[SPAM-HEADER] - Re: Diversity - was: Fiber cut in SF area - Email has different SMTP TO: and MIME TO: fields in the email addresses

Wed Apr 15 15:54:26 UTC 2009

On Wed, Apr 15, 2009 at 01:38:43PM +0100, Rod Beck wrote:
> There is no known way to provide cheap 10 wave protection. Not carrier
> grade. Protected 10 GigE service (LAN PHY 10 GigE) will tolerate a
> very high BER before switching. And the cost of switching STM64 is
> very high as well. 
> 
> Bottom line is that it will cost more than two diversely routed 10 gig
> waves. 
...
> Every span has to be protected.

Hi Rod,

I don't think thats true. Most "carrier grade" DWDM platforms deployed 
over the last few years have been capable of doing protected 10GE LAN 
PHY service without a SONET/STM layer and without costing more than two 
diversely routed waves.

Also, many of the modern systems in use by modern competetive carriers 
are capable of providing > 2 degree (ring) protection. They essentially 
act like an optical "switch", and can automatically seek out (and signal 
via GMPLS) an available channel to restore or protect the overall path 
on a dynamic basis, and in more than 2 directions.

> There is no real market for protected 10 gig waves. Occasionally a
> bank will request the service, but backoff as soon as they see the
> price tag. 

I think the pricing is the result of trying to charge what the market
will bear rather than an underlying technical cost to deliver service.
Think "if the customer wants a want stop solution where we're managing
everything for them they should be willing to pay more for the
convenience".

> "Hopefully none of these customers had service and protect ckts that
> went down... I would be pissed as a ceo if that happen to my company. 
> Hopefully level3's new service offering is 100 at percent redundant as
> stated

Protected vs 2x diverse unprotected circuits each have their advantages 
and disadvantages. One thing a protected circuit is not good at is 
providing higher availability than 2x diverse unprotected circuits. 
That's because you're trading diversity at the endpoints for simplicity, 
so you've still done nothing to protect yourself against endpoint 
failures. Protected circuits may provide other advantages though, such 
as > 2 degree protection, or better latency than may be reasonably 
available to purchase independently. It depends on the carrier, the 
network, and even the customer to figure out which is the better 
solution.

> The new service offerings include: - Protected Wavelengths: Level 3
> now provides automatic protection-switching to a dedicated diversely
> routed wavelength in the event of a network failure. The protection
> switch, fully automated and managed by Level 3, happens at switching
> speeds approaching SONET restoration times. The single interface to
> the customer requires no additional capital cost for customer optical
> ports, and the diverse restoration path is fixed and fully known to
> the customer. These features allow customers to achieve fast
> restoration with predictable performance in their network without
> adding significant cost and routing complexity. -"

I believe this is what I was talking about above, on their Infinera 
platform. This is much more powerful than traditional ring designs.

> But bear in mind that DWDM infrastructure that does 80 to 120 waves 
> per fiber pair is very expensive.

I suppose expensive is in the eye of the beholder. Every modern
long-haul "carrier grade" DWDM platform I know of has done at least 80
channel 50GHz spacing at the same cost as a 40ch solution for quite a
few years now. Only in the metro space does the statement above hold
true.

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)