Configuring Virtual Chassis on Juniper EX Series

Reading Time: 3 minutes

You have two ways of configuring a Virtual Chassis (VC) on the Juniper EX Series. One method would be use VCP cables that will connect the two EX switches together (which will be written about shortly). The issue with VCP cables is that they are limited to 5 metres in length, which can be an issue if you wanted to create a VC and your switches were more than 5m apart or some other reason why it would be difficult to use VCP cables.

With that in mind, you are able to define port(s) (either copper or if you’re using an uplink module with an SFP fibre) that can connect the switches together and have them as the VC link. These ports are known as VCEP ports. Although you have the advantage of distance by using VCEP ports, the disadvantage is that: 1. You lose out on front port capacity and 2. The bandwidth between the switches is much lower. Using a dedicated VC cable gives you 64Gbps throughput per cable (max of 2 VC cables per switch) whereas using VCEP, if you’re using single copper or a 1Gbps fibre SFP+ 2Gbps (full duplex throughput) or 20Gbps (full duplex throughput) if you’re using a single 10Gbps link from the uplink module.

This page will detail how to configure VCEP Virtual Chassis.

Note: I was using 2 x 1Gbps interfaces from a fibre uplink module.

If you are using uplink modules you need to define these ports before setting the Virtual Chassis. You need to define whether you will be using the module as a 10G uplink or as a 1G uplink.

1. Show chassis hardware (this shows that the module is seen by the switch, however, it sees it as a 10G module. Where we are using 1G SPF the switch doesn’t see the SPF modules as shown under PIC 1)

Before the module has been defined:

root> show chassis hardware 
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                BP0214030110      EX4200-48T
Routing Engine 0 REV 23   750-033063   BP0214030110      EX4200-48T, 8 POE
FPC 0            REV 23   750-033063   BP0214030110      EX4200-48T, 8 POE
  CPU                     BUILTIN      BUILTIN           FPC CPU
  PIC 0                   BUILTIN      BUILTIN           48x 10/100/1000 Base-T
  PIC 1          REV 07   711-026017   CH0214081797      2x 10GE SFP+
    Xcvr 0       REV 02   NON-SFP+     PQN4G6N           SFP-SX
    Xcvr 2       REV 02   NON-SFP+     PQN4S6U           SFP-SX
Power Supply 0   REV 05   740-020957   AT0513484229      PS 320W AC
Fan Tray

We need to define the module as 1G module.

2. Set chassis fpc 0 pic 1 sfpplus pic-mode 1g / set chassis fpc 1 pic 1 sfpplus pic-mode 1g

Now that the module has been defined we can check that the switch is now seeing the additional interfaces and the the module is now 4x 1G SFP+ ports compared to the previous 2x 10G SPF+

3. Show chassis hardware

After the module has been defined:

root> show chassis hardware 
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                BP0214030110      EX4200-48T
Routing Engine 0 REV 23   750-033063   BP0214030110      EX4200-48T, 8 POE
FPC 0            REV 23   750-033063   BP0214030110      EX4200-48T, 8 POE
  CPU                     BUILTIN      BUILTIN           FPC CPU
  PIC 0                   BUILTIN      BUILTIN           48x 10/100/1000 Base-T
  PIC 1          REV 07   711-026017   CH0214081797      4x GE SFP+
    Xcvr 0       REV 02   740-011613   PQN4G6N           SFP-SX
    Xcvr 2       REV 02   740-011613   PQN4S6U           SFP-SX
Power Supply 0   REV 05   740-020957   AT0513484229      PS 320W AC
Fan Tray

4. Now the module has been defined we can set the VC-port on both switches. We make this request in Operational mode.

request virtual-chassis vc-port set pic-slot 1 port 2

5. We set VC as recommended by Juniper as having 2 Routing-Engines (RE) before setting a Linecard. The members are defined by the serial number of each device within the VC. So during the configure if you use show chassis hardware, you will be able to get the serial-number. Now we can set the virtual chassis:

set virtual-chassis preprovisioned
set virtual-chassis member 0 role routing-engine
set virtual-chassis member 0 serial-number xxxxxxxxxxx
set virtual-chassis member 1 role routing-engine
set virtual-chassis member 1 serial-number xxxxxxxxxxx

After this has been set and committed on both switches the Backup Member (member 1) will reset back to the login prompt screen (I was consoled into both and I assumed the worse, but the member 0 was acting as expected after a commit and-quit). To check everything was working I checked the virtual-chassis and vc-port:

root> show virtual-chassis vc-port 
fpc0:
--------------------------------------------------------------------------
Interface   Type              Trunk  Status       Speed        Neighbor
or                             ID                 (mbps)       ID  Interface
PIC / Port
vcp-0       Dedicated           1    Down         32000
vcp-1       Dedicated           2    Down         32000
1/2         Configured         -1    Up           1000         1   vcp-255/1/2

fpc1:
--------------------------------------------------------------------------
Interface   Type              Trunk  Status       Speed        Neighbor
or                             ID                 (mbps)       ID  Interface
PIC / Port
vcp-0       Dedicated           1    Down         32000
vcp-1       Dedicated           2    Down         32000
1/2         Configured         -1    Up           1000         0   vcp-255/1/2


root> show virtual-chassis 
Preprovisioned Virtual Chassis
Virtual Chassis ID: f1ec.bc12.8f6b
Virtual Chassis Mode: Enabled
                                           Mstr           Mixed Neighbor List
Member ID  Status   Serial No    Model     prio  Role      Mode ID  Interface
0 (FPC 0)  Prsnt    BP0214030110 ex4200-48t 129  Master*      N  1  vcp-255/1/2
1 (FPC 1)  Prsnt    BP0211489184 ex4200-48t 129  Backup       N  0  vcp-255/1/2
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Keeran Marquis

Network Engineer
Keeran Marquis is a Network Engineer. His main goal is to learn everything within the Networking field, pick up a little bit of scripting, be a poor man sysadmin and share whatever he knows! All Posts are his own views, opinions and experiences, no guarantees they will work for you but point you in the right direction 🙂
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