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| Doubts Remain About NTT's ADSL Service
January 25, 1999 (TOKYO) -- Nippon Telegraph and Telephone Corp. held
a briefing on Jan. 19 about its asymmetric digital subscriber line (ADSL)
service, which is due to begin this fall.
|However, industry watchers say many points were unsatisfactorily explained,
and some aspects of the briefing raised uncertainties about the future
of the service.
The service will be called ADSL Access Line. It will offer access lines
for Internet connection to Internet service providers.
Over 100 providers and other people attended the briefing, indicating
strong interest in the forthcoming ADSL service.
The main topic was the points-of-interface (POIs) for connecting provider
networks with NTT's ADSL Access Line.
NTT will set up POIs in local exchanges (stations) closest to subscriber
residences or in central offices (stations) that interconnect the exchanges
within a prefecture or region. The provider installs a router in either
type of NTT site to connect to the ADSL Access Line service.
Providers that operate within a specific locality will use a local exchange.
Providers that deliver services over a wide area will route data for
all subscribers via a central office. However, ADSL Access Line will
be limited initially to about 10 exchanges in the Tokyo and Osaka regions,
which means that only 10 POIs will be available.
The connection interface will use 156Mbps asynchronous transfer mode
That was all the information given at the briefing, and providers had
many questions. NTT was asked about its intentions in regard to connection
through a main distributing frame (MDF). Providers also wanted to know
whether NTT would provide a shaping function for adjusting transmission
speed across multiple ADSL lines.
To connect to the NTT network if traffic shaping is not provided, providers
will have to install high-speed lines that have a capacity equal to
the transmission speed of ADSL Access Line multiplied by the number
of subscribers. This would increase backbone charges, so the provider
would be unable to offer a low-cost ADSL service.
In reply, NTT said that it would consider MDF connection upon request,
"but MDF poses quite a few problems." In regard to traffic shaping,
NTT gave a non-committal response.
So far, NTT's Open Computer Network (OCN) Service Division is the only
organization to have announced that it will use ADSL Access Line. Providers
are unlikely to utilize the service very much unless NTT sets reasonable
charges and includes traffic shaping and other functions that enable
providers to deliver services cheaply.
� Nippon Telegraph and Telephone to Buy 250 ADSL
� Nippon Telegraph and Telephone to Offer ADSL Service
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