Re: 3PMD Proposal
Bernd,
The patchcord is used on bad 62.5 micron MMF to guarantee 500-MHz-km minimum
bandwidth. I am not surprised that you could find a piece of MMF that could
support a 500-m link at 10-Gb/s at 1300nm, but such fiber is quite rare.
With a 500 MHz-km bandwidth, it is hard to see a 10-Gb/s link going farther
than about 75 m. Unless you can provide a patchcord solution that will
guarantee > 2500 MHz-km on worst-case 62.5 micron multimode fiber, your
1300-nm serial approach is doomed to failure. On the other hand, if you do
have some clever new mode-conditioning scheme to accomplish this, we would
all like the details as soon as possible!
Best Regards,
Brian Lemoff
Agilent Technologies
> -----Original Message-----
> From: Bernd.Prediger@xxxxxxxxxxxx [mailto:Bernd.Prediger@xxxxxxxxxxxx]
> Sent: Thursday, June 15, 2000 3:31 AM
> To: david_cunningham@xxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> Subject: AW: 3PMD Proposal
>
>
>
> David,
> "min. overfilled launch" as in the Ottawa presentation from
> Del may imply the use of a patch cord. At least myself (and
> maybe others) missed it.
> Anyway, a patch cord is a solution that guarentees greater
> distance over old fiber and that's good.
> For our 5 distance objectives this could mean that a serial
> 1300nm solution fulfills them all probably long term at lower
> cost then a CWDM just by adding a patch cord were necessary.
> In this matter I agree with Ed Cornejo that most (90%+) of
> the LX GBE applications today work without patch cord. We
> tested serial 10 Gig on random fiber over 500m without any problem!
>
> Best wishes
>
> Bernd
>
> -----Ursprüngliche Nachricht-----
> Von: david_cunningham@xxxxxxxxxxx
> [mailto:david_cunningham@xxxxxxxxxxx]
> Gesendet am: Dienstag, 13. Juni 2000 23:45
> An: stds-802-3-hssg@xxxxxxxx
> Betreff: FW: 3PMD Proposal
>
>
>
> -----Original Message-----
> From: CUNNINGHAM,DAVID (A-SanJose,ex1)
> Sent: Tuesday, June 13, 2000 10:27 AM
> To: 'Larry Miller'
> Cc: 'Stds-802-3-Hssg@xxxxxxxx'
> Subject: RE: 3PMD Proposal
>
>
> Larry,
> as far as I know it has always been stated that the
> offset launch
> patchcord was part of the WWDM proposal, so there should be
> no surprises
> there.
>
> Regarding: "The offset patchcord has been terribly unpopular with us"
>
> For 1 Gigabit Ethernet this may be your and your companies position.
> However, it must be remembered that from a technical point of view
> 1000BASE-LX with the offset launch patchcord is the ONLY way
> to robustly (in
> a worst case sense) go beyond 300 m on installed 160/500 and 200/500
> multimode fiber (not the new multimode fiber types with RML
> specifications).
> It is true that 1000BASE-SX links typically go further than
> 300 m - but this
> is by no means guaranteed.
>
> Regarding: "adding so much cost that it nearly doubles the
> cost of 1 Gb MM
> LX links."
>
> If customers want to use installed links with lengths of up
> to at least 550m
> whilst avoiding the much larger cost of installing new
> multimode fiber -
> then the offset launch patchcord makes very good economic
> sense. I know
> that some equipment suppliers suggest their customers use
> 1000BASE-LX with
> the patchcords for such cases.
>
> Regarding: "Is the Agilent 4X WWDM going to work with SMF? I
> will be wanting
> to know that...."
>
> The WWDM proposal to the IEEE 802.3ae is for a PMD that is capable of
> operating on either SMF or MMF - just like 1000BASE-LX does.
> That it is will
> be mandatory that is the WWDM PMD is dual use for SMF and MMF.
>
> Best wishes,
> David.
>
> -----Original Message-----
> From: Larry Miller [ mailto:ldmiller@xxxxxxxxxxxxxxxxxx
> <mailto:ldmiller@xxxxxxxxxxxxxxxxxx> ]
> Sent: Tuesday, June 13, 2000 6:59 AM
> To: david_cunningham@xxxxxxxxxxx
> <mailto:david_cunningham@xxxxxxxxxxx> ;
> Bernd.Prediger@xxxxxxxxxxxx; piers_dawe@xxxxxxxxxxx
> Cc: Stds-802-3-Hssg@xxxxxxxx <mailto:Stds-802-3-Hssg@xxxxxxxx>
> Subject: RE: 3PMD Proposal
>
>
>
> Arghhhh!!! Are we really back to that, David? The offset
> patchcord has been
> terribly unpopular with us, adding so much cost that it
> nearly doubles the
> cost of 1 Gb MM LX links.
>
> Is the Agilent 4X WWDM going to work with SMF? I will be
> wanting to know
> that.....
>
> Larry Miller
>
> -----Original Message-----
> From: david_cunningham@xxxxxxxxxxx
> [SMTP:david_cunningham@xxxxxxxxxxx]
> Sent: Monday, June 12, 2000 9:04 PM
> To: Bernd.Prediger@xxxxxxxxxxxx; piers_dawe@xxxxxxxxxxx
> Cc: Stds-802-3-Hssg@xxxxxxxx
> Subject: RE: 3PMD Proposal
>
>
> Bernd,
> the offset launch patchcord is assumed for the 1300 nm
> WWDM case for
> 10 Gigabit Ethernet. As was documented in IEEE 802.3z
> 1000BASE-LX the
> offset launch patchcord ensures a worst-case minimum bandwidth of 500
> MHz.km. For 1300 nm links the inclusion of the offset launch
> patchcord
> obsoleted the 385 Mhz.km modal bandwidth value that was
> present in some
> older drafts of the 1000BASE-LX clause.
>
> In conclusion, since the offset launch patchcord is
> part of the 1300
> nm WWDM
> proposal 500 MHz.km is the correct modal bandwidth to use for
> the multimode
> links.
>
> Best wishes,
>
> David.
>
> -----Original Message-----
> From: Bernd.Prediger@xxxxxxxxxxxx [ mailto:Bernd.Prediger@xxxxxxxxxxxx
> <mailto:Bernd.Prediger@xxxxxxxxxxxx> ]
> Sent: Wednesday, June 07, 2000 9:49 AM
> To: piers_dawe@xxxxxxxxxxx
> Cc: Stds-802-3-Hssg@xxxxxxxx
> Subject: 3PMD Proposal
>
>
>
> Hello Piers,
> I just got through Del's presentation from Ottawa again and
> stumpled over
> your calculation for the "Minimum Range" of CWDM over
> installed MM-Fiber
> (Slide 4).
> You calculated 2-300m for all 500MHz*km fiber but I
> understood that since
> Gigabit Ethernet the worst case effective bandwidth everbody
> agreed on is
> 375MHz*km. Our calculation with the latter value let to about 180m.
> What am I missing here? (Of course we used your spreadsheet!)
> Best wishes
> Bernd
>