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Linus Torvalds1da177e2005-04-16 15:20:36 -07001Traffic Shaper For Linux
2
3This is the current BETA release of the traffic shaper for Linux. It works
4within the following limits:
5
6o Minimum shaping speed is currently about 9600 baud (it can only
7shape down to 1 byte per clock tick)
8
9o Maximum is about 256K, it will go above this but get a bit blocky.
10
11o If you ifconfig the master device that a shaper is attached to down
12then your machine will follow.
13
14o The shaper must be a module.
15
16
17Setup:
18
19 A shaper device is configured using the shapeconfig program.
20Typically you will do something like this
21
22shapecfg attach shaper0 eth1
23shapecfg speed shaper0 64000
24ifconfig shaper0 myhost netmask 255.255.255.240 broadcast 1.2.3.4.255 up
25route add -net some.network netmask a.b.c.d dev shaper0
26
27The shaper should have the same IP address as the device it is attached to
28for normal use.
29
30Gotchas:
31
32 The shaper shapes transmitted traffic. It's rather impossible to
33shape received traffic except at the end (or a router) transmitting it.
34
35 Gated/routed/rwhod/mrouted all see the shaper as an additional device
36and will treat it as such unless patched. Note that for mrouted you can run
37mrouted tunnels via a traffic shaper to control bandwidth usage.
38
39 The shaper is device/route based. This makes it very easy to use
40with any setup BUT less flexible. You may need to use iproute2 to set up
41multiple route tables to get the flexibility.
42
43 There is no "borrowing" or "sharing" scheme. This is a simple
44traffic limiter. We implement Van Jacobson and Sally Floyd's CBQ
45architecture into Linux 2.2. This is the preferred solution. Shaper is
46for simple or back compatible setups.
47
48Alan