MikroTik CRS504-4XQ-IN 4×100G QSFP28 Switch RouterOS

The MikroTik CRS504-4XQ-IN is MikroTik's entry point into 100G switching — four QSFP28 ports, a Marvell 98DX4310 dedicated 100G switch ASIC, dual hot-swap AC PSU slots, and RouterOS v7 License 5 in a compact 1U rack enclosure at USD 799.00. MikroTik's own framing: "your most affordable, compact, energy-efficient doorway to the world of 100 Gigabit networking." It is the correct switch when exactly four 100G ports are needed — connecting a CCR2216 core router to a CRS518-16XS-2XQ-RM distribution switch, aggregating four 100G uplinks from downstream 25G switches, or anchoring a compact 100G core in a small ISP PoP or advanced lab environment.

**Marvell 98DX4310 — the dedicated 100G switch ASIC**

The 98DX4310 is Marvell's Prestera DX switch ASIC designed specifically for 4× QSFP28 (100G) port switching — hardware-offloaded Layer 2 switching and Layer 3 routing across all four ports at line rate. VLAN (802.1Q), MAC address forwarding, STP/RSTP, LACP 802.3ad, IGMP snooping, ACL, QoS, and jumbo frame processing are all handled in the ASIC without CPU involvement. The QCA9531 management CPU (single-core MIPSBE, 650 MHz, 64 MB RAM) handles RouterOS v7 control plane — configuration, scripting, SNMP, and routing protocol management — while the 98DX4310 handles all data plane forwarding. MikroTik's words: "The mighty Marvell DX4310 switch-chip will handle everything without breaking a sweat!"

**4× QSFP28 — 100G, 40G, and 4×25G breakout on every port**

Each of the four QSFP28 ports operates independently in multiple modes — no port is constrained to a single speed or topology:

- **100G point-to-point:** Connect directly to a CCR2216, CRS518, or any 100GBASE-CR4/SR4/LR4 device via DAC (XQ+DA0001, XQ+DA0003) or optical transceiver (XQ+85MP01D, XQ+31LC02D, XQ+31LC10D).

- **40G:** Connect to legacy QSFP+ infrastructure via the same DAC and transceiver family.

- **4×25G breakout:** Use a breakout DAC (DQ+BC0003-DS+) to split one QSFP28 port into four independent 25G SFP28 connections — connecting up to four 25G devices per port, 16× 25G devices total across all four ports.

- **Mixed:** Each port operates independently — 100G on port 1, 40G on port 2, 4×25G breakout on port 3, 10G/1G on port 4 simultaneously.

MikroTik explicitly highlights this flexibility: "you can mix and match all kinds of connections: 100 Gigabits on one port, 40 Gigabits on the other, 4x25 Gigabits on the third, and maybe even some 10G or 1G cables on the fourth."

**Multiple power inputs — three DC paths + dual hot-swap AC PSU**

The CRS504-4XQ-IN has five total power input paths: 2× AC hot-swap PSU slots (100–240V, 47–63 Hz, IEC cord), DC jack (36–57V), 802.3bt PoE-in (43–57V), and 2-pin terminal (36–57V). The dual AC PSU slots provide hot-swap redundancy — PSU failure causes zero downtime. The three DC inputs (including 802.3bt PoE-in on the management port) provide power flexibility for DC-distributed rack environments or deployments where AC mains is unavailable. At 41W max (25W without attachments), the CRS504-4XQ-IN's power budget is substantially lower than the CRS518-16XS-2XQ-RM's 95W — reflecting the four-port versus 18-port port count difference.

**Real-world MikroTik deployment — Genomics Data Network**

MikroTik documents the CRS504-4XQ-IN's production use in the Genomics Data Network — a high-capacity research network for cancer treatment scientists processing genome data requiring "exceptionally fast connections." The same deployment established Latvia as the first Baltic country to connect to the pan-European research network at 100 Gigabit. For wirelessnetware.ca's Canadian customer base, this is a concrete production validation of the CRS504-4XQ-IN's 100G switching capability in a high-throughput, mission-critical research environment — directly analogous to ISP backbone aggregation or university campus 100G core switching.

**RouterOS v7 License 5 — ISP and enterprise routing**

License 5 provides unlimited BGP and OSPF instances — directly relevant for a CRS504-4XQ-IN deployed as a 100G aggregation switch in a small or medium ISP or enterprise network. WireGuard, IPsec, VLAN, firewall, scripting, SNMP, and ARM64 container support are available at License 5. Note: License 5 versus the CRS518's License 6 — for most ISP and enterprise deployments at the CRS504-4XQ-IN's four-port scale, License 5's routing instance limits are not a practical constraint.

**5-year software support guarantee:** RouterOS v7 updates free for life of product or minimum 5 years from date of purchase.

**Canadian market note:** CE, EAC, RoHS only — no FCC, no IC (ISED) published. Wired switch, no wireless transmitter — no ISED wireless advisory applies. Confirm CSA/cUL electrical safety requirements with distributor before listing, particularly given the dual AC PSU input at up to 41W.

Key specifications:

- **Product code:** CRS504-4XQ-IN

- **Switch ASIC:** Marvell 98DX4310 (Prestera DX)

- **Management CPU:** QCA9531, single-core MIPSBE, 650 MHz

- **RAM / Storage:** 64 MB / 16 MB FLASH

- **OS:** RouterOS v7, License 5

- **QSFP28 ports (100G):** 4× (breakout-capable: 40G, 4×25G, 10G, 1G)

- **10/100 Ethernet (management):** 1×

- **Serial console:** RJ45

- **AC PSU slots:** 2× (hot-swap, 100–240V, 47–63 Hz)

- **DC inputs:** 3× (DC jack 36–57V + 802.3bt PoE-in 43–57V + 2-pin terminal 36–57V)

- **Fans:** 2×

- **PCB temperature monitor:** Yes

- **Max power:** 41W (25W without attachments)

- **IP rating:** IP20

- **Operating temp:** -40°C to +70°C

- **Dimensions:** 320 × 185 × 44 mm

- **MTBF:** ~200,000 hours at 25°C

- **Certifications:** CE, EAC, RoHS — no FCC, no IC

- **Included:** Rack ears (CRS504), K10 screw kit, 2× IEC cord

- **Suggested price:** USD 799.00