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Manual Pages  — IF_NTB


if_ntb – Virtual Ethernet interface for Non-Transparent Bridges



To compile this driver into your kernel, place the following lines in your kernel configuration file: device ntb device ntb_transport device if_ntb

Or, to load the driver as a module at boot, place the following line in loader.conf(5):


The following tunables are settable from the loader(8):
hw.if_ntb.num_queues Limits maximal number of queues per interface. Default is unlimited.


The if_ntb driver attaches on top of the ntb_transport(4) driver to utilize one or more of its packet queues to create virtual Ethernet network interface between the systems. Typical MTU for the interface is about 64KB to reduce overhead. Default MAC address for the interface is randomly generated.

The if_ntb driver does not implement any real hardware offload, but since PCIe link is protected by CRC32, in some situations it may be possible to save some CPU cycles by enabling fake checksum offload on both link sides via setting rxcsum and txcsum interface options.




The if_ntb driver was developed by Intel and originally written by Carl Delsey <Mt carl@FreeBSD.org>. Later improvements were done by Conrad E. Meyer <Mt cem@FreeBSD.org> and Alexander Motin <Mt mav@FreeBSD.org>.


Linux supports only one queue per interface, so manual configuration may be required for compatibility.

IF_NTB (4) September 2, 2017

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