Re: AW: [EFM] PON Optics Telephone Conference, December 5th
Could it be that continuos collisions with NO backoffs (forget controlled
random and maxLimits)
on a shared medium is what not an Ethernet (CSMA/CD). -:)
Thanks,
Sanjeev
At 11:01 AM 12/13/2002 -0800, Hugh Barrass wrote:
>Jonathan,
>
>I think the answer to your questions below would be "none of the above"
>(although OAM frames & EDSL do change things they are not really relevant
>to this discussion). Instead we could consider
>the adoption of a Multiple Access medium to be a new technology which does
>increase the jitter compared to the point-point media previously specified.
>
>Personally, I can't see how a shared medium could possibly be considered
>as part of the CSMA/CD working group...
>
>Hugh.
>
>(BTW that last paragraph was humorous)
>
>Jonathan Thatcher wrote:
>
> > Roy,
> >
> > What does "How 802.3ah will perform relative to the "jitter" issue has
> yet to be seen. It is most likely that the data stability that LAN
> people are used to will no longer be there" mean?
> >
> > Does extending the 5km to 10km impact jitter / data stability?
> > Does adding OAM frames impact jitter / data stability?
> > Does support of bidirectional rather than dual fiber transceivers
> impact jitter / data stability?
> > Does EDSL solution impact jitter / data stability?
> >
> > What, exactly, are you trying to say? That because of EFM, Ethernet is
> no longer Ethernet?
> >
> > jonathan
> >
> > | -----Original Message-----
> > | From: Roy Bynum [mailto:rabynum@xxxxxxxxxxxxxx]
> > | Sent: Friday, December 13, 2002 8:24 AM
> > | To: Mccammon, Kent G.; 'Richard Brand'
> > | Cc: Mccammon, Kent G.; stds-802-3-efm@ieee.org
> > | Subject: RE: AW: [EFM] PON Optics Telephone Conference, December 5th
> > |
> > |
> > |
> > | Kent,
> > |
> > | Until 802.3ah, Ethernet does not induce any jitter in the
> > | transmission of
> > | application data. I spent over a year in the lab looking at
> > | this. The
> > | 802.3 stack, up until now was a pure streaming environment
> > | without any
> > | store and forward queues.
> > |
> > | This may sound like a bit of heresy as I am the original host
> > | master for
> > | MCI. The worst culprit in inducing jitter in the transmission of
> > | application data in today's environment is Internet Protocol.
> > | This occurs
> > | across all vendor lines using IP stack code from multiple vendors. I
> > | believe that it is because the IP stack is fairly "deep" and
> > | there are
> > | several locations in the stack where some form of "store and
> > | forward" is
> > | required. (Even forward looking code does not solve this problem.)
> > |
> > | You can have your lab people verify this. Testing applications in
> > | non-routing environments will change the level of jitter that
> > | introduced in
> > | the communications infrastructure. This effect of streaming
> > | switching was
> > | one of the main reasons that the "legacy free service
> > | providers" were able
> > | to deliver packet voice that had better clarity and sound
> > | quality than the
> > | local RBOC. Testing using a non-routing stack such as
> > | NetBEUI will change
> > | the amount of jitter that is introduced at the end systems
> > | supporting the
> > | applications. Interactive video becomes very "tight" in a
> > | non-IP environment.
> > |
> > | How 802.3ah will perform relative to the "jitter" issue has yet to be
> > | seen. It is most likely that the data stability that LAN
> > | people are used
> > | to will no longer be there.
> > |
> > | Thank you,
> > | Roy Bynum
> > |
> > |
> > |
> > | At 09:30 PM 12/8/2002 -0800, Mccammon, Kent G. wrote:
> > |
> > |
> > | >Richard,
> > | >Controlling jitter over an Ethernet network is a project
> > | that we support in
> > | >other forums than 802.3ah. My comment and question was
> > | attempting to
> > | >gather more information in the debate over common PMD timing
> > | specifications.
> > | >If the Options A-D in the debate of PON timing have
> > | different possible
> > | >services enabled, I think that is a fair question to ask on
> > | this exploder.
> > | >I don't support multiple Gigabit PON timing specifications
> > | each one for a
> > | >only subset of potential service applications.
> > | >Thanks,
> > | >-Kent
> > | >
> > | > > -----Original Message-----
> > | > > From: Richard Brand [mailto:rbrand@xxxxxxxxxxxxxxxxxx]
> > | > > Sent: Friday, December 06, 2002 12:34 PM
> > | > > To: Roy Bynum
> > | > > Cc: kmccammon@tri.sbc.com; stds-802-3-efm@ieee.org
> > | > > Subject: Re: AW: [EFM] PON Optics Telephone Conference,
> > | December 5th
> > | > >
> > | > >
> > | > > Roy:
> > | > > So here we go. I agree with everything you state except that
> > | > > Kent did not ask about "Leased Circuit Private Line services
> > | > > " or "Ethernet Private Line" but about T1 services over a
> > | > > draft 802.3 P2MP network. In addition Ethernet private line
> > | > > or leased line services are just as much out of scope for
> > | > > 802.3 as is TDM based T1 services. That's why we have taken
> > | > > on that work in the MEF with a close liaison to the ITU work
> > | > > to which you make reference. That also gets into
> > | > > encapsulation, but that is surely out of scope for .3.
> > | > > Therefore, I am correct in saying that your message did not
> > | > > answer his question. I do believe Arial's note makes an
> > | > > attempt to address the efficiency question, but I
> > | > > believe that the potential for added jitter is real. It is
> > | > > however, out of scope
> > | > > for .3. Kent, any comments?
> > | > > Regards,
> > | > > Richard
> > | > >
> > | > >
> > | > > Roy Bynum wrote:
> > | > >
> > | > > > Richard,
> > | > > >
> > | > > > You are incorrect. 802.3 in and of itself can NOT be used
> > | > > to provide
> > | > > > Leased Circuit Private Line services. I am the author of
> > | > > the term and
> > | > > > definition of "Ethernet Private Line" services. Ethernet
> > | > > Private Line
> > | > > > is based on SONET/SDH, not 802.3
> > | > > >
> > | > > > ITU standards for leased circuit private line services
> > | specifically
> > | > > > states that the customer of the leased circuit has
> > | exclusive use of
> > | > > > the circuit facility. This is in contrast to "packet"
> > | > > services that do
> > | > > > emulation via a "virtual" circuit. Since 802.3ah PON does
> > | > > not provides
> > | > > > virtual circuit emulation via the frame "header", called a
> > | > > "preamble"
> > | > > > by 802.3 and not any type of physical or time based facilities
> > | > > > segregation, it falls under the category of a
> > | > > "packet/frame" service
> > | > > > technology, not a leased circuit service technology.
> > | > > >
> > | > > > The existing ITU standards already provides for
> > | permanent virtual
> > | > > > circuit emulation at fixed bandwidths over packet/cell
> > | > > based services.
> > | > > > These can be at T1 or any other fixed bandwidth. The
> > | ITU standards
> > | > > > makes a specific distinction between the "leased circuit"
> > | > > services and
> > | > > > the emulated circuit services over packet/cell/frame transport
> > | > > > protocols.
> > | > > >
> > | > > > I didn't write the ITU standards. I just spent the last
> > | year that I
> > | > > > was at Worldcom researching the specifics of defined
> > | standards for
> > | > > > different types of data communications services.
> > | > > >
> > | > > > 802.3 in and of itself does not provide leased circuit
> > | private line
> > | > > > services. The fact that a single customer using 802.3 can be
> > | > > > provisioned as the only customer on a "dark" fiber,
> > | makes the dark
> > | > > > fiber, a leased circuit private line service, not the
> > | 802.3. This
> > | > > > format would also hold for 802.3ah copper facilities that
> > | > > are used by
> > | > > > a single customer.
> > | > > >
> > | > > > The service "Ethernet Private Line" is not based on an
> > | > > 802.3 standard,
> > | > > > other than it provides a "mapping" for Ethernet frames. The
> > | > > ITU x.86
> > | > > > "Ethernet over LAPS" provides for "mapping" of Ethernet
> > | frames into
> > | > > > SONET/SDH by replacing the IFG/Preamble with LAPS, a HDLC
> > | > > derivative
> > | > > > and then using TDM nature of SONET/SDH to provision the
> > | > > service as a
> > | > > > standard leased circuit facility. This would also hold
> > | for g.GFP.
> > | > > >
> > | > > > Thank you,
> > | > > > Roy Bynum
> > | > > >
> > | > > > At 02:40 PM 12/5/2002 -0800, Richard Brand wrote:
> > | > > > >Thomas:
> > | > > > >I would offer that Roy's note does not answer question 1
> > | > > and I have
> > | > > > >sent a note to Roy to detail. As Kent is aware, there is
> > | > > an ongoing
> > | > > > >project in the MEF right now to specify circuit
> > | services (read TDM
> > | > > > >including T1) over Ethernet including 802.3 networks.
> > | > > > >The timing issue could be critical to some implementations
> > | > > and is one of the
> > | > > > >reasons I voted "no" in Kauai. Vipal, do you want to
> > | take it on?
> > | > > > >Regards,
> > | > > > >Richard Brand
> > | > > > >
> > | > > > >
> > | > > > >
> > | > > > >Thomas.Murphy@xxxxxxxxxxxx wrote:
> > | > > > >
> > | > > > > > Hi Kent,
> > | > > > > >
> > | > > > > > Thanks for your input on this topic. I believe that
> > | question 1)
> > | > > > > > has already been addressed by Roy Bynum; there are
> > | > > others who are
> > | > > > > > in a better position to answer this than me.
> > | > > > > >
> > | > > > > > Regarding testing I see two different levels/types
> > | of testing.
> > | > > > > > Firstly there is module testing where different
> > | response times
> > | > > > > > will not present a problem (the response time is
> > | > > probably one of
> > | > > > > > the parameters that would be determined). Beyond
> > | this there is
> > | > > > > > then system/interoperability testing. When testing with
> > | > > > > 'non-intelligent'
> > | > > > > > equipment, the guardband between bursts would be set to the
> > | > > > > > Upper-Bound values agreed upon. By guardband I mean the
> > | > > time delay
> > | > > > > > between the Tx_On signal and the time when the Rx
> > | > > starts examining
> > | > > > > > bit to determine the BER. With an intelligent system, i.e.
> > | > > > > > protocol implementation with negotiated parameters,
> > | > > > > > interoperability is not a problem as the optimal
> > | > > guardband is calculated.
> > | > > > > >
> > | > > > > > The above tests determine if one Tx communicates
> > | optically with
> > | > > > > > the
> > | > > > > expected
> > | > > > > > BER
> > | > > > > > with another Rx. Setting the guardband equal to the
> > | upper limit
> > | > > > > > determines that the timing requirements of the combined
> > | > > link are
> > | > > > > > met. Direct module testing delivers the individual Rx and Tx
> > | > > > > > times. Hence, I don't see a problem with testing
> > | > > depending on the
> > | > > > > > option choice for the timing parameters.
> > | > > > > >
> > | > > > > > Regards
> > | > > > > >
> > | > > > > > Tom
> > | > > > > >
> > | > > > > > -----Ursprüngliche Nachricht-----
> > | > > > > > Von: Mccammon, Kent G. [mailto:kmccammon@xxxxxxxxxxx]
> > | > > Gesendet am:
> > | > > > > > Donnerstag, 5. Dezember 2002 02:45
> > | > > > > > An: Murphy Thomas (COM FO D O); stds-802-3-efm@ieee.org;
> > | > > > > > Vipul_Bhatt@xxxxxxxx; wdiab@xxxxxxxxx
> > | > > > > > Betreff: RE: [EFM] PON Optics Telephone Conference,
> > | December 5th
> > | > > > > >
> > | > > > > > Tom,
> > | > > > > > Since I have a conflict with the call tomorrow and I am
> > | > > interested
> > | > > > > > in this decision, here are some questions.
> > | > > > > >
> > | > > > > > 1)Do any of the options for PON timing impact the
> > | delivery of
> > | > > > > > services such as toll quality voice, a T1, or multicast
> > | > > video? We
> > | > > > > > had this concern previously and the answer previously
> > | > > was claimed
> > | > > > > > to be only an efficiency hit for loose timing. Are
> > | the modeling
> > | > > > > > assumptions to compare efficiency valid for TDM
> > | services or is
> > | > > > > > that not a consideration in this debate to date? 2)The
> > | > > negotiation
> > | > > > > > of timing parameters rather than a tight
> > | specification have any
> > | > > > > > impact on future interoperability testing? If we ever
> > | > > decide to
> > | > > > > > test interoperability of EPON OLT and ONT, can a lab testing
> > | > > > > > system be reasonably built to test compliance to a
> > | > > specification
> > | > > > > > for OLT/ONT timing for the various options under
> > | debate? 3)Do
> > | > > > > > operating temperature swings have an impact on timing
> > | > > options. Is
> > | > > > > their
> > | > > > > > reason to add extra margin or extra negotiation
> > | time of timing
> > | > > > > > parameters due to temperature variations? What about
> > | > > cold start in
> > | > > > > > cold temperatures, that was an issue for power
> > | levels, does it
> > | > > > > > also impact the electronics of the PMD?
> > | > > > > >
> > | > > > > > Comment: As an advocate of PON technologies I echo
> > | my earlier
> > | > > > > > comments
> > | > > > > about
> > | > > > > > striving for common PON PMD to get the volume
> > | started in today's
> > | > > > > economy. I
> > | > > > > > am optimistic a compromise can be found in January. Thanks,
> > | > > > > > -Kent
> > | > > > > >
> > | > > > > > > -----Original Message-----
> > | > > > > > > From: Thomas.Murphy@xxxxxxxxxxxx
> > | > > > > > > [mailto:Thomas.Murphy@xxxxxxxxxxxx]
> > | > > > > > > Sent: Wednesday, December 04, 2002 10:12 AM
> > | > > > > > > To: stds-802-3-efm@ieee.org; Vipul_Bhatt@ieee.org;
> > | > > wdiab@xxxxxxxxx
> > | > > > > > > Subject: [EFM] PON Optics Telephone Conference,
> > | December 5th
> > | > > > > > >
> > | > > > > > >
> > | > > > > > > Hello Again,
> > | > > > > > >
> > | > > > > > > Attacted two possible approaches to this discussion
> > | > > forming two
> > | > > > > > > decision trees. Glen and I worked on these I I
> > | did not have a
> > | > > > > > > chance to co-ordinate with him and refine to one
> > | slide. The
> > | > > > > > > first slide is mine and I would like to start here as
> > | > > it allows
> > | > > > > > > us to generate values without having to make
> > | > > decisions. When the
> > | > > > > > > values are agreed upon, we can work towards the
> > | decision and
> > | > > > > > > perhaps this is simpler with the values we have.
> > | > > > > > >
> > | > > > > > > If this does not work, we can try the seconf slide, Glen's
> > | > > > > > > approach, which is a more top-down attack.
> > | > > > > > >
> > | > > > > > > Talk to you tomorrow
> > | > > > > > >
> > | > > > > > > Tom
> > | > > > > > >
> > | > > > > > > <<PON Timing Decision Tree.ppt>>
> > | > > > > > >
> > | > > > > > > Hello All,
> > | > > > > > >
> > | > > > > > > Items to Be Covered
> > | > > > > > >
> > | > > > > > > 1) Determine the exact meaning of the terms "Fixed
> > | > > Value" and
> > | > > > > > > 'Upper Bound" in terms
> > | > > > > > > of their use for PMD timing parameters.
> > | > > > > > >
> > | > > > > > > 2) Try assign placeholder values for all of the options
> > | > > > > > >
> > | > > > > > > 3) Are these values fixed or bounded for the
> > | > > different options.
> > | > > > > > >
> > | > > > > > > 4) Other items
> > | > > > > > >
> > | > > > > > > Regards
> > | > > > > > >
> > | > > > > > > Tom
> > | > > > > > >
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