Code-Memo

Traffic control (tc)

What is tc?

tc configures Linux kernel queuing disciplines (qdisc) for:

• shaping (limit bandwidth)
• scheduling (latency/jitter control)
• policing
• packet classification/marking

Inspect qdiscs

tc qdisc show
tc qdisc show dev eth0

Simple shaping example (conceptual)

Add a token bucket filter (TBF) to limit egress bandwidth:

sudo tc qdisc add dev eth0 root tbf rate 10mbit burst 32kbit latency 400ms

Remove:

sudo tc qdisc del dev eth0 root

More advanced

• htb: hierarchical shaping
• fq_codel: latency-friendly queueing
• netem: emulate loss/delay/jitter (testing)

Netem example (testing only):

sudo tc qdisc add dev eth0 root netem delay 100ms loss 1%

Notes

• Changes are typically not persistent across reboot unless configured by networking tools
• Misconfiguration can cut you off on remote systems—be careful

Related

• Packet analysis (tcpdump, Wireshark)