Cisco UCS 2304 Fabric Extender Data Sheet

Data Sheet

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Updated:November 13, 2021

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Cisco UCS 2304 Fabric Extender

Cisco Unified Computing System overview

The Cisco Unified Computing System (Cisco UCS) is a next-generation data center platform that unites computing, network, storage access, and virtualization resources into a cohesive system designed to reduce Total Cost of Ownership (TCO) and increase business agility. The system integrates a low-latency, lossless 40 Gigabit Ethernet unified network fabric with enterprise-class, x86-architecture servers. The system is an integrated, scalable, multichassis platform in which all resources participate in a unified management domain (Figure 1).

The Cisco Unified Computing System is a highly available cohesive architecture

Figure 1.            

The Cisco Unified Computing System is a highly available cohesive architecture

Product overview

Cisco UCS 2304 Fabric Extender brings the unified fabric into the blade server enclosure, providing Gigabit Ethernet connectivity between the blade servers and the fabric interconnect, simplifying diagnostics, cabling, and management. It is a third-generation I/O Module (IOM) that shares the same form factor as the second-generation Cisco UCS 2200 Series Fabric Extenders and is backward compatible with the shipping Cisco UCS 5108 Blade Server Chassis.

The Cisco UCS 2304 connects the I/O fabric between the Cisco UCS 6300 Series Fabric Interconnects and the Cisco UCS 5100 Series Blade Server Chassis, enabling a lossless and deterministic Fibre Channel over Ethernet (FCoE) fabric to connect all blades and chassis together. Because the fabric extender is similar to a distributed line card, it does not perform any switching and is managed as an extension of the fabric interconnects. This approach removes switching from the chassis, reducing overall infrastructure complexity and enabling Cisco UCS to scale to many chassis without multiplying the number of switches needed, reducing TCO and allowing all chassis to be managed as a single, highly available management domain.

The Cisco UCS 2304 also manages the chassis environment (power supply, fans, and blades) in conjunction with the fabric interconnect. Therefore, separate chassis management modules are not required.

Cisco UCS 2304 Fabric Extenders fit into the back of the Cisco UCS 5100 Series chassis. Each Cisco UCS 5100 Series chassis can support up to two fabric extenders, allowing increased capacity and redundancy (Figure 2).

Rear of Cisco UCS 5108 Blade Server Chassis with Two Cisco UCS 2304 Fabric Extenders Inserted

Figure 2.            

Rear of Cisco UCS 5108 Blade Server Chassis with Two Cisco UCS 2304 Fabric Extenders Inserted

Cisco UCS 2304 Fabric Extender

The Cisco UCS 2304 Fabric Extender has four 40 Gigabit Ethernet, FCoE-capable, Quad Small Form-Factor Pluggable (QSFP+) ports that connect the blade chassis to the fabric interconnect. Each Cisco UCS 2304 can provide one 40 Gigabit Ethernet ports connected through the midplane to each half-width slot in the chassis, giving it a total eight 40G interfaces to the compute. Typically configured in pairs for redundancy, two fabric extenders provide up to 320 Gbps of I/O to the chassis.


There is an updated version of UCS-IOM-2304 (I.e., UCS-IOM-2304V2).

1.     You cannot mix UCS-IOM-2304V2 and UCS-IOM-2304 in the same chassis.

2.     UCS-IOM-2304V2 requires Cisco UCS Manager 4.0(4) or later.

Cisco SingleConnect Technology

Cisco® SingleConnect Technology provides an easy, intelligent, and efficient way to connect and manage computing in the data center. SingleConnect unifies LAN, SAN, and systems management into one simplified link for rack servers, blade servers, and virtual machines.

SingleConnect is an end-to-end I/O architecture. It incorporates Cisco UCS Virtual Interface Cards (VICs), Cisco UCS fabric interconnects, and Cisco Fabric Extender Technology (FEX Technology) to connect every server on a single network fabric and on a single network layer. SingleConnect innovations dramatically simplify IT operations and reduce data center costs and are exclusive to Cisco UCS.

SingleConnect provides one connection for:

      Rack servers and blade servers

      LAN, SAN, and systems management

      Physical servers and virtual machines

Features and benefits

Table 1 summarizes the main features and benefits of the Cisco UCS 2304.

Table 1.        Features and benefits



Management by Cisco UCS Manager

  Reduces TCO by removing management modules from the chassis, making the chassis stateless
  Provides a single, highly available management domain for all system chassis, reducing administrative tasks


Simplifies operation by automatically synchronizing firmware levels between the fabric extenders and the interconnects

Unified fabric

  Decreases TCO by reducing the number of Network Interface Cards (NICs), Host Bus Adapters (HBAs), switches, and cables needed
  Transparently encapsulates Fibre Channel packets into Ethernet

Automatic failover

Increases availability with an active/active data plane

Scalable bandwidth

Reduces TCO by optimizing overall system capacity to match actual workload demands

Environmental monitoring

Removes the need for chassis management modules

Lossless fabric

Provides a reliable, robust foundation for unifying LAN and SAN traffic on a single transport

Priority Flow Control (PFC)

  Simplifies management of multiple traffic flows over a single network link
  Supports different classes of service, allowing both lossless and classic Ethernet on the same fabric

Systemwide bandwidth management

Helps enable consistent and coherent Quality-of-Service (QoS) management throughout the system

Cisco Data Center Virtual Machine Fabric Extender (VM-FEX) technology

  Helps enable a consistent operational model between virtual and physical environments
  Provides the same level of network visibility for virtualized and nonvirtualized environments
  Improves diagnostic and troubleshooting capabilities in a virtual environment
  Simplifies network and security policy enforcement when migrating virtual machines from one host to another

QSFP+ ports

  Increases flexibility with a range of interconnect solutions, including copper Twinax cable for short runs and fiber for long runs
  Consumes less power per port than traditional solutions
  Helps enable cost-effective connections on fabric extenders with Cisco Fabric Extender Transceiver (FET) optics

Fabric port channel

  Provides flexibility to bundle fabric ports in a port channel

Product specifications


      Hardware forwarding at 960 Gbps

      Low-latency cut-through design, providing predictable, consistent traffic latency regardless of packet size, traffic pattern, or enabled features

Layer 2

      Layer 2 VLAN trunks

      IEEE 802.1Q VLAN encapsulation

      Support for up to 1024 VLANs and Virtual SANs (VSANs)

      Support for Data Center VM-FEX architecture

      Jumbo frames on all ports (up to 9216 bytes)

      Pause frames (IEEE 802.3x)


      Layer 2 IEEE 802.1p (Class of Service [CoS])

      CoS-based egress queuing

      Egress strict-priority queuing

      Egress port-based scheduling: Weighted Round-Robin (WRR)

      Eight hardware queues per port

High availability

      Up to two fabric extenders can work in the Cisco UCS 5100 Series Blade Server Chassis

      Active-active data-plane operation with failover

      Capability to fail over from one fabric extender to another in the event of a failure

      Active-passive management-plane operation

      Support for nonstop management-plane functions; if the active fabric extender fails, the passive fabric extender takes over the chassis management functions


      Management of fabric extenders integrated into Cisco UCS Manager (please refer to the Cisco UCS Manager data sheet for more information about management interfaces)

      Capability to manage blade server chassis components such as power supplies, fans, and blades in conjunction with the fabric interconnect

      Firmware levels between the fabric extender and fabric interconnect always synchronized

Low-Latency, Lossless 40 Gigabit Ethernet Unified Network Fabric

      PFC (per-priority pause frame support)

      Data Center Bridging Exchange (DCBX) Protocol

      IEEE 802.1Qaz: Bandwidth management

Industry standards

      IEEE 802.1p: CoS prioritization

      IEEE 802.1Q: VLAN tagging

      IEEE 802.3: Ethernet

      IEEE 802.3ad: Link Aggregation Control Protocol (LACP)

      IEEE 802.3ba: 40 Gigabit Ethernet

      QSFP+ support

Physical specifications

QSFP+ optics

Cisco UCS products support 40 Gigabit Ethernet QSFP+ copper Twinax cables for short distances and QSFP+ optics for longer distances. The 40 Gigabit Ethernet cables and transceivers qualified for FI 6332 and FI 6332-16UP are supported by Cisco UCS IOM 2304.


      Physical (height x width x depth): 7.64 x 1.36 x 7.2 in. (19.4 x 3.54 cm)

      Operating temperature: 32 to 104°F (0 to 40°C)

      Nonoperating temperature: -40 to 158°F (-40 to 70°C)

      Humidity: 5 to 95% (noncondensing)

      Altitude: 0 to 10,000 ft (0 to 3000m)


      2.8 lb (1.134 kg)

Regulatory standards compliance: Safety and EMC

Table 2 summarizes Cisco UCS 2304 regulatory compliance.

Table 2.        Regulatory standards compliance: Safety and EMC



Regulatory compliance

Products should comply with CE Markings according to directives 2004/108/EC and 2006/95/EC


  UL 60950-1
  CAN/CSA-C22.2 No. 60950-1
  EN 60950-1
  IEC 60950-1
  AS/NZS 60950-1

EMC: Emissions

  47CFR Part 15 (CFR 47) Class A
  AS/NZS CISPR22 Class A
  CISPR22 Class A
  EN55022 Class A
  ICES003 Class A
  VCCI Class A
  KN22 Class A
  CNS13438 Class A

EMC: Immunity

  KN 61000-4 series


The product is RoHS 5-compliant with exceptions for leaded Ball Grid Array (BGA) balls and lead press-fit connectors

Fabric Interconnect Support

The Cisco UCS 2304 Fabric Extender is designed to work with third generation of UCS Products.

Transceiver and Cable Support

The Cisco UCS 2304 Fabric Extender supports a variety of Ethernet connectivity options using Cisco 40-Gbps transceivers and 40-Gbs passive cables and active optical cables.

Table 3.        Cisco UCS 2304 Fabric Extender transceiver-support matrix

Product information



QSFP40G BiDi Short-reach Transceiver


QSFP 4x10GBASE-SR Transceiver Module, MPO, 300M


QSFP 40GBASE-LR4 OTN Transceiver, LC, 10KM


QSFP 40GBASE-LR4 Tmscvr Mod, LC, 10KM, Enterprise-Class


40GBASE-SR4 QSFP Transceiver Module with MPO Connector


40GBASE-SR4 QSFP Tmscvr Module, MPO Conn, Enterprise-Class


40G Line Extender for FEX


40GBASE/100GBASE SR-BiDi QSFP transceiver

Table 4.        Cisco UCS 2304 Fabric Extender cable-support matrix

Product information



40GBASE-CR4 Passive Copper Cable, 1M


40GBASE-CR4 Passive Copper Cable, 3M


40GBASE-CR4 Passive Copper Cable, 5M


40G BASE-CR4 Active Copper Cable, 7m


40GBASE Active Optical Cable, 1M


40GBASE Active Optical Cable, 2M


40GBASE Active Optical Cable, 3M


40GBASE Active Optical Cable, 7M


40GBASE Active Optical Cable, 10M


40GBASE Active Optical Cable, 15M

Note:      This is the list of supported transceivers and cables for Cisco UCS 2304 Fabric Extender only. Cross-reference this list against the supported transceivers and cables for the device on the opposing side of the link to confirm compatibility for both the devices.

Ordering information

Table 5 presents ordering information for the Cisco UCS 2304 and UCS 2304v2 Fabric Extenders.

Table 5.        Ordering information

Part Number



Cisco IOM 2304XP I/O Module (4 External, 8 Internal 40Gb Ports)


Cisco IOM 2304XP I/O Module (4 External, 8 Internal 40Gb Ports); Spare PID


Cisco IOM 2304V2XP I/O Module (4 External, 8 Internal 40Gb Ports)


Cisco IOM 2304V2XP I/O Module (4 External, 8 Internal 40Gb Ports); Spare PID

Warranty information

Find warranty information at on the Product Warranties page.

Cisco environmental sustainability

Information about Cisco’s environmental sustainability policies and initiatives for our products, solutions, operations, and extended operations or supply chain is provided in the “Environment Sustainability” section of Cisco’s Corporate Social Responsibility (CSR) Report.

Reference links to information about key environmental sustainability topics (mentioned in the “Environment Sustainability” section of the CSR Report) are provided in the following table:

Sustainability topic


Information on product material content laws and regulations


Information on electronic waste laws and regulations, including products, batteries, and packaging

WEEE compliance

Cisco makes the packaging data available for informational purposes only. It may not reflect the most current legal developments, and Cisco does not represent, warrant, or guarantee that it is complete, accurate, or up to date. This information is subject to change without notice.

Cisco Unified Computing Services

Using a unified view of data center resources, Cisco and our industry-leading partners deliver services that accelerate your transition to a unified computing environment. Cisco Unified Computing Services helps you quickly deploy your data center resources and optimize ongoing operations to better meet your business needs. For more information about these and other Cisco Data Center Services, visit

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