# TCP ROCCET :rocket: (RTT Oriented CUBIC Congestion control ExTension)

TCP ROCCET is a new TCP congestion control algorithm that reduces latency by detecting queuing.
Additionally, it is specially suited for 4G/5G cellular networks.

A peer-reviewed [paper on TCP ROCCET](https://opendl.ifip-tc6.org/db/conf/wons/wons2026/1571217211.pdf) was presented at the WONS 2026 conference.

## Install with apt
Add tcp-roccet-dkms to your source lists and install:
```
echo "deb [trusted=yes] https://apt.fury.io/timfuchs/ /" | sudo tee /etc/apt/sources.list.d/tcp-roccet.list
sudo apt update
sudo apt install tcp-roccet-dkms
```

### Loading and using the congestion control
Note: This change is not persistent, the module will not be loaded at boot.
```
sudo modprobe tcp_roccet
sudo sysctl net.ipv4.tcp_congestion_control=roccet
```

## Build from source

### Setup
Kernel headers are required:
* Debian: `sudo apt install linux-headers-generic`
* Fedora: `sudo dnf install kernel-devel`
(`sudo reboot`)

### Build 
`make`


## Loading & Unloading the Module  
**1.** Insert into Kernel: `sudo insmod tcp_roccet.ko`
In case you get the "Invalid module Format" error, it can help to reinstall the kernel-headers.

**2.** Use the Algorithm:
* Either via globally loading it: `sudo sysctl net.ipv4.tcp_congestion_control=roccet`
* Or via using it in specific measurements: `sudo iperf3 -c <Server-IP> -C roccet`

**3.** Unload the Module: `sudo rmmod tcp_roccet`


## Debugging (Using kprobe)
In order to debug the `tcp_roccet` congestion control algorithm, there exists a Kprobe module (`roccet_kprobe.c`). Using this, it is possible to inspect events generated by the algorithm. 

In order to use the Kprobe module, the following steps are necessary: 

**1. Specify the event to inspect**
For this, head into the `tcp_roccet.c` source code and find the function the Kprobe should attach to. 

For Example: 
```
__bpf_kfunc static void roccettcp_cong_avoid(struct sock *sk, u32 ack, u32 acked);
```
Specify this function name in the field `symbol_name` of the `kprobe` struct in `roccet_kprobe.c` 

Obtain the arguments in the kprobe using the `regs` field. 
(See the System V ABI for Linux under https://en.wikipedia.org/wiki/X86_calling_conventions#List_of_x86_calling_conventions)

**2. Build Kprobe module**
Use the provided Makefile to build the `roccet_kprobe.c` module for the local machine. (`make`)

For this the adequate linux-headers are required 
* Debian: `sudo apt install linux-headers-generic`
* Fedora: `sudo dnf install kernel-devel`

Required files for this are: 
* `Makefile` 
* `roccet_kprobe.c`
* `tcp_roccet.h`
* `tcp_roccet.c` (Optional; Need to remove corresponding entry in Makefile if missing)

**3. Load Kprobe module**
To then load the module use 
`sudo insmod roccet_kprobe.ko` 
If you are seeing the error "Unknown symbol in module" you need to first load the roccet algorithm.  

**4. See the trace output**
To see the trace output use
`sudo cat /sys/kernel/tracing/trace_pipe`

**5. Unload Kprobe module**
To remove the module again, use 
`sudo rmmod roccet_kprobe` 

_See more info at_ https://docs.kernel.org/trace/kprobes.html and https://www.kernel.org/doc/Documentation/trace/kprobetrace.rst