NEWS: Planned Modem Outage on April 21, 1999
The Springfield Off-Campus Modem Pool will be down on April 21, 1999 at 8:00 am for a
minimum of two hours for trunk reorganization and software reconfiguration.
All users of the Springfield off-campus modem pool (417-875-6996) will be unable to
connect during these hours. Short intervals will exist when part of the facilities
appear functional, but users are advised to stay off until after 10:00 a.m.
Otherwise, connection drops or login failures could occur.
April 6, 1999
Southwestern Bell Telephone and Missouri State University Networking have agreed that additional
preparations need to be completed prior to attempting this modem conversion.
Consequently, the modem pool will not be down on April 7th as originally planned
and the outage has been:
rescheduled for April 21st.
April 1, 1999
The Springfield off-campus modem pool consisting of 230 modems will be out of service starting at 8:00
a.m. on April 7, 1999. Services will be unavailable or unreliable until about
10:00 a.m. on the 7th assuming no serious problems arise with the
reconfigurations. During the changes users will, at times, be able to connect but
will fail authentication or will be dropped as the next change is applied. Users
are, therefore, advised to not attempt to use the services until after 10:00 a.m. on the
7th. If service restoration is delayed or if it become available earlier, the Missouri State University Help Desk will
be informed. You may check with them at 417-836-5891.
We will be attempting to perform three major tasks during this outage all of which are
aimed at improving service. The main tasks are:
 | SWBT trunk reorganization:
Southwestern Bell has, thus far, been unable to keep up with the trunking configuration
used on our ten PRI circuits delivering modem traffic to Missouri State University. Internal
documentation, database information, and switch configurations have proven to be
inconsistent and very erroneous. The trunks will be functioning properly, but (in
theory) a SWBT technician will view some inaccurate or inconsistent information and change
the switch. It is our supposition that this is what has been causing some of our
drop and call routing problems.
We will remove the complex system of routes and overflows used to fill multiple trunks
of two spans each and replace it with a single trunk of ten spans. This will
eliminate our ability to test individual spans, but it is thought that increased
reliability will be achieved through a much simpler configuration. All trunking
information should be purged and an accurate and consistent set of configurations will (in
theory) be documented and implemented.
|
| Implement NFAS signaling:
Each T1 type interface has 24 digital channels that operate at 64K per channel.
Each PRI (ISDN Primary Rate Interface) uses a T1 type circuit and allocates 23 channels at
bearer channels (B-Channels) and one signaling channel (D-Channel). Therefore, one
PRI can only support 23 modem calls. With 10 PRIs, we get 230 modems in the pool.
With NFAS, we will allocate one D-Channel to signal two PRIs instead of just one.
We will get [23B + D] + [24B] channels for a total of 47 lines for every 2 PRIs
giving us 235 modems which is 5 more modem lines than we had before for no extra cost.
While the gain is small, every modem helps: We'll get 5 more happy users.
The trade off is that if the PRI containing the D-Channel goes down, we'll loose 47
users instead of just dropping 23.
|
| Replace unreliable MICA modems:
Missouri State University Networking is hoping that the final parts will arrive which are required to
replace the problematic MICA Modems
with more reliable Microcom modems. These MICA modems have been responsible for
failed connections, modem drops, and poor connection rates.
We will hopefully shutdown the AS5300 with MICA modems, remove the MICAs, install
Microcom, reconfigure the machine, and bring it back online while SWBT is working on the
trunk reorganization. Since the MICAs fit in half the space as the Microcoms, we
will either be installing a loaner AS5200 or our permanent AS5300 chassis with Microcom
modems. This will only occur if all parts arrive from Cisco on time.
|
Thank you for your patience and understanding on this matter. The time selected
is the lowest usage time for our modem pool that occurs during normal business hours kept
by SWBT and Missouri State University. Please refer any question to the Missouri State University Help Desk at
417-836-5891.
|
