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NAME | SYNOPSIS | DESCRIPTION | SAMPLED PACKETS METADATA FIELDS | OPTIONS | EXAMPLES | SEE ALSO | COLOPHON |
Packet sample action in tc(8) Linux Packet sample action in tc(8)
sample - packet sampling tc action
tc ... action sample rate RATE group GROUP [ trunc SIZE ] [ index
INDEX ]
tc ... action sample index INDEX
The sample action allows sampling packets matching classifier.
The packets are chosen randomly according to the rate parameter, and
are sampled using the psample generic netlink channel. The user can
also specify packet truncation to save user-kernel traffic. Each
sample includes some informative metadata about the original packet,
which is sent using netlink attributes, alongside the original packet
data.
The user can either specify the sample action parameters as presented
in the first form above, or use an existing sample action using its
index, as presented in the second form.
The metadata are delivered to userspace applications using the
psample generic netlink channel, where each sample includes the
following netlink attributes:
PSAMPLE_ATTR_IIFINDEX
The input interface index of the packet, if there is one.
PSAMPLE_ATTR_OIFINDEX
The output interface index of the packet. This field is not
relevant on ingress sampling
PSAMPLE_ATTR_ORIGSIZE
The size of the original packet (before truncation)
PSAMPLE_ATTR_SAMPLE_GROUP
The psample group the packet was sent to
PSAMPLE_ATTR_GROUP_SEQ
A sequence number of the sampled packet. This number is
incremented with each sampled packet of the current psample
group
PSAMPLE_ATTR_SAMPLE_RATE
The rate the packet was sampled with
rate RATE
The packet sample rate. RATE is the expected ratio between
observed packets and sampled packets. For example, RATE of 100
will lead to an average of one sampled packet out of every 100
observed.
trunc SIZE
Upon set, defines the maximum size of the sampled packets, and
causes truncation if needed
group GROUP
The psample group the packet will be sent to. The psample
module defines the concept of groups, which allows the user to
match specific sampled packets in the case of multiple
sampling rules, thus identify only the packets that came from
a specific rule.
index INDEX
Is a unique ID for an action. When creating new action
instance, this parameter allows to set the new action index.
When using existing action, this parameter allows to specify
the existing action index. The index must 32bit unsigned
integer greater than zero.
Sample one of every 100 packets flowing into interface eth0 to
psample group 12:
tc qdisc add dev eth0 handle ffff: ingress
tc filter add dev eth0 parent ffff: matchall \
action sample rate 100 group 12 index 19
Use the same action instance to sample eth1 too:
tc qdisc add dev eth1 handle ffff: ingress
tc filter add dev eth1 parent ffff: matchall \
action sample index 19
tc(8), tc-matchall(8) psample(1)
This page is part of the iproute2 (utilities for controlling TCP/IP
networking and traffic) project. Information about the project can
be found at
⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
If you have a bug report for this manual page, send it to
netdev@vger.kernel.org, shemminger@osdl.org. This page was obtained
from the project's upstream Git repository
⟨git://git.kernel.org/pub/scm/linux/kernel/git/shemminger/iproute2.git⟩
on 2017-07-05. If you discover any rendering problems in this HTML
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the information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
iproute2 31 Jan 2017 Packet sample action in tc(8)