3.8. net_cls
The
net_cls subsystem tags network packets with a class identifier (classid) that allows the Linux traffic controller (tc) to identify packets originating from a particular cgroup. The traffic controller can be configured to assign different priorities to packets from different cgroups.
- net_cls.classid
net_cls.classidcontains a single value that indicates a traffic control handle. The value ofclassidread from thenet_cls.classidfile is presented in the decimal format while the value to be written to the file is expected in the hexadecimal format. For example,0x100001represents the handle conventionally written as10:1in the format used by the ip utility. In thenet_cls.classidfile, it would be represented by the number1048577.The format for these handles is:0xAAAABBBB, where AAAA is the major number in hexadecimal and BBBB is the minor number in hexadecimal. You can omit any leading zeroes;0x10001is the same as0x00010001, and represents1:1. The following is an example of setting a10:1handle in thenet_cls.classidfile:~]#
echo 0x100001 > /cgroup/net_cls/red/net_cls.classid~]#cat /cgroup/net_cls/red/net_cls.classid1048577
Refer to the man page for tc to learn how to configure the traffic controller to use the handles that the
net_cls adds to network packets.
