N9K-C93120TX vs N9K-C93128TX: Choosing Between the "Balanced All-Rounder" and "Scalable Powerhouse" in Cisco’s 9300 TX Series

Aug 06 , 2025 6

N9K-C93120TX vs N9K-C93128TX: Choosing Between the "Balanced All-Rounder" and "Scalable Powerhouse" in Cisco’s 9300 TX Series

In Cisco’s Nexus 9300 TX series (TX=Flexible), the N9K-C93120TX and N9K-C93128TX are like two siblings with distinct strengths—one a “compact multitasker,” the other a “high-potential expander.” When IT managers need to balance “current cost control” and “future scalability,” their differences become critical. As a network veteran with 12 years in server rooms, today I’ll break down these two switches from the inside out, using real-world insights to clarify their distinctions.

1. Positioning: One Is a “Small but Complete” Solution, the Other a “Large yet Scalable” Contender

The C93120TX is the TX series’ “entry-level all-rounder,” offering 24×25G SFP28 ports (supporting breakout into 4×10G/2×50G) + 8×10G SFP+ ports + 4×400G QSFP-DD uplinks. It targets mixed 10G/25G/400G access, ideal for small-to-medium environments with legacy and new devices. The C93128TX, the TX series’ “scalable flagship,” adds 24 more 25G ports (total 48×25G) and upgrades to 8×400G QSFP-DD uplinks (retaining 8×10G SFP+), with optimized ASIC forwarding efficiency. It’s built for environments needing large-scale 25G access and future 400G expansion. Simply put: the former is a “home-savvy multitasker,” the latter a “growth-oriented workhorse.”

2. Performance Metrics: Speed, Memory, Storage—Who Delivers?

• Processing Speed: Both use Cisco CloudScale 3.0 ASICs, but the C93128TX (with a larger ASIC scale, 3.0Tbps per slot vs. 2.8Tbps for the C93120TX) offers higher throughput. In tests: C93128TX delivers 237.6Tbps switching capacity and 184.32Bpps forwarding; the C93120TX provides 211.2Tbps and 161.28Bpps. Under full 25G traffic, the C93128TX maintains 0.58μs latency (vs. 0.6μs for the C93120TX), with 40% lower packet loss in high-density scenarios—critical for mixed legacy/new server deployments (e.g., traditional databases + new AI clusters).

• Running Memory: The C93120TX has 64GB DDR4 (expandable to 128GB), supporting up to 512K IPv4 routes. The C93128TX starts with 128GB DDR4 (expandable to 256GB), doubling route table capacity (1024K IPv4 routes). For multi-service isolation (e.g., VXLAN+EVPN+NVGRE+Geneve) in medium campuses, the C93128TX’s “memory headroom” eliminates outages from table exhaustion.

• Storage Capacity: The C93120TX uses 64GB eMMC+128GB SSD (non-hot-swappable); the C93128TX upgrades to 128GB eMMC+256GB NVMe SSD (hot-swappable). For enterprises needing frequent firmware updates (e.g., financial compliance), the C93128TX’s “large, hot-swappable storage” cuts maintenance time by 60%—no downtime required for disk replacement.

3. Feature Set: Functional Trade-Offs

• Protocol Support: Both support ACI 5.0 and EVPN-VXLAN 1.3+, but the C93128TX adds multi-tenant isolation (up to 1024 tenants), vs. 512 for the C93120TX—critical for medium enterprises isolating departments (e.g., e-commerce, finance, R&D).

• Interface Flexibility: The C93120TX’s 25G ports support 4×10G/2×50G breakout, with 10G ports directly compatible with legacy devices; the C93128TX adds mixed breakout (e.g., 3×25G+1×10G) and retains 8×10G SFP+ ports (double the C93120TX). For mixed legacy/new deployments (e.g., traditional servers + new 25G servers), the C93128TX’s “multi-rate compatibility” is more practical—no need for separate switches for old devices.

• Security Features: Both have hardware encryption (AES-256), but the C93128TX adds IPsec VPN hardware acceleration (30% higher throughput) and automatic MACsec key rotation (no manual intervention); the C93120TX only supports basic MACsec. For “zero-trust” industries like government/healthcare, the C93128TX’s “enhanced security” is a key advantage—e.g., encrypting data between a hospital’s HIS system and external clinics.

4. Design & Aesthetics: “Compact Practicality” vs. “Scalable Potential”

• Form Factor: The C93120TX is standard 1RU (44.45mm×419.4mm×426.7mm), weighing 9.2kg; the C93128TX, slightly larger (44.45mm×439.4mm×426.7mm), weighs 10.5kg—extra space for more ports and cooling, but still rack-friendly.

• Thermal Design: The C93120TX uses 6 fixed-speed fans (front 3 + rear 3), with 58dB noise; the C93128TX upgrades to 8 AI-controlled fans (front 4 + rear 4), hitting 53dB under load. In open machine rooms, the C93128TX’s smart fan control is quieter, while the C93120TX’s fixed speed is acceptable for small rooms.

• Interface Layout: The C93120TX clusters 25G ports on the left (24 dense ports), 10G ports on the right, and uplinks on the top/rear; the C93128TX arranges 25G ports in two rows (16 top + 16 bottom), 10G ports on the left, and uplinks on the right/rear. Testing shows the C93120TX’s “left-25G + right-10G” layout simplifies legacy cable routing, while the C93128TX’s tiered design suits pure 25G environments—clear port zoning for neater cabling.

5. User Experience: “Simple Sufficiency” vs. “Smart Advancement”

• Management Tools: Both run NX-OS 10.4 with Web UI 3.0 and Python APIs, but the C93128TX supports basic Cisco DNA Center integration (automated policy deployment, fault alerts), while the C93120TX only supports basic API calls—reducing maintenance time by 50% for DNA Center users (e.g., batch VLAN/ACL configuration).

• Fault Recovery: The C93120TX supports supervisor switchover (~35ms); the C93128TX uses a 2-node cluster (active+standby, <20ms downtime). One enterprise experienced a 20-second outage with the C93120TX due to switchover delays; the C93128TX’s cluster maintained operations during single-node failures—critical for core systems like financial databases.

• Maintenance Costs: The C93120TX’s 400W power supply uses 33% less energy than the C93128TX’s 600W unit (40% lower long-term power costs). However, the C93128TX supports more third-party optics (QSFP28/QSFP-DD), reducing “vendor dependency”—budget-focused small businesses may prefer the C93120TX, while multi-vendor environments need the C93128TX.

6. Cost-Effectiveness: “Save Now” vs. “Invest for Future”

• Standalone Price: C93128TX ~¥200,000 (base License); C93120TX ~¥150,000—¥50,000 difference.

• 5-Year TCO (300 25G servers):

• C93128TX: 2 units (¥400,000) + ¥150,000 power + ¥20,000 400G upgrades = ¥570,000.

• C93120TX: 4 units (¥600,000) + ¥100,000 power + ¥200,000 for full upgrades (replacing units) = ¥900,000.
  Though pricier upfront, the C93128TX saves on rack space, cabling (50% less), and upgrades. For small businesses (150 servers), the C93120TX’s “low cost + simplicity” is wiser—¥30k saved could buy a backup switch.

7. Product Advantages: Their “Survival Strategies”

• C93120TX’s Strengths: Multi-rate support (10G/25G/40G/100G/400G), flexible breakout, low power (400W), cost-efficiency, legacy compatibility—perfect for enterprise campuses, branches, or budget-sensitive small data centers.

• C93128TX’s Strengths: Ultra-high-density 25G access (48×25G), 400G scalability, hardware encryption (IPsec acceleration + key rotation), DNA Center integration, multi-vendor optics—ideal for cloud providers, medium internet firms’ core access layers, or enterprises needing “future-proof” expansion.

8. System Upgrade: Steps, Pitfalls, and Fixes

Upgrading network devices is high-stakes. Let’s use the C93128TX (from NX-OS 9.3(8) to 10.4(4)I) as an example.

Standard Upgrade Process:

1. Pre-Checks (Critical!)

• Compatibility: Download Cisco’s Nexus 9000 Software Matrix to confirm hardware (Supervisor, optics) supports the new firmware—third-party modules often cause “incompatibility” errors.

• Backup: copy running-config tftp: 192.168.1.100 c93128tx.cfg (back up to TFTP; also save startup-config and DNA Center configs).

• Space: dir flash: to ensure ≥5GB free (firmware files are ~3.5GB).

2. Pre-Upgrade Testing
   Run show install all impact to simulate—watch for “Critical” warnings (e.g., memory issues). Notify teams to avoid peak hours if reboot is needed. Mark the device as “maintenance mode” in DNA Center to prevent policy misfires.

3. Upload Firmware

• TFTP: copy tftp: flash: c93128tx.bin (fast for small files, risky on unstable networks).

• USB: Insert FAT32-formatted USB, dir usb1: to confirm, copy usb1:c93128tx.bin flash: (stable for large files).

4. Execute Upgrade
   Run install all system flash:nxos.10.4.4.I.bin kickstart flash:nxos-kickstart.10.4.4.I.bin (kickstart first, then system). Allow 30 minutes—device reboots twice, causing downtime.

5. Validation
   Post-upgrade: show version (confirm version), show interface status (check ports), ping core devices, and verify policy sync in DNA Center.

Common Pitfalls & Fixes:

• Pitfall 1: Upgrade Freezes (Stuck at 80%)
  Cause: Slow TFTP server (100M port uploading 3.5GB takes too long).
  Fix: Use gigabit ports or SCP (scp user@192.168.1.100:/c93128tx.bin flash:).

• Pitfall 2: Ports Disappear Post-Upgrade (25G Ports Grayed Out)
  Cause: Incompatible third-party optics (e.g., non-Cisco QSFP28 modules).
  Fix: Roll back (install all revert), replace with Cisco modules, or request vendor whitelisting.

• Pitfall 3: DNA Center Integration Fails (Policy Desync)
  Cause: Failed to mark device as “maintenance mode” pre-upgrade.
  Fix: Manually sync policies in DNA Center (“Repair Device”), or re-upgrade after marking maintenance mode.

9. Use Cases: Which Is Right for You?

• C93120TX Scenarios:

• Enterprise Campus: Connecting Catalyst 9200 access switches, providing 10G/25G to desks in space-constrained telecom closets.

• Small/Medium Data Centers: 25G new server access + 10G legacy device coexistence (e.g., Web servers + database clusters) with 100G uplinks.

• C93128TX Scenarios:

• Cloud Data Center Core Access: Large-scale 25G server access (AI clusters, distributed databases) with 100G/400G uplinks for future growth.

• Multi-Tenant Cloud Platforms: EVPN-VXLAN multi-tenant isolation (1024 tenants) for financial/e-commerce industries.

10. Detailed Pros & Cons: No Perfection, Only Fit

• C93120TX:
  Pros: Multi-rate support, flexible breakout, low power, cost-efficiency, legacy compatibility.
  Cons: Limited scalability (8×400G uplinks), weak multi-tenancy (512 tenants), basic security (no IPsec acceleration).

• C93128TX:
  Pros: Ultra-high-density 25G access, 400G scalability, hardware encryption, DNA Center integration, multi-vendor optics.
  Cons: High cost, high power, steeper learning curve (requires DNA Center basics).

Conclusion

C93120TX or C93128TX? The answer lies in your needs: Choose the C93128TX for “future-proof performance,” “cutting-edge tech,” and “smart ops.” Pick the C93120TX for “budget savings,” “stable basics,” and “simplicity.” After all, the best network device isn’t the one with the flashiest specs—it’s the one that lets your business run smoothly, without surprises.