Nokia 7750 SR — FP4 and FP5
The Nokia 7750 SR is a carrier-grade core/edge router built on Nokia's proprietary FP (Forwarding Plane) ASIC family. Both FP4 and FP5 generations use a fully shared packet memory architecture with a dedicated pre-buffer stage.
FP4 Line Cards
| Field |
Value |
| Total Buffer |
~64 GB per line card |
| Buffer Model |
Fully shared ingress + egress |
| Pre-buffer |
Multi-million packet capacity |
| Default Queues |
128k ingress / 128k egress |
| Queue Reallocation |
8k increments |
| Throughput Class |
~3 Tbps per NPU |
| Target Interfaces |
Up to 400G |
FP5 Line Cards
| Field |
Value |
| Total Buffer |
32–64 GB per line card |
| Buffer Model |
Fully shared ingress + egress (enhanced) |
| Pre-buffer |
10.8M–21.6M packets (64-byte units) |
| Default Queues |
128k ingress / 128k egress |
| Queue Reallocation |
16k increments |
| Throughput Class |
~6 Tbps per NPU |
| Target Interfaces |
400G / 800G |
Key Architectural Points
- Buffer is not statically assigned to ports — the entire pool is shared across all interfaces on a line card
- A pre-buffer stage absorbs microbursts before the forwarding pipeline classifies traffic
- Queues can be reallocated between ingress and egress without changing the total buffer pool size
- FP5 improves efficiency and scale over FP4 without a significant raw buffer size increase
FP4 vs FP5 Comparison
| Feature |
FP4 |
FP5 |
| Buffer size |
~64 GB/LC |
32–64 GB/LC |
| Pre-buffer |
Multi-million pkts |
10.8M–21.6M pkts |
| Queue realloc increment |
8k |
16k |
| Throughput class |
~3 Tbps |
~6 Tbps |
| Target interfaces |
up to 400G |
400G / 800G |
| Key strength |
Deterministic buffering |
Efficiency + scale |
See the Nokia SR Platform architecture page for deeper detail on shared buffer pools, pre-buffering, and QoS coupling.
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