---
title: "Replay PCAP on capture ports (PIO Slow)"
slug: "replay-pcap-on-capture-ports-pio"
updated: 2025-04-13T15:03:01Z
published: 2025-04-13T15:03:01Z
canonical: "docs.fmad.io/replay-pcap-on-capture-ports-pio"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fmad.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Replay PCAP on capture ports (PIO Slow)

FMADIO can replay PCAP traffic at low speed while simultaneously capturing at full line rate. This can be very helpful for debugging or other troubleshooting and does not require changing the FPGA firmware from Capture to Replay mode. This Replay mode uses PIO (Programmed IO), whose bandwidth is relatively low and unsuitable for full high bandwidth packet relay.

Support SKUS:

- FMADIO-5214
- FMADIO-5414
- FMADIO-5514
- FMADIO-100Gv2

The general approach is

```plaintext
cat <pcap name> |  sudo /opt/fmadio/bin/stream_generate_f100 --replay_pio
```

or replaying from the Capture storage

- <capture name> can be found using FMADIO CLI `show capture list` ( [https://docs4.fmad.io/docs/fmadiocli-configure-capture#show-capture-list](https://docs4.fmad.io/docs/fmadiocli-configure-capture#show-capture-list) )

```plaintext
sudo stream_cat <capture name> |  sudo /opt/fmadio/bin/stream_generate_f100 --replay_pio
```

## PIO Replay from Capture File

An example is below that pipes data from a previously captured file. The exact name of the capture file can be found using `sudo stream_dump`

Example

```plaintext
fmadio@fmadio100v2-228:$ sudo stream_cat testk9k_b_20200727_0106 | sudo ./stream_generate_f100  --replay_pio

Packet Gen: Jul 27 2020 00:24:51
map 0x7f73115e0000
0x7f7308c4a000
StartChunk: 3856856
PCAP Nano
Replay Pkts:         1 Drop:         0 Total:0.000GB 0.579Gbps
Replay Pkts:     40225 Drop:         0 Total:0.056GB 0.451Gbps
Replay Pkts:     80542 Drop:         0 Total:0.113GB 0.451Gbps
Replay Pkts:    120730 Drop:         0 Total:0.169GB 0.451Gbps
Replay Pkts:    160842 Drop:         0 Total:0.225GB 0.450Gbps
Replay Pkts:    200879 Drop:         0 Total:0.281GB 0.450Gbps
Replay Pkts:    240992 Drop:         0 Total:0.337GB 0.450Gbps
Replay Pkts:    281222 Drop:         0 Total:0.394GB 0.450Gbps
Replay Pkts:    321452 Drop:         0 Total:0.450GB 0.450Gbps
Replay Pkts:    361580 Drop:         0 Total:0.506GB 0.450Gbps
Replay Pkts:    401815 Drop:         0 Total:0.563GB 0.450Gbps
Replay Pkts:    442053 Drop:         0 Total:0.619GB 0.450Gbps
Replay Pkts:    482276 Drop:         0 Total:0.675GB 0.450Gbps
Replay Pkts:    522380 Drop:         0 Total:0.731GB 0.450Gbps
Replay Pkts:    562478 Drop:         0 Total:0.787GB 0.450Gbps
Replay Pkts:    602678 Drop:         0 Total:0.844GB 0.450Gbps
Replay Pkts:    642979 Drop:         0 Total:0.900GB 0.450Gbps
Replay Pkts:    683165 Drop:         0 Total:0.956GB 0.450Gbps
Replay Pkts:    723334 Drop:         0 Total:1.013GB 0.450Gbps
Replay Pkts:    763528 Drop:         0 Total:1.069GB 0.450Gbps
Replay Pkts:    803801 Drop:         0 Total:1.125GB 0.450Gbps
Replay Pkts:    843917 Drop:         0 Total:1.181GB 0.450Gbps
Replay Pkts:    884163 Drop:         0 Total:1.238GB 0.450Gbps
Replay Pkts:    924157 Drop:         0 Total:1.294GB 0.450Gbps
```

## PIO Replay from local PCAP

The following example pipes a PCAP on the local file system (/mnt/store0/tmp/imix.pcap) to replay the traffic

```plaintext
fmadio@fmadio100v2-228$ cat imix10.pcap | sudo stream_generate_f100  --replay_pio

Packet Gen: Jul 28 2020 01:05:12
SetAffinity: CPU 1 Index:18
PCAP Nano
Replay Pkts:         1 Drop:         0 Total:0.000GB 0.506Gbps
Replay Pkts:    137652 Drop:         0 Total:0.049GB 0.389Gbps
Replay Pkts:    273955 Drop:         0 Total:0.097GB 0.390Gbps
Replay Pkts:    411187 Drop:         0 Total:0.146GB 0.391Gbps
Replay Pkts:    548794 Drop:         0 Total:0.196GB 0.391Gbps
Replay Pkts:    686374 Drop:         0 Total:0.244GB 0.391Gbps
Replay Pkts:    822256 Drop:         0 Total:0.293GB 0.390Gbps
Replay Pkts:    955237 Drop:         0 Total:0.340GB 0.389Gbps
Replay Pkts:   1092409 Drop:         0 Total:0.389GB 0.389Gbps
Replay Pkts:   1227813 Drop:         0 Total:0.437GB 0.389Gbps
Replay Pkts:   1361926 Drop:         0 Total:0.485GB 0.388Gbps
Replay Pkts:   1498830 Drop:         0 Total:0.534GB 0.388Gbps
Replay Pkts:   1634867 Drop:         0 Total:0.582GB 0.388Gbps
Replay Pkts:   1771895 Drop:         0 Total:0.631GB 0.388Gbps
Replay Pkts:   1907879 Drop:         0 Total:0.680GB 0.388Gbps
Replay Pkts:   2039344 Drop:         0 Total:0.726GB 0.387Gbps
Replay Pkts:   2176207 Drop:         0 Total:0.775GB 0.388Gbps
Replay Pkts:   2310531 Drop:         0 Total:0.823GB 0.387Gbps
Replay Pkts:   2446486 Drop:         0 Total:0.871GB 0.387Gbps
Replay Pkts:   2583970 Drop:         0 Total:0.921GB 0.388Gbps
Replay Pkts:   2722008 Drop:         0 Total:0.970GB 0.388Gbps
Replay Pkts:   2859852 Drop:         0 Total:1.019GB 0.388Gbps
Replay Pkts:   2997241 Drop:         0 Total:1.068GB 0.388Gbps
Replay Pkts:   3134724 Drop:         0 Total:1.117GB 0.388Gbps
```