Dell Networking S3124 Managed Switch

The Dell Networking S3124 is a 1RU managed campus access switch with 24 auto-sensing 10/100/1000Mb RJ45 ports, two dedicated 10Gb SFP+ uplinks, two GbE combo media ports and a hot-swap expansion bay, running Dell Networking OS9 with full line-rate Layer 2 and Layer 3 forwarding.

Where it belongs in a network

The S3124 is a wiring-closet and small-MDF access switch. Twenty-four copper ports is the right density for a single floor plate, a branch office, a lab rack or a distribution frame that feeds patch panels rather than a whole building. Because OS9 gives it the same line-rate IPv4 and IPv6 routing table as its 48-port sibling, it can also sit as a small collapsed core in an office that does not justify a separate distribution layer: OSPFv2/v3, BGP-4, IS-IS, policy-based routing, VRRP and 511 VRF-lite instances are all present in the same image.

The two dedicated 10Gb SFP+ ports on the front are uplinks, not shared with the access ports and not shared with the stacking fabric. Twenty-four gigabit access ports against twenty gigabits of dedicated uplink is a 1.2:1 oversubscription ratio at full line rate. Populate the expansion bay with the two-port 10GbE module and that becomes forty gigabits of uplink against twenty-four of access - more uplink than the access layer can ever generate.

Stacking and the expansion bay

Two dedicated stacking ports sit on the rear of the chassis, each rated at 21Gbps, giving 84Gbps of full-duplex stacking bandwidth. Up to twelve switches join a single stack, managed under one IP address, for a maximum of 624 ports presented as one logical device. Stacking cables are available in 0.25m, 1m and 3m, which is enough to reach across a rack or between two adjacent racks but not across a room - plan stack members physically together.

Because the stacking ports are separate from the front-panel SFP+ ports, stacking costs you no uplink capacity. That is a real architectural difference from switches that stack over their uplinks, and it is the reason the family scales cleanly: a twelve-unit stack still has twenty-four dedicated 10Gb SFP+ uplinks available to the core.

The single hot-swap expansion bay accepts either a two-port 10GBASE-T RJ45 module or a two-port 10GbE SFP+ module. Choose 10GBASE-T when the uplink is short structured copper and you want to avoid optics entirely; choose SFP+ when the uplink is fiber, when you need a DAC to a top-of-rack switch, or when you want the lower per-port power draw of a passive twinax run.

Operating system and management

Every S3100 ships with Dell Networking OS9 - the same image and the same command language used across the Dell S-series and N-series of the period, so a team already running OS9 elsewhere does not learn a second CLI. Management is by CLI over console, Telnet or SSHv2, by SNMP v1/v2c/v3 including Dell OpenManage Network Manager, and by a dedicated out-of-band 10/100/1000BASE-T management port that is entirely separate from the data plane. A USB Type-A port on the front takes configuration from a flash drive, and the switch carries dual firmware images on-board so an upgrade can be rolled back without a console session.

The feature set is genuinely enterprise-grade rather than a cut-down campus stack. Layer 3 includes OSPFv2 and OSPFv3, BGP-4 with IPv6 multiprotocol extensions, IS-IS, RIP, VRRP, PIM-SM and IGMPv1/v2/v3, with 16K IPv4 and 8K IPv6 routes and 511 VRF-lite instances for tenant or zone isolation. VLT provides active-active dual-homing without spanning-tree blocking. Interoperability with Cisco PVST+ is built in, which matters when the switch is going into a mixed-vendor campus. Security covers 802.1X with RADIUS, MAC Authentication Bypass, tiered authentication so one port can accept several methods in priority order, TACACS+ accounting and FIPS 140-2 approved cryptography. sFlow v5 and Routed Port Monitoring give you visibility across a Layer 3 domain without dedicated taps, and OpenFlow 1.3 is available for SDN deployments.

Where this model sits in the S3100 series

All five S3100 switches share the same 1RU chassis, the same Dell Networking OS9 image, the same stacking architecture and the same expansion bay. They differ in three things only: port count, port media, and whether the copper ports deliver PoE+.

• S3124 (this page)
• Dell Networking S3124F
• Dell Networking S3124P
• Dell Networking S3148
• Dell Networking S3148P

If you need the same 1GbE density with an open network operating system rather than OS9, look at the Dell Networking S3048-ON, which uses ONIE to install an alternate NOS and offers a choice of airflow direction.

Condition, testing and support

Every unit is professionally refurbished: inspected, cleaned, configuration-wiped, firmware-checked and functionally tested on every port before it ships, and it ships with warranty. Refurbished S3100-series hardware is the sensible way to buy this generation - the platform is mature, the OS9 feature set is stable and fully documented, and the secondary market is where the supply now is.

Power supplies, expansion modules, stacking cables, rail kits and optics are configurable above. If you need a specific optic mix, a particular PoE supply configuration or a quantity for a multi-closet rollout, request a quote and we will build it to your bill of materials.