LR POS is good for 80km/50 miles - add into that the non-crow-flying-path of
the fibre, plug optical splices, etc.and you *have* to go with the
SDH/SONET-switched option. David makes valid points re the SLA for repair
of dark fibre - the only way telcos can make 2-hour SLAs is by use of the
redundant/resilient ring-based nature of their networks - ie they will
re-route your circuit, rather than having to physically fix anything within
the SLA time.
Saying that, I have worked in the Internet arm of a telco, and if you can
get dark fibre "on the house" as it were, then it can be very convenient as
there is not the constaint of a particular circuit being tied to a
speed/technology type. They run GE over dark fibre extensively thru their
MAN infrastructure - it can be a really nice way to run flat Vlans around
the place. Also migrating from STM-X to STM-Y (OC-X to OC-Y if you like)
can just be a case of swapping the fibre between interfaces at each end.
Ultimately, I suppose if distance is not a limitation, then it comes down to
cost - your telco isn't going to sell you dark fibre at the price of an
STM-1, if you're then going to pump STM-16 down it ;-)
btw - if anyone buys LAN-interconnect type solutions, the try putting FE or
GE down your 10Mb/s interconnect - you might be pleasantly suprised
Andy
----- Original Message -----
From: "David Chandler"
To:
Sent: Monday, April 16, 2001 5:21 PM
Subject: Re: Dark Fiber question [7:769]
> there will be about 100 miles of fiber between
> the two sites. That is quite a bit beyond the
> range of one run of single mode fiber, so there
> will have to be ADM, repeaters, etc. between the
> two sites.
>
> Second: Having the carrier provide, and therefor
> be responsible for all that equipment, fiber,
> and right-away is the way to go. If your fiber
> got cut, and the carrier does not have explicit
> responsibility to provide you with a working
> OC-48, then your problem is not their problem..
>
> We have a few OC-48 rings coming in for our
> local access. They are probably the most
> dependable thing the company uses, but if they
> do fail, and the protect cards fail. It will
> surely happen at 3:00 am on a sunday morning, so
> be sure to get some home phone #s of people at
> the carrier. It's important that they feel your
> pain.... :->
>
>
> DaveC
>
>
>
> JP wrote:
> >
> > All,
> >
> > A question about normal practice of renting dark fiber.
> > We have two sites about 60 miles apart, each site has a cisco GSR. We
are
> > going to connect them together with OC-48 PoS interface cards(haven't
> bought
> > cards yet).
> > My question is, should I ask for a pair of dark fiber from the carrier
or
> > just ask for an OC48 sonet connection between these two sites?
> > I guess the dark fiber gives us less impact by the carrier's network,
but
> we
> > would not be able to use any APS, as no ADM from the carrier will be
> > involved. Unless, we want to buy our own ADM, which is not likely to
happen
> > at all.
> >
> > This is the first time we run into this kind of setup, we need some
> > experience/suggestion before going any further.
> >
> > Thanks
> > JP
> > FAQ, list archives, and subscription info:
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