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Silver rack-mount router with two front Ethernet ports

Cisco Systems, Inc.

Cisco Systems, Inc. ISR4321/K9 firewall appliance 2GE 4GB DRAM 4GB Flash

SKU CH-F69G-3F58B MPN ISR4321/K9

Delivers 50 to 100 Mbps throughput with dual gigabit LAN ports, 4 GB DRAM and 4 GB flash in a compact 1U chassis

  • ProtocolsIPv4, IPv6, static routes, Routing Information Protocol Vers
  • Speed10/100/1000Mbps
  • SecurityUL 60950-1 CAN/CSA C22.2 No. 60950-1 EN 60950-1 AS/NZS 60950
  • LAN Ports2 x 10/100/1000Mbps
  • Throughput50 Mbps to 100 Mbps
  • Console Port1 GE (Integrated Out of Band)
  • Gigabit connectivity for branch offices with two 10/100/1000Mbps LAN ports
  • Out-of-band management via integrated 1 GE console port
  • Reliable operation from 0 to 40ºC at sea level
  • Safety certified to UL 60950-1 and international equivalents
  • Compact 1.75" height fits standard 1U rack space

Cisco ISR 4321 Branch Router

The Cisco ISR 4321 is a compact branch-office router delivering 50 to 100 Mbps throughput with two onboard Gigabit Ethernet ports. It ships with 4 GB DRAM and 4 GB flash memory as standard. Two NIM slots and one ISC slot allow modular WAN or voice expansion for growing sites.

Thermals Power and Noise

The unit operates from 32 to 104 °F at altitudes up to 10 000 ft and 32 to 95 °F up to 15 000 ft, with non-operating tolerance from -13 to 158 °F. Relative humidity ranges from 5 % to 85 % operating and 5 % to 95 % non-operating. Safety certifications include UL 60950-1, CAN/CSA C22.2 No. 60950-1, EN 60950-1, IEC 60950-1, AS/NZS 60950-1 and GB-4943.

Upgrade Path and Fit

This router replaces older single-WAN appliances that lack modular NIM or ISC flexibility and integrated out-of-band management. The jump is worthwhile when a branch needs secure IPv4 and IPv6 routing with BGP, OSPF or EIGRP across MPLS and internet links. It is not suited for data-centre cores requiring line-rate 10 Gbps interfaces or high-density carrier-grade throughput.

Highlights

  • Gigabit connectivity for branch offices with two 10/100/1000Mbps LAN ports
  • Out-of-band management via integrated 1 GE console port
  • Reliable operation from 0 to 40ºC at sea level
  • Safety certified to UL 60950-1 and international equivalents
  • Compact 1.75" height fits standard 1U rack space

Specifications

BrandCisco Small Business
ModelISR4321/K9
ProtocolsIPv4, IPv6, static routes, Routing Information Protocol Versions 1 and 2 (RIP and RIPv2), Open Shortest Path First (OSPF), Enhanced IGRP (EIGRP), Border Gateway Protocol (BGP), BGP Router Reflector, Intermediate System-to-Intermediate System (IS-IS), Multicast Internet Group Management Protocol Version 3 (IGMPv3), Protocol Independent Multicast sparse mode (PIM SM), PIM Source Specific Multicast (SSM), RSVP, CDP, ERSPAN, IPSLA, CNS, Call Home, EEM, IKE, ACL, EVC, DHCP, FR, DNS, LISP, OTV, HSRP, RADIUS, AAA, AVC, Distance Vector Multicast Routing Protocol (DVMRP), IPv4-to-IPv6 Multica
Speed10/100/1000Mbps
SecurityUL 60950-1
CAN/CSA C22.2 No. 60950-1
EN 60950-1
AS/NZS 60950-1
IEC 60950-1
GB-4943
LAN Ports2 x 10/100/1000Mbps
Throughput50 Mbps to 100 Mbps
Console Port1 GE (Integrated Out of Band)
TemperatureOperating Conditions:
32 to 104ºF (0 to 40ºC) (altitude 0-10000 ft) (altitude 0-3000m)
32 to 95ºF (0 to 35ºC) (altitude 10000-15000ft) (altitude 3000m-4600m)
Nonoperating Conditions: -13 to 158ºF (-25 to 70ºC)
HumidityOperating Conditions:
Relative humidity: 5% to 85%
Short-term humidity: 5% to 90%, not to exceed 0.024 kg water/kg of dry air
Nonoperating Conditions:
Relative humidity: 5% to 95%
Dimensions14.55" x 11.6" x 1.75"
Weight9.14 lbs. + 1.2 lbs. Typical weight (fully loaded with modules)
Package ContentsISR 4321 with 2 onboard GE, 2 NIM slots, 1 ISC slot, 4 GB Flash Memory default, 4 GB DRAM default
Shipping weight6.12 kg
Package size660 × 508 × 210 mm

Questions about this item

How do I install the ISR4321/K9 in a rack and what step is often missed?

Mount the 1.75 inch high chassis using the included brackets, then seat the 4 GB DRAM and 4 GB Flash modules fully before powering on — the step most often missed is not locking the NIM and ISC slot covers after inserting modules.

What maintenance will the ISR4321/K9 need over time?

Replace the internal fan assembly when airflow noise increases, and swap the 4 GB Flash if write cycles degrade — both are field-replaceable units accessible after removing the top cover.

What limit appears first when the ISR4321/K9 runs sustained traffic at 100 Mbps throughput?

The 100 Mbps throughput ceiling is reached before CPU or memory saturation, so sustained loads above that rate will queue packets at the two onboard GE ports.

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