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Re: Long distance links


Please be aware that there are currently Gigabit Ethernet products in the
market that can detect a link failure in several microseconds.  Of course
detection is different from "management resolution" such as the opening of
an alternative path.  However, this is at least three orders of magnitude
less than the telecom industry goal of 50 milliseconds.  Smart silicon and
software engineers should be able to do lots with that :-)

Brian MacLeod

-----Original Message-----
From: Rohit Mittal <mittal.rohit@xxxxxxxxxxx>
To: rtaborek@xxxxxxxxxxxxxxxx <rtaborek@xxxxxxxxxxxxxxxx>
Cc: HSSG <stds-802-3-hssg@xxxxxxxx>
Date: Monday, August 30, 1999 2:34 PM
Subject: Re: Long distance links

>Rich et al,
>One of the things you need to consider is that SONET has extensive error
>"built-in" the overhead to allow speedy detection of failures before they
>to serious levels. SONET provides rapid fault isolation.
>Now, if you use TCP/IP for the same tasks, you are going to add latency
>because the frame/data will have to pass through many layers before any
fault is
>detected. That is the problem in moving up the protocol stack.
>For instance, SONET allows less than 50ms time for signal restoration (due
to cut
>fiber etc.). I do not see anything in Ethernet which can provide equivalent
>- maybe Far end fault detector but doesn't that takes a long time to
>IMO, the best solution is just to encapsulate ethernet frames as data bits
in a
>SONET frame. That way SONET can provide the management features for
>expensive mantainence and Ethernet can travel as is. Am I overlooking
>Rohit Mittal
>Engineering, Microlinear Corp.
>> Mark,
>> I believe you're on the right track insofar as digging to the root of the
>> management issue. The fact of the matter is that Ethernet does it one
way, and
>> SONET does it another. My sense is the same as yours: "...instead of
>> transporting management info on dedicated
>> circuits, use TCP/IP and packets.  It's the histroric trend, moving up
>> protocol stack."
>> I have asked numerous questions over this reflector trying to get at the
core of
>> requirements for WAN management. I've seen no responses to those
questions. BTW,
>> I'm sill very much interested in hearing the responses to these
>> Without knowing the requirements for SONET WAN management, I have to
>> that Ethernet Management, ULP (e.g. Ping, SNMP, Browser) management
>> Etherenet PHY capabilities for determining things like the BER of each
>> represent sufficient architecture to implement WAN management equivalent
>> superior to that of SONET.
>> Best Regards,
>> Rich
>> --
>> "Gerhold, Mark" wrote:
>> > All,
>> >
>> > It sounds as if one of the biggest issues here is with the optical
>> > repeaters.  If I understand correctly, Sonet repeaters are instrumented
>> > that the administrator can isolate problems without sending out a
>> >
>> > Consider using a 2-port "LAN" switch instead of a repeater.  Switches
>> > provide lots of remote maintenance features, including
>> >
>> > o Ping (for I'm alive)
>> > o SNMP (for tons of performance statistics, and alarms)
>> > o Browser management (for ease of use)
>> >
>> > With a switch, instead of transporting management info on dedicated
>> > circuits, use TCP/IP and packets.  It's the histroric trend, moving up
>> > protocol stack.
>> >
>> > Here's a question on a similar vein.  Are WDM amplifiers instrumented
>> > isolate BER problems?  I thought they did optical amplification.
>> > BER info sounds tough.
>> >
>> > Thanks,(signing off)
>> >
>> > Mark Gerhold
>> > Unisys
>> >
>> >