I am having an extremely slow network

netperf -H 11.x.x.21

TCP STREAM TEST from ( port 0 AF_INET to 11.x.x.21 (11.x.x.19) port 0 AF_INET

Recv   Send    Send  Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

2288  16384  16384    10.16       0.41   

I dont understand why 11.x.x.21 is showing

ethtool eth0

Settings for eth0:
Supported ports: [ FIBRE ]
Supported link modes:   1000baseT/Full 
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes:  1000baseT/Full 
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Speed: 1000Mb/s

Duplex: Half

Transceiver: internal
Auto-negotiation: on
Supports Wake-on: g
Wake-on: g
Link detected: yes

tried ethtool -r eth0 but no change at all.

so Manually changed by

ethtool -s eth0 speed 1000 duplex full autoneg off

But still no change in netperf ouptput

ethtool -i eth0

driver: bnx2
version: 2.1.11
firmware-version: bc 5.0.6 NCSI 2.0.3
bus-info: 0000:10:00.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes


00:10.0 PIC: Intel Corporation 7500/5520/5500/X58 Physical and Link Layer Registers Port 0 (rev 13)

Any idea:

why auto negotiation put NIC to half duplex and

Why manually changing to Full duplex couldnt solve anything.

  • 1
    If you manually configure duplex and speed settings, then this should also be configured on the individual switch port.
    – Dan
    Dec 3, 2013 at 14:25
  • 1
    Have you checked if on the switch side the negotiation is also set to auto and not half duplex? Also might be due to a broken cable.
    – Chris
    Dec 3, 2013 at 14:26
  • @Chris i forgot to mention that after reboot it came up wit this [ 28.088830] bnx2 0000:10:00.0: eth0: NIC SerDes Link is Up, 1000 Mbps full duplex Dec 3, 2013 at 14:50
  • So it means your problem is solved or is it still slow?
    – Chris
    Dec 3, 2013 at 15:30
  • If i restart its detecting proper duplex mode,not able to do i with ethtool Dec 3, 2013 at 15:58

1 Answer 1


First check that the setting on the device you connect to, do match (1000, autoneg, full-duplex).

Second swap the cable.

Third swap the port you are connecting to.

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