A key difference between Cisco ISR4331/K9 and ISR4321/K9 is Configurable Ethernet Ports: ISR4331/K9 — 3 x onboard 1G RJ-45/SFP configurable ports; ISR4321/K9 — 2 x onboard 1G RJ-45/SFP configurable ports. They also differ in Built-in 1GE Ports (3 vs 2) and Expansion Slots (2 NIM slot(s) and 1 SM-X slot(s) vs 2 NIM slot(s) and 0 SM-X slot(s)). Consider how configurable ethernet ports affects the deployment, then review the remaining differences before choosing the exact Product ID. The table below shows 39 specifications available for both models. Confirm licenses, accessories, power supplies and regional suffixes before ordering.
Start with the differences that have the greatest effect on capacity, connectivity, software, power and deployment fit.
3 onboard Gigabit Ethernet routed ports using 2 RJ-45 connectors and 2 SFP connectors
2 onboard Gigabit Ethernet routed ports using 2 RJ-45 connectors and 1 SFP connector
3
2
2 NIM slot(s) and 1 SM-X slot(s)
2 NIM slot(s) and 0 SM-X slot(s)
0.1 Gbps
0.05 Gbps
250W AC supply; DC ordered as separate ISR4331-DC SKU
125W external AC supply; optional external PoE supply; no DC supply
3
2
Review the differences in this order to identify the model that best fits the intended deployment.
Size the platform for the branch, aggregation or edge role using the Cisco throughput metric that matches the planned traffic mode.
Confirm built-in WAN media and speeds, then check NIM, SM-X or other module support for current and future circuits.
Verify SD-WAN or routing software, subscriptions, memory, storage and the required power-redundancy design.
Send your port, performance, license, quantity or deployment requirements. A CCIE-level network engineer will review the shortlist and help identify the better-fit Product ID.
| Comparison parameter | ||
|---|---|---|
| Product ID | ISR4331/K9 | ISR4321/K9 |
| Product and ordering | ||
| Product Type | ISR4331/K9 Cisco 4000 Series Integrated Services Router | ISR4321/K9 Cisco 4000 Series Integrated Services Router |
| Form Factor | ISR4331/K9 1RU | ISR4321/K9 1RU |
| Router Role | ISR4331/K9 Modular branch integrated services router | ISR4321/K9 Modular branch integrated services router |
| Routing and WAN performance | ||
| Configurable Ethernet PortsDifferent | ISR4331/K9 3 onboard Gigabit Ethernet routed ports using 2 RJ-45 connectors and 2 SFP connectors | ISR4321/K9 2 onboard Gigabit Ethernet routed ports using 2 RJ-45 connectors and 1 SFP connector |
| Configurable Ethernet Port CountDifferent | ISR4331/K9 3 | ISR4321/K9 2 |
| Integrated LAN Switch Ports | ISR4331/K9 Not applicable | ISR4321/K9 Not applicable |
| Integrated LAN Port Count | ISR4331/K9 Not applicable | ISR4321/K9 Not applicable |
| Built-in 1GE PortsDifferent | ISR4331/K9 3 | ISR4321/K9 2 |
| Built-in 10GE Ports | ISR4331/K9 0 | ISR4321/K9 0 |
| Expansion SlotsDifferent | ISR4331/K9 2 NIM slot(s) and 1 SM-X slot(s) | ISR4321/K9 2 NIM slot(s) and 0 SM-X slot(s) |
| NIM Slots | ISR4331/K9 2 | ISR4321/K9 2 |
| SM-X SlotsDifferent | ISR4331/K9 1 | ISR4321/K9 0 |
| Service Module Support | ISR4331/K9 Cisco NIM and model-dependent SM-X service modules with online insertion/removal | ISR4321/K9 Cisco NIM and model-dependent SM-X service modules with online insertion/removal |
| Ports and interfaces | ||
| Management Ports | ISR4331/K9 1 x dedicated 10/100/1000BASE-T management Ethernet | ISR4321/K9 1 x dedicated 10/100/1000BASE-T management Ethernet |
| Console Ports | ISR4331/K9 RJ-45 and mini-USB console; RJ-45 auxiliary port | ISR4321/K9 RJ-45 and mini-USB console; RJ-45 auxiliary port |
| Performance and scale | ||
| Aggregate Licensed ThroughputDifferent | ISR4331/K9 0.1 Gbps | ISR4321/K9 0.05 Gbps |
| Configuration, licensing and management | ||
| Routing Protocols | ISR4331/K9 Static routing, BGP, OSPF, EIGRP, IS-IS, RIP, MPLS and VRF | ISR4321/K9 Static routing, BGP, OSPF, EIGRP, IS-IS, RIP, MPLS and VRF |
| Management Model | ISR4331/K9 Cisco Catalyst Center, WebUI, CLI, NETCONF/RESTCONF and SNMP | ISR4321/K9 Cisco Catalyst Center, WebUI, CLI, NETCONF/RESTCONF and SNMP |
| Licensing | ISR4331/K9 Cisco Smart Licensing; performance and feature licenses by platform | ISR4321/K9 Cisco Smart Licensing; performance and feature licenses by platform |
| Required Subscription | ISR4331/K9 Not required for autonomous routing; subscription required for managed SD-WAN services | ISR4321/K9 Not required for autonomous routing; subscription required for managed SD-WAN services |
| USB Ports | ISR4331/K9 1 x USB 2.0 Type-A storage port plus 1 x Mini-USB console | ISR4321/K9 1 x USB 2.0 Type-A storage port plus 1 x Mini-USB console |
| Memory and software | ||
| Default DRAM | ISR4331/K9 4 GB | ISR4321/K9 4 GB |
| Maximum DRAMDifferent | ISR4331/K9 16 GB | ISR4321/K9 8 GB |
| Storage | ISR4331/K9 4 GB | ISR4321/K9 4 GB |
| Operating System | ISR4331/K9 Cisco IOS XE | ISR4321/K9 Cisco IOS XE |
| Minimum Software Release | ISR4331/K9 Not published by Cisco | ISR4321/K9 Not published by Cisco |
| PoE and power | ||
| Integrated PoE Support | ISR4331/K9 PoE through compatible EtherSwitch modules and PoE power options | ISR4321/K9 PoE through compatible EtherSwitch modules and PoE power options |
| Default PoE Budget | ISR4331/K9 Not applicable | ISR4321/K9 Not applicable |
| Default Power SupplyDifferent | ISR4331/K9 250W AC supply; DC ordered as separate ISR4331-DC SKU | ISR4321/K9 125W external AC supply; optional external PoE supply; no DC supply |
| Power Redundancy | ISR4331/K9 Not applicable | ISR4321/K9 Not applicable |
| Physical and environmental | ||
| Dimensions (H × W × D)Different | ISR4331/K9 44.45 × 438.15 × 438.15 mm | ISR4321/K9 44.55 × 369.57 × 294.64 mm |
| WeightDifferent | ISR4331/K9 6.2 kg | ISR4321/K9 3.5 kg |
| Operating Temperature | ISR4331/K9 0 to 40 °C | ISR4321/K9 0 to 40 °C |
| Storage Temperature | ISR4331/K9 -40 to 70 °C | ISR4321/K9 -40 to 70 °C |
| Storage Humidity | ISR4331/K9 5% to 95% | ISR4321/K9 5% to 95% |
| Operating Humidity | ISR4331/K9 5% to 85% | ISR4321/K9 5% to 85% |
| Operating Altitude | ISR4331/K9 0–3,050 m | ISR4321/K9 0–3,050 m |
| MTBFDifferent | ISR4331/K9 587,250 hours | ISR4321/K9 593,270 hours |
| Warranty | ISR4331/K9 Cisco 90-day limited hardware warranty | ISR4321/K9 Cisco 90-day limited hardware warranty |
“Not listed” means that no confirmed value is currently available for that model and parameter.
Use the exact Product ID when requesting a quote, because suffixes can identify different licenses, regions or configurations. Open an available product page for details and pricing, or request a project quote from our team.
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