What happened?
What happened? Given the conversations on the reflector, I was under the
impression that 10GbE was going to remain at +100PPM clock. I come into the
meeting a little late and someone that I do not recognize is making a
presentation that 10GbE needed to be a full SONET client interface in order
to support the OTN Digital Wrapper. The next thing I knew, a vote was being
taken on putting the clock at +20PPM. I did not see a liaison letter from
either ITU or T1X1 at the 802.3 Plenary in March, so I am not sure why
presentations from ITU or T1X1 were being presented.
This has me very concerned. In the first place, I did not see any reference
to what the standards from ITU and T1X1 require for NORMAL operation of a
full SONET/SDH client interface, included in the presentation that I saw.
In order to prevent synchronization alarms in the rest of the transmission
network, the SONET/SDH client is required to support loop timing or have a
direct link to the Stratum Clock source. The alternative operation, called
"Maintenance operation" allows for a +20PPM clock, which creates a sync
alarm which has to be manually disabled. This is the reason that the
telephony carriers force the Packet Over SONET vendor to support loop
timing and full Stratum clock synchronization link through. I know that
most of the people of the reflector do not understand this, which is one
reason that I believe that the vote to change the clock tolerance passed.
For those that do not have it, I have attached T1X1 416-1999. Please take a
look at Section 6. This is the T1X1 standard that is referenced as part of
the WIS (Clause 50). Note that in Clause 50, support and compliance with
Section 6 is specifically excluded.
I do not believe that there is any technical reason to put the clock at
+20PPM instead of +100PPM. I did not see any reason given in the comments
that were made on draft 3.0.
There is the argument that being forced to support +100PPM clock on the
regenerators will cost the service providers more. What I heard is that the
additional cost to the regenerators/transducers is less than 0.0001% of the
total cost. Most of the cost of a regenerator/transducer is in the optics,
which will not change. Changing the clock is in the electronics, which is
very in-expensive. Given that they will no longer be required to support
electrical level multiplexing, and the very EXPENSIVE SONET/SDH ADMs,
carriers will actually spend less to support 10GbE at +100PPM than
multiplexing it at +20PPM.
I do not believe that this issue is settled.
Thank you,
Roy Bynum
What happened? Given the conversations on the reflector, I was under the
impression that 10GbE was going to remain at +100PPM clock. I come into the
meeting a little late and someone that I do not recognize is making a
presentation that 10GbE needed to be a full SONET client interface in order
to support the OTN Digital Wrapper. The next thing I knew, a vote was being
taken on putting the clock at +20PPM. I did not see a liaison letter from
either ITU or T1X1 at the 802.3 Plenary in March, so I am not sure why
presentations from ITU or T1X1 were being presented.
This has me very concerned. In the first place, I did not see any reference
to what the standards from ITU and T1X1 require for NORMAL operation of a
full SONET/SDH client interface, included in the presentation that I saw.
In order to prevent synchronization alarms in the rest of the transmission
network, the SONET/SDH client is required to support loop timing or have a
direct link to the Stratum Clock source. The alternative operation, called
"Maintenance operation" allows for a +20PPM clock, which creates a sync
alarm which has to be manually disabled. This is the reason that the
telephony carriers force the Packet Over SONET vendor to support loop
timing and full Stratum clock synchronization link through. I know that
most of the people of the reflector do not understand this, which is one
reason that I believe that the vote to change the clock tolerance passed.
For those that have it, take a look at T1X1.416-1999. Please look at
Section 6. This is the T1X1 standard that is referenced as part of the WIS
(Clause 50). Note that in Clause 50, support and compliance with Section 6
is specifically excluded, which would also exclude the +20PPM clock under
"maintenance operation".
I do not believe that there is any technical reason to put the clock at
+20PPM instead of +100PPM. I did not see any reason given in the comments
that were made on draft 3.0.
There is the argument that being forced to support +100PPM clock on the
regenerators will cost the service providers more. What I heard is that the
additional cost to the regenerators/transducers is less than 0.0001% of the
total cost. Most of the cost of a regenerator/transducer is in the optics,
which will not change. Changing the clock is in the electronics, which is
very in-expensive. Given that they will no longer be required to support
electrical level multiplexing, and the very EXPENSIVE SONET/SDH ADMs,
carriers will actually spend less to support 10GbE at +100PPM than
multiplexing it at +20PPM.
I do not believe that this issue is settled.
Thank you,
Roy Bynum