Understanding SRX Series Chassis Cluster Slot Numbering and Physical Port and Logical Interface Naming
See the hardware documentation for your particular model (SRX Series Services Gateways) for details about SRX Series devices. See Interfaces User Guide for Security Devices for a full discussion of interface naming conventions.
After the devices are connected as a cluster, the slot numbering on the SRX acting as node 1 changes and thus the interface numbering will change. The slot number for each slot in both nodes is determined using the following formula:
cluster slot number = (node ID * maximum
slots per node) + local slot number
In chassis cluster mode, the interfaces on the SRX acting as node 1 are renumbered internally.
This topic describes the slot numbering and physical port and logical interface naming conventions for SRX Series devices in a chassis cluster and includes following sections:
Chassis Cluster Slot Numbering and Physical Port and Logical Interface Naming for SRX300, SRX320, SRX340, SRX345, SRX380, SRX550M, and SRX1500 Devices
For SRX340 and SRX345 devices, the fxp0 interface is a dedicated port. For SRX300 and SRX320 devices, after you enable chassis clustering and reboot the system, the built-in interface named ge-0/0/0 is repurposed as the management interface and is automatically renamed fxp0.
For SRX300, SRX320, SRX340, SRX345, and SRX380 devices, after you enable chassis clustering and reboot the system, the build-in interface named ge-0/0/1 is repurposed as the control interface and is automatically renamed fxp1.
For SRX550M devices, control interfaces are dedicated Gigabit Ethernet ports.
SRX1500 devices have 16 GE interfaces and 4 XE ports.
Table 1 shows the slot numbering, as well as the physical port and logical interface numbering, for both of the SRX Series devices that become node 0 and node 1 of the chassis cluster after the cluster is formed.
Table 1: Chassis Cluster Slot Numbering and Physical Port and Logical Interface Naming
Model | Chassis | Maximum Slots Per Node | Slot Numbering in a Cluster | Management Physical Port/Logical Interface | Control Physical Port/Logical Interface | Fabric Physical Port/Logical Interface |
---|---|---|---|---|---|---|
SRX1500 | Node 0 | 1 | 0 | fxp0 | Dedicated Control port | Any Ethernet port |
em0 | fab0 | |||||
Node 1 | 7 | fxp0 | Dedicated Control port | Any Ethernet port | ||
em0 | fab1 | |||||
SRX340,SRX345, and SRX380 | Node 0 | 5 (PIM slots) | 0—4 | fxp0 | ge-0/0/1 | Any Ethernet port |
fxp0 | fxp1 | fab0 | ||||
Node 1 | 5—9 | fxp0 | ge-5/0/1 | Any Ethernet port | ||
fxp0 | fxp1 | fab1 | ||||
SRX320 | Node 0 | 3 (PIM slots) | 0—2 | ge-0/0/0 | ge-0/0/1 | Any Ethernet port |
fxp0 | fxp1 | fab0 | ||||
Node 1 | 3—5 | ge-3/0/0 | ge-3/0/1 | Any Ethernet port | ||
fxp0 | fxp1 | fab1 | ||||
SRX300 | Node 0 | 1(PIM slot) | 0 | ge-0/0/0 | ge-0/0/1 | Any Ethernet port |
fxp0 | fxp1 | fab0 | ||||
Node 1 | 1 | ge-1/0/0 | ge-1/0/1 | Any Ethernet port | ||
fxp0 | fxp1 | fab1 | ||||
550M | Node 0 | 9 (PIM slots) | 0—8 | ge-0/0/0 | ge-0/0/1 | Any Ethernet port |
fxp0 | fxp1 | fab0 | ||||
Node 1 | 9—17 | ge-9/0/0 | ge-9/0/1 | Any Ethernet port | ||
fxp0 | fxp1 | fab1 |
After you enable chassis clustering, the two chassis joined together cease to exist as individuals and now represent a single system. As a single system, the cluster now has twice as many slots. (See Figure 1, Figure 2, Figure 3, Figure 4, and Figure 7.)







Chassis Cluster Slot Numbering and Physical Port and Logical Interface Naming for SRX4600 Devices
The SRX4600 devices use dedicated HA control and fabric ports.
Table 2 and Table 3 show the slot numbering, as well as the physical port and logical interface numbering, for both of the SRX Series devices that become node 0 and node 1 of the chassis cluster after the cluster is formed.
Table 2: Chassis Cluster Slot Numbering, and Physical Port and Logical Interface Naming for SRX4600 Devices
Model | Chassis Cluster | Maximum Slots Per Node | Slot Numbering in a Cluster | Management Physical Port/Logical Interface | Control Physical Port/Logical Interface | Fabric Physical Port/Logical Interface |
---|---|---|---|---|---|---|
SRX4600 | Node 0 | 1 | 0-6 | fxp0 | Dual (redundant) MACsec-enabled HA control ports (10GbE) are xe-0/0/0 and xe-0/0/1 | Dual (redundant) MACsec-enabled HA fabric ports (10GbE) Dual Fabric ports with macsec enabled are xe-0/0/2 and xe-0/0/3 |
Node 1 | 7-13 |
Table 3: Chassis Cluster Interface Renumbering for SRX4600
Device | Renumbering Constant | Node 0 Interface Name | Node 1 Interface Name |
---|---|---|---|
SRX4600 | 7 | xe-1/0/0 | xe-8/0/0 |
Table 4: Chassis Cluster Fabric Interface Details for SRX4600
Interfaces | Used as Fabric Port? | Supports Z-Mode Traffic? | Supports MACsec? |
---|---|---|---|
Dedicated fabric ports | Yes | Yes | Yes |
8X10-Gigabit Ethernet Interface SFPP ports | No | No | No |
4X40-Gigabit Ethernet Interface QSFP28 ports | Yes | Yes | No |
4x10-Gigabit Ethernet Interface SFPP ports | No | No | No |
2X100-Gigabit Ethernet Interface QSFP28 slots | No | No | No |
Mix and match of fabric ports are not supported. That is, you cannot use one 10-Gigabit Ethernet interface and one 40-Gigabit Ethernet interface for fabric links configuration. Dedicated fabric link supports only 10-Gigabit Ethernet Interface.
Figure 8 shows the slot numbering for both of the SRX Series devices that become node 0 and node 1 of the chassis cluster after the cluster is formed.

Chassis Cluster Slot Numbering and Physical Port and Logical Interface Naming for SRX4100 and SRX4200 Devices
The SRX4100 and SRX4200 devices use two 1-Gigabit
Ethernet/10-Gigabit Ethernet ports, labeled as CTL
and FAB
as control port and fabric port respectively.
Supported fabric interface types for SRX4100 and SRX4200 devices are 10-Gigabit Ethernet (xe) (10-Gigabit Ethernet Interface SFP+ slots).
Table 5 shows the slot numbering, as well as the physical port and logical interface numbering, for both of the SRX Series devices that become node 0 and node 1 of the chassis cluster after the cluster is formed
Table 5: Chassis Cluster Slot Numbering, and Physical Port and Logical Interface Naming for SRX4100 and SRX4200 Devices
Model | Chassis Cluster | Maximum Slots Per Node | Slot Numbering in a Cluster | Management Physical Port/Logical Interface | Control Physical Port/Logical Interface | Fabric Physical Port/Logical Interface |
---|---|---|---|---|---|---|
SRX4100 | Node 0 | 1 | 0 | fxp0 | Dedicated control port, em0 | Dedicated fabric port, any Ethernet port (for dual fabric-link), fab0 |
Node 1 | 7 | Dedicated fabric port, and any Ethernet port (for dual fabric-link), fab1 | ||||
SRX4200 | Node 0 | 1 | 0 | fxp0 | Dedicated control port,em0 | Dedicated fabric port, and any Ethernet port (for dual fabric-link), fab0 |
Node 1 | 7 | Dedicated fabric port, and any Ethernet port (for dual fabric-link), fab1 |
Figure 9 and Figure 10 shows the slot numbering for both of the SRX Series devices that become node 0 and node 1 of the chassis cluster after the cluster is formed.


The node 1 renumbers its interfaces by adding the total number of system FPCs to the original FPC number of the interface. For example, see Table 6 for interface renumbering on the SRX Series devices (SRX4100 and SRX4200).
Table 6: Chassis Cluster Interface Renumbering for SRX4100 and SRX4200
Device | Renumbering Constant | Node 0 Interface Name | Node 1 Interface Name |
---|---|---|---|
SRX4100 | 7 | xe-0/0/0 | xe-7/0/0 |
SRX4200 | 7 | xe-0/0/1 | xe-7/0/1 |
On SRX4100 and SRX4200 devices, when the system comes up as chassis cluster, the xe-0/0/8 and xe-7/0/8 interfaces are automatically set as fabric interfaces links. You can set up another pair of fabric interfaces using any pair of 10-Gigabit interfaces to serve as the fabric between nodes. Note that, the automatically created fabric interfaces cannot be deleted. However, you can delete the second pair of fabric interfaces (manually configured interfaces).
Chassis Cluster Slot Numbering and Physical Port and Logical Interface Naming for SRX5800, SRX5600, and SRX5400 Devices
For chassis clustering, all SRX Series devices have a built-in management interface named fxp0. For most SRX Series devices, the fxp0 interface is a dedicated port.
For the SRX5000 line, control interfaces are configured on SPCs.
Table 7 shows the slot numbering, as well as the physical port and logical interface numbering, for both of the SRX Series devices that become node 0 and node 1 of the chassis cluster after the cluster is formed.
Table 7: Chassis Cluster Slot Numbering, and Physical Port and Logical Interface Naming for SRX5000 Line Devices
Model | Chassis Cluster | Maximum Slots Per Node | Slot Numbering in a Cluster | Management Physical Port/Logical Interface | Control Physical Port/Logical Interface | Fabric Physical Port/Logical Interface |
---|---|---|---|---|---|---|
SRX5800 | Node 0 | 12 (FPC slots) | 0—11 | Dedicated Gigabit Ethernet port | Control port on an SPC | Any Ethernet port |
fxp0 | em0 | fab0 | ||||
Node 1 | 12—23 | Dedicated Gigabit Ethernet port | Control port on an SPC | Any Ethernet port | ||
fxp0 | em0 | fab1 | ||||
SRX5600 | Node 0 | 6 (FPC slots) | 0—5 | Dedicated Gigabit Ethernet port | Control port on an SPC | Any Ethernet port |
fxp0 | em0 | fab0 | ||||
Node 1 | 6—11 | Dedicated Gigabit Ethernet port | Control port on an SPC | Any Ethernet port | ||
fxp0 | em0 | fab1 | ||||
SRX5400 | Node 0 | 3 (FPC slots) | 0—2 | Dedicated Gigabit Ethernet port | Control port on an SPC | Any Ethernet port |
fxp0 | em0 | fab0 | ||||
Node 1 | 3—5 | Dedicated Gigabit Ethernet port | Control port on an SPC | Any Ethernet port | ||
fxp0 | em0 | fab1 |
After you enable chassis clustering, the two chassis joined together cease to exist as individuals and now represent a single system. As a single system, the cluster now has twice as many slots. (See Figure 11.)

FPC Slot Numbering in SRX Series Device Cards
SRX5600 and SRX5800 devices have Flex I/O Cards (Flex IOCs) that have two slots to accept the following port modules:
SRX-IOC-4XGE-XFP 4-Port XFP
SRX-IOC-16GE-TX 16-Port RJ-45
SRX-IOC-16GE-SFP 16-Port SFP
You can use these port modules to add from 4 to 16 Ethernet ports to your SRX Series device. Port numbering for these modules is
where slot is the number of the slot in the device in which the Flex IOC is installed; port module is 0 for the upper slot in the Flex IOC or 1 for the lower slot when the card is vertical, as in an SRX5800 device; and port is the number of the port on the port module. When the card is horizontal, as in an SRX5400 or SRX5600 device, port module is 0 for the left-hand slot or 1 for the right-hand slot.
SRX5400 devices support only SRX5K-MPC cards. The SRX5K-MPC cards also have two slots to accept the following port modules:
SRX-MIC-10XG-SFPP 10-port-SFP+ (xe)
SRX-MIC-20GE-SFP 20-port SFP (ge)
SRX-MIC-1X100G-CFP 1-port CFP (et)
SRX-MIC-2X40G-QSFP 2-port QSFP (et)
See the hardware guide for your specific SRX Series model (SRX Series Services Gateways).