Re: [802.3ae] Link Fault Signalling
Thank you Pat...
"THALER,PAT (A-Roseville,ex1)" wrote:
>
> Burt,
>
> To continue on where Ben left off, the PMD and PMA don't have the capability
> to generate LF, but they also don't have the capability to generate a data
> stream that will achieve sync at the other end when they are not receiving a
> good transmit data stream from their PCS. So, if the PMA or PMD detect a
> fault on a path, they won't send out a valid stream on that path. The PCS
> that receives what they send will detect a fault and it will send LF to the
> RS. Any fault between RS sublayers should result in LF being sent to the RS
> that is on the receiving end of the path with the fault.
>
> Pat
>
> -----Original Message-----
> From: Ben Brown [mailto:bbrown@xxxxxxxx]
> Sent: Friday, December 07, 2001 8:30 AM
> To: Burt Christian
> Cc: HSSG (E-mail)
> Subject: Re: [802.3ae] Link Fault Signalling
>
> Burt,
>
> You're getting closer.
>
> Burt Christian wrote:
> >
> > > 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.
>
> This is correct.
>
> > >
> > > 2. If a fault is detected on the transmit path at any sublayer
> > > including MAC, RS, PCS, PMA or PMD on the transmit path,
> > > LFOS will be generated and transmitted by the PCS to the PMA.
> > > (Although if a fault is detected on the transmit path at PCS,
> > > PMA or PMD, it cannot be guaranteed that the LFOS would be
> > > generated by the PCS and if they are, whether they will get
> > > through the PMA or PMD.)
>
> The standard does not dictate what happens with faults in the MAC
> and RS. However, faults below the RS result in LFOS being generated
> across the link where they are received by the link partner and sent
> to the RS. Some devices in this path cannot generate LF (such as
> the PMA and PMD) and must result in sending bad/no data/light.
>
> Regards,
> Ben Brown
>
> > >
> > > Thanks.
> > >
> > > Burt S, Christian.
> > > Ceyba Inc.,
> > > Systems Specialist
> > > Tel : (613)599-5797
> > > Fax : (613)599-1247
> > > burt@xxxxxxxxx www.ceyba.com
> > >
> > >
> > > > -----Original Message-----
> > > > From: Grow, Bob [mailto:bob.grow@xxxxxxxxx]
> > > > Sent: Wednesday, December 05, 2001 7:51 PM
> > > > To: Burt Christian; HSSG (E-mail)
> > > > Subject: RE: [802.3ae] Link Fault Signalling
> > > >
> > > >
> > > > The RS only forces the transmit path to Remote Fault or Idle.
> > > > It never
> > > > generates Local Fault. The PCS only forces the data path to
> > > > Local Fault
> > > > (whether toward the RS or toward the fiber). At a RS receive
> > > > (i.e., the
> > > > link fault state machine), reception of Local Fault causes
> > > > the transmit path
> > > > RS to force Remote Fault; and reception of Remote Fault
> > > > causes the transmit
> > > > path RS to force Idle.
> > > >
> > > > --Bob Grow
> > > >
> > > > -----Original Message-----
> > > > From: Burt Christian [mailto:burt@xxxxxxxxx]
> > > > Sent: Tuesday, December 04, 2001 7:07 PM
> > > > To: HSSG (E-mail)
> > > > Subject: [802.3ae] Link Fault Signalling
> > > >
> > > >
> > > >
> > > > Hi,
> > > >
> > > > I wanted to ensure that my understanding of the RS Link Fault
> > > > Signalling mechanism is correct. I am trying to understand the
> > > > mechanism rather than the details of the protocol. If someone
> > > > can please confirm the following description to be correct, I
> > > > would appreciate it.
> > > >
> > > > 1. If a fault on either the transmit path or the receive path
> > > > of PMD or PMA is detected then regardless of the quality of
> > > > the signal received by the PCS on the receive path, Local
> > > > Fault Ordered Sets will be transmitted by the PCS to the RS.
> > > >
> > > > 2. Once the RS Link Fault Signalling State Machine (Figure 46-9)
> > > > has entered the FAULT state with link_fault == Local Fault, RS
> > > > will start transmiting Remote Fault Ordered Sets on the transmit
> > > > path.
> > > >
> > > > One thing I would like to confirm is that the Local Fault Ordered
> > > > Set will never be transmitted by the RS on the link where the link
> > > > is defined as the communication channel between two RS peers. This
> > > > is quite clear based on the very last section of 46.3.4.3 but I
> > > > would like to ensure that I am not missing anything.
> > > >
> > > > Thank you.
> > > >
> > > > Burt S, Christian.
> > > > Ceyba Inc.,
> > > > Systems Specialist
> > > > Tel : (613)599-5797
> > > > Fax : (613)599-1247
> > > > burt@xxxxxxxxx www.ceyba.com
> > > >
> > >
>
> --
> -----------------------------------------
> Benjamin Brown
> AMCC
> 2 Commerce Park West
> Suite 104
> Bedford NH 03110
> 603-641-9837 - Work
> 603-491-0296 - Cell
> 603-626-7455 - Fax
> 603-798-4115 - Home Office
> bbrown@xxxxxxxx
> -----------------------------------------
--
-----------------------------------------
Benjamin Brown
AMCC
2 Commerce Park West
Suite 104
Bedford NH 03110
603-641-9837 - Work
603-491-0296 - Cell
603-626-7455 - Fax
603-798-4115 - Home Office
bbrown@xxxxxxxx
-----------------------------------------