Cisco NCS 540 Large Density Router 1Tbps 400G 600 Mpps Capacity

The Cisco NCS 540 Large Density Router is a 1RU, temperature-hardened service provider platform with QSFP28 and QSFP56-DD interfaces, Ethernet speeds from 1G through 400G, up to 1 Tbps throughput, and forwarding performance up to 600 Mpps. It is designed for converged IP transport, routed optical networking, mobile and fixed broadband aggregation, metro transport, and outdoor or indoor deployments in environmentally protected cabinets.

Product positioning and deployment role

The platform combines high-density Ethernet interfaces with Cisco IOS XR routing, transport, timing, automation, telemetry, and service-provider operational capabilities. Its interface range supports 1GE, 10GE, 25GE, 40GE, 50GE, 100GE, 200GE, and 400GE operational modes, subject to the selected chassis model and supported transceiver.

The NCS 540 Large Density family is particularly suitable where the design requires:

• Compact 1RU installation.
• Front-to-back airflow.
• High-density 25G access interfaces.
• 400G uplinks or coherent optical transport.
• SFP56-based 50G connectivity.
• Class C timing performance.
• SyncE and IEEE 1588 PTP.
• Integrated GNSS timing reference.
• Segment Routing, MPLS, EVPN, and service-provider routing.
• Environmental hardening for sealed cabinets.
• AC, DC, or mixed AC/DC power redundancy.
• IOS XR programmability and model-driven management.

The platform is not specified as a PoE system. No PoE ports or PoE power budget are listed. It should therefore be positioned as a routed transport and aggregation platform rather than a powered access switch.

Chassis and interface comparison

Both systems use a 4-core 1.5 GHz x86 CPU, 16 GB DRAM, and 64 GB storage. Both provide two hot-swappable AC/DC power supplies, six fixed fans in a 5+1 arrangement, front-to-back airflow, integrated GNSS, SyncE, PTP, and the same physical dimensions.

The two chassis should not be selected solely on the basis of the number of high-speed ports. The interface mode required by the optical design is the primary selection criterion. The N540-24Q8L2DD-SYS provides eight 50GE-capable interfaces in addition to its 24-port 25GE block. The N540-24Q2C2DD-SYS instead provides two 100GE/40GE interfaces. Confirm the required optical module, breakout mode, port speed, and IOS XR support before finalizing the bill of materials.

Throughput and forwarding capacity

The family is specified for up to 1 Tbps throughput and up to 600 Mpps forwarding performance. These figures describe platform capability and should not be treated as a guaranteed application throughput under every feature combination.

Presales sizing should account for:

1. The number of 25G, 50G, 100G, and 400G interfaces required.
2. Whether 400G ports will operate as native 400GE or in supported breakout or lower-speed modes.
3. Aggregate ingress and egress traffic levels.
4. MPLS, EVPN, Segment Routing, multicast, QoS, ACL, telemetry, and OAM requirements.
5. Packet-size distribution, especially for small-packet workloads.
6. Redundancy requirements and the traffic level that must be maintained after a link or chassis failure.
7. Optical reach and coherent module requirements.
8. Timing class requirements for mobile transport or other synchronization-sensitive services.

The datasheet specifies low-latency forwarding and Class C compliance, but it does not provide a numerical latency value. A design requiring a contractual latency target must obtain the applicable platform and transceiver performance data separately.

Hardware architecture and resilience

Each chassis contains two hot-swappable AC/DC power supply bays. The supplies provide 1+1 redundancy, and an AC and DC power supply combination is supported. This allows designs using dual power feeds or mixed facility power, provided the site power architecture and selected supplies are compatible.

The listed power supply PIDs are:

• N540-PWR400-A
• N540-PWR400-D

The cooling system contains six fixed fans in a 5+1 arrangement. Airflow is front to back. Rack and cabinet design must preserve the front-to-back airflow path and prevent recirculation of heated exhaust air.

The platform supports surge levels specified under IEC 61000-4-5:

• AC: 1 kV differential mode and 2 kV common mode.
• DC: 1 kV differential mode and 1 kV common mode.

Surge tolerance does not replace site-level grounding, bonding, transient protection, or cabinet engineering. For outside-plant use, the router must be protected from airborne contaminants, dust, moisture, insects, pests, corrosive gases, polluted air, and other reactive elements.

IOS XR capabilities

The software feature set supports the functions required for service-provider aggregation, transport, and edge roles.

Layer 2

Supported Layer 2 functions include:

• Layer 2 forwarding and bridging.
• Bridge Domains.
• Ethernet Flow Points.
• IEEE 802.1Q VLANs and Q-in-Q.
• Ethernet Link Aggregation Groups.
• LACP based on IEEE 802.3ad.
• G.8032.
• Spanning Tree Protocol.
• Jumbo frames on all ports.

These functions support demarcation, aggregation, Ethernet wholesale, and bridged service delivery. The exact service scale, MTU value, and feature interaction limits should be validated against the intended release and configuration.

Layer 3 and routing

Layer 3 capabilities include IPv4 and IPv6 unicast routing, physical and sub-interface Layer 3 interfaces, VRF, OSPFv2, OSPFv3, IS-IS, IS-ISv6, MP-BGP, ECMP, BFD, VRRP, IRB with BVI, and GRE.

These functions support routed access, aggregation, interconnection, dual-stack services, and multi-tenant separation. VRF and MP-BGP are relevant where the router must carry multiple customer, wholesale, management, or transport routing domains.

MPLS, EVPN, and Segment Routing

MPLS functions include:

• Label Edge Router and Label Switch Router operation.
• LDP.
• BGP Labeled Unicast.
• MPLS Traffic Engineering with RSVP-TE.
• Static, T-LDP, and EVPN-VPWS point-to-point L2VPN.
• VPLS and EVPN multipoint L2VPN.
• L2 and L3 EVPN with Anycast IRB.
• 6PE and 6VPE.
• LFA and RSVP-TE fast reroute.

Segment Routing capabilities include SR-MPLS, SRv6, segment routing extensions for IS-IS, OSPF, and BGP, BGP Egress Peer Engineering, SR Traffic Engineering, Flex-Algo, SR-PCE, TI-LFA, SR On-Demand Next-hop, and SR Performance Measurement.

A presales design should identify whether the deployment uses MPLS, SR-MPLS, SRv6, or a combined migration architecture. The presence of a feature in the platform feature list does not by itself define scale, licensing, interoperability, or support for every possible topology.

Multicast

The router supports IPv4 and IPv6 multicast routing, PIM-SM, PIM-SSM, IGMPv3, MLDv2, mLDP profiles 6, 7, and 14, multicast VPN, and P2MP-TE profiles 8 and 10.

These capabilities are relevant for mobile content distribution, video transport, enterprise multicast, and provider VPN services. Validate the multicast control-plane model and required tunnel technology during the design phase.

QoS

QoS functions include:

• Class-based three-level hierarchical QoS.
• Virtual Output Queueing.
• Policing and shaping.
• Multi-level priority queuing.
• Classification using Layer 2, Layer 3, and Layer 4 fields.
• Remarking.
• WRED.
• Deep packet buffering.

QoS sizing should begin with service classes, committed and peak rates, oversubscription ratios, queue priorities, and congestion behavior. The datasheet does not provide queue counts or buffer capacity values, so those values should not be assumed during a service-level design.

Timing and synchronization

Both models provide SyncE and PTP, an internal GNSS receiver, and timing interfaces for 1PPS, 10 MHz, time-of-day, and a GNSS antenna.

The GNSS receiver supports:

• GPS.
• Galileo.
• GLONASS.
• BeiDou.

The platform supports IEEE 1588-2008 roles and functions including T-GM, T-BC, T-TSC, A-PTS, and virtual port. Listed profiles and standards include G.8265.1, G.8275.1, G.8275.2, multi-profile operation, and G.8273.2 Class C.

Timing class differs by model:

• N540-24Q8L2DD-SYS: Class C for 400G and 50G.
• N540-24Q2C2DD-SYS: Class C for 100G and 400G.

For mobile transport, confirm the required frequency, phase, and time accuracy, GNSS antenna design, holdover requirements, PTP topology, boundary clock placement, and SyncE reference architecture.

Security, assurance, and operations

Security features include control-plane and management-plane protection, Local Packet Transport Services, AAA, TACACS+, SSH, IPv4 and IPv6 Layer 3 ingress and egress ACLs, Layer 2 ingress ACLs, and Unicast RPF.

Hardware and software security features include a Trust Anchor module infrastructure, secure boot, image signing, and runtime defense.

Operational tools include CDP, LLDP, ICMP, DHCP relay, IP SLA, MPLS OAM, Ethernet CFM, Y.1731 delay measurement and synthetic loss measurement, TWAMP and TWAMP-Light responders, hardware-based timestamping, Y.1564, model-driven and event-driven telemetry, NetFlow, SPAN, ERSPAN, and PW-SPAN.

Management interfaces include CLI, SNMP MIB, NETCONF/gRPC using XML, JSON, and GPB, native and OpenConfig or IETF YANG models, RPM-based software infrastructure, ZTP, and third-party application hosting.

The platform also supports Cisco DDoS Edge Protection for on-box detection and blocking of DDoS attacks. The listed use cases include mobility traffic using GTP and other IPv4, IPv6, and MPLS traffic.

Environmental and physical specifications

The datasheet identifies acoustic compliance standards but does not provide an acoustic noise value in dBA. It also does not provide an MTBF figure. Those omissions should be recorded as open items in a formal bid or environmental qualification review.

For outdoor or outside-plant deployment, use an environmentally sealed enclosure with a heat exchanger. The stated acceptable enclosure guidance includes GR-487 cabinets, or closures with at least NEMA 4 or IP66 protection.

Regulatory and sustainability considerations

The platform is designed to meet GR-63-CORE and GR-1089-CORE. Listed safety standards include ANSI/UL 60950-1, CAN/CSA C22.2 No. 60950-1, ANSI/UL 62368-1, CAN/CSA C22.2 No. 62368-1, and EN/IEC 62368-1.

Listed EMC standards include 47CFR Part 15 Class A, AS/NZS CISPR22 Class A, CISPR22 Class A, EN55022 Class A, ICES003 Class A, VCCI Class A, EN61000-3-2, EN61000-3-3, KN22 Class A, and CNS13438 Class A. EMC immunity references include EN55024, CISPR24, EN300386, and the KN 61000-4 series.

The product is RoHS-6 compliant with stated exceptions for leaded BGA balls and lead press-fit connectors.

Ordering matrix

Supported transceivers must be selected from the NCS 540 Transceiver Module Group Compatibility Matrix. The chassis PID alone does not identify the required optic, breakout assembly, reach, wavelength, or coherent module.

Software license matrix

Service, warranty, and support

Available service capabilities include architecture-led professional services, deployment and optimization assistance, migration support, operational improvement, direct access to network experts, and Smart Call Home for proactive diagnostics and real-time alerts.

The hardware warranty is a one-year limited warranty. It includes hardware replacement with a ten-day turnaround from receipt of a Return Materials Authorization.

Presales proposals should identify the selected service level, software entitlement model, replacement process, operating site requirements, transceiver matrix validation, power-feed design, and any required professional services as separate line items.