, you must attach a profile to the bridge domain. The minimum configuration is an empty profile if BVI is configured. An empty profile enables the default configuration options and settings for IGMP snooping, as listed in the Default IGMP Snooping Configuration Settings.
Note |
The internal-querier is a requirement under the IGMP snooping profile if BVI is not configured under L2VPN. |
You can attach IGMP snooping profiles to bridge domains or to ports under a bridge domain. The following guidelines explain the relationships between profiles attached to ports and bridge domains:
Any IGMP Snooping profile attached to a bridge domain, even an empty profile, enables IGMP snooping. To disable IGMP snooping, detach the profile from the bridge domain.
An empty profile configures IGMP snooping on the bridge domain and all ports under the bridge using default configuration settings.
A bridge domain can have only one IGMP snooping profile attached to it (at the bridge domain level) at any time.
Port profiles are not in effect if the bridge domain does not have a profile attached to it.
IGMP snooping must be enabled on the bridge domain for any port-specific configurations to be in effect.
If a profile attached to a bridge domain contains port-specific configuration options, the values apply to all of the ports under the bridge, including all mrouter and host ports, unless another port-specific profile is attached to a port.
When a profile is attached to a port, IGMP snooping reconfigures that port, disregarding any port configurations that may exist in the bridge-level profile.
To create a profile, use the igmp snooping profile command in global configuration mode.
To attach a profile to a bridge domain, use the igmp snooping profile command in l2vpn bridge group bridge domain configuration mode. To attach a profile to a port, use the igmp snooping profile command in the interface configuration mode under the bridge domain. To detach a profile, use the no form of the command in the appropriate configuration mode.
When you detach a profile from a bridge domain or a port, the profile still exists and is available for use at a later time. Detaching a profile has the following results:
If you detach a profile from a bridge domain, IGMP snooping is deactivated in the bridge domain.
If you detach a profile from a port, IGMP snooping configuration values for the port are instantiated from the bridge domain profile.
You cannot make changes to an active profile. An active profile is one that is currently attached.
If the active profile is configured under the bridge, you must detach it from the bridge, and reattach it.
If the active profile is configured under a specific bridge port, you must detach it from the bridge port, and reattach it.
Another way to do this is to create a new profile incorporating the desired changes and attach it to the bridges or ports, replacing the existing profile. This deactivates IGMP snooping and then reactivates it with parameters from the new profile.
|
Scope |
Feature |
Default Value |
|
|---|---|---|---|
|
Bridge Domain |
IGMP snooping |
Disabled on a bridge domain until an enabling IGMP snooping profile is attached to the bridge domain. |
|
|
internal querier |
By default Internal Querier is disabled. To enable Internal Querier, add it to the IGMP snooping profile. Internal Querier is not recommended, when BVI and IGMP snooping is configured under a bridge. |
||
|
last-member-query-count |
2 |
||
|
last-member-query-interval |
1000 (milliseconds) |
||
|
minimum-version |
2 (supporting IGMPv2 and IGMPv3) |
||
|
querier query-interval |
60 (seconds)
|
||
|
report-suppression |
Enabled (enables report suppression for IGMPv2 and proxy-reporting for IGMPv3) |
||
|
querier robustness-variable |
2 |
||
|
router alert check |
Enabled |
||
|
tcn query solicit |
Disabled |
||
|
tcn flood |
Enabled |
||
|
ttl-check |
Enabled |
||
|
unsolicited-report-timer |
1000 (milliseconds) |
||
|
Port |
immediate-leave |
Disabled |
|
|
mrouter |
No static mrouters configured; dynamic discovery occurs by default. |
||
|
router guard |
Disabled |
||
|
static group |
None configured |
The minimum-version command determines which IGMP versions are supported by IGMP snooping in the bridge domain:
When minimum-version is 2, IGMP snooping intercepts IGMPv2 and IGMPv3 messages. This is the default value.
When minimum-version is 3, IGMP snooping intercepts only IGMPv3 messages and drops all IGMPv2 messages.
IGMPv1 is not supported. The scope for this command is the bridge domain. The command is ignored in a profile attached to a port.
The group membership interval (GMI) controls when IGMP snooping expires stale group membership states. The show igmp snooping group command shows groups with an expiry time of 0 until that stale state is cleaned up following the next query interval.
The GMI is calculated as:
GMI = (robustness-variable * query-interval) + maximum-response-time
where:
maximum-response-time (MRT) is the amount of time during which receivers are required to report their membership state.
robustness-variable is an integer used to influence the calculated GMI.
query-interval is the amount of time between general queries.
Values for the components in the GMI are obtained as follows:
MRT is advertised in the general query, for both IGMPv2 and IGMPv3.
If the querier is running IGMPv2, IGMP snooping uses the IGMP-snooping-configured values for the robustness-variable and query-interval. These parameter values must match the configured values for the querier. In most cases, if you are interacting with other Cisco routers, you should not need to explicitly configure these values—the default values for IGMP snooping should match the default values of the querier. If they do not, use the querier robustness-variable and querier query-interval commands to configure matching values.
IGMPv3 general queries convey values for robustness-variable and query-interval (QRV and QQI, respectively). IGMP snooping uses the values from the query, making the IGMP snooping GMI exactly match that of the querier.
|
Feature Name |
Release Information |
Feature Description |
|---|---|---|
|
EVPN All-Active Multi-homed Multicast Source Behind a BVI |
Release 7.11.1 |
We have enhanced multicast routing efficiency, load balancing, and latency in EVPN topology by optimizing redundancy and enabling support for All-Active (AA) multicast multi-homed sources. The multi-homed multicast data sources are located behind a Bridge-Group Virtual Interface (BVI), while multicast receivers can be in either the core or a bridge domain. This feature introduces the following changes:
|
EVPN AA multi-homed refers to a specific deployment model within the EVPN technology. In the multi-homed setup, a customer site or device (CE) is connected to multiple provider edge (PE) routers or attachment circuits (ACs). Multi-homing provides redundancy and load balancing by allowing a CE to connect to multiple PE routers, enabling traffic to be distributed across different paths. In case of a link (CE to PE and local PE to remote PE) or router failure, traffic can be quickly redirected to an alternate path.
In multi-homing, an AA mode means that all the links or paths between the EVPN sites are active and forwarding traffic simultaneously. This is in contrast to other deployment models, such as Single-Active or Port-Active Load-balancing mode, where only a subset of the links is active at any given time.
Placing the CE device behind the BVI interface has the following advantages:
It allows for a simplified configuration on the CE side. The CE only needs to be configured with a single default gateway, which is the BVI interface. The CE doesn't have to manage multiple interfaces or deal with complex routing protocols.
The BVI interface also enables efficient replication and forwarding of multicast traffic to the appropriate multicast distribution trees within the service provider network. This eliminates the need for the CE to handle multicast replication, reducing its processing load and potentially improving overall multicast performance.
Placing the CE behind the BVI accept interface allows for greater flexibility in multi-homing scenarios. The CE can connect to multiple provider edge (PE) routers through the BVI accept interface, enabling seamless failover and load balancing between the PE routers during link or router failures.
The network must support the following topology, protocols, and features to use the EVPN AA multi-homed multicast source feature:
EVPN Control Plane with BGP
BVI
IGMP Snooping and MLD Snooping
MLDP, MPLS, and OSPF (for L3 multicast receivers at core)
Native multicast, MVPN GRE, or mVPN Profile 14 (core)
For more information related to EVPN technology and supported protocols, refer EVPN Features chapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 5500 Series Routers.
For more information related to IGMP Snooping and MLD Snooping features, refer Implementing Layer 2 Multicast chapter in Multicast Configuration Guide for Cisco NCS 5500 Series Routers.
The EVPN AA multi-homed multicast source feature enables multicast data packet support for multi-homed sources in an EVPN AA (All-Active) topology.
In this setup, the multicast traffic is forwarded to the core by EVPN with BVI as the accept interface.
This deployment model combines the benefits of AA forwarding and multi-homing. It’s particularly useful in scenarios where high availability, fault tolerance, and optimized bandwidth utilization are essential requirements.
The following illustration shows the multicast data traffic route between a multi-homed source and the multi-homed receivers.
In this illustration, the multicast data sources are connected behind a CE, which is multi-homed to PE-0 and PE-1. PE-1 is configured with a BVI that has an anycast IP address. The image displays an example where the BVI has the IP address 1.1.1.1. The receiver that is behind the MCR-0 has a PIM connection toward the multicast data source.
The data packet flow between the multicast data source and receiver occurs in the following manner:
The receiver, located behind Multicast Receiver (MCR-0), initiates an Internet Group Management Protocol (IGMP) join, which triggers a Protocol Independent Multicast (PIM) join towards the source.
The PIM join message reaches one of the PE routers (either PE-0 or PE-1) with the incoming or accept interface being the BVI and the outgoing interface leading towards the core network.
When the source sends traffic, it reaches one of the PE routers (PE-0 or PE-1). The next path for the traffic depends on the following IGMP snooping configurations:
If IGMP snooping is enabled and the multicast source is configured for both IPv4 and IPv6 traffic, the traffic is forwarded to either a route with a BVI interface or the default IGMP snoopig route.
If IGMP snooping is disabled, the traffic floods the multicast ID (MCID) on the bridge. As part of the flood MCID logic, the packet is recycled for the BVI and flooded to all the ACs, including the EVPN Optimized Local Egress (OLE). The recycled packets for the BVI undergo Layer 3 lookup. If there is a route with the BVI as an accepted interface, the packet is forwarded to the Olist for Layer 3 forwarding.
Note |
The same packet is not sent back to the CE device due to SHL (Split Horizon Label) filtering for EVPN traffic. |
The supported scenarios for AA MH multicast are as follows:
IPv4 SSM with BVI as accept interface is supported.
IPv4 SM with BVI as accept interface is supported.
IPv6 SSM with BVI as accept interface is supported.
IPv4 SSM without BVI (only layer 2 multicast) and multicast source behind L2 is supported.
IPv4 SM without BVI as accept interface (only layer 2 multicast) is supported.
IPv6 SSM without BVI as accept interface (only layer 2 multicast) is supported.
IPv6 SM without BVI as accept interface (only layer 2 multicast) is supported.
This feature has the following limitations:
IPv6 SM with BVI as accept interface is not supported.
Dual-homed source and Dual-homed receiver over MLDP profile on the same BD is not supported. It is recommended to disable MVPN peering between the MH nodes to prevent redundant traffic path formation in the core.
Layer 2 IPv6 traffic is only supported on NCS 5700 fixed port routers and NCS 5500 modular routers (NCS 5700 line cards [Mode: Native]).
In an EVPN dual-home AA scenario:
If the multicast source and receiver are in the same BD, the receiver might receive permanent traffic duplication.
Transient traffic duplication might occur when the DH node role changes between DF and nDF.
In a BD, the following EVPN configuration is not supported:
Multicast source—ESI1=BE-X.A
Multicast receiver—ESI1=BE-X.B
Note |
ESI is the Ethernet Segment identifier, whereas X.Aand X.B represents two AC ports for the bundle interface BE. |
In a BD, the following EVPN configuration is not supported:
Multicast source—ESI1=BE-X.A (NCS 5700 line cards)
Multicast receiver—ESI1=BE-Y.A (NCS 5500 line cards)
Note |
ESI is the Ethernet Segment identifier, whereas X.Aand Y.A represents two AC ports for the bundle interface BE. |
To configure an EVPN All-Active Multi-homed multicast source with a BVI interface, use the following example configuration:
Router#configure
Router(config)#l2vpn
Router(config-l2vpn)#bridge group BG1
Router(config-l2vpn-bg)#bridge-domain BD1
Router(config-bg-bd)#multicast-source ipv4-ipv6
Router(config-bg-bd)#mld snooping profile mldsn
Router(config-bg-bd)#igmp snooping profile igmpsn
Router(config-bg-bd)#interface Bundle-Ether1
Router(config-bg-bd-ac)#exit
Router(config-bg-bd)#interface TenGigE0/0/0/23.1
Router(config-bg-bd-ac)#exit
Router(config-bg-bd)#routed interface BVI1
Router(config-bg-bd)#evi 3000
Router(config-bg-bd-bvi)#commitThis section shows the EVPN All-Active Multi-homed multicast source with BVI as accept interface running configuration.
l2vpn
bridge group bg1
bridge-domain bd1
multicast-source ipv4-ipv6
mld snooping profile mldsn
igmp snooping profile igmpsn
interface Bundle-Ether1
!
interface TenGigE0/0/0/23.1
!
routed interface BVI1
!
evi 3000
!
!
!
!
Default behavior in EVPN involves collapsing core replications into L2 multicast routes (BD, S, G). To modify this behaviour and collapse EVPN Core to Bridge ingress multicast ID (MCID) and Snooping default routes instead of L2 multicast routes, use the following command:
Router(config)# hw-module multicast evpn ole-collapse-disableSample Configuration
Router(config)# hw-module multicast evpn ole-collapse-disable
Mon Apr 3 20:37:39.218 UTC
/*To apply the disable or re-enable EVPN OLE collapse settings, you must reload the chassis and all the installed line cards*/
Router# commit
Mon Apr 3 20:37:46.886 UTC
Router# end
Router# admin
Mon Apr 3 20:37:52.234 UTC
lab connected from 1.1.1.1 using ssh on sysadmin-vm:0_RP0
Reloading the RP in Order to apply the HW-cli Evpn ole collapse disable command to set
sysadmin-vm:0_RP0# hw-module location 0/RP0 reload
Mon Apr 3 20:38:15.290 UTC+00:00
Reload hardware module ? [no,yes]
/*Verification After Reload*/
Router# sh dpa objects global location 0/0/cPU0 | i evpn
Mon Apr 3 20:48:38.939 UTC
ofa_bool_t mcast_evpn_ole_collapse_disable => TRUE.
Router# sh running-config | i hw-
Mon Apr 3 20:48:43.575 UTC
hw-module multicast evpn ole-collapse-disableVerify that you have configured multicast over BVI. The BVI acts as a forwarding interface for the L3 multicast packets.
/*PE-0*/
Router# show mrib vrf green ipv4 route 40.0.0.5
Mon May 8 12:15:44.924 UTC
(40.0.0.5,232.0.0.1) RPF nbr: 40.0.0.5 Flags: RPF
Up: 00:04:03
Incoming Interface List
BVI1 Flags: F A LI, Up: 00:04:03
Outgoing Interface List
BVI1 Flags: F A LI, Up: 00:04:03
/*Local L3 multicast join*/
TenGigE0/0/0/0.2 Flags: F NS LI, Up: 00:04:03
/*PE-1*/
Router# show mrib vrf green ipv4 route 40.0.0.5 detail
Thu May 11 09:19:07.958 UTC
(40.0.0.5,232.0.0.1) Ver: 0x1008 RPF nbr: 40.0.0.5 Flags: RPF EID, FGID: 15481, Statistics enabled: 0x0, Tunnel RIF: 0xffffffff, Tunnel LIF: 0xffffffff
Up: 05:29:49
RPF-ID: 0, Encap-ID: 262146
Incoming Interface List
BVI1 Flags: F A LI, Up: 05:29:49
Outgoing Interface List
BVI1 Flags: F A LI, Up: 05:29:49
/*Remote L3 join from multicast receiver learnt on PE-1. Multicast traffic to remote L3 multicast receiver is forwarded from PE-1*/
Lmdtgreen Flags: F LMI TR, Up: 05:27:02, Head LSM-ID: 0x00001
/*Local L3 multicast join*/
TenGigE0/0/0/23.2 Flags: F NS LI, Up: 05:29:48The first two tasks are required to configure basic IGMP snooping configuration.
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
configure |
|
|
Step 2 |
igmp snooping profile profile-name Example: |
Enters IGMP snooping profile configuration mode and creates a named profile. The default profile enables IGMP snooping. You can commit the new profile without any additional configurations, or you can include additional configuration options to the profile. You can also return to the profile later to add configurations, as described in other tasks in this module. |
|
Step 3 |
Optionally, add commands to override default configuration values. |
If you are creating a bridge domain profile, consider the following:
If you are creating a port-specific profile, consider the following:
You can detach a profile, change it, and reattach it to add commands to a profile at a later time. |
|
Step 4 |
commit |
You must attach a profile to a bridge domain or to a port to have it take effect. See one of the following tasks:
To activate IGMP snooping on a bridge domain, attach an IGMP snooping profile to the bridge domain, as described in the following steps.
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
configure |
|
|
Step 2 |
l2vpn Example: |
Enters Layer 2 VPN configuration mode. |
|
Step 3 |
bridge group bridge-group-name Example: |
Enters Layer 2 VPN VPLS bridge group configuration mode for the named bridge group. |
|
Step 4 |
bridge-domain bridge-domain-name Example: |
Enters Layer 2 VPN VPLS bridge group bridge domain configuration mode for the named bridge domain. |
|
Step 5 |
multicast-source ipv4 Example: |
Configures Layer 2 multicast routes with IGMP snooping. |
|
Step 6 |
igmp snooping profile profile-name Example: |
Attaches the named IGMP snooping profile to the bridge domain, enabling IGMP snooping on the bridge domain. |
|
Step 7 |
commit |
|
|
Step 8 |
show igmp snooping bridge-domain detail Example: |
(Optional) Verifies that IGMP snooping is enabled on a bridge domain and shows the IGMP snooping profile names attached to bridge domains and ports. |
|
Step 9 |
show l2vpn bridge-domain detail Example: |
(Optional) Verifies that IGMP snooping is implemented in the forwarding plane (Layer 2) on a bridge domain. |
To deactivate IGMP snooping on a bridge domain, remove the profile from the bridge domain using the following steps.
Note |
A bridge domain can have only one profile attached to it at a time. |
| Command or Action | Purpose | |||
|---|---|---|---|---|
|
Step 1 |
configure |
|||
|
Step 2 |
l2vpn Example: |
Enters Layer 2 VPN configuration mode. |
||
|
Step 3 |
bridge group bridge-group-name Example: |
Enters Layer 2 VPN VPLS bridge group configuration mode for the named bridge group. |
||
|
Step 4 |
bridge-domain bridge-domain-name Example: |
Enters Layer 2 VPN VPLS bridge group bridge domain configuration mode for the named bridge domain. |
||
|
Step 5 |
no igmp snooping disable Example: |
Detaches the IGMP snooping profile from the bridge domain, disabling IGMP snooping on that bridge domain.
|
||
|
Step 6 |
commit |
|||
|
Step 7 |
show igmp snooping bridge-domain detail Example: |
(Optional) Verifies that IGMP snooping is disabled on a bridge domain. |
||
|
Step 8 |
show l2vpn bridge-domain detail Example: |
(Optional) Verifies that IGMP snooping is disabled in the forwarding plane (Layer 2) on a bridge domain. |
IGMP snooping must be enabled on the bridge domain for port-specific profiles to affect IGMP snooping behavior.
| Command or Action | Purpose | |||
|---|---|---|---|---|
|
Step 1 |
configure |
|||
|
Step 2 |
l2vpn Example: |
Enters Layer 2 VPN configuration mode. |
||
|
Step 3 |
bridge group bridge-group-name Example: |
Enters Layer 2 VPN bridge group configuration mode for the named bridge group. |
||
|
Step 4 |
bridge-domain bridge-domain-name Example: |
Enters Layer 2 VPN bridge group bridge domain configuration mode for the named bridge domain. |
||
|
Step 5 |
interface interface-type interface-number Example: |
Enters Layer 2 VPN VPLS bridge group bridge domain interface configuration mode for the named interface or PW. |
||
|
Step 6 |
multicast-source ipv4 Example: |
Configures L2 multicast routes in L2 multicast with IGMP Snooping. |
||
|
Step 7 |
Do one of the following:
Example: |
Attaches the named IGMP snooping profile to the port.
The no form of the command detaches a profile from the port. Only one profile can be attached to a port. |
||
|
Step 8 |
commit |
|||
|
Step 9 |
show igmp snooping bridge-domain detail Example: |
(Optional) Verifies that IGMP snooping is enabled on a bridge domain and shows the IGMP snooping profile names attached to bridge domains and ports. |
||
|
Step 10 |
show l2vpn bridge-domain detail Example: |
(Optional) Verifies that IGMP snooping is implemented in the forwarding plane (Layer 2) on a bridge domain. |
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
configure |
|
|
Step 2 |
show l2vpn forwarding bridge-domain [bridge-group-name:bridge-domain-name] mroute ipv4 [group group_IPaddress ] [hardware {ingress | egress}] [detail]location node-id Example: |
Displays multicast routes as they are converted into the forwarding plane forwarding tables. Use optional arguments to limit the display to specific bridge groups or bridge domains. If these routes are not as expected, check the control plane configuration and correct the corresponding IGMP snooping profiles. |
|
Step 3 |
show l2vpn forwarding bridge-domain [bridge-group-name:bridge-domain-name] mroute ipv4 summary location node-id Example: |
Displays summary-level information about multicast routes as stored in the forwarding plane forwarding tables. Use optional arguments to limit the display to specific bridge domains. |
The following examples show how to enable IGMP snooping on Layer 2 VPLS bridge domains on :
Create two profiles.
igmp snooping profile profile1
!
igmp snooping profile profile2
mrouter
!
Configure two physical interfaces for L2 transport.
interface GigabitEthernet0/8/0/38
negotiation auto
l2transport
no shut
!
!
interface GigabitEthernet0/8/0/39
negotiation auto
l2transport
no shut
!
!
Add interfaces to the bridge domain. Attach bridge_profile to the bridge domain and port_profile to one of the Ethernet interfaces. The second Ethernet interface inherits IGMP snooping configuration attributes from the bridge domain profile.
l2vpn
bridge group bg1
bridge-domain bd1
igmp snooping profile profile1
interface GigabitEthernet0/8/0/38
igmp snooping profile profile2
interface GigabitEthernet0/8/0/39
!
!
!
Verify the configured bridge ports.
show igmp snooping port
Configure two profiles.
multicast-source ipv4
igmp snooping profile profile1
igmp snooping profile profile2
!
Configure VLAN interfaces for L2 transport.
interface GigabitEthernet0/8/0/8
negotiation auto
no shut
!
!
interface GigabitEthernet0/8/0/8.1 l2transport
encapsulation dot1q 1001
rewrite ingress tag pop 1 symmetric
!
!
interface GigabitEthernet0/8/0/8.2 l2transport
encapsulation dot1q 1002
rewrite ingress tag pop 1 symmetric
!
!
Attach a profile and add interfaces to the bridge domain. Attach a profile to one of the interfaces. The other interface inherits IGMP snooping configuration attributes from the bridge domain profile.
l2vpn
bridge group bg1
bridge-domain bd1
multicast-source ipv4
igmp snooping profile profile1
interface GigabitEthernet0/8/0/8.1
igmp snooping profile profile2
interface GigabitEthernet0/8/0/8.2
!
!
!
Verify the configured bridge ports.
show igmp snooping port
Configure two IGMP snooping profiles.
multicast-source ipv4
igmp snooping profile profile1
!
multicast-source ipv4
igmp snooping profile profile2Configure interfaces as bundle member links.
interface GigabitEthernet0/0/0/0
bundle id 1 mode on
negotiation auto
!
interface GigabitEthernet0/0/0/1
bundle id 1 mode on
negotiation auto
!
interface GigabitEthernet0/0/0/2
bundle id 2 mode on
negotiation auto
!
interface GigabitEthernet0/0/0/3
bundle id 2 mode on
negotiation auto
!
Configure the bundle interfaces for L2 transport.
interface Bundle-Ether 1
l2transport
!
!
interface Bundle-Ether 2
l2transport
!
!
Add the interfaces to the bridge domain and attach IGMP snooping profiles.
l2vpn
bridge group bg1
bridge-domain bd1
multicast-source ipv4
igmp snooping profile profile1
interface bundle-Ether 1
multicast-source ipv4
igmp snooping profile profile2
interface bundle-Ether 2
!
!
!
Verify the configured bridge ports.
show igmp snooping port
Configurations performed on peer 1:
1. Layer 2 Base Configuration
hostname peer1
!
interface Bundle-Ether2
!
interface Bundle-Ether2.2 l2transport
encapsulation dot1q 2
rewrite ingress tag pop 1 symmetric
!
interface TenGigE0/0/0/0
bundle id 2 mode on
no shut
!
2. EVPN Configuration
hostname peer1
!
router bgp 100
bgp router-id 1.1.1.1
bgp graceful-restart
address-family l2vpn evpn
!
neighbor 3.3.3.3
remote-as 100
update-source Loopback0
address-family l2vpn evpn
!
!
!
evpn
evi 2
advertise-mac
!
!
interface Bundle-Ether2
ethernet-segment
identifier type 0 02.02.02.02.02.02.02.02.02
bgp route-target 0002.0002.0002
!
!
!
3. IGMPv2 Snoop Configurations
hostname peer1
!
router igmp
version 2
!
!
l2vpn
bridge group VLAN2
bridge-domain VLAN2
multicast-source ipv4
igmp snooping profile 1
interface Bundle-Ether2.2
!
evi 2
!
!
!
multicast-source ipv4
igmp snooping profile 1
!
Configurations Performed on Peer 2:
1. Layer 2 Base Configuration
hostname peer2
!
interface Bundle-Ether2
!
interface Bundle-Ether2.2 l2transport
encapsulation dot1q 2
rewrite ingress tag pop 1 symmetric
!
interface TenGigE0/0/0/0
bundle id 2 mode on
no shut
!
2. EVPN Configuration
hostname peer2
!
router bgp 100
bgp router-id 2.2.2.2
bgp graceful-restart
address-family l2vpn evpn
!
neighbor 3.3.3.3
remote-as 100
update-source Loopback0
address-family l2vpn evpn
!
!
!
evpn
evi 2
advertise-mac
!
!
interface Bundle-Ether2
ethernet-segment
identifier type 0 02.02.02.02.02.02.02.02.02
bgp route-target 0002.0002.0002
!
!
!
3. IGMPv2 Snoop Configurations
hostname peer2
!
router igmp
version 2
!
!
l2vpn
bridge group VLAN2
bridge-domain VLAN2
multicast-source ipv4
igmp snooping profile 1
interface Bundle-Ether2.2
!
evi 2
!
!
!
multicast-source ipv4
igmp snooping profile 1
!
In this example, the receiver sends an IGMPv2 join for the group 239.0.0.2. On Peer2, this group has a D Flag, that means the actual IGMP joined peer2, but not peer1. On Peer1, this group has a B flag, that means this group is learnt from BGP with the EVPN sync feature.
RP/0/RP0/CPU0:peer1#show igmp snooping group
Fri Aug 31 22:27:46.363 UTC
Key: GM=Group Filter Mode, PM=Port Filter Mode
Flags Key: S=Static, D=Dynamic, B=BGP Learnt, E=Explicit Tracking, R=Replicated
Bridge Domain VLAN10:VLAN10
Group Ver GM Source PM Port Exp Flgs
----- --- -- ------ -- ---- --- ----
239.0.0.2 V2 - * - BE2.2 never B
RP/0/RP0/CPU0:peer2#show igmp snooping group
Fri Aug 31 22:27:49.686 UTC
Key: GM=Group Filter Mode, PM=Port Filter Mode
Flags Key: S=Static, D=Dynamic, B=BGP Learnt, E=Explicit Tracking, R=Replicated
Bridge Domain VLAN10:VLAN10
Group Ver GM Source PM Port Exp Flgs
----- --- -- ------ -- ---- --- ----
239.0.0.2 V2 - * - BE2.2 74 D
In this example, when the source 126.0.0.100 sends traffic to group 239.0.0.2, you see both Peer1 and Peer2 are sending PIM join upstream. The incoming interface for (*,G) and (S,G) should be the interface toward the RP and source respectively. For both Peer1 and Peer2, the outgoing interface should be the BVI interface facing the receiver.
RP/0/RP0/CPU0:peer1#show mrib route
:
:
(*,239.0.0.2) RPF nbr: 30.0.0.4 Flags: C RPF
Up: 00:13:41
Incoming Interface List
HundredGigE0/0/0/1 Flags: A NS, Up: 00:13:41
Outgoing Interface List
BVI2 Flags: F NS LI, Up: 00:13:41
(126.0.0.100,239.0.0.2) RPF nbr: 30.0.0.4 Flags: RPF
Up: 00:03:34
Incoming Interface List
HundredGigE0/0/0/1 Flags: A, Up: 00:03:34
Outgoing Interface List
BVI2 Flags: F NS, Up: 00:03:34
:
:
RP/0/RP0/CPU0:peer2#show mrib route
:
:
(*,239.0.0.2) RPF nbr: 50.0.0.4 Flags: C RPF
Up: 00:13:33
Incoming Interface List
HundredGigE0/0/0/2 Flags: A NS, Up: 00:13:33
Outgoing Interface List
BVI2 Flags: F NS LI, Up: 00:13:33
(126.0.0.100,239.0.0.2) RPF nbr: 50.0.0.4 Flags: RPF
Up: 00:03:24
Incoming Interface List
HundredGigE0/0/0/2 Flags: A, Up: 00:03:24
Outgoing Interface List
BVI2 Flags: F NS, Up: 00:03:24
:
:
As described in the previous example, both peer1 and peer2 have BVI2 as outgoing interface. However, only one of the peer should forward the traffic. Designated forwarder election elects one of them to do the forwarding. In this example, peer2 is selected as the forwarder. Peer1 has Bundle-Ether2.2 marked as NDF.
RP/0/RP0/CPU0:peer1#show l2vpn forwarding bridge-domain VLAN2:VLAN2 mroute ipv4 hardware ingress detail location 0/0/cPU0
Bridge-Domain: VLAN2:VLAN2, ID: 0
:
:
Bridge-Domain: VLAN2:VLAN2, ID: 0
Prefix: (0.0.0.0,239.0.0.2/32)
P2MP enabled: N
IRB platform data: {0x0, 0x2d, 0x0, 0x0}, len: 32
Bridge Port:
EVPN, Xconnect id: 0x80000001 NH:2.2.2.2
Bundle-Ether2.2, Xconnect id: 0xa0000015 (NDF)
RP/0/RP0/CPU0:peer2#show l2vpn forwarding bridge-domain VLAN2:VLAN2 mroute ipv4 hardware ingress detail location 0/0/cPU0
:
:
Bridge-Domain: VLAN2:VLAN2, ID: 0
Prefix: (0.0.0.0,239.0.0.2/32)
P2MP enabled: N
IRB platform data: {0x0, 0x30, 0x0, 0x0}, len: 32
Bridge Port:
EVPN, Xconnect id: 0x80000001 NH:1.1.1.1
Bundle-Ether2.2, Xconnect id: 0xa0000029
|
Related Topic |
Document Title |
|---|---|
|
Configuring MPLS VPLS bridges |
Implementing Virtual Private LAN Services on Cisco IOS XR Software module in the MPLS Configuration Guide |
|
Getting started information |
|
|
Configuring EFPs and EFP bundles |
Interface and Hardware Component Configuration Guide for Cisco NCS 560 Series Routers |
|
Standards1 |
Title |
|---|---|
|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
— |
|
MIBs |
MIBs Link |
|---|---|
|
No MIBs support IGMP snooping. |
To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml |
|
RFCs |
Title |
|---|---|
|
RFC-4541 |
Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches |
|
Description |
Link |
|---|---|
|
The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. |
Multicast Listener Discovery (MLD) snooping provides a way to constrain multicast traffic at Layer 2. By snooping the MLD membership reports sent by hosts in the bridge domain, the MLD snooping application can set up Layer 2 multicast forwarding tables to deliver traffic only to ports with at least one interested member, significantly reducing the volume of multicast traffic.
MLD snooping uses the information in MLD membership report messages to build corresponding information in the forwarding tables to restrict IPv6 multicast traffic at Layer 2. The forwarding table entries are in the form <Route, OIF List>, where:
Route is a <*, G> route or <S, G> route.
OIF List comprises all bridge ports that have sent MLD membership reports for the specified route plus all multicast router (mrouter) ports in the bridge domain.
For more information regarding MLD snooping, refer the Multicast Configuration Guide for Cisco NCS 560 Series Routers.
The network must be configured with a layer2 VPN.
You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
BVI under bridge domain is supported.
Receiver behind L2 ACs in the same L2 bridge domain is supported.
Source behind L2 ACs in the same L2 bridge domain is only supported on NCS 5700 fixed port routers and NCS 5700 line cards [Mode: Compatibility; Native].
MLDv1 not supported over BVI.
EVPN MLD sync is not supported.
VPLS is not supported.
On the NCS 5700 line cards, MLD snooping can be enabled alongside IGMP snooping only.
The router-alert-check disable configuration command is not supported.
EVPN dual-home source AA is not supported on the NCS 5500 line cards line cards.
Both IGMP and MLD snooping configurations are necessary to enable MLD snooping on the NCS 5700 line cards.
EVPN configuration must have the control-word-disable configuration.
PIM control packets (join and hello) processing is not supported when snooping is enabled, so a multicast router selection based on PIM packets won't occur.
Explicit host tracking.
Multicast Admission Control.
Security filtering.
Report rate limiting.
Multicast router discovery.
IPv6 multicast is not supported for a multicast source that is behind the BVI interface. For example, the below configuration is not supported:
l2vpn
bridge group 1
bridge-domain 1
multicast-source ipv6
mld snooping profile grp1
In an EVPN dual-home AA scenario:
If the multicast source and receiver are in the same bridge domain (BD), the receiver might receive permanent traffic duplication.
In an EVPN dual-home receiver AA scenario, transient traffic duplication is expected when the DH node role changes from DF to nDF and vice versa.
Source=ESI1=BE-X.A, Receiver=ESI1=BE-X.B under the same BD is not supported (where X.A and X.B represent two AC ports for the bundle interface BE).
Source=ESI1=BE-X.A (for NCS 5700 line cards), Receiver=ESI2=BE-Y.A (for NCS 5500 line cards) under the same BD is not supported (where X.A and Y.A represent two AC ports for the bundle interface BE).
In its basic form, it reduces bandwidth consumption by reducing multicast traffic that would otherwise flood an entire VPLS bridge domain.
With the use of some optional configurations, it provides security between bridge domains by filtering the MLD reports received from hosts on one bridge port and preventing leakage towards the hosts on other bridge ports.
MLD supports the following HA features:
Process restarts
RP Failover
Stateful Switch-Over (SSO)
Non-Stop Forwarding (NSF)—Forwarding continues unaffected while the control plane is restored following a process restart or route processor (RP) failover.
Line card online insertion and removal (OIR)
MLD snooping operates at the bridge domain level. When MLD snooping is enabled on a bridge domain, the snooping functionality applies to all ports under the bridge domain, including:
Physical ports under the bridge domain.
Ethernet flow points (EFPs)—An EFP can be a VLAN, VLAN range, list of VLANs, or an entire interface port.
Ethernet bundles—Ethernet bundles include IEEE 802.3ad link bundles and Cisco EtherChannel bundles. From the perspective of the MLD snooping application, an Ethernet bundle is just another EFP. The forwarding application in the randomly nominates a single port from the bundle to carry the multicast traffic.
Note |
The efp-visibility configuration is required when a bridge has attachment circuits as VLAN sub-interfaces from the same bundle-ether or physical interface. |
MLD snooping classifies each port as one of the following:
Multicast router ports (mrouter ports)—These are ports to which a multicast-enabled router is connected. Mrouter ports are usually dynamically discovered, but may also be statically configured. Multicast traffic is always forwarded to all mrouter ports, except when an mrouter port is the ingress port.
Host ports—Any port that is not an mrouter port is a host port.
MLD snooping discovers mrouter ports dynamically. You can also explicitly configure a port as an emrouter port.
Discovery- MLD snooping identifies upstream mrouter ports in the bridge domain by snooping mld query messages and Protocol Independent Multicast Version 2 (PIMv2) hello messages. Snooping PIMv2 hello messages identifies mld nonqueriers in the bridge domain.
Static configuration—You can statically configure a port as an mrouter port with the mrouter command in a profile attached to the port. Static configuration can help in situations when incompatibilities with non-Cisco equipment prevent dynamic discovery.
The following tables describe the traffic handling behavior by MLD mrouters and host ports.
|
Traffic Type |
Received on MRouter Ports |
Received on Host Ports |
|---|---|---|
|
IP multicast source traffic |
Forwards to all mrouter ports and to host ports that indicate interest. |
Forwards to all mrouter ports and to host ports that indicate interest. |
|
MLD general queries |
Forwards to all ports. |
— |
|
MLD group-specific queries |
Forwards to all other mrouter ports. |
Dropped |
|
MLDv1 joins |
Examines (snoops) the reports.
|
Examines (snoops) the reports.
|
|
MLDv2 reports |
Ignores |
Ignores |
|
MLDv1 leaves |
Invokes last member query processing. |
Invokes last member query processing. |
|
Traffic Type |
Received on MRouter Ports |
Received on Host Ports |
|---|---|---|
|
IP multicast source traffic |
Forwards to all mrouter ports and to host ports that indicate interest. |
Forwards to all mrouter ports and to host ports that indicate interest. |
|
MLD general queries |
Forwards to all ports. |
— |
|
MLD group-specific queries |
If received on the querier port floods on all ports. |
— |
|
MLDv1 joins |
Handles as MLDv2 IS_EX{} reports. |
Handles as MLDv2 IS_EX{} reports. |
|
MLDv2 reports |
|
|
|
MLDv1 leaves |
Handles as MLDv2 IS_IN{} reports. |
Handles as MLDv2 IS_IN{} reports. |
Multicast IPv6 packets received from core, which has BVI as forwarding interface, is forwarded to access over snooped L2 AC or interface.
Note |
|
Routers use the Internet Group Management Protocol (IGMP) (IPv4) and Multicast Listener Discovery (MLD) (IPv6) to learn whether members of a group are present on their directly attached subnets. Hosts join multicast groups by sending IGMP or MLD report messages.
MLDv1 and MLDv2 are supported on . However, MLDv2 is enabled when you configure MLD by default.
MLDv2 shares feature parity with IGMPv3 with respect to all supported interface types with the exception of PPoE and subinterfaces. MLDv2 enables a node to report interest in listening to packets only from specific multicast source addresses.
A BVI interface is a routed interface representing a set of interfaces (bridged) in the same L2 broadcast domain. MLD join messages coming in or out of this broadcast domain passes through the BVI interface.
|
Feature Name |
Release Information |
Feature Description |
|---|---|---|
|
Multicast Traffic over Layer 2 IPv6 Network |
Release 7.9.1 |
This feature allows you to forward the IPv6 multicast packets only to the interested MLD-snooped Access Controllers (AC), whereas in the default case, the bridge floods the IPv6 multicast packets to all AC. Routers use Multicast Listener Discovery (MLD) protocol to discover the devices in a network and create route entries in an IPv6 multicast network. This feature introduces following CLI:
|
The Multicast Traffic over Layer 2 IPv6 Network (L2MC IPv6) is an optimized forwarding technique, and it helps in saving the bandwidth. By default, the bridge floods IPv6 multicast packets to all AC, whereas the L2MC IPv6 feature allows you to forward the IPv6 multicast packets only to the interested MLD-snooped AC.
When IPv6 multicast packets are received over Layer 2 AC and interfaces, the lookup gets done for Virtual Switch Interfaces (VSI), Groups (G), and Services (S) or for VSI and G. The VSI details show the VLAN or VXLAN segment to which the packet belongs, while the G and S identify the multicast groups and services to which the packet should be forwarded. Based on this lookup, the traffic is forwarded to the interested receivers connected to the Layer 2 AC.
The MLD control packets received over Layer 2 AC are snooped and punted to create the route entries. This route entries are needed to avail the following supports:
Layer 2 Multicast IPv6 support.
EVPN sync support for IPv4 routes.
This feature is supported on routers that have the Cisco NC57 line cards installed and operate in native and compatible modes.
This feature doesn’t support MLD sync.
With L2MC IPv6 support, the existing L2MC IPv4 scale reduces proportionally.
router(config)# l2vpn
router(config-l2vpn)# bridge group 1
router(config-l2vpn-bg)#bridge-domain 1
router(config-l2vpn-bg-bd)#multicast-source ipv6
router(config-l2vpn-bg-bd)#efp-visibility
router(config-l2vpn-bg-bd)#mld snooping profile prof1
router(config-l2vpn-bg-bd)#igmp snooping profile prof1
router(config-l2vpn-bg-bd)#interface TenGigE0/0/0/0
router(config-l2vpn-bg-bd-ac)#exit
router(config-l2vpn-bg-bd)#interface TenGigE0/0/0/4.1
router(config-l2vpn-bg-bd-ac)#exit
router(config-l2vpn-bg-bd)#interface TenGigE0/0/0/4.2
router(config-l2vpn-bg-bd-ac)#exit
router(config-l2vpn-bg-bd)#routed interface BVI1
router(config-l2vpn-bg-bd-bvi)#exit
!
!
router(config-l2vpn-bg-bd)#mld snooping profile prof1
router(config-l2vpn-bg-bd)#internal-querier
!
router(config-l2vpn-bg-bd)#igmp snooping profile prof1
router(config-l2vpn-bg-bd)#system-ip-address 1.2.3.4
router(config-l2vpn-bg-bd)#internal-querierNote |
With BVI configurations, there is no need to have internal queries address configured MLD snooping profile. It implies that you can make BVI as querier under BVI configuration. |
The following command shows the information about group membership in the Layer 2 Forwarding tables.
router# show mld snooping group
Flags Key: S=Static, D=Dynamic, E=Explicit Tracking
Bridge Domain bg1:bd1
Group Ver GM Source PM Port Exp Flg
Ff12:1:1::1 V2 Exc - - GigabitEthernet0/1/1/0 122 DE
Ff12:1:1::1 V2 Exc 2002:1::1 Inc GigabitEthernet0/1/1/1 5 DE
Ff12:1:1::1 V2 Exc 2002:1::1 Inc GigabitEthernet0/1/1/2 never S
Ff12:1:1::1 V2 Exc 2002:1::1 Exc GigabitEthernet0/1/1/3 - DE
Ff12:1:1::1 V2 Exc 2002:1::2 Inc GigabitEthernet0/1/1/0 202 DE
Ff12:1:1::1 V2 Exc 2002:1::2 Exc GigabitEthernet0/1/1/1 - DE
Ff12:1:1::2 V2 Exc 2002:1::1 Inc GigabitEthernet0/1/1/0 145 DE
Ff12:1:1::2 V2 Exc 2002:1::1 Inc GigabitEthernet0/1/1/1 0 DE
Ff12:1:1::2 V2 Exc 2002:1::1 Exc GigabitEthernet0/1/1/2 11 DE
Bridge Domain bg1:bd4
Group Ver GM Source PM Port Exp Flg
Ff24:1:1::2 V1 Exc - - GigabitEthernet0/1/1/0 122 DE
Ff28:1:1::1 V1 - - - GigabitEthernet0/1/1/1 33 DE
Ff29:1:2::3 V1 Exc - - GigabitEthernet0/1/2/0 122 DE
Ff22:1:2::3 V2 Exc 2000:1:1::2 Exc GigabitEthernet0/1/2/1 5 DEThe following command summarizes the number of bridge domains, mrouter ports, host ports, groups, and sources configured on the router.
router#show mld snooping summary
Bridge Domains: 1
MLD Snooping Bridge Domains: 1
Ports: 3
MLD Snooping Ports: 3
Mrouters: 0
STP Forwarding Ports: 0
ICCP Group Ports: 0
MLD Groups: 0
Member Ports: 0
MLD Source Groups: 0
Static/Include/Exclude: 0/0/0
Member Ports (Include/Exclude): 0/0Multicast Listener Discovery (MLD) snooping provides a way to constrain multicast traffic at L2. By snooping the MLD membership reports sent by hosts in the bridge domain, the MLD snooping application can set up L2 multicast forwarding tables. This table is later used to deliver traffic only to ports with at least one interested member, significantly reducing the volume of multicast traffic.
MLDv2 support over BVI enables implementing IPv6 multicast routing over a L2 segment of the network that is using an IPv6 VLAN. The multicast routes are bridged via BVI interface from L3 segment to L2 segment of the network.
MLDv2 snooping over BVI enables forwarding MLDv2 membership reports received over the L2 domain to MLD snooping instead of MLD.
You cannot configure ttl-check and disable router-alert-check on the router for mld messages.
Static mrouters are not supported for MLD snooping.
Querier is supported for MLDV2, but it is not supported on MLDV1.
This configuration enables a multicast router acting as a MLD querier to send out group-and-source-specific query:
router# config
RP0/0/RP0/CPU0:router(config)# mld snooping profile grp1
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# system-ip-address fe80::1 link-local
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# internal-querier
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# commit
Use the show mld snooping profile detail command to verify the MLD snooping configuration:
router# show mld snooping profile detail
Thu Nov 22 13:58:18.844 UTC
MLD Snoop Profile grp1:
System IP Address: fe80::1
Bridge Domain References: 2
Port References: 12
MLD Snoop Profile grp10:
System IP Address: fe80::5610
Bridge Domain References: 0
Port References: 0
/* Enter the global configuration mode */
RP/0/RP0/CPU0:router # configure
/* Enters MLD snooping profile configuration mode and creates a named profile. */
RP/0/RP0/CPU0:router(config)# mld snooping profile default-bd-profile
RP/0/RP0/CPU0:router # commit
The default profile enables MLD snooping. You can commit the new profile without any additional configurations, or you can include additional configuration options to the profile. You can also return to the profile later to add configurations, as described in other tasks in this module.
If you are creating a bridge domain profile, consider the following:
An empty profile is appropriate for attaching to a bridge domain. An empty profile enables MLD snooping with default configuration values.
You can optionally add more commands to the profile to override default configuration values.
If you include port-specific configurations in a bridge domain profile, the configurations apply to all ports under the bridge, unless another profile is attached to a port.
If you are creating a port-specific profile, consider the following:
While an empty profile could be attached to a port, it would have no effect on the port configuration.
When you attach a profile to a port, MLD snooping reconfigures that port, overriding any inheritance of configuration values from the bridge-domain profile. You must repeat the commands in the port profile if you want to retain those configurations.
You can detach a profile, change it, and reattach it to add commands to a profile at a later time.
RP/0/RP0/CPU0:router(config)# show running-config
configure
mld snooping profile default-bd-profile
!Verify that the MLD snooping profile is created:
RP/0/RP0/CPU0:router#show mld snooping profile
Profile Bridge Domain Port
------- ------------- ----
default-bd-profile 0 0
grp1 1 2
grp10 1 2
To deactivate MLD snooping from a bridge domain, remove the profile from the bridge domain:
Note |
A bridge domain can have only one profile attached to it at a time. |
/* Enter the global configuration mode followed by the bridge group and the bridge domain mode */
RP0/0/RP0/CPU0:router# configuration
RP0/0/RP0/CPU0:router(config)# l2vpn
RP0/0/RP0/CPU0:router(config-l2vpn)# bridge group GRP1
RP0/0/RP0/CPU0:router(config-l2vpn-bg)# bridge domain ISP1
/* Detache the MLD snooping profile from the bridge domain. This disables MLD snooping on that bridge domain */
/* Note: Only one profile can be attached to a bridge domain at a time. If a profile is attached, MLD snooping is enabled.
If a profile is not attached, MLD snooping is disabled. */
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd)# no mld snooping profile
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd)# commit
RP0/0/RP0/CPU0:router# show running-config
configuration
l2vpn
bridge-group GRP1
bridge-domain ISP1
no mld snooping profile
!
MLD snooping must be enabled on the bridge domain for port-specific profiles to affect MLD snooping behavior.
Note |
Static mrouter port configuration is a port-level option and should be added to profiles intended for ports. It is not recommended to add mrouter port configuration to a profile intended for bridge domains. |
/* Enter the global configuration mode */
RP0/0/RP0/CPU0:router# configuration
/* Enter the MLD snooping profile configuration mode and create a new profile or accesses an existing profile.*/
RP0/0/RP0/CPU0:router(config)# mld snooping profile mrouter-port-profile
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# mrouter
/* Configures a static mrouter on a port. */
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# commit
RP0/0/RP0/CPU0:router# show running-config
configuration
mld snooping profile mrouter-port-profile
mrouter
!
RP0/0/RP0/CPU0:router# show mld snooping profile mrouter-port-profile
MLD Snoop Profile mrouter-port-profile:
Static Mrouter: Enabled
Bridge Domain References: 0
Port References: 0
To prevent multicast routing protocol messages from being received on a port and, therefore, prevent a port from being a dynamic mrouter port, follow these steps. Note that both router guard and static mrouter commands may be configured on the same port.
MLD snooping must be enabled on the bridge domain for port-specific profiles to affect MLD snooping behavior.
Note |
Router guard configuration is a port-level option and should be added to profiles intended for ports. It is not recommended to add router guard configuration to a profile intended for bridge domains. To do so would prevent all mrouters, including MLD queriers, from being discovered in the bridge domain. |
/* Enter the global configuration mode and create the Bridge Group GRP1 and the Bridge Domain ISP1*/
RP0/0/RP0/CPU0:router# configuration
/* Enter the MLD snooping profile configuration mode and create a new profile or accesses an existing profile. */
RP0/0/RP0/CPU0:router(config)# mld snooping profile host-port-profile
/* Configure router guard. This protects the port from dynamic discovery.*/
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# router-guard
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd)# commit
RP0/0/RP0/CPU0:router# show running-config
configuration
mld snooping profile host-port-profile
router-guard
!
Verify that the router guard config in the named profile is enabled:
RP0/0/RP0/CPU0:router# show mld snooping profile host-port-profile detail
MLD Snoop Profile host-port-profile:
Router Guard: Enabled
Bridge Domain References: 0
Port References: 0
To add the MLD snooping immediate-leave option to an MLD snooping profile:
/* Enter the global configuration mode. */
RP0/0/RP0/CPU0:router# configuration
/* Enter MLD snooping profile configuration mode and create a new profile or accesses an existing profile. */
RP0/0/RP0/CPU0:router(config)# mld snooping profile host-port-profile
/* Enable the immediate-leave option */
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# immediate-leave
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd)# commit
If you add the immediate-leave option:
to a profile attached to a bridge domain, it applies to all ports under the bridge.
to a profile attached to a port, it applies to the port.
RP0/0/RP0/CPU0:router# show running-config
configuration
mld snooping profile host-port-profile
immediate-leave
!
Verify that the immediate leave config in the named profile is enabled:
RP0/0/RP0/CPU0:router# show mld snooping profile host-port-profile detail
MLD Snoop Profile host-port-profile:
Immediate Leave: Enabled
Router Guard: Enabled
Bridge Domain References: 0
Port References: 0
MLD snooping must be enabled on the bridge domain for this procedure to take effect.
/* Enter the global configuration mode. */
RP0/0/RP0/CPU0:router# configuration
/* Enter MLD snooping profile configuration mode and create a new profile or accesses an existing profile. */
RP0/0/RP0/CPU0:router(config)# mld snooping profile internal-querier-profile
/* Configure an IP address for internal querier use. The default system-ip-address value (0.0.0.0) is not valid for the internal querier.
You must explicitly configure an IP address. Enter a valid link-local IPv6 address. */
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# system-ip-address fe80::98 link-local
/* Enable an internal querier with default values for all options.*/
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# internal-querier
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# commit
RP0/0/RP0/CPU0:router# show running-config
configuration
mld snooping profile internal-querier-profile
system-ip-address fe80::98 link-local
internal-querier
!
Note |
Internal Querier is not recommended, when BVI and MLD snooping is configured under a bridge. |
Verify that the internal querier config is enabled:
RP0/0/RP0/CPU0:router# show mld snooping profile internal-querier-profile detail
MLD Snoop Profile internal-querier-profile:
System IP Address: fe80::98
Internal Querier Support: Enabled
Bridge Domain References: 0
Port References: 0
To add one or more static groups or MLDv2 source groups to an MLD snooping profile, follow these steps:
MLD snooping must be enabled on the bridge domain for port-specific profiles to affect MLD snooping behavior.
/* Enter the global configuration mode. */
RP0/0/RP0/CPU0:router# configuration
/* Enter MLD snooping profile configuration mode and create a new profile or accesses an existing profile. */
RP0/0/RP0/CPU0:router(config)# mld snooping profile host-port-profile
/* Configure a static group. */
/* Note: Repeat this step to add additional static groups. */
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# static group fe80::99 source fe80::99
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# commit
If you add the static group option:
to a profile attached to a bridge domain, it applies to all ports under the bridge.
to a profile attached to a port, it applies to the port.
RP0/0/RP0/CPU0:router# show running-config
configuration
mld snooping profile host-port-profile
static group fe80::99 source fe80::99
!
RP0/0/RP0/CPU0:router# show mld snooping bridge-domain f1:100 detail
Bridge Domain Profile Act Ver #Ports #Mrtrs #Grps #SGs
------------- ------- --- --- ------ ------ ----- ----
f1:100 grp1 Y v2 3 1 1000 1002
Profile Configured Attributes:
System IP Address: fe80::99
Minimum Version: 1
Report Suppression: Enabled
Unsolicited Report Interval: 1000 (milliseconds)
TCN Query Solicit: Disabled
TCN Membership Sync: Disabled
TCN Flood: Enabled
TCN Flood Query Count: 2
Router Alert Check: Disabled
TTL Check: Enabled
nV Mcast Offload: Disabled
Internal Querier Support: Disabled
Querier Query Interval: 125 (seconds)
Querier LMQ Interval: 1000 (milliseconds)
Querier LMQ Count: 2
Querier Robustness: 2
Startup Query Interval: 31 seconds
Startup Query Count: 2
Startup Query Max Response Time: 10.0 seconds
Mrouter Forwarding: Enabled
P2MP Capability: Disabled
Default IGMP Snooping profile: Disabled
IP Address: fe80::f278:16ff:fe63:4d81
Port: BVI1000
Version: v2
Query Interval: 125 seconds
Robustness: 2
Max Resp Time: 10.0 seconds
Time since last G-Query: 97 seconds
Mrouter Ports: 1
Dynamic: BVI1000
STP Forwarding Ports: 0
ICCP Group Ports: 0
Groups: 1000
Member Ports: 0
V2 Source Groups: 1002
Static/Include/Exclude: 0/1002/0
Member Ports (Include/Exclude): 1002/0
RP0/0/RP0/CPU0:router# configure
/* Create two profiles. */
RP0/0/RP0/CPU0:router(config)# mld snooping profile bridge_profile
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# mld snooping profile port_profile
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# mrouter
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# exit
RP0/0/RP0/CPU0:router(config)#
/* Configure two physical interfaces for L2 support.*/
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/8/0/38
RP0/0/RP0/CPU0:router(config-if)# negotiation auto
RP0/0/RP0/CPU0:router(config-if)# l2transport
RP0/0/RP0/CPU0:router(config-if)# no shut
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# interface GigabitEthernet0/8/0/39
RP0/0/RP0/CPU0:router(config-if)# negotiation auto
RP0/0/RP0/CPU0:router(config-if)# l2transport
RP0/0/RP0/CPU0:router(config-if)# no shut
RP0/0/RP0/CPU0:router(config-if)# exit
/* Add interfaces to the bridge domain. Attach bridge_profile to the bridge domain and port_profile to one of the Ethernet interfaces.
The second Ethernet interface inherits MLD snooping configuration attributes from the bridge domain profile.*/
RP0/0/RP0/CPU0:router(config)# l2vpn
RP0/0/RP0/CPU0:router(config-l2vpn)# bridge group bg1
RP0/0/RP0/CPU0:router(config-l2vpn-bg)# bridge-domain bd1
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd)# mld snooping profile bridge_profile
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd-mld-snooping)# interface GigabitEthernet0/8/0/38
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd-mld-snooping-if)# mld snooping profile port_profile
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd-mld-snooping-if)# interface GigabitEthernet0/8/0/39
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd-mld-snooping-if)# exit
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd-mld-snooping)# exit
RP0/0/RP0/CPU0:router(config-l2vpn-bg-bd)# commit
RP0/0/RP0/CPU0:router# show running-config
configuration
mld snooping profile bridge_profile
!
mld snooping profile port_profile
mrouter
!
interface GigabitEthernet0/8/0/38
negotiation auto
l2transport
no shut
!
!
interface GigabitEthernet0/8/0/39
negotiation auto
l2transport
no shut
!
!
l2vpn
bridge group bg1
bridge-domain bd1
mld snooping profile bridge_profile
interface GigabitEthernet0/8/0/38
mld snooping profile port_profile
interface GigabitEthernet0/8/0/39
!
!
!
Verify the configured bridge ports.
RP0/0/RP0/CPU0:router# show mld snooping port
Bridge Domain f10:109
State
Port Oper STP Red #Grps #SGs
---- ---- --- --- ----- ----
BVI1009 Up - - 0 0
GigabitEthernet0/8/0/38 Up - - 1000 1000
GigabitEthernet0/8/0/39 Up - - 1000 1000
This example assumes that the front-ends of the bundles are preconfigured. For example, a bundle configuration might consist of three switch interfaces, as follows:
/* Configure the front-ends of the bundles consisting of three switch interfaces.*/
RP0/0/RP0/CPU0:router# configure
RP0/0/RP0/CPU0:router(config)# interface bundle-ether 1
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/0
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/1
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/2
RP0/0/RP0/CPU0:router(config-if)# channel-group 1 mode on
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/3
RP0/0/RP0/CPU0:router(config-if)# channel-group 1 mode on
RP0/0/RP0/CPU0:router(config-if)# exit
/* Configure two MLD snooping profiles. */
RP0/0/RP0/CPU0:router(config)# mld snooping profile bridge_profile
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# exit !
RP0/0/RP0/CPU0:router(config)# mld snooping profile port_profile
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# mrouter
RP0/0/RP0/CPU0:router(config-mld-snooping-profile)# exit
/* Configure interfaces as bundle member links. */
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/0
RP0/0/RP0/CPU0:router(config-if)# bundle id 1 mode on
RP0/0/RP0/CPU0:router(config-if)# negotiation auto
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/1
RP0/0/RP0/CPU0:router(config-if)# bundle id 1 mode on
RP0/0/RP0/CPU0:router(config-if)# negotiation auto
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/2
RP0/0/RP0/CPU0:router(config-if)# bundle id 2 mode on
RP0/0/RP0/CPU0:router(config-if)# negotiation auto
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface GigabitEthernet0/0/0/3
RP0/0/RP0/CPU0:router(config-if)# bundle id 2 mode on
RP0/0/RP0/CPU0:router(config-if)# negotiation auto
RP0/0/RP0/CPU0:router(config-if)# exit
/* Configure the bundle interfaces for L2 transport. */
RP0/0/RP0/CPU0:router(config)# interface Bundle-Ether 1
RP0/0/RP0/CPU0:router(config-if)# l2transpor
RP0/0/RP0/CPU0:router(config-if)# exit
RP0/0/RP0/CPU0:router(config)# interface Bundle-Ether 2
RP0/0/RP0/CPU0:router(config-if)# l2transpor
RP0/0/RP0/CPU0:router(config-if)# exit
/* Add the interfaces to the bridge domain and attach MLD snooping profiles. */
RP0/0/RP0/CPU0:router(config)# l2vpn
RP0/0/RP0/CPU0:router(config-l2vpn)# bridge group bg1
RP0/0/RP0/CPU0:router(config-l2vpn-bg)# mld snooping profile bridge_profile
RP0/0/RP0/CPU0:router(config-l2vpn-bg-mld-snooping-profile)# interface bundle-Ether 1
RP0/0/RP0/CPU0:router(config-l2vpn-bg-mld-snooping-profile-if)# mld snooping profile port_profile
RP0/0/RP0/CPU0:router(config-l2vpn-bg-mld-snooping-profile-if)# interface bundle-Ether 2
RP0/0/RP0/CPU0:router(config-l2vpn-bg-mld-snooping-profile-if)# commit
RP0/0/RP0/CPU0:router# show running-config
configuration
interface Port-channel1
!
interface GigabitEthernet0/0/0/0
!
interface GigabitEthernet0/0/0/1
!
interface GigabitEthernet0/0/0/2
channel-group 1 mode on
!
interface GigabitEthernet0/0/0/3
channel-group 1 mode on
!
mld snooping profile bridge_profile
!
mld snooping profile port_profile
mrouter
!
interface GigabitEthernet0/0/0/0
bundle id 1 mode on
negotiation auto
!
interface GigabitEthernet0/0/0/1
bundle id 1 mode on
negotiation auto
!
interface GigabitEthernet0/0/0/2
bundle id 2 mode on
negotiation auto
!
interface GigabitEthernet0/0/0/3
bundle id 2 mode on
negotiation auto
!
interface Bundle-Ether 1
l2transport
!
!
interface Bundle-Ether 2
l2transport
!
!
l2vpn
bridge group bg1
bridge-domain bd1
mld snooping profile bridge_profile
interface bundle-Ether 1
mld snooping profile port_profile
interface bundle-Ether 2
!
!
!
RP0/0/RP0/CPU0:router# show mld snooping port
Bridge Domain BG1:BD1
State
Port Oper STP Red #Grps #SGs
---- ---- --- --- ----- ----
HundredGigE0/0/0/3 Up - - 1 1
HundredGigE0/0/0/7 Up - - 1 1
HundredGigE0/19/0/11 Up - - 1 1
HundredGigE0/19/0/5 Up - - 1 1
RP/0/RP1/CPU0:Router#
Multicast IRB provides the ability to route multicast packets between a bridge group and a routed interface using a bridge-group virtual interface (BVI). It can be enabled with multicast-routing. THE BVI is a virtual interface within the router that acts like a normal routed interface. For details about BVI, refer Interface and Hardware Component Configuration Guide for Cisco NCS 560 Series Routers
BV interfaces are added to the existing VRF routes and integrated with the replication slot mask. After this integration, the traffic coming from a VRF BVI is forwarded to the VPN.
Bundles
Satellites
EFPs (physical, vlans, etc)
Supported only on Ethernet line cards and enhanced ethernet line cards.
Support only for IPv4
The CE-PE is collapsed into 1 router (IRB) and IGMP snooping is enabled on the BVIs.
BVI type is included in a multicast VRF. After the BVI slot mask is included in the VRF route slot mask, the traffic from the VRF BVI is forwarded to the VPN/ core.
|
Feature Name |
Release Information |
Description |
|---|---|---|
|
Access Pseudowire in VPLS Bridge Domains |
Release 7.6.1 |
You can configure EVPN in the access node under the same bridge domain as EVPN in the core and create a pseudowire (PW) to the nearest PE that binds the access circuits using EVPN. This PW between the access PE and the single-homed PE ensures that the access nodes can leverage the benefits of EVPN. |
You can enable VPLS Access Pseudowire in a Bridge Domain (BD) where flooding is enabled.
VPLS is a multipoint Layer 2 VPN technology that connects two or more customer devices using bridging techniques. In scenarios where an L3 multicast route has invalid or incorrect OLEs (Output List Element: a hardware instance of a multicast outgoing interface in a multicast route), instead of dropping the packets, they are sent again to the receiver. If the L3 multicast route already has valid OLE entries apart from the invalid ones, at the receiver end, you can see duplicate packets.
To ensure an uninterrupted flow of packets, the egress traffic management model employs a two-pass model. When you enable access pseudowire, in the two-pass model, at egress, the duplicate IP packet is recycled and gets embedded and egresses from the bundle-ether as OLE.
Following figure shows the interconnection between the provider edge (PE) routers over IP/MPLS networks. The VPLS network requires a bridge domain (Layer 2 broadcast domain) on each PE router. It is responsible for all flooding broadcast frames and multicast replications. The PEs are connected with Pseudowires (PWs).
This feature is not supported when IGMP snooping is enabled.
The multicast L3 to L2 traffic is supported only in flood BD configuration.
To enable Access Pseudowire in a VPLS BD, use the following command:
Router#configure terminal
Router(config)#hw-module multicast access-pw-enable
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