Cisco Catalyst 3850: 480Gbps StackBandwidth & 40G Wireless

Powered by the Cisco Unified Access Data Plane (UADP) ASIC, the Catalyst 3850 Series is a premium enterprise access-tier switch offering deep wired-wireless convergence. It provides up to 480 Gbps of stacking bandwidth via StackWise-480 and native wireless controller capabilities supporting up to 40G of wireless throughput per switch. The platform scales easily with high-density Multigigabit, 10G/40G uplinks, and versatile PoE+/UPOE power provisioning.

Switch Models and Configurations

When sizing the Catalyst 3850 for access layer deployments, evaluate the downlink port speeds and PoE requirements. Select the UPOE (60W) models when provisioning for next-generation endpoints such as VDI clients, IP turrets, or dense Wi-Fi 6 access points, as these demand higher power budgets. Multigigabit models (XU/X48U) are mandatory if you intend to reuse existing Cat5e/Cat6 cabling runs while scaling access speeds beyond 1 Gbps. SFP/SFP+ models are strictly for fiber aggregation scenarios, where building core-to-distribution or distribution-to-access uplinks exceed copper distance limitations.

Network Modules

Network module selection is dictated by the upstream core/distribution interface speeds and the oversubscription ratio target. Utilize the 4x10G or 8x10G modules when aggregating multiple 48-port switches to prevent uplink bottlenecks, specifically in environments pushing heavy East-West traffic or 40G wireless capacity. The 2x40G (QSFP+) module is critical for backbone connectivity in high-density core topologies, while 4x1G modules are reserved exclusively for legacy 1G distribution layers where 10G is not yet deployed.

Power Supplies

Power supply dimensioning requires calculating the maximum potential draw of all connected PoE/PoE+/UPOE devices plus chassis overhead. Dual power supplies should operate in power-sharing mode for maximum PoE output, or redundant mode for N+1 reliability. If deploying 48-port switches populated with full 30W PoE+, dual 1100WAC units are required. 440WDC models are mandated for telco environments or facilities utilizing -48V DC battery plants.

Technical FAQ

Q: What is the maximum number of switches that can be stacked using StackWise-480?
A: You can stack up to 9 Catalyst 3850 switches in a single StackWise-480 ring, achieving an aggregate stack bandwidth of 480 Gbps.

Q: Does the 3850 support non-blocking wire-speed switching across all ports?
A: Yes, the UADP ASIC ensures non-blocking, wire-rate switching for all copper and fiber interfaces, including Multigigabit and 10G/40G uplinks, even with deep packet inspection enabled.

Q: Can I mix different interface types in a Catalyst 3850 stack?
A: Yes, copper, fiber (SFP/SFP+), and Multigigabit models of the 3850 can be mixed within the same StackWise-480 stack, provided they run the same IOS-XE software level and license tier.

Q: What are the power requirements for supporting full UPOE (60W) across all ports?
A: To provide 60W of UPOE across all 48 ports (2880W total), the switch must be equipped with dual 1100W AC power supplies and utilize Cisco StackPower to draw from a shared power pool, as a single switch’s internal supplies cap at 2200W.