| Linux Advanced Routing & Traffic Control HOWTO | ||
|---|---|---|
| Prev | Chapter 14. Advanced & less common queueing disciplines | Next |
All qdiscs discussed so far are egress qdiscs. Each interface however can also have an ingress qdisc which is not used to send packets out to the network adaptor. Instead, it allows you to apply tc filters to packets coming in over the interface, regardless of whether they have a local destination or are to be forwarded.
As the tc filters contain a full Token Bucket Filter implementation, and are also able to match on the kernel flow estimator, there is a lot of functionality available. This effectively allows you to police incoming traffic, before it even enters the IP stack.
The ingress qdisc itself does not require any parameters. It differs from other qdiscs in that it does not occupy the root of a device. Attach it like this:
# tc qdisc add dev eth0 ingress |
For a contrived example how the ingress qdisc could be used, see the Cookbook.