Travis Johnson wrote:
Matt,
We have not considered that, but it comes down to cost as well. We
charge a $500 setup fee to get the fiber installed at the customer prem.
It costs us about $1,000 to actually get the fiber installed including
the Cisco switch with GBIC's. I understand the idea of CWDM and ADMs,
but at the same time I see a downside. If one of the GBIC modules fails
at the customer prem, they are down. With our current configuration,
they would still be up and running. It would also add one more point of
failure at each customer.
Doing the ADM approach would cost about the same. You are correct that
without the Cisco you can't provide protection. However, you do get
greater protection for your overall network with the ADM approach. This
is because 2 failed Ciscos take out all nodes between the two failed
Ciscos. In the case of the ADMs, only the active Ethernet part of the
device can fail, which means the individual node goes down, but not the
ring.
We adopted the KISS (keep it simple stupid) principle when we started
doing the fiber. We run STP on the main switch at our NOC, so really
traffic only goes out one GBIC at our NOC unless there is a problem. At
that point, we get email notification and using our SNMP system, we can
tell exactly where the problem is and get it fixed quickly. Right now we
are only moving about 50Mbps of traffic, so even only having 1Gbps of
capacity should work for many, many years to come.
That is a smart way to go. Trying to get more sophisticated with fiber
can get expensive fast. We are selling a good number of GigE circuits on
our fiber ring, so we have capacity issues that precluded us from using
the approach you are taking.
We use a hybrid CWDM/DWDM approach. This means that initially we use
CWDM for nodes until we have 4 channels in use. We make sure only to use
the bottom and top 2 channels of CWDM. This then allows us to run DWDM
later in the space of the middle 4 channels of CWDM. This is all done by
popping in different cards with either passive CWDM filters or active
DWDM electronics.
-Matt
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