Related Documentation
- MX Series
- Active-Active Bridging and VRRP over IRB Functionality on MX Series Routers Overview
- Configuring Active-Active Bridging and VRRP over IRB in Multichassis Link Aggregation on MX Series Routers
- Example: Configuring Multichassis Link Aggregation in an Active-Active Mode on MX Series Routers
- Example: Configuring Multichassis Link Aggregation for Layer 3 Unicast Using VRRP on MX Series Routers
Example: Configuring Multichassis Link Aggregation for Layer 3 Multicast Using VRRP on MX Series Routers
There are two methods for enabling Layer 3 multicast functionality across a multichassis link aggregation group (MC-LAG). You can choose either to configure the Virtual Router Redundancy Protocol (VRRP) or synchronize the MAC addresses for the Layer 3 interfaces of the routers participating in the MC-LAG to load balance the traffic. The procedure to configure VRRP for use in a Layer 3 multicast MC-LAG is included in this example.
Requirements
This example uses the following hardware and software components:
- Four Juniper Networks MX Series routers
- Junos OS Release 11.2 or later running on all four routers
Before you configure an MC-LAG for Layer 3 multicast using VRRP, be sure that you understand how to:
- Configure aggregated Ethernet interfaces on a router.
- Configure the Link Aggregation Control Protocol (LACP) on aggregated Ethernet interfaces on a router.
- Configure the Virtual Router Redundancy Protocol (VRRP) on a router.
Overview
In this example, you configure an MC-LAG across two routers by including interfaces from both routers in an aggregated Ethernet interface (ae1). To support the MC-LAG, create a second aggregated Ethernet interface (ae0) for the interchassis control link-protection link (ICL-PL). Configure a multichassis protection link for the ICL-PL, Inter-Chassis Control Protocol (ICCP) for the peers hosting the MC-LAG, and Layer 3 connectivity between MC-LAG peers.
![]() | Note: Layer 3 connectivity is required for ICCP. |
To complete the configuration, enable VRRP by completing the following steps:
- Create a routed VLAN interface (RVI).
- Create a VRRP group and assign a virtual IP address that is shared between each router in the VRRP group.
- Enable a member of a VRRP group to accept all packets destined for the virtual IP address if it is the master in the VRRP group.
Consider a sample topology in which a customer edge router, CE, is connected to two provider edge (PE) routers, PE1 and PE2, respectively. The two PE devices each have a link aggregation group (LAG) connected to the CE device. The configured mode is active-active, meaning that both PE routers’ LAG ports are active and carrying traffic at the same time. PE1 and PE2 are connected to a single service provider router, P.
In Figure 1, from the perspective of the CE device, all four ports belonging to a LAG are connected to a single service provider device. Because the configured mode is active-active, all four ports are active, and the CE device load-balances the traffic to the peering PE devices. On the PE routers, a regular LAG is configured facing the CE device.
On one end of an MC-LAG is an MC-LAG client device, such as a server, that has one or more physical links in a LAG. This client device does not need to detect the MC-LAG. On the other side of an MC-LAG are two MC-LAG routers. Each of the routers has one or more physical links connected to a single client device. The routers coordinate with each other to ensure that data traffic is forwarded properly.
Topology Diagram
Figure 1 shows the topology used in this example.
Figure 1: MC-LAG Active-Active on MX Series Routers

Configuring the PE Routers
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them in a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level , and then enter commit from configuration mode.
Router PE1
Router PE2
Router PE1
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Router PE1:
Specify the number of aggregated Ethernet interfaces to be created.
[edit chassis]user@PE1# set aggregated-devices ethernet device-count 5Specify the members to be included within the aggregated Ethernet bundles.
[edit interfaces]user@PE1# set ge-1/0/1 gigether-options 802.3ad ae1user@PE1# set ge-1/0/6 gigether-options 802.3ad ae0Configure the interfaces that connect to senders or receivers, the interchassis link(ICL) interfaces, and the ICCP interfaces.
[edit interfaces]user@PE1# set ge-1/1/1 flexible-vlan-tagginguser@PE1# set ge-1/1/1 encapsulation flexible-ethernet-servicesuser@PE1# set ge-1/1/1 unit 0 encapsulation vlan-bridgeuser@PE1# set ge-1/1/1 unit 0 vlan-id-range 100-110user@PE1# set ge-1/1/4 flexible-vlan-tagginguser@PE1# set ge-1/1/4 encapsulation flexible-ethernet-servicesuser@PE1# set ge-1/1/4 unit 0 encapsulation vlan-bridgeuser@PE1# set ge-1/1/4 unit 0 vlan-id-range 100-110user@PE1# set ge-1/0/2 unit 0 family inet address 100.100.100.1/30Configure parameters on the aggregated Ethernet bundles.
[edit interfaces ae0]user@PE1# set flexible-vlan-tagginguser@PE1# set encapsulation flexible-ethernet-servicesuser@PE1# set unit 0 encapsulation vlan-bridgeuser@PE1# set unit 0 vlan-id-range 100-110user@PE1# set unit 0 multi-chassis-protection 100.100.100.2 interface ge-1/1/4.0
[edit interfaces ae1]user@PE1# set flexible-vlan-tagginguser@PE1# set encapsulation flexible-ethernet-servicesuser@PE1# set unit 0 encapsulation vlan-bridgeuser@PE1# set unit 0 vlan-id-range 100-110user@PE1# set unit 0 multi-chassis-protection 100.100.100.2 interface ge-1/1/4.0Configure LACP on the aggregated Ethernet bundles.
[edit interfaces ae0 aggregated-ether-options]user@PE1# set lacp activeuser@PE1# set lacp system-priority 100user@PE1# set lacp system-id 00:00:00:00:00:05user@PE1# set lacp admin-key 1
[edit interfaces ae1 aggregated-ether-options]user@PE1# set lacp activeuser@PE1# set lacp system-priority 100user@PE1# set lacp system-id 00:00:00:00:00:05user@PE1# set lacp admin-key 1- The multichassis aggregated Ethernet identification number (mc-ae-id) specifies which link aggregation group the aggregated Ethernet interface belongs to. The ae0 interfaces on Router PE1 and Router PE2 are configured with mc-ae-id 5. The ae1 interfaces on Router PE1 and Router PE2 are configured with mc-ae-id 10. (To refer to the configuration on Router PE2, see Router PE2).
Configure the MC-LAG interfaces.
[edit interfaces ae0 aggregated-ether-options]user@PE1# set mc-ae mc-ae-id 5user@PE1# set mc-ae redundancy-group 10user@PE1# set mc-ae chassis-id 1user@PE1# set mc-ae mode active-activeuser@PE1# set mc-ae status-control active
[edit interfaces ae1 aggregated-ether-options]user@PE1# set mc-ae mc-ae-id 10user@PE1# set mc-ae redundancy-group 10user@PE1# set mc-ae chassis-id 1user@PE1# set mc-ae mode active-activeuser@PE1# set mc-ae status-control activeThe redundancy-group 10 statement is used by ICCP to associate multiple chassis that perform similar redundancy functions and to establish a communication channel so that applications on peering chassis can send messages to each other. The ae0 and ae1 interfaces on Router PE1 and Router PE2 are configured with the same redundancy group redundancy-group 10.
The chassis-id statement is used by LACP for calculating the port number of the MC-LAG's physical member links. Router PE1 uses chassid-id 1 to identify both its ae0 and ae1 interfaces. Router PE2 (as shown in Router PE2) uses chassis-id 0 to identify both its ae0 and ae1 interfaces.
The mode statement indicates whether an MC-LAG is in active-standby mode or active-active mode. Chassis that are in the same group must be in the same mode.
- The ports within a bridge domain share the same flooding or broadcast characteristics in order to perform Layer 2 bridging.
Configure a domain that includes the set of logical ports.
[edit bridge-domains bd0]user@PE1# set domain-type bridgeuser@PE1# set vlan-id alluser@PE1# set service-id 20user@PE1# set interface ae0.0user@PE1# set interface ae1.0user@PE1# set interface ge-1/0/3.0user@PE1# set interface ge-1/1/1.0user@PE1# set interface ge-1/1/4.0The bridge-level service-id statement is required to link related bridge domains across peers (in this case Router PE1 and Router PE2), and should be configured with the same value.
Configure ICCP parameters.
[edit protocols iccp]user@PE1# set local-ip-addr 100.100.100.1user@PE1# set peer 100.100.100.2 redundancy-group-id-list 10user@PE1# set peer 100.100.100.2 liveness-detection minimum-interval 1000- You must configure the same unique network-wide configuration for a service in the set of PE routers providing the service. This service ID is required if the multichassis aggregated Ethernet interfaces are part of a bridge domain.
Configure the service ID at the global level.
[edit switch-options]user@PE1# set service-id 10
Step-by-Step Procedure
To enable VRRP on the MC-LAGs :
- Assign the priority for each router in the VRRP groups.
Note: The router configured with the highest priority is the master.
PE1
[edit interfaces]user@PE1# set vlan unit 100 family inet address 10.1.1.11/24 vrrp-group 1 priority 200user@PE1 #set vlan unit 200 family inet address 10.1.1.21/24 vrrp-group 2 priority 200PE2
[edit interfaces]user@PE2# set vlan unit 100 family inet address 10.1.1.10/24 vrrp-group 1 priority 150user@PE2# set vlan unit 200 family inet address 10.1.1.20/24 vrrp-group 2 priority 150 - Enable the router to accept all packets destined for the
virtual IP address if it is the master in a VRRP group.
PE1
[edit interfaces]user@PE1# set vlan unit 100 family inet address 10.1.1.11/24 vrrp-group 1 accept-dataPE2
[edit interfaces]user@PE2# set vlan unit 100 family inet address 10.1.1.10/24 vrrp-group 1 accept-datauser@PE2# set vlan unit 200 family inet address 10.1.1.20/24 vrrp-group 2 accept-data
Step-by-Step Procedure
To configure OSPF as the Layer 3 protocol:
- Configure an OSPF area .[edit protocols ospf]user@PE1# set area 0.0.0.0
- Assign the VLAN interfaces for the MC-LAGs as interfaces
to the OSPF area .[edit protocols ospf area 0.0.0.0]user@PE1# set interface ge-1/1/1.0user@PE1# set interface ge-1/4/1.0
- Configure the minimum receive interval, minimum transmit
interval, and transmit interval threshold for a Bidirectional Forwarding
Detection (BFD) session for the OSPF interfaces .[edit protocols ospf area 0.0.0.0]user@PE1# set interface ge-1/1/1.0 bfd-liveness-detection minimum-receive-interval 700user@PE1# set interface ge-1/1/1.0 bfd-liveness-detection transmit-interval minimum-interval 350user@PE1# set interface ge-1/1/1.0 bfd-liveness-detection transmit-interval threshold 500user@PE1# set interface ge-1/4/1.0 bfd-liveness-detection minimum-receive-interval 700user@PE1# set interface ge-1/4/1.0 bfd-liveness-detection transmit-interval minimum-interval 350user@PE1# set interface ge-1/4/1.0 bfd-liveness-detection transmit-interval threshold 500
Step-by-Step Procedure
To configure PIM as the multicast protocol:
- Configure a static rendezvous point (RP) address .[edit protocols pim]user@PE1# set rp static address 1.0.0.3
- Configure the address ranges of the multicast groups for
which PE1 and PE2 can be a rendezvous point (RP).[edit protocols pim rp static address 1.0.0.3]user@PE1# set group-ranges 239.0.0.0/8
- Enable PIM on the VLAN interfaces for the MC-LAGs on PE1
and PE2.[edit protocols pim]user@PE1# set interface ge-1/1/1.0 version 2user@PE1# set interface ge-1/4/1.0 version 2
- Configure each PIM interface’s priority for being
selected as the designated router (DR).
An interface with a higher priority value has a higher probability of being selected as the DR.
[edit protocols pim]user@PE1# set interface ge-1/1/1.0 priority 600user@PE1# set interface ge-1/4/1.0 priority 200 - Configure the minimum receive interval, minimum transmit
interval, and transmit interval threshold for a Bidirectional Forwarding
Detection (BFD) session for the PIM interfaces on PE1 and PE2.[edit protocols pim]user@PE1# set interface ge-1/1/1.0 bfd-liveness-detection minimum-receive-interval 700user@PE1# set interface ge-1/1/1.0 bfd-liveness-detection transmit-interval minimum-interval 350user@PE1# set interface ge-1/1/1.0 bfd-liveness-detection transmit-interval threshold 500user@PE1# set interface ge-1/4/1.0 bfd-liveness-detection minimum-receive-interval 700user@PE1# set interface ge-1/4/1.0 bfd-liveness-detection transmit-interval minimum-interval 350user@PE1# set interface ge-1/4/1.0 bfd-liveness-detection transmit-interval threshold 500
Step-by-Step Procedure
To enable RSTP:
- Enable RSTP globally on all interfaces.
[edit]
user@PE1# set protocols rstp interface ae1.0 mode point-to-point - Configure the MC-LAG interfaces as edge ports on PE1 and
PE2.
Note: The ae1 interface is a downstream interface. This is why RSTP and bpdu-block-on-edge need to be configured.
[edit]
user@PE1# set protocols rstp interface ae1.0 edge - Enable BPDU blocking on all interfaces except for the
ICL-PL interfaces on PE1 and PE2.
Note: The ae1 interface is a downstream interface. This is why RSTP and bpdu-block-on-edge need to be configured.
[edit]
user@PE1# set protocols rstp bpdu-block-on-edge
Results
From configuration mode, confirm your configuration by entering the show bridge-domains, show chassis, show interfaces, show protocols, and show switch-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Repeat the procedure for Router PE2, using the appropriate interface names and addresses.
Configuring the CE Router
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them in a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level , and then enter commit from configuration mode.
Router CE
Router CE
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Router CE:
Specify the number of aggregated Ethernet interfaces to be created.
[edit chassis]user@CE# set aggregated-devices ethernet device-count 2Specify the members to be included within the aggregated Ethernet bundle.
[edit interfaces]user@CE# set ge-2/0/2 gigether-options 802.3ad ae0user@CE# set ge-2/0/3 gigether-options 802.3ad ae0Configure an interface that connects to senders or receivers.
[edit interfaces ge-2/1/6]user@CE# set flexible-vlan-tagginguser@CE# set encapsulation flexible-ethernet-servicesuser@CE# set unit 0 encapsulation vlan-bridgeuser@CE# set unit 0 vlan-id-range 100-110Configure parameters on the aggregated Ethernet bundle.
[edit interfaces ae0]user@CE# set flexible-vlan-tagginguser@CE# set encapsulation flexible-ethernet-servicesuser@CE# set unit 0 encapsulation vlan-bridgeuser@CE# set unit 0 vlan-id-range 100-500- The active statement initiates transmission of LACP packets.
Configure LACP on the aggregated Ethernet bundle.
[edit interfaces ae0 aggregated-ether-options]user@CE# set lacp activeuser@CE# set lacp system-priority 100For the system-priority statement, a smaller value indicates a higher priority. The device with the lower system priority value determines which links between LACP partner devices are active and which are in standby mode for each LACP group. The device on the controlling end of the link uses port priorities to determine which ports are bundled into the aggregated bundle and which ports are put in standby mode. Port priorities on the other device (the noncontrolling end of the link) are ignored.
- The ports within a bridge domain share the same flooding or broadcast characteristics in order to perform Layer 2 bridging.
Configure a domain that includes the set of logical ports.
[edit bridge-domains bd0]user@CE# set domain-type bridgeuser@CE# set vlan-id alluser@CE# set interface ge-2/1/6.0user@CE# set interface ae0.0
Results
From configuration mode, confirm your configuration by entering the show bridge-domains, show chassis, and show interfaces commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Configuring the Provider Router
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them in a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level , and then enter commit from configuration mode.
Router P
Router P
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Router P:
Specify the number of aggregated Ethernet interfaces to be created.
[edit chassis]user@P# set aggregated-devices ethernet device-count 2Specify the members to be included within the aggregated Ethernet bundle.
[edit interfaces]user@P# set ge-1/0/5 gigether-options 802.3ad ae1user@P# set ge-1/0/11 gigether-options 802.3ad ae1Configure an interface that connects to senders or receivers.
[edit interfaces ge-1/1/3]user@P# set flexible-vlan-tagginguser@P# set encapsulation flexible-ethernet-servicesuser@P# set unit 0 encapsulation vlan-bridgeuser@P# set unit 0 vlan-id-range 100-500Configure parameters on the aggregated Ethernet bundle.
[edit interfaces ae1]user@P# set flexible-vlan-tagginguser@P# set encapsulation flexible-ethernet-servicesuser@P# set unit 0 encapsulation vlan-bridgeuser@P# set unit 0 vlan-id-range 100-110Configure LACP on the aggregated Ethernet bundle.
[edit interfaces ae1 aggregated-ether-options]user@P# set lacp activeuser@P# set lacp system-priority 100Configure a domain that includes the set of logical ports.
[edit bridge-domains bd0]user@P# set vlan-id alluser@P# set domain-type bridgeuser@P# set interface ge-1/1/3.0user@P# set interface ae1.0
Results
From configuration mode, confirm your configuration by entering the show bridge-domains, show chassis, and show interfaces commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Verification
Confirm that the configuration is working properly by running the following commands:
- show iccp
- show interfaces ae0
- show interfaces ae1
- show interfaces mc-ae
- show pim interfaces
- show vrrp
- show l2-learning instance extensive
Troubleshooting
Troubleshooting a LAG That Is Down
Problem
The show interfaces terse command shows that the MC-LAG is down.
Solution
Check the following:
- Verify that there is no configuration mismatch.
- Verify that all member ports are up.
- Verify that the MC-LAG is part of family Ethernet switching (Layer 2 LAG).
- Verify that the MC-LAG member is connected to the correct MC-LAG member at the other end.
Related Documentation
- MX Series
- Active-Active Bridging and VRRP over IRB Functionality on MX Series Routers Overview
- Configuring Active-Active Bridging and VRRP over IRB in Multichassis Link Aggregation on MX Series Routers
- Example: Configuring Multichassis Link Aggregation in an Active-Active Mode on MX Series Routers
- Example: Configuring Multichassis Link Aggregation for Layer 3 Unicast Using VRRP on MX Series Routers
Published: 2015-02-23
Related Documentation
- MX Series
- Active-Active Bridging and VRRP over IRB Functionality on MX Series Routers Overview
- Configuring Active-Active Bridging and VRRP over IRB in Multichassis Link Aggregation on MX Series Routers
- Example: Configuring Multichassis Link Aggregation in an Active-Active Mode on MX Series Routers
- Example: Configuring Multichassis Link Aggregation for Layer 3 Unicast Using VRRP on MX Series Routers