Network switch MikroTik CRS112-8P-4S-IN — 8x Gigabit RJ-45 PoE (IEEE 802.3af/at), 4x SFP

CRS112-8P-4S-IN is a compact managed network switch with eight Gigabit RJ-45 ports that support Power over Ethernet (802.3af/at and passive PoE) and four SFP slots for fiber uplinks up to 1 Gbps. The unit includes a 28 V 3.4 A power supply and has an additional rear DC jack that accepts 48–57 V input for alternative PoE power sourcing. PoE output is delivered over mode B (pins 4,5 + and 7,8 -).

Advantages

The switch combines eight Gigabit Ethernet ports with four SFP ports for flexible copper and fiber connectivity, and supports both autosensing 802.3af/at PoE/PoE+ and passive PoE modes. It includes a 28 V 3.4 A power adapter and offers a secondary DC input for higher-voltage supplies, enabling powering of multiple PoE devices while maintaining gigabit uplink capability.

Suitable for

• Small office or branch networks requiring PoE for IP cameras, access points, or VoIP phones
• Retail or hospitality deployments with a mix of copper and fiber uplinks
• Environments that need a compact managed switch with multiple Gigabit ports and SFP uplinks

When it may not be suitable

This model is not designed for 10 Gbps switching or very high-density enterprise core deployments. Power budget is limited: with 18–28 V input the maximum per-port current is 1 A and total PoE budget is 2.8 A at 24 V, while with 48–57 V input the per-port current is limited to 450 mA and the total is 1.4 A at 48–57 V. For installations requiring higher per-port PoE power or larger total PoE budgets, a higher-capacity switch should be considered.

Key specifications

• Ports: 8 × Gigabit RJ-45 (10/100/1000), 4 × SFP
• PoE support: autosensing IEEE 802.3af/at and passive PoE (Mode B)
• Input voltage range: 18–57 V DC (28 V 3.4 A PSU included; secondary jack supports 48–57 V)
• PoE current limits: up to 1 A per port at 18–28 V, up to 450 mA per port at 48–57 V
• Total PoE budget: 2.8 A @ 24 V, 1.4 A @ 48–57 V
• Uplink speed (SFP): up to 1 Gbps
• Color: white
• Managed switch functionality: basic managed features (VLANs, switching)

How to use

Connect powered devices to the RJ-45 ports and fiber uplinks to the SFP slots as required. Use the included 28 V 3.4 A power supply for typical deployments; if higher-voltage PoE (48–57 V) is needed, connect an appropriate external 48–57 V DC supply to the rear DC jack (sold separately). The unit will autosense and provide correct PoE type to connected devices. Configure network settings and VLANs via the switch’s management interface according to your network topology.

What to consider before purchase

• Required PoE power per device and total PoE budget of the switch
• Whether 1 Gbps SFP uplinks meet your uplink capacity needs
• Need for higher-voltage (48–57 V) external PSU for full 802.3af/at power delivery
• Not suitable if 10 Gbps switching or very high PoE budgets are required

Usage recommendations

For typical small office or retail setups, use the included 28 V adapter and distribute PoE to low-to-moderate power devices (IP cameras, APs, VoIP phones). If you need to power multiple higher-power 802.3at devices, provide a compatible 48–57 V DC supply to the secondary jack and verify total current requirements before deployment.