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Configure 10Gbps network capture

To ensure efficient data capture with minimal packet loss over high-volume 10Gb network interfaces, Splunk Stream lets you deploy an alternate Stream forwarder, which supports 10Gbps data capture on compatible network interfaces.

This page shows you how to optimize your Linux environment and configure Stream forwarder to enable 10Gbps data capture on compatible devices.

Operating system requirements

Dedicated 10Gb capture mode is supported on 64-bit Linux platforms (kernel version 2.6.32 or later). A variety of network devices are supported.

Note: Dedicated 10Gb capture mode has been tested on RHEL/CentOS only.

Optimize Linux environment

For best results with dedicated capture mode, update your kernel boot parameters for hugepages, as follows:

  1. Edit /etc/grub.conf.
  2. Add these parameters to your kernel boot line to configure sixteen 1GB hugepages: default_hugepagesz=1G hugepagesz=1G hugepages=16. You may need to adjust the number of hugepages to fit your hardware configuration. For example, after adding these parameters, your kernel boot line might look like this:
    kernel /vmlinuz-2.6.32-573.3.1.el6.x86_64 ro root=/dev/mapper/vg_cmload02-lv_root rd_LVM_LV=vg_cmload02/lv_root rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=vg_cmload02/lv_swap  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM default_hugepagesz=1G hugepagesz=1G hugepages=16 rhgb quiet
  3. Reboot your linux machine.

Note: Updating kernel boot parameters for dedicated capture mode is optional, though highly recommended.

Configure 10Gb dedicated capture mode

The following configuration steps apply to independent stream forwarder (streamfwd) deployments only. You must be a root user to run streamfwd in dedicated capture mode.

Step 1: Enable dedicated capture mode in streamfwd.conf

  1. Edit local/streamfwd.conf.
  2. Add dedicatedCaptureMode = 1. For example:
    port = 8889
    ipAddr =
    dedicatedCaptureMode = 1
  3. Restart Splunk.

Step 2: Identify compatible interfaces

Use the streamfwd --iflist command to identity the interface on which you want to capture 10Gbps traffic. You can capture packets at 10Gbps on any interface listed under Dedicated capture mode compatible devices. For example:

# ./linux_x86_64/bin/streamfwd --iflist
Dedicated capture mode compatible devices
0000:04:00.0 driver=uio_pci_generic if=
0000:04:00.1 driver=uio_pci_generic if=
0000:05:00.0 driver=uio_pci_generic if=
0000:05:00.1 driver=uio_pci_generic if=

Dedicated capture mode non-compatible devices
0000:02:00.0 driver=tg3 if=eth4 *Active*
0000:02:00.1 driver=tg3 if=eth5
0000:02:00.2 driver=tg3 if=eth6
0000:02:00.3 driver=tg3 if=eth7

Step 3: Specify network address in streamfwd.conf

  1. Edit local/streamfwd.conf.
  2. Specify the network address of the 10Gbps-compatible device. For example:
    port = 8889
    ipAddr =
    dedicatedCaptureMode = 1
    streamfwdcapture.0.interface = 0000:04:00.0

    Dedicated capture mode requires specifying network device(s) using the PCI bus address notation.

  3. Restart Splunk.
Last modified on 05 June, 2018
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This documentation applies to the following versions of Splunk Stream: 7.0.1

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