jumbo packets on em card.

[Clifton Royston]

On Wed, Apr 30, 2008 at 12:00:16PM +0000, freebsd-hackers-request at freebsd.org wrote:
> Date: Tue, 29 Apr 2008 17:43:42 +0530
> From: Sharad Chandra <sharadc at in.niksun.com>
> Subject: Re: jumbo packets on em card.
> To: Jeremy Chadwick <koitsu at freebsd.org>
> Cc: FreeBSD Hackers <freebsd-hackers at freebsd.org>
> Message-ID: <200804291743.43010.sharadc at in.niksun.com>
> Content-Type: text/plain;  charset="iso-8859-1"
> 
>  ,---- [Jeremy Chadwick wrote:]
> | On Tue, Apr 29, 2008 at 04:13:13PM +0530, Sharad Chandra wrote:
> | > I am getting a problem in setting em card to 1000baseTX. It shows "active
> | > status" with 100baseTX but as soon as i run "ifconfig em1 media
> | > 1000baseTX mediaopt full-duplex", it says *no carrier*. how can i set it
> | > to 1000base?
> |
> | The PHYs support auto-negotiation of speed and duplex, as per the 802.3
> | standard.
> |
> | Do you have a gigabit switch?  If so, does auto-negotiation (e.g. no
> | "mediaopt" or "media" settings) work?  If not, is the switch a managed
> | switch?  If so, try explicitly setting the port on the switch to
> | 1000mbit, full duplex.  If not, then consider buying another switch.
> | Many consumer/residential switches do not do auto-negotiation properly,
> | resulting in "no carrier" or worse (bad throughput).
> 
> No, I am not using any switch. It is back-to-back connection. It is only 
> requirement for me.

  Bear in mind that because GigE uses more of the cable pairs in an
RJ-48 than 100baseTX does, a defective or improperly wired crossover
cable between two machines may work fine for 100baseTX and fail for
1000baseTX.

  I strongly suspect that that's your problem.  Try replacing the cable
or reterminating both ends and carefully checking the color/pin
assignments against a reference.

  -- Clifton

-- 
    Clifton Royston  --  cliftonr at iandicomputing.com / cliftonr at lava.net
       President  - I and I Computing * http://www.iandicomputing.com/
 Custom programming, network design, systems and network consulting services