DWDM Metro Access Design

Livio Zanol Puppim livio.zanol.puppim at gmail.com
Mon Mar 21 19:36:20 CDT 2011


I don't know if this is the appropriate list for this kind of subject, so if
anyone knows another specific list, please tell me...

I'm analysing several DWDM designs to implement at my city, but I'm still a
bit confusing about the Metro acess design. I'm supposed to build a physical
ring topology with 6 pairs of fiber with an hub-and-spoke logical topology.
The ring will have about 40Km. At the HUB we'll install our
point-of-presence with a MPLS equipment, and at the spokes we'll use only IP
routers. We need an flexible design where we can add or remove spokes as
needed with the minimum effort possible. We are planning to have, at a
initial deployment, about 200 hundred spokes, and all these spokes are
talking only with the HUB site. Everything should work like in an FTTH or
FTTB design, no other type of transportation is allowed (wireless and

We can't use SONET/SDH. The solution must be only IPoDWDM or complemented
with TDMoIP at the access equipment.

The problem, is that all documents that I'm reading specifies that we should
be worried with faults scenarios at the spokes, so that the optical network
does not stops. For example, if the OADM equipment at the spoke is down, the
lambda dropped at that site will be down too... Or at least, if we use a lot
of lambdas, we need to keep and eye at the points where we have

We need bandwidth from 10Mbps to 1000Mbps at these spokes.

My question is:
Is it possible to make such a network in a way that we don't need to worry
about faults (electrical or others) at the spokes? If so, how can I do this?

I don't want the spokes sites interfering directly at the operation for the
whole network.

Thanks for your help.


Lívio Zanol Puppim

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