- Network Status and Performance
T-1 Characteristics
Keck remote observers experienced during test runs that the T-1 link
was not responding during certain applications. The problem was traced
to the T-1 link itself which does not support B8ZS (Bipolar with eighth
zero supression). As a result, the T1 link will experience problems when
a string of 15 or more consecutive zeros is transmitted. This is a well
known characteristic of T-1 lines also known as the one-density requirement.
After studying various ways of fixing this problem, we have switched
the CSU/DSU to HDLC (High-level Data Link Control) with simple D4
framing and at a line speed of 1.53 Mbits. HDLC will invert the data
being sent, thereby reducing the possibility that a string of 15 or
more consecutive zeros will be sent. It is possible, but less likely
that data would include 15 consecutive ones. We will monitor the
performance to determine if this arrangement is satisfactory until
the fiber from HP to Humuula is installed, at which time B8ZS will
certainly be available.
Other options include relocating the T-1 line to the summit microwave
which does support B8ZS, or asking Hawaiian Tel to upgrade its radios.
The last option is very unlikely, as the costs to upgrade the microwaves
at HP and Mauna Loa are about $100,000.
FDDI Ring
The FDDI ring had two outages to report. One involved a burned
out power supply at JCMT, the second an overheated router at CFHT.
Unfortunately they occurred at approximately the same time resulting
in the isolation of CFHT and Keck from the Internet for a short time.
The CFHT and the JCMT routers have both been restored. However the
FDDI ring is wrapping at KECK and JCMT, a condition which will be
remedied within a few days.
- MKO Communications Infrastructure Improvement Plans
Steve Hardash presented an updated construction plan for Gemini
for the remainder of this year. San Juan Constructions has completed
80% of the road relocation work. It is anticipated that the
utilities relocation will start the week of April 17. Their first
order of business is to remove the old 24" infrastructure. The new
conduits will then be installed. HELCO, HawTel, and the fiber
optics cables will need to relocated before a majority of the
Gemini foundation work can begin. Some minor work is anticipated
to start in May. The fiber relocation is projected for the late
June to early July timeframe. The contractor chosen is Kailua
Kona Resort Corporation with T&T Electric the subcontractor and
Rich Bacon the consultant.
The detailed infrastructure
relocation plan has been discussed previously. The splicing is
planned to be performed at the new handhole close to HH16. Each
fiber optic cable, starting with the unused Subaru fiber sheath,
will be cut at HH15, pulled back individually to HH16 and pulled
into the new handhole where the splicing will take place. This
procedure is projected to take less than 6 hours. As a precautionary
measure an access hole about 50 ft south of HH16 will be dug up,
and the existing conduit cut in case it is not possible to pull
an individual fiber all the way back from HH15. In that case the
fiber will be cut at the access hole and pulled back to HH16.
We are also exploring the possibility of providing a 28.8 kbaud
PPP connection from the telescope facilities/base to Hale Pohaku
for access to Internet as a backup measure. Details will be
forthcoming.
Phase II which was rewritten since the last meeting to avoid
laying a temporary surface cable was reviewed. It was decided
that the following information should be provided by each
facility in time for the next meeting:
- Possibility/desire of replacing fiber from each facility
to the handhole,
- Congestion of the conduits leading into each facility,
- Distance between the handhole and termination point within
each facility.
Each facility will investigate the latter two points and forward the
information to IfA, in order for the IfA to come up with a cost
estimate of new fiber pull compared to re-using the old fibers.
- Interop Summary
The focus of Interop
has shifted from ATM everywhere to Ethernet switching for a LAN.
A summary of current ethernet
switch vendors is available. One concern which was brought up
was the corporate health of Proteon. Even though Proteon has limited
their development of high end routers, their financial position
is strong. Since we are not in the market for router upgrades at
the moment, it is not really an issue. The technology may have
changed significantly by the time we are ready for an upgrade at
which time we will reevaluate our hardware supplier.
Currently and forthcoming interesting conferences include
Internet World,
International WWW Conference,
INET 95.
- Other Business
Resplicing of Faulty Fibers
After extensive discussion, it was decided that IfA will
look into contracting out to Telecable Systems in Kona
to resplice the fibers
which were determined faulty recently. The facilities
will be recharged for their share of resplicing, which
include only those within their telescope. Resplicing
of fibers at the Summit Communications Room will be
paid for by IfA.
Facilities will be asked to approve the cost or issue
a purchase order before the work for their location
is contracted.
Interdome Fiber Link
Andrew Pickles indicated the desire to have fiber
communications to the remaining 24" telescope and
to CFHT. The use of the spare single mode fibers
between 88 inch and CFHT is a possibility. It would
require the use of single-mode to multi-mode converters.
Another possibility is to install subducts in the new
communications duct. Steve Hardash will explore the
cost involved.
- Next Meeting
Friday July 14, 1995, 10:00am at IfA (subject to change).
