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Diffstat (limited to 'share/man/man4/epair.4')
| -rw-r--r-- | share/man/man4/epair.4 | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/share/man/man4/epair.4 b/share/man/man4/epair.4 index 342b15b5612a..b406c423361b 100644 --- a/share/man/man4/epair.4 +++ b/share/man/man4/epair.4 @@ -25,7 +25,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd August 12, 2025 +.Dd September 4, 2025 .Dt EPAIR 4 .Os .Sh NAME @@ -108,6 +108,29 @@ As with any other Ethernet interface, can have a .Xr vlan 4 configured on top of it. +.Pp +The +.Nm +has RXCSUM and RXCSUM6 enabled because it may receive a packet where the +checksum has already been validated by a physical interface. +The +.Nm +supports TXCSUM and TXCSUM6 for TCP and UDP, but only by forwarding the order +to compute the checksum. +Thus, when using an +.Nm +interface, a TCP or UDP sender can offload checksum computation +to a physical interface. +Note that, in case the packet does not leave the host, the checksum is +unnecessary and will be ignored if offloaded. +Such packets contain an incorrect checksum, since it is not computed yet. +TXCSUM and TXCSUM6 are synchronized between the +.Nm +interface pair (i.e., enabling/disabling the capability on one end +enables/disables it on the other end). +In case one end is in a bridge and the bridge disabled TXCSUM or TXCSUM6, +this avoids a sender to send packets with checksum offloading into the +bridge by using the other end. .Sh SEE ALSO .Xr ioctl 2 , .Xr altq 4 , |