Why Broadcom NIC link fluctuates and bnx2 module traces are dump in logs ?

Issue

• Broadcom NIC with bnx2 module link goes Down/Up and following traces seen in /var/log/messages before fluctuation.

Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: <--- start FTQ dump --->
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: RV2P_PFTQ_CTL 00010000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: RV2P_TFTQ_CTL 00020000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: RV2P_MFTQ_CTL 00004000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: TBDR_FTQ_CTL 01004002
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: TDMA_FTQ_CTL 04010002
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: TXP_FTQ_CTL 04010002
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: TXP_FTQ_CTL 04010002
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: TPAT_FTQ_CTL 04010002
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: RXP_CFTQ_CTL 00008000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: RXP_FTQ_CTL 00100000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: COM_COMXQ_FTQ_CTL 00010000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: COM_COMTQ_FTQ_CTL 00020000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: COM_COMQ_FTQ_CTL 00010000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: CP_CPQ_FTQ_CTL 00004000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: CPU states:
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 045000 mode b84c state 80001000 evt_mask 500 pc 8000d60 pc 8000d60 instr 440fffe
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 085000 mode b84c state 80005000 evt_mask 500 pc 8000a4c pc 8000a4c instr 38420001
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0c5000 mode b84c state 80001000 evt_mask 500 pc 8004c14 pc 8004c14 instr 10e00088
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 105000 mode b8cc state 80000000 evt_mask 500 pc 8000a9c pc 8000a8c instr 3c028000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 145000 mode b880 state 80004000 evt_mask 500 pc 800d840 pc 800d1b0 instr 3b5a0400
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 185000 mode b8cc state 80000000 evt_mask 500 pc 8000930 pc 8000978 instr afbf0014
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: <--- end FTQ dump --->
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: <--- start TBDC dump --->
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: TBDC free cnt: 7
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: LINE     CID  BIDX   CMD  VALIDS
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 00    001200  7f28   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 01    000800  0dd0   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 02    001200  7f30   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 03    001100  3a90   00    [1c]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 04    001000  45c0   00    [7]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 05    000800  0dd8   00    [7f]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 06    001000  4598   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 07    001080  0cf8   00    [3]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 08    001180  1b48   00    [c0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 09    001080  0ce0   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0a    000800  0dc8   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0b    001200  7f58   00    [3f]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0c    000800  0dc0   00    [f0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0d    001080  0cd8   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0e    001000  4588   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 0f    001200  7f20   00    [fe]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 10    001200  7f18   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 11    001200  7f08   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 12    001000  45a0   00    [e0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 13    001000  45a8   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 14    001080  0ce8   00    [80]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 15    001080  0cf0   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 16    001180  1b50   00    [7]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 17    001200  7f38   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 18    001200  7f00   00    [0]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 19    001200  7f40   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 1a    001280  1a10   00    [30]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 1b    001200  7f48   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 1c    001300  0740   00    [78]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 1d    001200  7f50   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 1e    001000  45b0   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: 1f    001000  45b8   00    [ff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: <--- end TBDC dump --->
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: intr_sem[0] PCI_CMD[00100406]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: PCI_PM[19002008] PCI_MISC_CFG[92000088]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: EMAC_TX_STATUS[00000008] EMAC_RX_STATUS[00000007]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: RPM_MGMT_PKT_CTRL[40000088]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: HC_STATS_INTERRUPT_STATUS[01ff0000]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: PBA[00000000]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: <--- start MCP states dump --->
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: MCP_STATE_P0[0003610e] MCP_STATE_P1[0003610e]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: MCP mode[0000b880] state[80008000] evt_mask[00000500]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: pc[0800aff0] pc[0800d190] instr[afb60040]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: shmem states:
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: drv_mb[0103000f] fw_mb[0000000f] link_status[0000006b] drv_pulse_mb[00006ef3]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: dev_info_signature[44564903] reset_type[01005254] condition[0003610e]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: 000001c0: 01005254 42530085 0003610e 00000000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: 000003cc: 44444444 44444444 44444444 00000a28
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: 000003dc: 0004ffff 00000000 00000000 00000000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: 000003ec: 00000000 00000000 00000000 00000000
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: DEBUG: 0x3fc[0000ffff]
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: <--- end MCP states dump --->
Apr 17 10:56:43 HOSTNAME kernel: bnx2 0000:01:00.0: em1: NIC Copper Link is Down
Apr 17 10:56:45 HOSTNAME kernel: bnx2 0000:01:00.0: em1: NIC Copper Link is Up, 100 Mbps full duplex, receive & transmit flow control ON

• Why this is caused and what can be done ?