Cisco ISR 4000 vs Catalyst 8000
The Catalyst 8000 family is the modern replacement for the ISR 4000: same IOS XE, but multi-gigabit throughput, x86-based services with container hosting, and native SD-WAN/SASE. For any new branch or edge deployment, the Catalyst 8000 is the right platform; the ISR 4000 makes sense only for existing fleets nearing refresh.
Cisco ISR 4000 Series
The previous-generation integrated services router family for branch routing, now being phased out.
- Throughput from ~50 Mbps (ISR 4221) up to ~10 Gbps (ISR 4461)
- NIM and SM-X modular slots across the family
- Runs IOS XE with SD-WAN support
- Multiple models reaching end-of-sale/EOL
Cisco Catalyst 8000 Series
Current edge platform family (8200/8300/8500) spanning small branch to aggregation, built for SD-WAN and SASE.
- Scales from ~1 Gbps (8200) to ~100+ Gbps (8500)
- x86 multi-core with crypto offload and container hosting
- Native Cisco SD-WAN and SASE integration
- Spans branch, regional, and aggregation/headend roles
Cisco ISR 4000 Series vs Cisco Catalyst 8000 Series: spec comparison
| Spec | Cisco ISR 4000 Series | Cisco Catalyst 8000 Series |
|---|---|---|
| Generation | Previous-gen branch routers | Current edge platform family |
| Models | ISR 4221 / 4321 / 4331 / 4351 / 4431 / 4451 / 4461 | Catalyst 8200 / 8300 / 8500 |
| Throughput range | ~50 Mbps to ~10 Gbps | ~1 Gbps to ~100+ Gbps |
| Architecture | Multicore + dedicated forwarding | x86 multi-core with crypto offload |
| Module slots | NIM, SM-X | NIM, SM-X, PIM (model dependent) |
| SD-WAN | Supported (IOS XE SD-WAN) | Native, SASE-ready |
| Container / app hosting | Limited | Yes |
| Software | Cisco IOS XE | Cisco IOS XE |
| Lifecycle status | End-of-sale / approaching EOL | Current, full support |
Choose Cisco ISR 4000 Series if
Choose to retain the ISR 4000 only where you already operate a fleet, bandwidth needs are modest, and a refresh is not yet budgeted. Standardizing spares and configs on existing ISR 4000 units can justify deferring migration short-term.
Choose Cisco Catalyst 8000 Series if
Choose the Catalyst 8000 for all new deployments and refresh cycles. It spans the same branch roles as the ISR 4000 plus regional and aggregation, with far higher throughput, native SD-WAN/SASE, and application hosting on a modern x86 base.
Verdict
The Catalyst 8000 is the designated successor to the ISR 4000, sharing IOS XE while adding multi-gigabit-to-100G performance, native SD-WAN/SASE, and container hosting. Migrate new and refreshed sites to the Catalyst 8000; keep ISR 4000 only as a short-term measure where existing investment and low bandwidth allow.
Frequently asked questions
Is the Catalyst 8000 replacing the ISR 4000?
Yes. The Catalyst 8000 family (8200/8300/8500) is Cisco's successor to the ISR 4000 branch routers, with higher performance, native SD-WAN/SASE, and a longer support lifecycle.
Which Catalyst 8000 replaces my ISR 4000?
Roughly, the Catalyst 8200 maps to lower ISR 4000 models, the Catalyst 8300 to mid-to-high ISR 4000 branch routers, and the Catalyst 8500 to aggregation roles beyond the ISR 4000's reach.
Do ISR 4000 configs migrate to the Catalyst 8000?
Both run Cisco IOS XE, so configurations and operational practices carry over with minimal rework, easing the migration compared to a cross-OS platform change.
Is the ISR 4000 end of life?
Multiple ISR 4000 models have reached end-of-sale and are progressing through end-of-life milestones. New branch deployments should target the Catalyst 8000 family.
More Routing comparisons
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