Network Slowdowns?

Bill Hacker wbh at conducive.org
Fri Oct 13 10:36:16 PDT 2006


walt wrote:
Jamie wrote:
...
Someone suggested changing the duplex settings on the other side, I know
it's running full duplex on DragonFlyBSD, but.. I don't know how to even
find out linux side. I'll have to research that I guess.


ethtool works for me:
#ethtool eth0
Settings for eth0:
        Supported ports: [ MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: g
        Wake-on: d
        Current message level: 0x000000ff (255)
        Link detected: yes
http://sourceforge.net/projects/gkernel/
Are both ends 'local' to you?

Is there a (switching)hub in between?  Router? Just a cable?

Is anything else on the cable plant that you could disconnect for a time.

Are you in a high-noise environment? EG arc-welders, neon signs, oil-burner 
igniters, large motors w/o zero-crossing controls, even hotplates, fluorescents 
going bad, heaters, hot-water pots - and once a faulty scr in an electric steam 
iron.

Woudl loan you my Fluke 'Scopemeter', but ....distance...

- obvious next step of adding/subtracting/swapping-out, if so.

By this time, I suspect that at least one other person would have reported 
*something* similar with DFLY if it was a core code or driver issue.

As that seems not the case, it is more and more likely to be hardware/firmware, 
or something else quite specific to your environment alone.

Perchance does tcpdump show a good fast start, then a gradual clogging and slowdown?

- That was the symptom when I had SiS NIC troubles, tho' I initially blamed it 
on MTU size mismatch (other end was a 'broadand' cable-modem provider the other 
side of the island).

Bill





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