Supported Platforms
Example: Configuring Interchassis Redundancy for MX Series 3D Universal Edge Routers Using a Virtual Chassis
To provide interchassis redundancy for MX Series 3D Universal Edge Routers, you can configure a Virtual Chassis. A Virtual Chassis configuration interconnects two MX Series routers into a logical system that you can manage as a single network element. The member routers in a Virtual Chassis are interconnected by means of Virtual Chassis ports that you configure on Trio Modular Port Concentrator/Modular Interface Card (MPC/MIC) interfaces (network ports) on each MX Series router.
This example describes how to set up and configure a Virtual Chassis consisting of two MX Series routers:
Requirements
This example uses the following software and hardware components:
- Junos OS Release 11.2
- One MX240 3D Universal Edge Router
- One MX480 3D Universal Edge Router
See Table 1 for information about the hardware installed in each MX Series router.
![]() | Note: MX Series Enhanced Queuing IP Services DPCs (DPCE-R-Q model numbers) and MX Series Enhanced Queuing Ethernet Services DPCs (DPCE-X-Q model numbers) do not interoperate with features of the MX Series Virtual Chassis. If any MX Series Enhanced Queuing DPCs are installed in a router to be configured as a member of a Virtual Chassis, you must ensure that these DPCs are offline before you configure the Virtual Chassis. |
Overview and Topology
To configure the Virtual Chassis shown in this example, you must create a preprovisioned configuration at the [edit virtual-chassis] hierarchy level on the router to be designated as the master of the Virtual Chassis. The preprovisioned configuration includes the serial number, member ID, and role for each member router (also known as member chassis) in the Virtual Chassis. When a new member router joins the Virtual Chassis, the software compares its serial number against the values specified in the preprovisioned configuration. If the serial number of a joining router does not match any of the configured serial numbers, the software prevents that router from becoming a member of the Virtual Chassis.
After you commit the preprovisioned configuration on the master router, you must assign the preprovisioned member IDs by issuing the request virtual-chassis member-id set administrative command on each router, which causes the router to reboot. When the reboot is complete, you create one or more Virtual Chassis ports by issuing the request virtual-chassis vc-port set administrative command on each router. The Virtual Chassis forms when the line cards in both member routers are back online.
This example configures a Virtual Chassis that interconnects two MX Series routers, and uses the basic topology shown in Figure 1. For redundancy, two Virtual Chassis ports are configured on each member router.
Figure 1: Sample Topology for a Virtual Chassis with Two MX Series Routers

Table 1 shows the hardware and software configuration settings for each MX Series router in the Virtual Chassis. You use some of these settings in the preprovisioned configuration and when you assign the member IDs and create the Virtual Chassis ports.
Table 1: Components of the Sample MX Series Virtual Chassis
Router Name | Hardware | Serial Number | Member ID | Role | Virtual Chassis Ports | Network Port Slot Numbering |
---|---|---|---|---|---|---|
gladius | MX240 router with:
| JN10C7135AFC | 0 | routing-engine (master) | vcp-2/2/0 | FPC 0 – 11 |
trefoil | MX480 router with:
| JN115D117AFB | 1 | routing-engine (backup) | vcp-2/0/0 | FPC 12 – 23 (offset = 12) |
Configuration
To configure a Virtual Chassis consisting of two MX Series routers, perform these tasks:
- Preparing for the Virtual Chassis Configuration
- Creating and Applying Configuration Groups for the Virtual Chassis
- Configuring Preprovisioned Member Information for the Virtual Chassis
- Enabling Graceful Routing Engine Switchover and Nonstop Active Routing
- Configuring Member IDs and Rebooting the Routers to Enable Virtual Chassis Mode
- Configuring Virtual Chassis Ports to Interconnect Member Routers
Preparing for the Virtual Chassis Configuration
Step-by-Step Procedure
To prepare for configuring an MX Series Virtual Chassis:
- Make a list of the serial numbers of both routers that
you want to configure as part of the Virtual Chassis.
The chassis serial number is located on a label affixed to the side of the of the MX Series chassis. Alternatively, you can obtain the chassis serial number by issuing the show chassis hardware command, which is especially useful if you are accessing the router from a remote location. For example:
user@gladius> show chassis hardware
Hardware inventory: Item Version Part number Serial number Description Chassis JN10C7135AFC MX240 .
.
.
Fan Tray 0 REV 01 710-021113 JT0119 MX240 Fan Tray - Note the desired role (routing-engine) for each
router in the Virtual Chassis.
In a two-router Virtual Chassis configuration, you must designate each router with the routing-engine role, which enables either router to function as the master or backup of the Virtual Chassis.
- The master router maintains the global configuration and state information for all members of the Virtual Chassis, and runs the chassis management processes.
- The backup router synchronizes with the master router and relays chassis control information (such as line-card presence and alarms) to the master router. If the master router is unavailable, the backup router takes mastership of the Virtual Chassis to preserve routing information and maintain network connectivity without disruption.
- Note the member ID (0 or 1) to be assigned to each router
in the Virtual Chassis.
In this example, the master router is assigned member ID 0, and the backup router is assigned member ID 1.
- Ensure that both MX Series routers in the Virtual Chassis
have dual Routing Engines installed, and that all four Routing Engines
in the Virtual Chassis are the same model.
For example, you cannot configure a Virtual Chassis if one member router has RE-S-2000 Routing Engines installed and the other member router has RE-S-1800 Routing Engines installed.
- Ensure that the necessary Trio Modular Port Concentrator/Modular
Interface Card (MPC/MIC) interfaces on which to configure the Virtual
Chassis ports are installed and operational in each router to be configured
as a member of the Virtual Chassis.
Note: An MX Series Virtual Chassis does not support a combination of 1-Gigabit Ethernet (ge media type) Virtual Chassis ports and 10-Gigabit Ethernet (xe media type) Virtual Chassis ports within the same Virtual Chassis. You must configure either all 10-Gigabit Ethernet Virtual Chassis ports or all 1-Gigabit Ethernet Virtual Chassis ports in the same Virtual Chassis. We recommend that you configure Virtual Chassis ports on 10-Gigabit Ethernet interfaces. This restriction has no effect on access ports or uplink ports in an MX Series Virtual Chassis configuration.
- If MX Series Enhanced Queuing IP Services DPCs (DPCE-R-Q
model numbers) or MX Series Enhanced Queuing Ethernet Services DPCs
(DPCE-X-Q model numbers) are installed in a router to be configured
as a member of the Virtual Chassis, make sure these DPCs are offline
before you configure the Virtual Chassis. Otherwise, the MX Series
Virtual Chassis configuration will not function.
Note: MX Series Enhanced Queuing IP Services DPCs (DPCE-R-Q model numbers) and MX Series Enhanced Queuing Ethernet Services DPCs (DPCE-X-Q model numbers) do not interoperate with features of the MX Series Virtual Chassis.
- Determine the desired location of the dedicated Virtual Chassis ports on both member routers, and use the Virtual Chassis ports to physically interconnect the member routers in a point-to-point topology.
- Ensure that both MX Series routers to be configured as members of the Virtual Chassis are running the same Junos OS release, and have basic network connectivity.
- Install the MX Virtual Chassis Redundancy Feature Pack license on each router to be configured as part of the Virtual Chassis.
- Install the necessary Junos OS feature licenses on each router to be configured as part of the Virtual Chassis.
Creating and Applying Configuration Groups for the Virtual Chassis
Step-by-Step Procedure
For a Virtual Chassis configuration consisting of two MX Series routers, each of which supports dual Routing Engines, you must create and apply the following configuration groups on the router to be designated as the master of the Virtual Chassis instead of using the standard re0 and re1 configuration groups:
- member0-re0
- member0-re1
- member1-re0
- member1-re1
![]() | Note: The membern-ren naming format for configuration groups is reserved for exclusive use by member routers in MX Series Virtual Chassis configurations. |
To create and apply configuration group information for the Virtual Chassis:
- Log in to the console on member 0 (gladius).
- In the console window on member 0, create and apply the member0-re0 configuration group.
- Delete the standard re0 configuration group from
the global configuration on member 0.
- Create and apply the member0-re1 configuration
group on member 0.
- Delete the standard re1 configuration group from
the global configuration on member 0.
- Create and apply the member1-re0 configuration
information on member 0.[edit]user@gladius# set groups member1-re0 system host-name trefoiluser@gladius# set groups member1-re0 system backup-router 10.9.0.1 user@gladius# set groups member1-re0 system backup-router destination 172.16.0.0/12 user@gladius# set groups member1-re0 system backup-router destination 10.9.0.0/16...user@gladius# set groups member1-re0 interfaces fxp0 unit 0 family inet address 10.9.3.97/21user@gladius# set apply-groups member1-re0
The examples in Steps 5 and 6 set the IP address for the fxp0 management interface and add an IP route for it in the event that routing becomes inactive.
- Create and apply the member1-re1 configuration
information on member 0.[edit]user@gladius# set groups member1-re1 system host-name trefoiluser@gladius# set groups member1-re1 system backup-router 10.9.0.1 user@gladius# set groups member1-re1 system backup-router destination 172.16.0.0/12 user@gladius# set groups member1-re1 system backup-router destination 10.9.0.0/16...user@gladius# set groups member1-re1 interfaces fxp0 unit 0 family inet address 10.9.3.98/21user@gladius# set apply-groups member1-re1
- Commit the configuration on member 0.
Best Practice: We recommend that you use the commit synchronize command throughout this procedure to save any configuration changes to the Virtual Chassis.
For an MX Series Virtual Chassis, the force option is the default and only behavior when you issue the commit synchronize command. Issuing the commit synchronize command for an MX Series Virtual Chassis configuration has the same effect as issuing the commit synchronize force command.
Results
Display the results of the configuration.
Possible completions: <[Enter]> Execute this command <group_name> Group name global Group name member0-re0 Group name member0-re1 Group name member1-re0 Group name member1-re1 Group name | Pipe through a command
apply-groups [ global member0-re0 member0-re1 member1-re0 member1-re1 ];
Configuring Preprovisioned Member Information for the Virtual Chassis
Step-by-Step Procedure
To configure the preprovisioned member information on member 0 (gladius):
- Log in to the console on member 0.
- Specify that you want to create a preprovisioned Virtual
Chassis configuration.[edit virtual-chassis]user@gladius# set preprovisioned
- Configure the member ID (0 or 1), role
(routing-engine), and chassis serial number for each member
router in the Virtual Chassis.[edit virtual-chassis]user@gladius# set member 0 role routing-engine serial-number JN10C7135AFCuser@gladius# set member 1 role routing-engine serial-number JN115D117AFB
- Disable detection of a split in the Virtual Chassis configuration.
(By default, split detection in an MX Series Virtual Chassis is enabled.)[edit virtual-chassis]user@gladius# set no-split-detection
Best Practice: We recommend that you disable split detection for a two-member MX Series Virtual Chassis configuration if you think the backup router is more likely to fail than the Virtual Chassis port links to the backup router. Configuring redundant Virtual Chassis ports on different line cards in each member router reduces the likelihood that all Virtual Chassis port links to the backup router will fail.
- (Optional) Enable tracing of Virtual Chassis operations.[edit virtual-chassis]user@gladius# set traceoptions file vccpuser@gladius# set traceoptions file size 100muser@gladius# set traceoptions flag all
- Commit the configuration.
Results
Display the results of the configuration.
Enabling Graceful Routing Engine Switchover and Nonstop Active Routing
Step-by-Step Procedure
Before you configure member IDs and Virtual Chassis ports, you must enable graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) on both member routers in the Virtual Chassis.
To enable graceful Routing Engine switchover and nonstop active routing:
- Enable graceful Routing Engine switchover and nonstop
active routing on member 0 (gladius):
- Log in to the console on member 0.
- Enable graceful switchover.[edit chassis redundancy]user@gladius# set graceful-switchover
- Enable nonstop active routing.[edit routing-options]user@gladius# set nonstop-routing
- Commit the configuration on member 0.[edit system]user@gladius# commit synchronize
- Enable graceful Routing Engine switchover and nonstop
active routing on member 1 (trefoil):
- Log in to the console on member 1.
- Enable graceful switchover.[edit chassis redundancy]user@trefoil# set graceful-switchover
- Enable nonstop active routing.[edit routing-options]user@trefoil# set nonstop-routing
- Commit the configuration on member 1.[edit system]user@trefoil# commit synchronize
Note: When you configure nonstop active routing, you must include the commit synchronize statement at the [edit system] hierarchy level. Otherwise, the commit operation fails.
For an MX Series Virtual Chassis, the force option is the default and only behavior when you use the commit synchronize statement. Including the commit synchronize statement for an MX Series Virtual Chassis configuration has the same effect as including the commit synchronize force statement.
Configuring Member IDs and Rebooting the Routers to Enable Virtual Chassis Mode
Step-by-Step Procedure
To configure (set) the preprovisioned member ID for each MX Series router in the Virtual Chassis, use the request virtual-chassis member-id set command. Assigning the member ID causes the router to reboot in preparation for forming the Virtual Chassis.
![]() | Note: If you issue the request virtual-chassis member-id set command without first installing an MX Virtual Chassis Redundancy Feature Pack license on both member routers, the software displays a warning message that you are operating without a valid Virtual Chassis software license. |
To configure the member ID and reboot each router to enable Virtual Chassis mode:
- Log in to the console on member 0 (gladius).
- Set the member ID on member 0.user@gladius> request virtual-chassis member-id set member 0
This command will enable virtual-chassis mode and reboot the system.
Continue? [yes,no] yes
Issuing the request virtual-chassis member-id command causes the router to reboot in preparation for membership in the Virtual Chassis.
- Log in to the console on member 1 (trefoil).
- Set the member ID on member 1.user@trefoil> request virtual-chassis member-id set member 1
This command will enable virtual-chassis mode and reboot the system.
Continue? [yes,no] yes
Results
Display the results of the configuration on each router. At this point in the procedure, all line cards are offline, and the routers are each designated with the Master role because they are not yet interconnected as a fully formed Virtual Chassis. In addition, member 1 (trefoil) remains in Amnesiac state (has no defined configuration) until the Virtual Chassis forms and the configuration is committed.
For member 0 (gladius):
{master:member0-re0}
user@gladius> show virtual-chassis status
Preprovisioned Virtual Chassis Virtual Chassis ID: 4f2b.1aa0.de08
Mastership Neighbor List
Member ID Status Serial No Model priority Role ID Interface 0 (FPC 0- 11) Prsnt JN10C7135AFC mx240 129 Master*
For member 1 (trefoil):
Amnesiac (ttyd0) login: user Password:
...
{master:member1-re0}
Virtual Chassis ID: eabf.4e50.91e6 Virtual Chassis Mode: Disabled Mastership Neighbor List
Member ID Status Serial No Model priority Role ID Interface 1 (FPC 12- 23) Prsnt JN115D117AFB mx480 128 Master*
Configuring Virtual Chassis Ports to Interconnect Member Routers
Step-by-Step Procedure
To interconnect the member routers in an MX Series Virtual Chassis, use the request virtual-chassis vc-port set command to configure (set) Virtual Chassis ports on Trio Modular Port Concentrator/Modular Interface Card (MPC/MIC) interfaces.
![]() | Note: If you issue the request virtual-chassis vc-port set command without first installing an MX Virtual Chassis Redundancy Feature Pack license on both member routers, the software displays a warning message that you are operating without a valid Virtual Chassis software license. |
To configure Virtual Chassis ports on Trio MPC/MIC interfaces to connect the member routers in the Virtual Chassis:
- Configure the Virtual Chassis ports on member 0 (gladius).
- Log in to the console on member 0.
- Configure the first Virtual Chassis port that connects
to member 1 (trefoil).
{master:member0-re0}
user@gladius> request virtual-chassis vc-port set fpc-slot 2 pic-slot 2 port 0
vc-port successfully set
After the Virtual Chassis port is created, it is renamed vcp-slot/pic/port (for example, vcp-2/2/0), and the line card associated with that port comes online. The line cards in the other member router remain offline until the Virtual Chassis forms. Each Virtual Chassis port is dedicated to the task of interconnecting member routers in a Virtual Chassis, and is no longer available for configuration as a standard network port.
- When vcp-2/2/0 is up, configure the second Virtual
Chassis port that connects to member 1.
{master:member0-re0}
user@gladius> request virtual-chassis vc-port set fpc-slot 2 pic-slot 3 port 0
vc-port successfully set
- Configure the Virtual Chassis ports on member 1 (trefoil).
- Log in to the console on member 1.
- Configure the first Virtual Chassis port that connects
to member 0 (gladius).
{master:member1-re0}
user@trefoil> request virtual-chassis vc-port set fpc-slot 2 pic-slot 0 port 0
vc-port successfully set
- When vcp-2/0/0 is up, configure the second Virtual
Chassis port that connects to member 0.
{master:member1-re0}
user@trefoil> request virtual-chassis vc-port set fpc-slot 5 pic-slot 2 port 0
vc-port successfully set
When all of the line cards in all of the member routers are online, and the Virtual Chassis has formed, you can issue Virtual Chassis commands from the terminal window of the master router (gladius).
- Verify that the Virtual Chassis is properly configured
and operational.
{master:member0-re0}
user@gladius> show virtual-chassis status
{master:member0-re0}
user@gladius> show virtual-chassis vc-port all-members
See the Verification section for information about interpreting the output of these commands.
- Commit the configuration on the master router.{master:member0-re0}[edit system]user@gladius# commit synchronize
This step is required to ensure that the configuration groups and Virtual Chassis configuration are propagated to both members of the Virtual Chassis.
Verification
To confirm that the Virtual Chassis configuration is working properly, perform these tasks:
- Verifying the Member IDs and Roles of the Virtual Chassis Members
- Verifying the Operation of the Virtual Chassis Ports
- Verifying Neighbor Reachability
Verifying the Member IDs and Roles of the Virtual Chassis Members
Purpose
Verify that the member IDs and roles of the routers belonging to the Virtual Chassis are properly configured.
Action
Display the status of the members of the Virtual Chassis configuration:
{master:member0-re0}
user@gladius> show virtual-chassis status
Preprovisioned Virtual Chassis Virtual Chassis ID: a5b6.be0c.9525
Mastership Neighbor List Member ID Status Serial No Model priority Role ID Interface 0 (FPC 0- 11) Prsnt JN10C7135AFC mx240 129 Master* 1 vcp-2/2/0
1 vcp-2/3/0 1 (FPC 12- 23) Prsnt JN115D117AFB mx480 129 Backup 0 vcp-2/0/0
0 vcp-5/2/0
Meaning
The value Prsnt in the Status column of the output confirms that the member routers specified in the preprovisioned configuration are currently connected to the Virtual Chassis. The display shows that member 0 (gladius) and member 1 (trefoil), which were both configured with the routing-engine role, are functioning as the master router and backup router of the Virtual Chassis, respectively. The Neighbor List displays the interconnections between the member routers by means of the Virtual Chassis ports. For example, member 0 is connected to member 1 through vcp-2/2/0 and vcp-2/3/0. The asterisk (*) following Master denotes the router on which the command was issued. The Mastership priority value is assigned by the software and is not configurable in the current release.
Verifying the Operation of the Virtual Chassis Ports
Purpose
Verify that the Virtual Chassis ports are properly configured and operational.
Action
Display the status of the Virtual Chassis ports for both members of the Virtual Chassis.
{master:member0-re0}
user@gladius> show virtual-chassis vc-port all-members
member0: -------------------------------------------------------------------------- Interface Type Trunk Status Speed Neighbor or ID (mbps) ID Interface Slot/PIC/Port 2/2/0 Configured 3 Up 10000 1 vcp-2/0/0 2/3/0 Configured 3 Up 10000 1 vcp-5/2/0 member1: -------------------------------------------------------------------------- Interface Type Trunk Status Speed Neighbor or ID (mbps) ID Interface Slot/PIC/Port 2/0/0 Configured 3 Up 10000 0 vcp-2/2/0 5/2/0 Configured 3 Up 10000 0 vcp-2/3/0
Meaning
The output confirms that the Virtual Chassis ports you configured are operational. For each member router, the Interface or Slot/PIC/Port column shows the location of the Virtual Chassis ports configured on that router. For example, the Virtual Chassis ports on member0-re0 (gladius) are vcp-2/2/0 and vcp-2/3/0. In the Trunk ID column, the value 3 indicates that a trunk has formed; if a trunk is not present, this field displays the value -1 . In the Status column, the value Up confirms that the interfaces associated with the Virtual Chassis ports are operational. The Speed column displays the speed of the Virtual Chassis port interface. The Neighbor ID/Interface column displays the member IDs and Virtual Chassis port interfaces that connect to this router. For example, the connections to member 0 (gladius) are through vcp-2/0/0 and vcp-5/2/0 on member 1 (trefoil).
Verifying Neighbor Reachability
Purpose
Verify that each member router in the Virtual Chassis can reach the neighbor routers to which it is connected.
Action
Display the neighbor reachability information for both member routers in the Virtual Chassis.
{master:member0-re0}
user@gladius> show virtual-chassis active-topology all-members
member0:
--------------------------------------------------------------------------
Destination ID Next-hop
1 1(vcp-2/2/0.32768)
member1:
--------------------------------------------------------------------------
Destination ID Next-hop
0 0(vcp-2/0/0.32768)
Meaning
The output confirms that each member router in the
Virtual Chassis has a path to reach the neighbors to which it is connected.
For each member router, the Destination ID specifies the
member ID of the destination (neighbor) router. The Next-hop column displays the member ID and Virtual Chassis port interface
of the next-hop to which packets for the destination ID are forwarded.
For example, the next-hop from member 0 (gladius) to member
1 (trefoil) is through Virtual Chassis port interface vcp-2/2/0.32768.
Published: 2013-02-11
Supported Platforms
Related Documentation
Published: 2013-02-11