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Re: DACS vendor (additional details)

  • From: Ron Buchalski
  • Date: Thu Sep 23 15:53:17 1999


A simpler solution which would require less space, power, money, wire pairs, and administration for your group:

1) Provision a few Channelized DS3s into your LEC network
2) Install Channelized DS3 into your router
3) Let the LEC be responsible for owning/managing the DACS, and provisioning the FT1s/T1s onto the T1s within the channelized DS3s.

You'll save the space and power normally required for banks of T1 CSUs and the DACS, and you won't need to manage the crossconnects for the DACS.

Circuit-wise, it should cost you less to provision your T1s into your facility via a few DS3s rather than fifty T1s, and you won't eat up your incoming telco wire facilities quickly.

From: Peter Polasek <[email protected]>
To: Richard Newcomb <[email protected]>
CC: Peter Polasek <[email protected]>, [email protected],Derrick Bishop <[email protected]>
Subject: Re: DACS vendor (additional details)
Date: Thu, 23 Sep 1999 10:05:05 -0400 (EDT)

On Wed, 22 Sep 1999, Richard Newcomb wrote:

> Peter,
> What is your configuration need, and capacity(payload) requirement
> regarding bandwidth. Also, one would need to understand how many
> DS0's (zeros) per DS1 you wish to split, and if any of them will
> need to be paired, as in dual channel ISDN.
> Richard Newcomb


Thanks for your response. I should have provided more details in
my message. I am CC'ing this response to the group so that these
details are clear. I have already received several useful responses
and will issue a summary when the message frequency drops.

We will be splitting T1's into 128's, 256's, ... (not 56Kb lines
because the lower bandwidth lines have 56Kb local loops). The T1
lines would typically be split into a maximum of eight various
speed ports (128-512, occasionally 56, but not typically). I am
assuming that products exist to split directly into a 256Kb without
requiring that multiple 56's to be bundled, but this may not be the
case (I would appreciate clarification on this point). We may
subsequently use it for 56K lines, so a chassis that supports both
8-way and 24-way cards is helpful. Approximately 50 T1's are currently
candidates for splitting to lower bandwidth. Our preference is to use
multiple small capacity DACS rather than larger 'megaDACs' to minimize
the impact of a chassis failure. We will have at least one unpopulated
hot spare in each location.


> Original Message:
> -----------------
> We are considering using Digital Access Cross Connect units (DACS)
> to split T1 local loops into fractional T channels. Given that
> our current knowledge of DACS does not extend significantly beyond
> the ability to spell the acronym, I am soliciting advice from the
> network group for recommended hardware vendors. Cost is not an
> object, we are primarily concerned with choosing the 'industry
> standard' manufacturer with the highest reliability and knowledgeable
> technical support. Please share your experiences (positive or
> negative) with DACS equipment. In an effort to minimize traffic on
> the NANOG list, I request that responses be sent to my e-mail address
> and I will submit a summary when all the votes are in. The vendors
> under consideration now are Adtran, Eastern Research, StarDAX, and
> Fisher Price (we have some reservations about the latter product).
> Thanks in advance,
> Peter Polasek
> [email protected]

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