RE: Distance Objectives: 2nd motion
- To: "Thirion, Walt" <wthirion@xxxxxxxxxx>, stds-802-3-hssg-distance@xxxxxxxx
- Subject: RE: Distance Objectives: 2nd motion
- From: "Chang, Edward S" <Edward.Chang@xxxxxxxxxx>
- Date: Tue, 29 Jun 1999 10:49:56 -0400
- Sender: owner-stds-802-3-hssg-distance@xxxxxxxxxxxxxxxxxx
Thanks for clarification.
However, I do not mean the final data rate, the serial data rate, of which
you are describing.
I mean, there are two basic data rates, one is the serial data rate of 10
Gbps, the another one is the parallel data rate of 2.5 Gbps which will be
multiplexed into the serial data rate of 10 Gbps eventually.
Both approaches need fiber to transmit data, and are quite different in
speed, so the cable length.
My question is whether the cable lengths we are specifying are based on 2.5
Gbps or 10 Gbps?
Another approach is specify the cable length first, then see what will fit
I am still not quite clear yet. I believe we are defining the length based
on 2.5 Gbps data rate, yet we are also trying to include 10 Gbps data rate
in 100 meter length.
Although, one way or the other, it does not bother me; however, I like to
know clearly to be able to determined length more accurately.
From: Thirion, Walt [mailto:wthirion@xxxxxxxxxx]
Sent: Monday, June 28, 1999 11:16 AM
Subject: RE: Distance Objectives: 2nd motion
The Speed ad hoc has pretty much narrowed it down to either 10.00 Gb/s
or 9.58 Gb/s with a slight bias towards exactly 10.
We have had some discussion about leaving it open for other speeds, but
there has been very little discussion beyond that.
Level One Communications
> -----Original Message-----
> From: owner-stds-802-3-hssg-distance@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-3-hssg-distance@xxxxxxxxxxxxxxxxxx]On Behalf Of
> Chang, Edward S
> Sent: Monday, June 28, 1999 6:34 AM
> To: Jonathan Thatcher; stds-802-3-hssg-distance@xxxxxxxx
> Subject: RE: Distance Objectives: 2nd motion
> So far we are proposing distance numbers which are basically
> numbers we can pin down eventually.
> The question is we have two speeds on the table; namely, 10
> Gbps and 2.5
> Gbps. What speeds we have in mind for those distance
> proposals? Since
> two speeds are 1 to 4 ratio , a big difference, logically we
> should have two
> groups of distance proposal, one for 2.5 Gbps and another for 10 Gbps.
> Otherwise, it seems our strategy is to pick distance first, then fit
> whatever technologies?
> Ed Chang
> -----Original Message-----
> From: Jonathan Thatcher [mailto:jonathan@xxxxxxxxxxxxx]
> Sent: Friday, June 25, 1999 7:38 PM
> To: stds-802-3-hssg-distance@xxxxxxxx
> Subject: Distance Objectives: 2nd motion
> Assuming general agreement on my first proposed motion (or
> maybe even if
> not): there are several, potential interesting distances that
> are candidates
> (there may be more, but this seems to be an adequate list to
> start with):
> 1. 100 meters over MMF (850 and 1300)
> 2. 300 meters over MMF (850? and 1300?)
> 3. 500 (550) meters over MMF (850? and 1300?)
> 4. 3 km over SMF (1300)
> 5. 5 km over SMF (1300)
> 6. 10 km over SMF (1300)
> 7. 20-40 km over SMF (1300)
> 8. 80-120 km over SMF (1500)
> To sort through these, I think we need to consider some of
> the "traditional"
> assumptions/arguments/positions that were used in Gigabit
> Ethernet when
> making decisions about fiber, wavelength, and distance:
> a. We should support the existing infrastructure (meaning the
> existing cable
> b. We should minimize the number of PHY choices
> c. We should minimize the cost of implementation
> There is a corollary to "a." (called a' = "a prime") which
> is: we should try
> to go as far as we went at slower speeds over the same media.
> Let me start with 4, 5, and 6. Since we currently specify 5 km in the
> 1000BASE-LX standard, according to "a.", we should support at
> least 5 km.
> Using this assumption, we would eliminate 4. To the best of
> my knowledge,
> all the LX solutions in existence support 10 km (these parts
> typically meet
> the Fibre Channel 10 km solution while running at the GbE speed),
> effectively making "a" a 10 km requirement
> Debatable issue 1 is therefore: support the LX distance as
> specified or as
> commonly implementable in the industry (5 or 6).
> Questions about 7 are most interesting if the group picks 6
> over 5 but could
> be independent, I will assume the former. We are all aware
> that solutions to
> the 10 km LX actually run at much greater distances because of the
> conservatism of the standard. We therefore see practical
> applications that
> achieve 20 to 40 km. These are not guaranteed to be interoperable.
> Debatable issue 1a is therefore (assuming issue 1 selects 6
> over 5): support
> the LX distance as commonly implementable or as available in
> the industry (6
> or 7).
> Questions about 8 are similar to those of 7 when taken
> independently. Most
> arguments supporting 7 would also apply to 8. The major
> rationale for doing
> either would be to take what are now proprietary solutions
> and make them
> interoperable. If members believe that the market for these
> solutions will
> be significant for 10 gig, then there will be interest in making these
> solutions interoperable (standards based). If not, this will
> continue to be
> a custom space.
> Debatable issue 2 is therefore: How interesting is this
> potential market
> space. Is it sufficient to create a standard?
> 1, 2, and 3 are significantly more difficult. Especially
> since we do not yet
> know if we can support assumption "a." without significantly
> impacting "c."
> (I can barely imagine the flurry of opinions on this topic).
> We also don't
> know where the majority opinion will go with respect to
> specifying new fiber
> types (e.g. high bandwidth MMF). In short, it might not be possible to
> satisfy both "a" and "c" simultaneously to the convincing of
> 75% of the
> Debatable issue 3 is therefore: what gives first "a" or "c"?
> There is more that can be said here, but I have a more
> important idea I
> would like to convey.
> I would recommend the following: first, conclude the 1st
> general motion on
> space per my previous append. The second section on that
> motion will help to
> the members to resolve what they are going to do about about
> the debatable
> issues here. The third portion of that motion does not impact this
> discussion, since connection to the WAN can be accomplished with any
> distance solution.
> Next, bring forward a main motion that is easily passable and
> covers the
> least controversial components of 1 through 8. I recommend a
> selection of 4,
> 5, or 6. (assuming you think that only one of the three will
> be kept (see
> "b")). Each can be placed in the motion text with the intent
> to select only
> one. Votes can be taken from least to most likely to succeed
> to see where
> the 75% vote can be achieved.
> Note: This technique is frequently used in discussions of
> allocation of
> money: "We move to collect from the membership ($0, $100,
> $1000, $50,000,
> $1,000,000) to be given to the HSSG chair to use at his
> discretion." You
> vote starting with the $1,000,000 and continue down the list
> till you reach
> 75% consensus, then stop. This is simpler and faster than
> picking a single
> number and having it amended to death. The 0$ is, of course,
> silly here
> because if something higher than or equal to $100 is not
> passed, the motion
> failed anyway.
> Then make a motion(s) to add a line(s) to the previous
> objective (now a
> passed motion) that includes something about 1 through 3. Given the
> diversity of the group, a more general motion has a greater chance of
> success than a more restrictive motion. An overly general
> motion ("do the
> best you can on MMF") has no chance. The same technique could
> be used as
> above (support a distance of at least (100, 300, 550) meters
> over multimode
> fiber). I am assuming here that the group will want to have some MMF
> solution (see "a") and will therefore pass at least 100
> meters. Note that
> this motion would set the lower bound!
> Make a motion to add to the previous objective a direction to
> or not investigate the use of higher BW MMF.
> Make a motion to add to the previous objective support of a 1550 nm
> Make a motion to add to the previous objective support of a
> longer distance
> 1300 nm solution.
> Explain the process and content of each motion to the group prior to
> starting. This way the membership will understand when the
> appropriate time
> is to discuss/amend the motion (i.e. per the above process,
> the chair would
> consider out of order any amendment and/or discussion during
> the initial
> motion on LW, SMF, that relates to MMF as this would be covered in a
> subsequent motion). The only problem is, I think, that
> someone might think
> that at this point of the process the HSSG should investigate
> more potential
> solutions than should be supported in the end. If so, then add another
> motion that adds a line to the objective to limit the number
> of solutions to
> N in the final standard.
> I am suggesting this process because I believe that we must
> exit the process
> with an objective on distance, which is the mission of this
> ad-hoc. I am
> optimistic that this or a similar procedure would accomplish
> that goal.
> There are alternatives to this which would be simpler and quicker (for
> instance, a single motion that contains the correct wording
> to allow it to
> pass with 75% vote). The problem is, if that vote fails, we
> got nuthin' and
> that ain't acceptable.