Description

This article describes the issue of all members of a VC, which is enabled in the normal mode, becoming inactive, when a new member being enabled in the mixed mode is added.

Symptoms

If any new member with the mixed mode being enabled is added to an existing VC, which is enabled in the normal mode, all members of VC will become inactive.

Solution

When a new switch is installed, with the mixed mode being enabled, in an existing virtual chassis, all members of the virtual chassis will be changed to the inactive/line card state. Even the new member is removed from the virtual chassis, all of the members will still remain in the line card mode. 

{master:0}[edit]
user@switch# run show virtual-chassis

Virtual Chassis ID: 53b7.cf06.9503
Virtual Chassis Mode: Enabled < Mixed mode is not enabled. Mstr Mixed Neighbor List
Member ID Status Serial No Model prio Role Mode ID Interface
0 (FPC 0) Prsnt BR0200000997 ex4200-24f 128 Master* N 1 vcp-0
2 vcp-1
1 (FPC 1) Prsnt BR0200000019 ex4200-24f 128 Linecard N 2 vcp-0
0 vcp-1
2 (FPC 2) Prsnt BR0200000803 ex4200-24f 128 Backup N 1 vcp-0
0 vcp-1
 
New member with Mixed mode enabled: 
{master:0}
user@switch> show virtual-chassis

Virtual Chassis ID: d4a8.3f43.c5ae
Virtual Chassis Mode: Mixed < New member with mixed mode enabled. Mstr Mixed Neighbor List
Member ID Status Serial No Model prio Role Mode ID Interface
0 (FPC 0) Prsnt BR0200000828 ex4200-24f 128 Master* Y 
Member ID for next new member: 1 (FPC 1)
In the following excerpt, you can see that all members changed to the line card mode and the newly added member will take the 0 member ID. As the new member is the primary, it will push its configuration to all of the other members: 
{master:0}
user@switch> show virtual-chassis

Virtual Chassis ID: 53b7.cf06.9503
Virtual Chassis Mode: Mixed
Mstr Mixed Neighbor List
Member ID Status Serial No Model prio Role Mode ID Interface
0 (FPC 0) Prsnt BR0200000828 ex4200-24f 128 Master* Y 1 vcp-1 1 (FPC 1) 
Inactive BR0200000997 ex4200-24f 128 Linecard N 0 vcp-0
2 vcp-1
2 (FPC 2) Inactive BR0200000803 ex4200-24f 128 Linecard N 3 vcp-0
1 vcp-1
3 (FPC 3) Inactive BR0200000019 ex4200-24f 128 Linecard N 2 vcp-0

Member ID for next new member: 4 (FPC 4)
Even if the new member is isolated from the VC, all the members will remain in the line card mode. Now, to recover from this situation, you need to dismantle the whole VC, re-activate all members, and again build the whole VC.

If the new member is having the factory default configuration, it will push the factory default configuration to all members and the whole VC will become the factory default. 
user@switch> show virtual-chassis status

Virtual Chassis ID: 53b7.cf06.9503
Virtual Chassis Mode: Enabled
Mstr Mixed Neighbor List
Member ID Status Serial No Model prio Role Mode ID Interface
0 (FPC 0) NotPrsnt BR0200000828 ex4200-24f
1 (FPC 1) Inactive BR0200000997 ex4200-24f 128 Linecard N 2 vcp-1
2 (FPC 2) Inactive BR0200000803 ex4200-24f 128 Linecard* N 3 vcp-0
1 vcp-1
3 (FPC 3) Inactive BR0200000019 ex4200-24f 128 Linecard N 2 vcp-0
Note : Before adding any new members to the existing VC, always check the VC mode settings.

Modification History

2021-03-19: Updated the article terminology to align with Juniper's Inclusion & Diversity initiatives.