7 Replies Latest reply on Mar 9, 2017 7:59 PM by Intel Corporation

    82576 Gigabit Ethernet: Enabling MPE bit causes Unknown Unicast to accept




      We are using 82576 Gigabit Ethernet Controller, as per the document (8.10.1 Receive Control Register - RCTL (0x00100; R/W)

      , page No. 515) attached and also the ethtool output,


      - Even if the UPE (Unicast Promiscuous Enable) bit is reset (disabled) we still seem to receive any Unknown Unicast Packets.

      - If we disable the MPE (Multicast Promiscuous Enable) bit then we stop receiving any Unknown Unicast Packets.


      While I do not see any reason why any one would disable UPE and enable MPE, just wanted to know if it is expected behavior.

      Our assumption was that if the UPE bit is disabled then we should NOT receive any Unknown Unicast (assume we do not have any

      RAL entries for MAC filtering)


      Linux# ethtool -d eth1

      0x00000: CTRL (Device control register)               0x40D00240

             Invert Loss-Of-Signal:                         no

             Receive flow control:                          disabled

             Transmit flow control:                         disabled

             VLAN mode:                                     enabled

             Set link up:                                   1

             D3COLD WakeUp capability advertisement:        enabled

             Auto speed detect:                             disabled

             Speed select:                                  1000Mb/s

             Force speed:                                   no

             Force duplex:                                  no

      0x00008: STATUS (Device status register)              0x00080383

             Duplex:                                        full

             Link up:                                       link config

             Transmission:                                  on

             DMA clock gating:                              disabled

             TBI mode:                                      disabled

             Link speed:                                    1000Mb/s

             Bus type:                                      PCI Express

      0x00100: RCTL (Receive control register)              0x0400803A

             Receiver:                                      enabled

             Store bad packets:                             disabled

             Unicast promiscuous:                           disabled

             Multicast promiscuous:                         enabled

             Long packet:                                   enabled

             Descriptor minimum threshold size:             1/2

             Broadcast accept mode:                         accept

             VLAN filter:                                   disabled

             Cononical form indicator:                      disabled

             Discard pause frames:                          filtered

             Pass MAC control frames:                       don't pass

             Loopback mode:                                 normal

             Receive buffer size:                           2048