17.1 Unmanaged Switches

Chapter 12 introduced the Hirschmann product families at a high level. This chapter dives into each DIN rail product, starting with the simplest tier: unmanaged switches that require zero configuration.

Why Unmanaged Switches Exist

A PLC cell with four devices and no VLAN requirements does not need a managed switch. An unmanaged switch forwards frames at wire speed, draws minimal power, and introduces zero configuration risk. The SPIDER III and OCTOPUS unmanaged families serve this role in Hirschmann networks.

SPIDER III Standard Line

The Standard Line is the entry point of the Hirschmann portfolio. Each switch is a fanless, DIN-rail-mounted, store-and-forward Ethernet switch.

Specification	Value
Ports	Up to 10 FE or GE (max 2 fiber)
Housing	IP30 plastic or metal
Power	12/24 V DC (9.6 to 32 V DC)
Consumption	1.3 to 6.8 W
Temperature	0 C to +60 C, -40 C to +70 C variants
Hazardous location	IECEx Zone 2, ATEX Zone 2, ISA 12.12.01 Class 1 Div 2
Diagnostics	LEDs (power, link, data, speed)
Configurable parameters	None

The Standard Line has no management interface, no USB port, and no configurable parameters. It forwards frames and nothing else.

SPIDER III Premium Line

The Premium Line adds a USB configuration port and a fault relay contact. It remains unmanaged (no IP address, no SNMP, no CLI), but operators adjust QoS and port parameters via USB.

Specification	Value
Ports	Up to 26 FE or 8 GE (max 3 FE or 2 GE fiber)
Housing	IP40 metal
Power	12/24 V DC (9.6 to 32 V DC), redundant input
Consumption	2.4 to 9.0 W
Temperature	-40 C to +70 C
USB port	Configuration of QoS, port settings, thresholds
Fault relay	Alarm output for power supply failure
Configurable	QoS 802.1p/DSCP mapping, broadcast/multicast thresholds, port speed/duplex, flow control

Tip

The Premium Line fault relay integrates with PLC alarm inputs. Wire the relay contact to a digital input on the PLC to detect switch power supply failures without SNMP.

OCTOPUS Unmanaged

The OCTOPUS unmanaged switches mount outside control cabinets in harsh environments. IP65/67 rating, M12 D-coded connectors, and rail vehicle certifications make them suitable for rolling stock, trackside, and outdoor installations.

Specification	OCTOPUS 8TX-EEC	OCTOPUS 8TX PoE-EEC	OCTOPUS 5TX EEC
Ports	8 FE M12 D-coded	8 FE M12 D-coded	5 FE M12 D-coded
PoE	No	7 x PoE+ (35 W total)	No
Power	24 V DC	24 V DC	12-24 V DC
Temperature	-40 C to +70 C	-40 C to +70 C	-40 C to +70 C
Protection	IP65/67	IP65/67	IP65/67
Certifications	cUL, EN 50155, EN 45545, EN 50121-4, E1	cUL, E1	cUL

When to Use Unmanaged vs Managed

Caution

Unmanaged switches do not participate in MRP rings. Connecting an unmanaged switch to an MRP ring port breaks the ring. Use managed switches for all ring members.

Discovering Unmanaged Switches

Unmanaged switches have no IP address and do not respond to SNMP, ping, or LLDP. The only way to detect them on a network segment is through ARP scanning or MAC address table inspection on the upstream managed switch.

The following script uses ARP scanning to find active hosts on a subnet. Unmanaged switches do not appear directly, but the devices connected to them do.

from scapy.all import ARP, Ether, srp

def arp_scan(subnet: str) -> list[dict]:
    """Send ARP requests to all hosts on a subnet."""
    pkt = Ether(dst="ff:ff:ff:ff:ff:ff") / ARP(pdst=subnet)
    answered, _ = srp(pkt, timeout=2, verbose=False)
    return [{"ip": rcv.psrc, "mac": rcv.hwsrc} for _, rcv in answered]

if __name__ == "__main__":
    for h in arp_scan("192.168.1.0/24"):
        print(f"{h['ip']:>15}  {h['mac']}")

Multiple hosts sharing the same upstream port on the managed switch, combined with Hirschmann OUI prefixes (00:80:63), confirm an unmanaged Hirschmann switch in the path.

Key Takeaways

Standard Line: zero configuration

SPIDER III Standard Line switches forward frames with no setup. Use them for simple cells where VLANs, redundancy, and monitoring are unnecessary.

OCTOPUS: IP67 for harsh environments

M12 connectors, -40 C to +70 C, and rail certifications. Use OCTOPUS unmanaged switches outside cabinets on trains and in outdoor installations.

What Comes Next

Unmanaged switches handle the simplest cells. The next section covers lite managed switches (LEMUR and GECKO) that add basic management, redundancy, and diagnostics at a lower cost than full managed devices.

References

• Belden/Hirschmann. (2024). Hirschmann Essentials Product Catalog. Belden Inc.
• Belden/Hirschmann. (2024). SPIDER III Data Sheet. Belden Inc.