I found this section of a Telephony Online article interesting:
Though networking trends point toward an evolution
to mesh networks, nationwide carrier networks
currently lack the physical diversity that would
help carriers realize the benefits of true mesh
networking, Poll said. Qwest, for example, has
about three or four cross-country arteries that
correspond to railway rights of way. Replacing
that with a more mesh-like architecture would
increase the complexity of operating the network.
For one thing, it would require more uniformity
in the capacities of various network routes.
"You'd have to have units of 10 Gb/s traffic
between all points on the network before this
becomes economically viable," Poll said. "When
you place IP capacity, you have to place a lot
of standby capacity to carry traffic along
different paths. If we could get greater
physical diversity in place, we could greatly
diminish the amount of standby capacity we
have to take."
In order to realize the benefits of mesh
networking, Poll said, carriers will need to
cooperate with each other more than they
currently do, using fiber swaps to increase
the geographic diversity of network paths.
http://telephonyonline.com/access/news/ofc-qwest-optical-0226/
To keep this OT as much as possible, my question is if a mesh-configuration
of backup routes (where one link could provide 'protection' for many) would
be considered a sufficient replacement for SONET rings, or if the Qwest CTO
is really trying to get out of providing sub 50-msec protected loops and
encouraging L3 and above protection schemes, so that they can even further
over-subscribe their network.
Frank
Frank Bulk - iNAME wrote:
To keep this OT as much as possible, my question is if a mesh-configuration
of backup routes (where one link could provide 'protection' for many) would
be considered a sufficient replacement for SONET rings, or if the Qwest CTO
is really trying to get out of providing sub 50-msec protected loops and
encouraging L3 and above protection schemes, so that they can even further
over-subscribe their network.
It's cool that the telecommunications companies have caught up with the times. they're only about 44 years late.
http://www.rand.org/pubs/research_memoranda/RM3097/RM3097.chapter2.html
That said the 3 cross country fiber paths they have weren't dictated by the network model they were operating under but rather Southern/Union Pacific's available right-of-way and Philip Anschutz's relatively efficent use of capital.
UU/MFS tried running IP on the ‘protect’ path of their SONET rings 10 years ago. It didn’t work then.
More seriously, you can avoid using protected links for IP (which is what Qwest seems to suggest) easily, and allegedly using MPLS/FRR you could have sub-second reroute times without having full dedicated protect path.
Building your network on preemptable links (the protect-side) as UU did back in the day is probably of the “I encourage my competitors to do this” solutions.
Paul “Selling more grillz than George Foreman” Wall
Well, it works so long as whoever was trying to troubleshoot the circuits at 3am on US Thanksgiving understands that having the system "switch to protect" is quite bad, in the sense that it causes both sides to go down at once (I seem to remember there was a protect paths built for each side of the original ring using a loopback).
Other than the unfamiliarity with the concept demonstrated by phone companies, I didn't notice any great fundamental problem with the idea. The extra 10G of capacity across the Atlantic was arguably more useful in the grand scheme of things than the being able to recover from a single-point failure at SONET speeds. It's probably fair to say there's more real-time traffic on the network today than there was then, however.
I have never worked for UU/MFS, lest anybody draw that conclusion.
Joe
Then you probably haven't been on the ass end of a continental fibre link
drop. That actually mattered.
Adrian
If both sides of your SONET ring drop, then surely you're as dead in the water as you would be if each side of the ring was being used as a separate, unprotected circuit.
(But quite possibly I'm missing your point.)
Joe
Well, the "someone goes and uses as much of their link capacity as they
can, then they lose a 10ge circuit, and suddenly everything is degraded
beyond usefulness."
I'm way, way out of the loop with such things these days, but the few times
this has happened on a specific Perth <-> Sydney circuit which almost
everyone seems to use, -everything- degrades. As in, Perth seems almost
completely isolated from the rest of the country. I'm very surprised said "O"
provider doesn't have a redundant path for all the MPLS tunnels that happen
to go over it. 
Adrian