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Example: Adding an EX4500 Switch to a Nonprovisioned Virtual Chassis

 

A Virtual Chassis is multiple switches operating as a single network entity. You might want to expand an existing Virtual Chassis by adding EX4500 switches to it. You can include up to ten EX4500 switches in an EX4500 Virtual Chassis or a mixed EX4200 and EX4500 Virtual Chassis.

This example describes how to add two EX4500 switches to an existing EX4200 Virtual Chassis that was nonprovisioned. A nonprovisioned configuration is a Virtual Chassis whose roles were assigned automatically rather than configured statically (preprovisioned).

Requirements

This example uses the following hardware and software components:

  • Junos OS Release 11.1 or later for EX Series switches

  • Two EX4200 switches interconnected into a nonprovisioned Virtual Chassis

  • Two standalone EX4500 switches with Virtual Chassis modules

Before you begin, be sure you have:

  1. An operational EX4200 Virtual Chassis with two member EX4200 switches that was configured using a nonprovisioned configuration.
  2. Installed the same version of Junos OS Release 11.1 or later for all members of the Virtual Chassis and on the EX4500 switches.
Note

You must use Junos OS Release 11.4 or later if you are including three or more EX4500 switches in an EX4500 Virtual Chassis or a mixed EX4200 and EX4500 Virtual Chassis.

Overview and Topology

You can create an EX4200 Virtual Chassis by cabling two operational EX4200 switches together using the dedicated Virtual Chassis ports (VCPs) on each EX4200 switch. When you cable a Virtual Chassis using the dedicated VCPs, the switches run a master election algorithm that determines the Virtual Chassis roles for each member switch. The master election algorithm first checks the mastership priority ID. The mastership priority ID is any number between 0 and 255. The switch with the higher mastership priority ID is elected into the master role and the other switch, unless it has been configured with a mastership priority value of 0, is elected into the backup role.

The default mastership priority ID for an EX4200 or EX4500 switch is 128. Both EX4200 switches are using this default mastership priority ID in the operational EX4200 Virtual Chassis in this example.

Note

We recommend that you use the commit synchronize command to save any configuration changes that you make to a Virtual Chassis.

Table 1 shows the default configuration settings for the two-member Virtual Chassis before the EX4500 member switches are added to the Virtual Chassis.

Table 1: Components of the EX4200 Virtual Chassis Before the EX4500 Member Switches Are Added

Member SwitchHardwareMember IDRole and Priority

SWA-0

EX4200 switch

0

Master: mastership priority 128

SWA-1

EX4200 switch

1

Backup: mastership priority 128

Table 2 shows the configuration of the mixed EX4200 and EX4500 Virtual Chassis after the EX4500 member switches are added to the Virtual Chassis and the EX4500 switches have been configured in the master and backup roles.

Table 2: Final Mixed EX4200 and EX4500 Virtual Chassis Components

Member SwitchHardwareMember IDRole and Priority

SWA-0

EX4200 switch

0

Linecard: mastership priority 0

SWA-1

EX4200 switch

1

Linecard: mastership priority 0

SWA-2

EX4500 switch

2

Master: mastership priority 255

SWA-3

EX4500 switch

3

Backup: mastership priority 255

Figure 1 shows the hardware topology of the mixed EX4200 and EX4500 Virtual Chassis.

Figure 1: Mixed EX4200 and EX4500 Virtual Chassis Topology (Nonprovisioned Configuration)
Mixed
EX4200 and EX4500 Virtual Chassis Topology (Nonprovisioned Configuration)

Configuration

Step-by-Step Procedure

To add two EX4500 switches to an existing EX4200 Virtual Chassis:

  1. Log in to the EX4200 Virtual Chassis.
  2. Set all member switches into mixed mode:
    user@switch> request virtual-chassis mode mixed all-members
  3. Reboot all member switches in the Virtual Chassis:
    user@switch> request system reboot
  4. Power on SWA-2, the EX4500 switch that you want to function in the master role.
  5. Power on SWA-3, the EX4500 switch that you want to function in the backup role.
  6. Set the PIC mode to the Virtual Chassis mode on both SWA-2 and SWA-3:
    user@switch> request chassis pic-mode virtual-chassis
  7. Configure SWA-2 and SWA-3 as a member of the mixed EX4200 and EX4500 Virtual Chassis:
    user@switch> request virtual-chassis mode mixed
  8. Reboot the EX4500 switches.
  9. Cable SWA-2 into the Virtual Chassis using the dedicated VCP on the back of the EX4200 member switch and the dedicated VCP on the Virtual Chassis module in the EX4500 switch.Note

    We recommend cabling one VCP into the Virtual Chassis, waiting for the new switch to be recognized by the Virtual Chassis, then cabling the other VCP on the new switch into the Virtual Chassis.

    If you immediately cable both VCPs into the existing Virtual Chassis, one of the Virtual Chassis member switches might become nonoperational for several seconds. Network traffic to that member switch is dropped during the downtime.

    The switch will return to the normal operational state with no user intervention, and normal operation of the Virtual Chassis will resume after this downtime.

  10. Cable SWA-3 into the Virtual Chassis using the dedicated VCP on the back of the EX4200 member switch and the dedicated VCP on the Virtual Chassis module in the EX4500 switch.Note

    We recommend cabling one VCP into the Virtual Chassis, waiting for the new switch to be recognized by the Virtual Chassis, then cabling the other VCP on the new switch into the Virtual Chassis.

    If you immediately cable both VCPs into the existing Virtual Chassis, one of the Virtual Chassis member switches might become nonoperational for several seconds. Network traffic to that member switch is dropped during the downtime.

    The switch will return to the normal operational state with no user intervention, and normal operation of the Virtual Chassis will resume after this downtime.

  11. Log in to the Virtual Chassis and set the mastership priority for the EX4200 switches to 0 and the EX4500 switches to 255:
    [edit virtual-chassis]

    user@SWA–0# set member 0 mastership-priority 0

    user@SWA–0# set member 1 mastership-priority 0

    user@SWA–0# set member 2 mastership-priority 255

    user@SWA–0# set member 3 mastership-priority 255

    Note

    A switch with a mastership priority ID of 0 never assumes the master or backup role within a Virtual Chassis. This configuration ensures that the EX4200 member switches remain in the linecard roles even during Virtual Chassis topology changes.

    If you want the EX4200 switches to assume the master or backup roles, assign the switches a mastership priority between 1 and 255.

Verification

To confirm that the Virtual Chassis configuration is operational, perform these tasks:

Verifying Virtual Chassis Availability and Roles

Purpose

Verify that the Virtual Chassis is up and that the member switches are in the correct roles.

Action

List the member switches and roles.

Meaning

The show virtual-chassis command lists the member switches interconnected in a Virtual Chassis configuration with the member IDs that have been assigned by the master, the mastership priority values, and the roles. It also displays the neighbor members with which each member is interconnected. The output shows that the switches have the correct mastership priorities and roles.