ISR4331/K9
1RU
ISR4351/K9
2RU
Cisco router comparison
ISR4331/K9 vs ISR4351/K9
A key difference between Cisco ISR4331/K9 and ISR4351/K9 is Form Factor: ISR4331/K9 — 1RU; ISR4351/K9 — 2RU. They also differ in Expansion Slots (2 NIM slot(s) and 1 SM-X slot(s) vs 3 NIM slot(s) and 2 SM-X slot(s)) and NIM Slots (2 vs 3). Consider how form factor 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.
2models compared
39specs shown for every model
9differences found
Change comparison
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At-a-glance comparison
Key performance and configuration differences
Start with the differences that have the greatest effect on capacity, connectivity, software, power and deployment fit.
ISR4331/K9
2 NIM slot(s) and 1 SM-X slot(s)
ISR4351/K9
3 NIM slot(s) and 2 SM-X slot(s)
ISR4331/K9
2
ISR4351/K9
3
ISR4331/K9
0.1 Gbps
ISR4351/K9
0.2 Gbps
ISR4331/K9
250W AC supply; DC ordered as separate ISR4331-DC SKU
ISR4351/K9
430W AC supply; DC option
ISR4331/K9
1
ISR4351/K9
2
Buying decision
How to choose between ISR4331/K9 and ISR4351/K9
Review the differences in this order to identify the model that best fits the intended deployment.
-
01
Traffic and deployment role
Size the platform for the branch, aggregation or edge role using the Cisco throughput metric that matches the planned traffic mode.
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02
Interfaces and expansion
Confirm built-in WAN media and speeds, then check NIM, SM-X or other module support for current and future circuits.
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03
Software, licensing and power
Verify SD-WAN or routing software, subscriptions, memory, storage and the required power-redundancy design.
Before ordering
Confirm the exact Product ID, license tier, power supplies, accessories and regional requirements.
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Detailed comparison
Full specification comparison
| Comparison parameter | ||
|---|---|---|
| Product ID | ISR4331/K9 | ISR4351/K9 |
| Product and ordering | ||
| Product Type | Cisco 4000 Series Integrated Services Router | Cisco 4000 Series Integrated Services Router |
| Form Factor | 1RU | 2RU |
| Router Role | Modular branch integrated services router | Modular branch integrated services router |
| Routing and WAN performance | ||
| Configurable Ethernet Ports | 3 x onboard 1G RJ-45/SFP configurable ports | 3 x onboard 1G RJ-45/SFP configurable ports |
| Configurable Ethernet Port Count | 3 | 3 |
| Integrated LAN Switch Ports | Not applicable | Not applicable |
| Integrated LAN Port Count | Not applicable | Not applicable |
| Built-in 1GE Ports | 3 | 3 |
| Built-in 10GE Ports | 0 | 0 |
| Expansion Slots | 2 NIM slot(s) and 1 SM-X slot(s) | 3 NIM slot(s) and 2 SM-X slot(s) |
| NIM Slots | 2 | 3 |
| SM-X Slots | 1 | 2 |
| Service Module Support | Cisco NIM and model-dependent SM-X service modules with online insertion/removal | Cisco NIM and model-dependent SM-X service modules with online insertion/removal |
| Ports and interfaces | ||
| Management Ports | 1 x dedicated 10/100/1000BASE-T management Ethernet | 1 x dedicated 10/100/1000BASE-T management Ethernet |
| Console Ports | RJ-45 and mini-USB console; RJ-45 auxiliary port | RJ-45 and mini-USB console; RJ-45 auxiliary port |
| Performance and scale | ||
| Aggregate Licensed Throughput | 0.1 Gbps | 0.2 Gbps |
| Configuration, licensing and management | ||
| Routing Protocols | Static routing, BGP, OSPF, EIGRP, IS-IS, RIP, MPLS and VRF | Static routing, BGP, OSPF, EIGRP, IS-IS, RIP, MPLS and VRF |
| Management Model | Cisco Catalyst Center, WebUI, CLI, NETCONF/RESTCONF and SNMP | Cisco Catalyst Center, WebUI, CLI, NETCONF/RESTCONF and SNMP |
| Licensing | Cisco Smart Licensing; performance and feature licenses by platform | Cisco Smart Licensing; performance and feature licenses by platform |
| Required Subscription | Not required for autonomous routing; subscription required for managed SD-WAN services | Not required for autonomous routing; subscription required for managed SD-WAN services |
| USB Ports | USB Type-A storage ports and mini-USB console | USB Type-A storage ports and mini-USB console |
| Memory and software | ||
| Default DRAM | 4 GB | 4 GB |
| Maximum DRAM | 16 GB | 16 GB |
| Storage | 4 GB | 4 GB |
| Operating System | Cisco IOS XE | Cisco IOS XE |
| Minimum Software Release | Not published by Cisco | Not published by Cisco |
| PoE and power | ||
| Integrated PoE Support | PoE through compatible EtherSwitch modules and PoE power options | PoE through compatible EtherSwitch modules and PoE power options |
| Default PoE Budget | Not applicable | Not applicable |
| Default Power Supply | 250W AC supply; DC ordered as separate ISR4331-DC SKU | 430W AC supply; DC option |
| Power Redundancy | Model-dependent optional redundant AC or DC power supplies | Model-dependent optional redundant AC or DC power supplies |
| Physical and environmental | ||
| Dimensions (H × W × D) | 44.45 × 438.15 × 438.15 mm | 88.9 × 438.15 × 469.9 mm |
| Weight | 6.2 kg | 17.1 kg |
| Operating Temperature | 0 to 40 °C | 0 to 40 °C |
| Storage Temperature | -40 to 70 °C | -40 to 70 °C |
| Storage Humidity | 5% to 95% | 5% to 95% |
| Operating Humidity | 5% to 85% | 5% to 85% |
| Operating Altitude | 0–3,050 m | 0–3,050 m |
| MTBF | 587,250 hours | 566,310 hours |
| Warranty | Cisco 1-year limited hardware warranty | Cisco 1-year limited hardware warranty |
“Not listed” means that no confirmed value is currently available for that model and parameter.
Price, stock & lead time
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