Traffic shaping and QoS
A full pipe treats every packet the same — which means your backup can drown your video call, and a busy download can make the whole server feel sluggish. Traffic shaping decides what gets priority when the link is busy.
When a link is not full, everything flows freely and shaping does nothing. The moment it fills, though, packets queue — and which packets wait decides whether your interactive traffic stays snappy or stutters behind a bulk transfer. Traffic shaping is how you make that choice deliberately instead of leaving it to chance.
Priority is the core idea
Some traffic is latency-sensitive — a call, a game, an interactive session — and a little delay ruins it. Other traffic is bulk — a backup, a download — and nobody notices if it is a second slower. Quality of Service means giving the sensitive traffic priority through the queue, so the bulk waits instead of the call. See latency and bandwidth.
Shaping vs policing
- Shaping — hold excess traffic in a queue and release it smoothly. Gentler; adds a little delay instead of dropping.
- Policing — drop (or mark) traffic over a limit outright. Harsher, but no buffering.
Taming the bulk transfer
The classic use: cap your backup or sync so it cannot consume the whole uplink and strangle everything else. A backup limited to, say, half the link finishes a little later and nobody’s session suffers for it. See backups.
It only helps at congestion
If your link genuinely has spare capacity, shaping is solving a problem you do not have — the honest fix for a constantly-full pipe is more capacity, not cleverer queuing. Shaping is for sharing a link fairly under load, not for conjuring bandwidth that is not there. See port speeds and unmetered.
Buffers can hurt
Oversized buffers cause “bufferbloat” — packets sit in a huge queue instead of being dropped, and latency balloons even though nothing is technically lost. Modern queue disciplines (fq_codel and friends) manage this well; the old instinct to just add more buffer makes interactive traffic worse, not better.
On your server and on our edge
You can shape outbound traffic on your own server with the kernel’s traffic control. For shaping that depends on the network itself — prioritising across our links — tell us what you are trying to protect and we will see what fits. See testing your connection properly.
Still stuck? Mail support@novogara.com — an engineer answers, at any hour. Back to the knowledge base