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000042_isdn-distribution-owner_Mon Jun 7 22:04:21 1993.msg
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Received: from nac.no ([129.240.2.40]) by relay.cs.toronto.edu with SMTP id <237314>; Mon, 7 Jun 1993 22:04:20 -0400
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Date: Mon, 7 Jun 1993 20:53:58 -0400
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From: Bob Smart <smart@mel.dit.csiro.au>
Message-ID: <9306080052.AA14894@squid.mel.dit.CSIRO.AU>
To: isdn@list.prime.com, isdn@teknologi.agderforskning.no
Cc: smart@mel.dit.csiro.au
Subject: ISDN bonding (inverse multiplexing) in Australia
The following was posted to the AARNet mailing list. Though it is
about Australian compatible equipment I think it will be of general
interest, and I am reposting it with the author's permission.
By the way I am sending this to both isdn mailing lists I am on.
Perhaps it is time for someone to repost information on the particular
areas of interest that the two lists are intended to address, and what
interconnection (if any) there is between the two lists.
Bob Smart
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Date: Mon, 07 Jun 93 21:20:38 +1000
To: aarnet-contacts@aarnet.edu.au
From: Mark Turner <Mark.Turner@aarnet.edu.au>
Subject: ISDN Aggregation Equipment
As promised some time ago, here is a summary of ISDN aggregation offerings
in Australia. It's based on both AARNet's technical evaluation and
comments provided by dis/satisfied users, and really only considers data
comms issues rather than voice or voice/data integration.
SCITEC
Offer two units: a BRI-8 and BRI-3 which support 8 and 3 basic rate
interfaces respectively on the network side. Comes with dual V35
or X21 interfaces on the DTE side. Provides just over a meg
of aggregation in BRI-8 format and 384k in BRI-3. Uses a proprietary
aggregation technique (Ascend Inverse Multiplexing), which is fairly
efficient (0.2% overhead). No primary rate interface as yet since these
boxes cannot operate to the larger Maxima 100 product. Supports
V25bis DTE controlled dialing - if you pay for it.
These boxes also offer dial on demand functionality, set to trigger
on things like time of day or traffic level - but to be honest
you have to be lucky to make this worthwhile over a SPVC arrangment
(typically less than 2 hours at peak per day, otherwise you may as
well go semi-permanent).
Management is via a terminal or a cute little handheld controller -
if you pay for it. No net-wide management protoco: communication
with remote equipment is via B channel. No rate adaption apparent.
DATACRAFT
DS2000, a modular environment housed in a chassis supporting up to
10 aggregation cards and either ONE 4-sbus or ONE dual PRA/G.703 network
interface. Aggregation cards (BCAM) offer up to a meg, or 4 meg if you pay for
it, and come with V35 or X21 interfaces. Aggregation protocol is AS4064,
which either uses an entire B-channel for aggregation, or 1/64th
of each. Not proprietary but it may as well be at the moment (see
below). V25bis.
BCAM aggregation cards can be replaced by a dual vanilla TA offering rate
adaption at 48 and 56 kbps.
Management is via a terminal, or a more glitzy PC windows arrangement - but
this is essentially a fancier configuration mechanism and there is
no real net-wide management protcol.
JTEC
Offer a full range, from a (soon to be released) fixed config aggregating
TA (128kbps), through a mid-price 6 slot J1500, to the 15 slot J1000/1800.
The J1000/1800 differ in backplane speed (128/256 B channels) and
can take any number of aggregation or ISDN interface cards (single PRA/G.703
or BRA per card) up to the chassis limit of 14 (one is used for the CPU).
The cute J1500 also loses one slot to CPU, but the other 5 can be used
for either BRA ISDN cards or BCAM cards (sames cards as the bigger
chassis), but NO PRA interface. The aggregation cards can do half a meg,
and also use AS4064. In theory this and the datacraft equipment should
interoperate but I wouldn't believe it until you see it...
Each card slot can also be occupied by a dual TA card offering
the FULL V110 rate adaption suite.
Management is very nice, using the D-channel to provide net-wide
management (i.e. you can communicate with any remote units from
one central station, providing both are connected to the ISDN). Telecom
do charge for D-channel usage above a set maximum no of messages
(some 3300 for a microlink and 50,000 for the macro) but, apparently,
its fairly hard to reach this (I'm a little sceptical but I guess it
really depends how much "management" you do). The management software
runs under windows on a PC and can either use an optional ISDN
card, or the in-built serial port.
Jtec seem to have the edge in terms of useful capabilties, although the
aggregation card speed could do with a boost to a meg
or so. Jtec also seem to be the only one of the three that have
taken the management issue really seriously, although the need for
sophisticated management of gloried TA's may be argued :-)
Datacraft's offering falls back in terms of rate adaption and
the lack of a low-medium end product. If you need 128 kbps to
a tail site then you have to go with the big chassis. End of story.
That said, for the high end of the market the DS2000 offers both
very high aggregation throughput and single card access to dual
PRA or quad BRA. If your looking at astronomical bandwidths you
may find the fact that the chassis can only take 2 PRA's limiting.
Scitec's current range is set back by the fact that it
has no PRA support, and thus encourages the prolification of
little boxes - managers of TA infested hubs can probably
sympathise with this one :-) I get the impression that, bandwidth
on demand notwithstanding, this range is better suited to
voice/video scenarios. It's hard to realise savings over
SPVC in a data environment, although if your growth is slow
the D on D feature may be worthwhile.
It's unfair for me to mention prices here, other than to say they
vary a great deal.
Jtec appear to have the largest slice of the market reachable via
AARNet.
Mark Turner
AARNet