nanog mailing list archives

Re: Routed optical networks


From: Eve Griliches <egriliches () gmail com>
Date: Tue, 2 May 2023 16:28:16 -0400

So right Jared....magic has been in the NPU capacity increase that's driven
the cost per 100G down on 1RU routers; and the integration of DSPs and more
into QSFP-DD form factors at much lower power than expected. The standards
for optical links are maturing as well, but we still have work to do on the
management side for the electrical interfaces.
Eve

On Tue, May 2, 2023 at 3:33 PM Jared Mauch <jared () puck nether net> wrote:



On May 2, 2023, at 2:29 PM, Etienne-Victor Depasquale via NANOG <
nanog () nanog org> wrote:

On Mon, May 01, 2023 at 02:56:47PM -0600, Matt Erculiani wrote:
In short, the idea is that optical networks are wasteful and routers
do a
better job making more use of a network's capacity than ROADMs. Take
the
extra router hop (or 3 or 8) versus short-cutting it with an optical
network because the silicon is so low-latency anyway that it hardly
makes a
difference now. Putting more GBs per second on fewer strands means
saving a
lot of money on infrastructure costs.

This is a very convoluted way of backing into the ole packet-switched
vs. circuit switched decision.

I don't follow.
While ROADMs can be thought of as circuit-switchers,
the number of concurrent clients and switching latency put ROADMs on a
different operational level than packet switchers, right?


I’ve seen proposals for an LSR MPLS/ROADAM type solution, where imagine
you are at a hop where in a long distance system solution, you would end up
with OEO, but instead you get directionality capability with an IP/MPLS
capable device.  As mentioned previously, the 400-ZR/ZR+/ZR-Bright/+0
optics are the latest example of that.

I know of a few companies that have looked at solutions like this, and can
expect there to be some interesting solutions that would appear as a
result.  Optical line systems tend to have pretty low power requirements
compared to a router, but some of the routers are getting pretty low power
as well when it comes to the power OPEX/bit, and if you have the ability to
deliver services as an integrated packet optical you could see reduced
costs and simplified components/sparing.

I’ll also say that I’ve not yet seen the price compression that I had
expected in the space yet, but I figure that’s coming.  We are seeing the
bits/watt ratio improve though, so for the same or less power consumption
you get more bits.  Some of this technology stuff is truly magical.

- Jared

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