Nexus 3500 Series Datasheet for Cisco Switches with Sub-200 ns Latency

The Cisco Nexus 3500 platform comprises fixed 1RU, 10-Gigabit Ethernet data-center switches designed for line-rate Layer 2 and Layer 3 forwarding, low latency, Top-of-Rack deployment, high-frequency trading, high-performance computing, big data, and traffic-monitoring environments. The platform includes the Nexus 3548, 3524, 3548-X, 3524-X, 3548-XL, and 3524-XL models.

Product Selection

The principal selection criteria are port count, software generation, memory capacity, latency mode, routing scale, and power consumption.

The original Nexus 3548 and 3524 use 4 GB of system memory and 2 GB of bootflash memory. The X-generation switches use 4 GB of system memory and 4 GB of bootflash memory. The XL models increase both system memory and bootflash memory to 16 GB and use a 2.5 GHz CPU to support the Cisco NX-OS Data Management Engine model.

All models use fixed SFP+ interfaces operating at 1 or 10 Gbps. The 3524 variants activate 24 ports as supplied and can be expanded to 48 ports with the applicable port upgrade license.

Latency and Algo Boost Operation

The platform ASIC supports Cisco Algo Boost technology and three operating modes:

• Normal mode provides low latency with the higher platform scale values. Latency is specified as low as 250 ns.
• Warp mode consolidates forwarding operations within the switch ASIC and provides latency as low as 200 ns. Warp mode uses reduced Layer 2 and Layer 3 hardware scale.
• Warp SPAN replicates traffic from one ingress port to destination ports with latency as low as 50 ns. This mode is intended for rapid traffic replication without normal packet processing or modification.

Normal mode supports 64,000 MAC addresses, 24,000 IPv4 unicast routes, and 64,000 IPv4 hosts. Warp mode supports 8,000 MAC addresses, 4,000 IPv4 unicast routes, and 8,000 IPv4 hosts. Both modes support 8,000 IPv4 multicast routes.

Warp mode is not appropriate where the normal-mode scale values are required. vPC is not supported in Warp mode. The design should therefore select the operating mode before validating the route, host, MAC, and redundancy requirements.

Algo Boost also supports NAT for IPv4 unicast routed packets without additional latency. The 3548-X and 3524-X introduce hardware-based multicast NAT. The Algo Boost license enables NAT, Warp mode, and Warp SPAN.

The platform also provides hardware-assisted active buffer monitoring. Buffer utilization can be sampled at intervals of 10 ns or less, allowing congestion events to be observed more closely than with software polling intervals exceeding 100 ms.

Hardware and Resiliency

Each switch is a fixed 1RU chassis with:

• Dual redundant, hot-swappable power supplies
• Four individual hot-swappable fans in a 3+1 redundant arrangement
• Forward and reversed airflow options
• One RS-232 serial console port
• One locator LED and locator LED button
• A 1-PPS timing port using an RF1.0/2.3 QuickConnect connector
• SFP+ data ports operating at 1 or 10 Gbps

The original 3548 and 3524 include two 10/100/1000-Mbps management ports, although only one management port is enabled and active, with no plan stated to enable both. The X and XL models provide one 10/100/1000-Mbps management port and two USB ports. The original models provide one USB port.

Airflow must be matched to the rack aisle design:

• Forward airflow is port-side exhaust. Air enters through the fan tray and power supplies and exits through the port side.
• Reversed airflow is port-side intake. Air enters through the port side and exits through the fan tray and power supplies.

Blue handles identify port-side exhaust components. Red handles identify port-side intake components. Power supplies and fan modules must use the same airflow direction as the chassis.

The power subsystem supports AC and DC power supplies, with two redundant supplies per switch. AC input is 100 to 240 VAC at 50 to 60 Hz. Power supply efficiency is specified at 89 to 91 percent at 220 V.

Performance, Scale, and Buffering

The 48-port switches provide 960 Gbps of switching capacity and 720 million packets per second forwarding. The 24-port switches provide 480 Gbps and 360 mpps. All models support line-rate Layer 2 and Layer 3 traffic on all ports.

Maximum configurable MTU is 9216 bytes on all ports. This supports jumbo-frame designs, but the end-to-end path, connected hosts, storage systems, and routed interfaces must use compatible MTU settings.

The buffer architecture provides 6 MB shared among 16 ports and 18 MB total. This is relevant when sizing for bursty traffic, multicast replication, monitoring aggregation, or traffic patterns with unequal ingress and egress rates. Active buffer monitoring should be included in operational monitoring for congestion-sensitive environments.

The hardware scale values common to the platform include:

NX-OS Features and Licensing

The default system software includes Layer 2 switching, VLANs, IEEE 802.1Q trunking, LACP, UDLD, MSTP, RSTP, spanning-tree safeguards, AAA, ACLs, storm control, CoPP, SSHv2, SNMP, syslog, PTP, advanced buffer monitoring, SPAN, and ERSPAN.

The Base license adds Layer 3 services including inter-VLAN routing, static routes, RIPv2, limited OSPFv2, EIGRP stub, HSRP, VRRP, PIM-SM, SSM, and MSDP.

The LAN Enterprise license adds advanced OSPFv2, EIGRP, BGP, and VRF-Lite. It requires the Base license.

Layer 3 functionality includes routed ports, SVIs, PortChannels, and subinterfaces, with a total of 1024 Layer 3 interfaces. The platform supports 24-way ECMP, IPv4 ACLs, VRF-aware unicast and multicast, VRF route leaking, HSRP, VRRP, and static and dynamic routing.

Layer 2 capabilities include up to 4096 VLANs, PVRST+, 64 MST instances, PortFast, Root Guard, Bridge Assurance, EtherChannel, LACP, Layer 2/3/4 PortChannel hashing, storm control, IEEE 802.3x flow control, and vPC. vPC requires Normal mode because it is not supported in Warp mode.

Security functions include standard and extended ingress ACLs, VACLs, PACLs, named ACLs, VTY ACLs, DHCP relay, CoPP, AAA, RADIUS, TACACS+, RBAC, AES management traffic, digital certificates for management between the switch and RADIUS server, and MS-CHAP.

Management and automation features include POAP, Python scripting, CLI, XML NETCONF, REST API support through Cisco Nexus Data Broker, SNMP versions 1, 2, and 3, RMON, NTP, syslog, configuration rollback, embedded packet analysis, SPAN, ERSPAN versions 2 and 3, Cisco Discovery Protocol, DCNM, Cisco OHMS, and Cisco Call Home.

Timing, Monitoring, and Traffic Visibility

IEEE 1588 PTP boundary-clock support is included. A 1-PPS output port is provided for measuring timing drift from a grandmaster; the datasheet states that 1-PPS output requires a future software revision.

Monitoring functions include SPAN, ERSPAN, packet filtering, packet sampling, packet truncation, and nanosecond-level timestamp insertion in ERSPAN headers when ERSPAN and PTP are used.

Cisco Nexus Data Broker can build a tap or SPAN aggregation infrastructure using multiple Nexus 3500 switches. It supports traffic aggregation, load balancing to monitoring tools, replication to multiple destinations, Layer 1 through Layer 4 filtering, packet truncation, and PTP-based timestamping. The Data Broker license is required for tap and SPAN aggregation functions, while the Base license is required for the feature.

Optics and Cabling

The SFP+ interfaces support 100 Mbps, 1 Gbps, and 10 Gbps connectivity through compatible transceivers. Supported options include multimode and single-mode optics, passive Twinax, active Twinax, and DWDM modules.

Forty-Gigabit Ethernet is created by combining four sequential SFP+ interfaces into a logical 40-Gigabit interface. Supported cabling includes QSFP to four SFP 10-Gbps passive copper splitter cables. The resulting interface is compliant with the IEEE 40-Gigabit Ethernet standard and can interoperate with devices using other 40-Gigabit interface form factors.

Presales cabling rules are straightforward:

1. Use SR optics or Twinax for short in-rack or adjacent-rack connections where the cable reach is suitable.
2. Use LR, ER, or DWDM optics for longer or specialized single-mode fiber paths.
3. Validate the transceiver on both endpoints before finalizing the bill of materials.
4. Use GLC-TE or other supported Gigabit optics when connecting to 100 Mbps or 1 Gbps infrastructure.
5. Confirm whether a design uses native 10-Gigabit links or four-lane 40-Gigabit breakout.

Environmental and Physical Requirements

All models share the following chassis dimensions and environmental limits:

An ASHRAE data-center environment is recommended. Rack planning must account for the 18.38-inch chassis depth, power-supply and fan airflow direction, cable bend radius, and front or rear service access.

MTBF is not specified in the provided product specifications. Acoustic noise is also not specified. These values should therefore be obtained from the applicable platform environmental qualification documentation before approving deployments with strict noise or reliability requirements.

Power and cooling planning should use the model-specific figures below:

The X models consume approximately 25 percent less power than the previous generation according to the product description. The XL models use the X-generation hardware basis but have higher CPU, memory, and bootflash specifications.

Ordering Matrix

The datasheet also identifies the following supported connectivity part numbers: SFP-10G-SR, SFP-10G-LR, SFP-10G-ER, DWDM-SFP10G-*, QSFP-4SFP10G-CU1M, QSFP-4SFP10G-CU3M, QSFP-4SFP10G-CU5M, SFP-H10GB-CU1M, SFP-H10GB-CU3M, SFP-H10GB-CU5M, SFP-H10GB-ACU7M, SFP-H10GB-ACU10M, GLC-TE, GLC-SX-MM, GLC-SX-MMD, GLC-LH-SM, and GLC-LH-SMD.

Warranty and Service

The Nexus 3000 Series includes a 1-year limited hardware warranty. Hardware replacement is provided with a 10-day turnaround from receipt of an approved Return Materials Authorization.

Available service options include Cisco SMARTnet Service, Cisco Advanced Services, Cisco Smart Call Home, and Cisco Online Health Management System. SMARTnet provides access to network experts and support resources for mission-critical incidents. Smart Call Home provides proactive diagnostics and real-time alerts. Advanced Services uses an architecture-led approach for deployment, optimization, migration, and operational planning.

For presales proposals, the hardware warranty should be listed separately from any optional support contract. SMARTnet, proactive monitoring, advanced implementation, replacement logistics, and operational assistance are service selections rather than inherent chassis capabilities.