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Re: Hari and train-up sequences

One of the advantages to providing an "auto-negotiation" type signalling
path is in signalling link faults.


At 11:25 PM 11/16/99 -0800, Rich Taborek wrote:
>Linda, Brad,
>I agree with Linda's direction to treat a 10 GbE link consisting of two Hari
>interfaces interconnected by a PMD medium based link as a single link and to
>define a link initialization protocol at the PCS layer. I don't see a
reason to
>separately initialize the individual Hari and PMD medium interfaces.
>Initialization sequences in Gigabit Ethernet, based on Fibre Channel, which 
>is in
>turn based on IBM's ESCON are very similar in nature and are essentially the 
>as that proposed by Linda in her last note (quoted below). This sequence is
>essentially implemented by the Auto-Negotiation protocol specified in 802.3z
>clause 37. For a trip down memory lane, take a look at the Link Startup 
>illustrated on page 9 of PCS proposal for Gigabit Ethernet:
>It may look complex, but one can't argue with the success of these 
>standards. I am
>very hesitant to endorse a much more complex standard (10 GbE) which does not
>provide the basic ability to reliably recover from common link errors.
>Separately, note that AN information exchange is actually data transported
>the Link Initialization "carrier" and should be considered on its own
merit. In
>the past, three classes of information have been transported using various
>Auto-Negotiation protocols:
>1) Link speed, protocol, and configuration determination which, if required, 
>be exchanged before link level protocols can execute;
>2) Link faults require the exchange of a least link protocols;
>3) General statistics, performance information, vendor IDs, etc. do not
>link protocols and can be exchanged via Ethernet packets.
>Careful though needs to be given as to the requirements for the exchange of
>traditional AN information.
>Best regards,
>Linda Cheng wrote
>> Hi Brad,
>> I'd like to see a link initialization defined at the PCS layer
>> between a local device and link partner.
>> It's something we need and something which doesn't have to
>> be complex.
>> A two-way handshake may look like 1) one end sends a stream of Link
>> messages indicating it is in the init state 2) the remote side must
>> respond with the Link message (some 10b codegroups chosen for this) and
>> after some time Link messages with acknowledges 3) when the local side
>> receives these it sends Link acknowledges for some time 4) when
>> either side receives Link acknowleges they are done and send Idles.
>> So the PMA would need to be ready before the Link message with
>> acknowleges are sent. By HARI I assume you mean PMA. HARI is the
>> interface between the PMA and PMD.
>> Linda
>> > From: "Booth, Bradley" <bradley.booth@xxxxxxxxx>
>> > To: stds-802-3-hssg@xxxxxxxx
>> > Subject: RE: Hari and train-up sequences
>> > Date: Tue, 16 Nov 1999 13:01:03 -0800
>> >
>> > I need some clarification here.  Are you proposing a link initialization 
>> > the Hari?  If so, are you also proposing a link initialization for the 
>> > device to link partner connection?  If you're proposing both, then are you
>> > proposing to have 3 stages of link initialization?  If so, I believe that
>> > this may add more complexity than we need to deal with.
>> >
>> > Cheers,
>> > Brad
>> ---------------------------------------------------------------
>> Linda Cheng                     Cisco Systems
>>                                 Desktop Switching Business Unit
>> (408) 527-2015 (phone)          170 West Tasman Drive
>> (408) 527-4698 (fax)            San Jose, CA 95134-1706
>> ---------------------------------------------------------------
>  ----------------------------------------------------------
>Richard Taborek Sr.   1441 Walnut Dr.   Campbell, CA 95008 USA
>Tel: 408-370-9233     Cell: 408-832-3957     Fax: 408-374-3645
>Email: rtaborek@xxxxxxxxxxxxx