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#1 2010-07-31 01:59:29

graysky
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Can't get a Gigabit connection with a gigabit switch

Just added a GS105 gigabit switch to the LAN at my parents house.  The Arch box is only connecting at 100 Mbps despite the fact that it has a gigalan PCI NIC in it.  Note that I don't have physical access to the machine is at my parents house and they are absolutely no help with Linux, so I have to troubleshoot this remotely via ssh or vnc.

If I query eth0 with ethtool it does indeed support gigalan speed:

# ethtool eth0
Settings for eth0:
    Supported ports: [ TP ]
    Supported link modes:   10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Full 
    Supports auto-negotiation: Yes
    Advertised link modes:  10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Full 
    Advertised auto-negotiation: Yes
    Speed: 100Mb/s
    Duplex: Full
    Port: Twisted Pair
    PHYAD: 0
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: pg
    Wake-on: g
    Current message level: 0x00000037 (55)
    Link detected: yes

If I force it with the -s command, the ssh session I'm in seems to freeze for about 30 sec then resume:

ethtool -s eth0 speed 1000 duplex full

Link speed is still 100 Mbps.

Suggestions are welcomed!

Last edited by graysky (2010-07-31 02:33:51)


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#2 2010-07-31 04:07:18

CountDuckula
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Registered: 2010-02-28
Posts: 151

Re: Can't get a Gigabit connection with a gigabit switch

It might be the old auto-negotiation at both ends of the link not agreeing who sets speed/duplex for link at gigabit speed. You may want to turn off auto-negotiation on your PC's NIC and try again.

Last edited by CountDuckula (2010-07-31 04:08:10)

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#3 2010-07-31 06:16:16

fukawi2
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From: .vic.au
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Re: Can't get a Gigabit connection with a gigabit switch

Are you sure you're using Cat 5e or Cat 6 network cable? Standard Cat 5 won't support gigabit speeds.

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#4 2010-07-31 08:00:06

graysky
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Re: Can't get a Gigabit connection with a gigabit switch

@CD - Remember that I'm doing this via an ssh session.  As a fail-safe, I set "shutdown -r 60" running in the background just in case I hosed the network!   I tried your suggestion, but doing so killed the network:

# ethtool -s eth0 autoneg off speed 1000 duplex full

Again, the ssh window just hung after I hit enter.  I couldn't ssh into the machine until it rebooted.

@fukawi2 - Good point.  I know the main run from the switch to the wall is Cat5e, but I'm not 100 % sure that the patch cable from the machine to the wall is cat5e.  I will have them check it and post back here.  Is there a Linux utility that can make some qualitative measurement of cable quality?  I remember that Realtek had some diagnostic that ran under Windows that would some how diagnose the individual pairs of a patch cable.  I searched around but found nothing like this for Linux hmm

Last edited by graysky (2010-07-31 09:38:46)


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#5 2010-07-31 09:47:38

fukawi2
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From: .vic.au
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Re: Can't get a Gigabit connection with a gigabit switch

graysky wrote:

@fukawi2 - Good point.  I know the main run from the switch to the wall is Cat5e, but I'm not 100 % sure that the patch cable from the machine to the wall is cat5e.  I will have them check it and post back here.  Is there a Linux utility that can make some qualitative measurement of cable quality?  I remember that Realtek had some diagnostic that ran under Windows that would some how diagnose the individual pairs of a patch cable.  I searched around but found nothing like this for Linux hmm

Not that I know of, sorry. Don't forget the cable in the wall too. Stupid cablers only put Cat5 between my office and my house when I asked for 5e so I can only get 100mbps from my office to my house sad

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#6 2010-07-31 09:55:11

graysky
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Re: Can't get a Gigabit connection with a gigabit switch

fukawi2 wrote:

Not that I know of, sorry. Don't forget the cable in the wall too. Stupid cablers only put Cat5 between my office and my house when I asked for 5e so I can only get 100mbps from my office to my house sad

I did all the runs in the walls and I know I used Cat5e (the same spool that I used for my own house which runs GigaLAN just fine).

PC <---> Wall <--------------------> Switch

Right now the only wildcard is the PC to wall connection.


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#7 2010-07-31 11:34:34

fukawi2
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From: .vic.au
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Re: Can't get a Gigabit connection with a gigabit switch

graysky wrote:

I did all the runs in the walls and I know I used Cat5e (the same spool that I used for my own house which runs GigaLAN just fine).

Fair enough then smile
Wish I had the skills (and more so the patience!) to do it myself!

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#8 2010-07-31 23:54:39

graysky
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Re: Can't get a Gigabit connection with a gigabit switch

Well, it wasn't the patch cord.  It has been swapped with one that works @ Gigabit speeds on another machine.  I can only conclude that it is either the switch, or the run that I installed.

Does anyone else have any ideas?

# lspci | grep net
00:09.0 Ethernet controller: D-Link System Inc Gigabit Ethernet Adapter (rev 11)

The damn NIC is clearly Gigabit able and I've used it before on my own network @ 1000 Mbps.

Last edited by graysky (2010-07-31 23:58:52)


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#9 2010-08-01 00:37:05

fukawi2
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From: .vic.au
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Re: Can't get a Gigabit connection with a gigabit switch

I'm out of ideas, unless it's a really long run, or like you mentioned, something in the punch down isn't quite right...

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#10 2010-08-01 03:17:50

CountDuckula
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Registered: 2010-02-28
Posts: 151

Re: Can't get a Gigabit connection with a gigabit switch

fukawi2 wrote:

Are you sure you're using Cat 5e or Cat 6 network cable? Standard Cat 5 won't support gigabit speeds.

FYI CAT5 can run at gigabit - it's just that it gets a litlle less happier doing it if the run gets close to the 100M mark. I had gigabit working fine at a distance of 50M over CAT5 but YMMV.

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#11 2010-08-01 12:08:47

graysky
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Re: Can't get a Gigabit connection with a gigabit switch

Thanks for the replies.  Looks like this is a problem with the netgear being a piece of shit.  Have a look at all the folks in the newegg reviews reporting a similar problem with some NICs.

Looks like I'm out $40 on this one...


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#12 2010-08-02 09:22:03

CountDuckula
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Registered: 2010-02-28
Posts: 151

Re: Can't get a Gigabit connection with a gigabit switch

graysky wrote:

Thanks for the replies.  Looks like this is a problem with the netgear being a piece of shit.  Have a look at all the folks in the newegg reviews reporting a similar problem with some NICs.

Looks like I'm out $40 on this one...

Yeah that happens sometimes due to poor chip sets involved, I had to hard code speed/duplex between two Cisco switches on occasions as they couldn't work it out for themselves - so spending thousands don't help sometimes. Netgear feature towards the lower end of my scale for reliable stuff...

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