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Pat, Rich, I didn't get a chance to ask you this last week in Raleigh. Do you have any comments on how the PCS should handle a FIFO under/over run condition?
Regards,
Shawn
> -----Original Message-----
> From: Rogers, Shawn
> Sent: Monday, January 14, 2002 4:22 PM
> To: 'rtaborek@xxxxxxxxxxxxx'; 'pat_thaler@xxxxxxxxxxx'
> Cc: HSSG (E-mail)
> Subject: RE: [802.3ae] Link Fault Signaling due to FIFO under/over run
>
>
> Rich, Pat, on a slightly different tack:
>
> if a PCS encounters a FIFO under/over run condition, but is
> still frame and or column synchronized, it should still post
> a LF to the RS. The condition I'm thinking of is handling a
> jumbo packet or a jabbering station. The question is how
> should the PCS come out of the under/over run condition?
>
> Should it:
> a. wait for MDIO intervention to clear it's link fault condition?
> b. wait for idles on the in-bound path?
> c. something else in clause 48 or 49 I haven't read yet.
>
> Regards,
> Shawn
> > -----Original Message-----
> > From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxx]
> > Sent: Monday, December 24, 2001 3:01 PM
> > To: HSSG (E-mail)
> > Subject: Re: [802.3ae] Link Fault Signalling
> >
> >
> >
> > Gal,
> >
> > You are correct. Fault recognition does not require the
> usage of LF/RF
> > sequences.
> >
> > Happy Holidays,
> > Rich
> >
> > --
> >
> > "Ofek, Gal" wrote:
> > >
> > > Pat,
> > >
> > > re:"The RS does not poll the MDIO"
> > > Of course, you're right!(formally...)
> > >
> > > re:"but if the PMD/PMA isn't getting good signal, the PCS
> > will not be
> > > able to get lock to the signal from the PMD/PMA"
> > >
> > > Still, in general, there will be cases in which a fault
> > will be indicated
> > > through the link status bit (1.1.7) and not
> > > through the LF/RF sequences, right?
> > >
> > > Thanks
> > > Happy&Merry Holidays
> > > Gal Ofek
> > > Intel Communications Group - ISRAEL(Omer)
> > > Email: gal.ofek@xxxxxxxxx
> > >
> > > -----Original Message-----
> > > From: THALER,PAT (A-Roseville,ex1) [mailto:pat_thaler@xxxxxxxxxxx]
> > > Sent: Thursday, December 20, 2001 8:54 PM
> > > To: rtaborek@xxxxxxxxxxxxx; HSSG (E-mail)
> > > Subject: RE: [802.3ae] Link Fault Signalling
> > >
> > > Rich,
> > >
> > > I want to clarify something. The local fault bit in a
> > device is only set
> > > when the device detects a problem; for example low power or
> > inability to
> > > acquire sync. It is not set in response to receiving a
> > Local Fault signal on
> > > its input.
> > >
> > > Gal,
> > >
> > > The RS does not poll the MDIO. The RS is not required or
> > expected to have a
> > > connection to the MDIO. If the receive side of the link
> > isn't working, the
> > > RS should receive LF. True the PMD/PMA doesn't send LF when
> > it detects a
> > > fault, but if the PMD/PMA isn't getting good signal, the
> > PCS will not be
> > > able to get lock to the signal from the PMD/PMA.
> > >
> > > The purpose of the MDIO is to allow the local management to
> > determine PHY
> > > layer status and localize problems. The MDIO is not
> > designed to support
> > > multiple masters so it would be awkward to have the
> > management agent and the
> > > RS both poll the MDIO.
> > >
> > > Regards,
> > > Pat
> > >
> > > -----Original Message-----
> > > From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxx]
> > > Sent: Wednesday, December 19, 2001 11:12 PM
> > > To: HSSG (E-mail)
> > > Subject: Re: [802.3ae] Link Fault Signalling
> > >
> > > Gal,
> > >
> > > Sorry about the late reply. Sometimes my email gets way backed up.
> > >
> > > Status register bit 1.1.7 is defined as Local Fault. This
> bit is set
> > > when a local fault condition exists. The local fault
> > condition may have
> > > been signaled via LF/RF signaling but this is only one
> > possibility. The
> > > others include LF detection at the receiver not via LF/RF
> > signaling and
> > > LF detection inboard of the receiver.
> > >
> > > Happy Holidays,
> > > Rich
> > >
> > > --
> > >
> > > > -----Original Message-----
> > > > From: Ofek, Gal [mailto:gal.ofek@xxxxxxxxx]
> > > > Sent: Monday, December 10, 2001 9:48 AM
> > > > To: 'rtaborek@xxxxxxxxxxxxx'
> > > > Cc: HSSG (E-mail)
> > > > Subject: RE: [802.3ae] Link Fault Signalling
> > > >
> > > > Rich,
> > > >
> > > > Thanks but I would like one more clarification:
> > > > Is the following true:
> > > > it is not enough that the RS
> > > > will relay totally on the Local/Remote fault signaling to
> > report for
> > > > link fault. It should also poll the link status bit (bit 1.1.7)
> > > > in order to get a complete indication about the link status.
> > > >
> > > > Yes?
> > > >
> > > > Thanks
> > > > Gal
> > > >
> > > > -----Original Message-----
> > > > From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxx]
> > > > Sent: Sunday, December 09, 2001 11:18 PM
> > > > Cc: HSSG (E-mail)
> > > > Subject: Re: [802.3ae] Link Fault Signalling
> > > >
> > > > Gal,
> > > >
> > > > No. I was creating a distinction between the stages of a
> > link fault and
> > > > the reporting of the fault. Here's a more complete
> > distinction in the
> > > > life of a fault. and LF
> > > >
> > > > a) the existence of a link fault condition;
> > > > b) the recognition and of the link fault condition (note
> > that some link
> > > > fault conditions may not be detected and recognized,
> > preventing their
> > > > reporting by a local fault message);
> > > > c) the reporting of a recognized link fault condition via
> > a local fault
> > > > message (note that this requires a "fault message
> > reporting facility"
> > > > such as an 8B/10B PCS or equivalent);
> > > >
> > > > In most cases, a link fault condition is recognized at
> > the DTE through
> > > > either reception of a local fault message or detection of
> > a link fault
> > > > condition. An example of a link fault condition which may escape
> > > > detection and recognition by any link element including
> > the DTE's is a
> > > > receiver failure where crosstalk from the associated
> > transmitter covers
> > > > up failure condition at the receiver.
> > > >
> > > > I hope this explanation helps,
> > > > Best Regards,
> > > > Rich
> > > >
> > > > --
> > > >
> > > > "Ofek, Gal" wrote:
> > > > >
> > > > > Do you mean that a situation in which a link is down
> > (fault condition)
> > > > > but no local fault will be generated is allowed?
> > > > >
> > > > > Thanks
> > > > > Gal
> > > > >
> > > > > -----Original Message-----
> > > > > From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxx]
> > > > > Sent: Sunday, December 09, 2001 7:32 AM
> > > > > Cc: HSSG (E-mail)
> > > > > Subject: Re: [802.3ae] Link Fault Signalling
> > > > >
> > > > > Chuck,
> > > > >
> > > > > I'll address two issues here. One is yours, the other
> > is other is
> > > > > related to kicking off Fault Messages.
> > > > >
> > > > > 1) Unidirectional link behavior is not supported
> > because it does not fit
> > > > > the scope of Ethernet objectives. Specifically, a
> > full-duplex link
> > > > > cannot be reinitialized properly when a fault occurs if
> > no feedback
> > > > > mechanism is provided to insure that both link
> > directions participate in
> > > > > initialization. I understand your point about this mode
> > of operation
> > > > > being about the scope of 802.3ae (and 802.3 in
> > general). However, even
> > > > > protocols like SONET provide other mechanisms, such as
> > DCC channels to
> > > > > accomplish the same thing. The problem is that the DCC
> > channel is only
> > > > > the feedback mechanism and provides no help in
> > resolving the actual
> > > > > fault, which is likely to require manual intervention
> > upon fault if the
> > > > > link is properly designed.
> > > > >
> > > > > 10GE employs LF/RF protocol as a means of quickly
> > determining the
> > > > > operational state of a link. If the link is not
> operational, an
> > > > > alternate link should be switched in.
> > > > >
> > > > > 2) Local Fault Ordered Sets are only generated upon
> > detection of a link
> > > > > fault condition when a capability exists that can
> > generate Local Fault
> > > > > Ordered Sets. Some sublayers and link elements such as
> > PMDs, retimers
> > > > > and PMAs may have the capability of detecting link
> > fault conditions but
> > > > > not of generating Local Fault Ordered Sets. In this
> > case, no error may
> > > > > be reported at all or an error may be reported through
> > an alternate
> > > > > means. IEEE 802.3ae has no requirement to generate
> > local fault ordered
> > > > > sets upon detection of a link fault condition.
> > > > >
> > > > > Best Regards,
> > > > > Rich
> > > > >
> > > > > --
> > > > >
> > > > > Chuck Harrison wrote:
> > > > > >
> > > > > > Ben, all --
> > > > > >
> > > > > > Ben Brown wrote:
> > > > > > >
> > > > > > > > > [BC] Thanks for the replies. My understanding
> > now is as follows:
> > > > > > > > >
> > > > > > > > > 1. If a fault is detected on the receive path,
> > at the PMD or
> > > > > > > > > the PMA, Local Fault Ordered Sets (LFOS)
> > will be transmitted
> > > > > > > > > by the PCS to the RS. Consequently, the RS
> > will send Remote
> > > > > > > > > Fault Ordered Sets (RFOS) to the PCS.
> > > > > > >
> > > > > > > [BB] This is correct.
> > > > > >
> > > > > > Agree 100%, this is the standard behavior and *must*
> > be supported.
> > > > > >
> > > > > > However, I recommend that silicon manufacturers implementing
> > > > > > RS consider whether they also wish to support a non-standard
> > > > > > mode in which LF->RF reflection does *not*
> > automatically occur.
> > > > > > This would allow their products to work in
> application niches
> > > > > > using a *unidirectional* optical link. (The transmit
> > end always
> > > > > > sees a receive LF, but goes on talking anyway.)
> > > > > >
> > > > > > I recognize this is outside the scope of 802.3ae, but some
> > > > > > industry segments would value this capability.
> > > > > >
> > > > > > Cheers,
> > > > > > Chuck Harrison
> > > > > > Far Field Associates, LLC
> > > > > > member, SMPTE DC28.1 Steering Committee on Digital Cinema
> >
> > ---------------------------------------------------------
> > Richard Taborek Sr. Intel Corporation
> > XAUI Sherpa Intel Communications Group
> > 3101 Jay Street, Suite 110 Optical Strategic Marketing
> > Santa Clara, CA 95054 Santa Clara Design Center
> > 408-496-3423 JAY1-101
> > Cell: 408-832-3957 mailto:rich.taborek@xxxxxxxxx
> > Fax: 408-486-9783 http://www.intel.com
> >
>