Are people still building SONET networks from scratch?
mansaxel at besserwisser.org
Sat Sep 8 23:45:39 CDT 2012
Subject: Re: Are people still building SONET networks from scratch? Date: Fri, Sep 07, 2012 at 10:50:31PM +1000 Quoting Julien Goodwin (nanog at studio442.com.au):
> A few of the engineers at $DAYJOB still try and claim SONET is easier to
> troubleshoot, but that hasn't been my practical experience.
> With ethernet it's something like:
> - Layer 1 - light levels (DoM on nearly everything)
> - Layer 1 - link pulse
> - Layer 2 - can I send frames
> SONET it's, in practice:
> - Layer 1 - light levels (DoM on newer kit, SOL on older)
> - Layer 2 - Seemingly random collection of alarms
> - Layer 2 - Is PPP up?
Just the fact that BFD had to be reinvented shows that there is ample
reason to prefer the steady-train-of-frames-with-status of SONET/SDH over
perhaps-nobody-sent-a-packet-or-the-line-is-dead quagmire of Ethernet --
I have run pretty large (for sweden) networks over SDH (POS linecards on
top of waves, not a full SDH system) and essentially similar networks as
GE over waves, and I truly prefer the failure modes and analysis tools
in SDH to the guesswork and afterthought patches of alohanet..
Still, the stupid f€%&€/# that make prices for linecards made me go GE
instead of OC48 for the most recent deployment. In Sweden, both vendors
claim about 6 times as much, per megabit, for SDH line cards.
This can't really make sense.
> As others have said doing a "diverse 1/10g ethernet" quote and a
> "protected SONET" quote may be worthwhile, and adding a 20% pad to the
> SONET one for staff training may also be perfectly justifiable.
Maybe training is more expensive (it takes some CPU to parse SLOF/SLOS
and PLOP etc) but it leads to lower OPEX since the "Maybe" factor is
essentially gone. Operationally it is quite worthwhile to say "I have
SLOS in my far end, which means somebody pulled a patch worngly in
your just terminated maintenance window." instead of "The line is dead,
can you please check something?" to your circuit provider.
Yeah, SDH and similar probably will die, but cheap aint good. Only.
Måns Nilsson primary/secondary/besserwisser/machina
MN-1334-RIPE +46 705 989668
Is this going to involve RAW human ecstasy?
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