CAKE SQM Setup Script

Interactive helper to install and configure CAKE (Common Applications Kept Enhanced) on a Linux interface. The script detects network interfaces, can create an IFB device for inbound shaping, and applies recommended CAKE options for low-latency, fair sharing.

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Table of Contents

• Status
• Features
• Requirements
• Usage
• Examples
• Design Notes
• Limitations & Next Steps
• Contributing
• License

Status

• Stable interactive script that detects interfaces and applies CAKE.
• Includes IFB creation + ingress redirect and safe removal mode.

Features

• Auto-detects network interfaces (hides helper devices like IFB).
• Detects existing CAKE qdiscs and offers to replace them.
• Creates ifb-<iface> for inbound shaping when needed.
• Uses recommended CAKE options for egress and ingress.
• Non-destructive --remove <iface> cleanup mode.

Requirements

• Linux
• iproute2 (ip), tc (iproute2), modprobe
• Optional: ethtool / iw for autodetecting link speed

Tested on (local machine)

• OS: CachyOS x86_64 — Kernel 6.19.2-2-cachyos
• Host: 82SB (IdeaPad Gaming 3 15ARH7)
• CPU: AMD Ryzen 7 6800H (16 threads)
• Memory: 58.54 GiB total
• GPUs: NVIDIA GeForce RTX 3050 Mobile (discrete), AMD Radeon 680M (integrated)
• Shell / Terminal: fish 4.5.0 / Konsole 25.12.2
• Desktop: KDE Plasma 6.6.0 (Wayland)
• Local IP (wlan0): 10.0.0.42/8
• Disk (root): ~472.6 GiB (xfs)

Verified on: 19 Feb 2026 (local test)

Install / Run

1. Make executable:

chmod +x cake-sqm-setup.sh

2. Run interactively (root required):

sudo ./cake-sqm-setup.sh

3. Remove CAKE from an interface (cleanup):

sudo ./cake-sqm-setup.sh --remove eth0

Usage (interactive)

• The script shows detected interfaces (hiding IFB helper devices).
• Select the interface number to configure (choose the physical WAN/egress if possible).
• Provide upload/download rates (examples: 10M, 800k, auto, unlimited).
  • auto attempts to read the interface speed using ethtool or iw.
  • unlimited installs CAKE without a bandwidth shaper.
• The script will optionally create an IFB device and redirect ingress traffic to it.
• Confirm to apply changes — the script replaces qdiscs atomically.

Examples

• Configure eth0 egress at 10 Mbit and ingress at 50 Mbit:

sudo ./cake-sqm-setup.sh
# choose interface 'eth0'
# upload: 10M
# download: 50M
# proceed: Y

• Remove CAKE and cleanup IFB for wlan0:

sudo ./cake-sqm-setup.sh --remove wlan0

Design Notes

• CAKE options used by default:
  • Egress: internet diffserv4 dual-srchost nat split-gso conservative
  • Ingress: internet diffserv4 dual-dsthost nat split-gso conservative
• The script detects IFB devices using kernel-reported link type (ip link show type ifb) — robust even if the interface name does not include "ifb".
• If an ifb-<iface> device already exists, the script will automatically reuse it (no prompt). If that IFB already has CAKE configured, the script will prompt whether to replace it — you may reply y/n or enter a bandwidth directly (for example unlimited) at that prompt to immediately replace with the provided bandwidth.
• IFS is intentionally restricted to newline+tab to avoid accidental word-splitting; the script handles array expansions safely.

Limitations & Next Steps

• Persistence: this script does not yet create a system startup unit to re-apply settings after reboot — can be added on request.
• Non-interactive mode: currently interactive; CLI flags can be added for automation.

Contributing

• Open an issue or PR with improvements or platform-specific fixes.
• Run the script locally and add tests for additional distributions.

License

MIT