Date: Mon, 12 Oct 2009 09:52:50 +0200 From: Ian FREISLICH <ianf@clue.co.za> To: pyunyh@gmail.com Cc: current@freebsd.org Subject: Re: alc(4) link autoselect problem Message-ID: <E1MxFi6-0007jF-OU@clue.co.za> In-Reply-To: <20091009194037.GI3843@michelle.cdnetworks.com> References: <20091009194037.GI3843@michelle.cdnetworks.com> <20091008170458.GC3843@michelle.cdnetworks.com> <20091007180257.GA3843@michelle.cdnetworks.com> <E1MvPZq-000Fqu-Ti@clue.co.za> <E1MvqOT-0000Oo-7F@clue.co.za> <E1Mw82O-0006kF-PA@clue.co.za>
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Pyun YongHyeon wrote:
> On Fri, Oct 09, 2009 at 07:29:08AM +0200, Ian FREISLICH wrote:
> > Pyun YongHyeon wrote:
> > > On Thu, Oct 08, 2009 at 12:38:45PM +0200, Ian FREISLICH wrote:
> > > > wgsw-24010# sh interfaces status ethernet g14
> > > > Flow Link Back
Mdix
> > > > Port Type Duplex Speed Neg ctrl State Pressure
Mode
> > > > -------- ------------ ------ ----- -------- ---- ----------- --------
----
> > ---
> > > > g14 1G-Copper Full 100 Enabled Off Up Disabled
Off
> > > >
> > >
> > > Hmm, does your switch have an option to enable/disable downshifting
> > > feature? If so, how about toggling the option?
> >
> > I'm not sure exactly what you mean. There's no configuration options
> > that obviously match.
> >
>
> Modern PHYs have ability to correct several cabling problems, for
> example,
> - pair swaps
> - pair skews
> - pair polarity
> - automatic MDI/MDIX
> - downshift to enable 10/100Mps link establishment with two
> pairs by downgrading the link speed to 10/100Mbps during
> auto-negotiation process when it can't establish 1000Mbps link.
> Existing cables used to connect 10/100Mbps link partners may
> have only two pairs. With two pairs PHYs can announce 1000Mbps
> capability to link partner but it can't establish the link as
> 1000Mbps link requires 4 pairs.
>
> Since F1 PHY seems to have above capability I just wanted to see
> whether disabling downshifting on link partner makes any
> difference.
Yes, if I tell the switch to negotiate but not to advertise
1000f, link negotiation works with this PHY:
wgsw-24010# sh interfaces advertise ethernet g14
Port: g14
Type: 1G-Copper
Link state: Up
Auto negotiation: Enabled
1000f 1000h 100f 100h 10f 10h
----- ----- ---- ---- --- ---
Admin Local link Advertisement no no yes yes yes yes
Oper Local link Advertisement no no yes yes yes yes
Oper Remote link Advertisement no no yes yes yes yes
Priority Resolution - - yes - - -
alc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=3198<VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,WOL_MCAST,WOL_MAGIC>
ether 00:25:b3:6f:ab:9a
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
Ian
--
Ian Freislich
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