EX Series Ethernet switches employ a fully-distributed forwarding architecture and they are implemented through Packet Forwarding Engines (PFEs). A PFE is a special ASIC developed by Juniper for EX Series switches. Different models of EX switches have different numbers of PFEs and the number of PFEs determines the total number of available access ports on the EX3200 Series switches. (Access ports are all those switch ports other than the uplink module ports.)

This article details the port to PFE mapping for EX8200, EX4200 and EX3200 Series Ethernet switches.

 

The numbers of PFEs on the different models of EX Series switches are as follows:

• EX8200 48-port line card – 2x PFEs and each PFE handles 24 ports

• EX4200 24-port – 2x PFEs; 1 PFE to handle 24x 1GbE ports and another PFE to handle the 2x 10GbE uplink ports

• EX4200 48-port – 3x PFEs; 1 PFE to handle 24x 1GbE ports, another PFE to handle the other 24x 1GbE ports, plus a third PFE to handle the 2x 10GbE uplink ports

• EX3200 24-port– 1x PFE; 1 PFE to handle 24x 1GbE ports or that same PFE to handle 20x 1GbE ports and 4x 1GbE uplink module ports

• EX3200 48-port – 2x PFEs; 1 PFE to handle 24x 1GbE ports, another PFE to handle the other 24x 1GbE ports; or if 1GbE uplink module is used, 1 PFE to handle 24x 1GbE ports another PFE to handle 20 1GbE ports and the 4x 1GbE uplink module ports

PFEs are in charge of all 1GbE ports, including both 1GbE access ports and 4x1GbE uplink module ports in the case of EX4200 and EX3200.

A PFE can support up to 24x1GbE ports.

This means that for EX4200 Series switches, there are enough PFEs to handle all ports, whereas EX3200 Series switches do not have enough PFEs to handle all ports.

Examples

• 48-port line card on EX8200 - 2 PFEs

Ports 0-23 are handled by first PFE.

Ports 24-47 are handled by second PFE.

• 24-port EX4200 – 2 PFEs

The first PFE is used to handle the 24 1GbE ports and the second PFE is used for the 4 uplink ports and the VC back plane ports.

• 48-port EX4200 – 3 PFEs

The first and third PFEs are used to handle the 48 1GbE ports and the second PFE is for the 4 uplink ports and the VC back plane ports.

• 24-port EX3200 – 1 PFE

4 ports cannot be supported since it has a total of 28 ports (24 access ports and 4 uplink ports).

• 48-port EX3200 – 2 PFEs

4 ports cannot be supported since it has a total of 52 ports (48 access ports and 4 uplink ports).

First PFE handles the 4x 1GbE uplink modules and second PFE handles 2x 10GbE uplink module.

Note that for EX3200-series switches, the four unsupported ports are the last four access ports. That is, the last four access ports are excluded from the whole switch ports. So, you can use all of the uplink ports and only 20 or 44 1GbE access ports.

Here is the show interface terse output with and without the 4x1GbE uplink module.

• Without the 4x1GbE uplink module

juniper@ex3200-24p> show interfaces terse
Interface               Admin Link Proto    Local                 Remote
ge-0/0/0                up    down
ge-0/0/1                up    down
ge-0/0/2                up    down
ge-0/0/3                up    down
ge-0/0/4                up    down
ge-0/0/5                up    down
ge-0/0/6                up    down
ge-0/0/7                up    down
ge-0/0/8                up    down
ge-0/0/9                up    down
ge-0/0/10               up    down
ge-0/0/11               up    down
ge-0/0/12               up    down
ge-0/0/13               up    down
ge-0/0/14               up    down
ge-0/0/15               up    down
ge-0/0/16               up    down
ge-0/0/17               up    down
ge-0/0/18               up    down
ge-0/0/19               up    down
ge-0/0/20               up    down         <<<<<<<<<<
ge-0/0/21               up    down         <<<<<<<<<<  The last 4 access ports
ge-0/0/22               up    down         <<<<<<<<<<    show up
ge-0/0/23               up    down         <<<<<<<<<<
bme0                    up    up 
--- snip 

• With the 4x1GbE uplink module

juniper@ex3200-24p> show interfaces terse   
Interface               Admin Link Proto    Local                 Remote
ge-0/0/0                up    down
ge-0/0/1                up    down
ge-0/0/2                up    down
ge-0/0/3                up    down
ge-0/0/4                up    down
ge-0/0/5                up    down
ge-0/0/6                up    down
ge-0/0/7                up    down
ge-0/0/8                up    down
ge-0/0/9                up    down
ge-0/0/10               up    down
ge-0/0/11               up    down
ge-0/0/12               up    down
ge-0/0/13               up    down
ge-0/0/14               up    down
ge-0/0/15               up    down
ge-0/0/16               up    down
ge-0/0/17               up    down
ge-0/0/18               up    down 
ge-0/0/19               up    down
ge-0/1/0                up    down     <<<<<<<<<  The last 4 access ports disappeared
ge-0/1/1                up    down     <<<<<<<<<   and 4 uplink module ports
ge-0/1/2                up    down     <<<<<<<<<   show up instead
ge-0/1/3                up    down     <<<<<<<<<
bme0                    up    up 
---- snip

Note: The restriction is only for EX3200 series switches and applies only when the 4x1GbE uplink module is in use. In other words, if a 2x10GbE uplink module is used instead, then you can still have all 24 or 48x1GbE access ports and 2x10GbE uplink ports.

 

2020-12-04: Article reviewed for accuracy; re-worded article and combined information from another KB with duplicate information