VA proposes a Sonet net for selected sites
If the plan gets the blessing of the Veterans Information Systems Network-5 committee,
VA's Maryland hospitals in Baltimore, Fort Howard and Perry Point will become nodes on an
OC-3 155-megabit/sec Synchronous Optical Network ring.
The network panel will set the ATM direction for the Maryland hospitals as well as
other hospitals in Washington and Martinsburg, W.Va., that together make up VISN-5.
The hospitals' current 1.5-megabit/sec T1 data and Integrated Services Digital Network
lines now cost VA about $17,000 per month. Swapping these circuits for a Sonet ring, to
which the Maryland hospitals would connect by 45-megabit/sec T3 ATM trunks, would raise
the cost to about $22,000 per month.
The higher price tag would buy more bandwidth and the ability to adjust the connections
to the type of traffic.
"We are only proposing it at this point, because this is a VISN decision. They
will decide where there's going to be ATM," said Marcelo Silva, the VAMHCS network
Reliable communications are essential for VAMHCS. The information systems containing
patient, laboratory and prescription data all reside on a Digital Equipment Corp.
VAXcluster in Baltimore.
From there, three T1 lines--one dedicated to imaging data--connect the Baltimore system
to the Fort Howard hospital. Similar T1 lines link Baltimore to Perry Point. For
redundancy, there is a single T1 between Fort Howard and Perry Point.
The 1.5-megabit/sec primary rate interface ISDN lines are exclusively for functions
such as daily morning videoconferences.
At each site, videoconferencing systems from Vtel Corp. of Austin, Texas, connect via
coder/decoder devices over ISDN lines.
A videoconferencing bridge in Baltimore lets the sites carry as many as six multipoint
Each facility has two ISDN lines, one from the governmentwide FTS 2000 program and one
supplied by the local telephone company, to get enough bandwidth. Each videoconferencing
session demands 384 kilobits/sec to 512 kilobits/sec.
VA doctors in Baltimore use the videoconferencing bridge to consult remotely with
doctors at the other hospitals about cases in new specialties such as teledermatology and
teleradiology. The ATM network would let the doctors videoconference from their desks.
There are even more lines for voice. Tie lines link the hospitals' private branch
exchanges, and a 10-megabit/sec microwave link supplied by VAMHCS' own equipment connects
the Baltimore hospital to the Baltimore Rehabilitation Extended Care Center.
VA officials are now upgrading the LAN in the Baltimore hospital. A Model 7000 router
from Cisco Systems Inc. of San Jose, Calif., provides connectivity for the T1 data lines
going out to Fort Howard and Perry Point and for the microwave link to the rehab center.
A second Cisco 7513 router gives the Baltimore hospital a T1 connection to VA's
nationwide frame relay network.
The routers support the Hot Standby Router Protocol, a feature of Cisco's Internetwork
Operating System for failover from one router to another without making any changes to IP
The Cisco 7000 links through full-duplex Fast Ethernet connections to Cisco Catalyst
5000 and Catalyst 5500 ATM/Fast Ethernet switches.
The 7513 router connects via OC-3 to a Cisco LightStream 1010 ATM switch and to the
The two Catalyst switches connect via Fast Ethernet to 11 Catalyst 5000s in wiring
closets, the Catalyst 5500 and the LightStream. The LightStream connects via OC-3 to
another 17 Catalyst 5000s in wiring closets.
A dozen desktop PC users typically share one Ethernet port on the switches in the
wiring closets. Servers and some power users get dedicated ports.
Cisco's LAN Emulation 2.0 (LANE) software bridges the Ethernet to the ATM network,
which supports switched virtual circuit connections that are set up dynamically rather
than as permanent virtual circuits.
Cisco's Simple Server Redundancy Protocol gives backup to LANE server components.
VAMHCS has redundancy not only for LAN services but also for external connections.
Marty Butcher, VAMHCS' associate chief for hospital information systems, said the
hospital buildings are now wired with Category 3 copper cable to desktop PCs.
Under VA's Telecommunications Infrastructure Project, they will get Category 5 wire and
TIP "is an agencywide initiative that's working out quite well," Butcher
said. "Perry Point has a campus environment, but in all the buildings, the cabling is
lower than Category 3 for terminals and things like that."
If the VISN-5 panel approves the plan for the ATM WAN, the equipment and Sonet ring
could be installed in six months to a year. A Cisco StrataCom IGX ATM switch at each of
the three hospitals would supply the ATM connectivity across the Sonet ring.
The 7513 router, and through it the hospital LAN, would connect to the new ATM
backbone. PBXes would have a 1.5-megabit/sec link to the IGX, and the codecs would get a
25-megabit/sec link to either the LightStream or the Catalyst 5500 ATM switch, and from
there to the IGX switch.
An ISDN/ATM bridge from First Virtual Corp. of Santa Clara, Calif., would still permit
videoconferencing with the outside world via ISDN.
If the common ATM network replaces the separate lines now used for data, voice and
video, VAMHCS officials could allocate the bandwidth to suit the application.
They say they favor a private ATM network, which would let them manage the various ATM
service classes such as variable or available bit rate for data applications and constant
bit rate for real-time video.
"The problem with public ATM services is this: Suppose I bought VBR service for
data but not CBR for voice and video. The cost of the service would change if my
requirements changed," Silva said. "With a private network, I control how much
VBR and CBR I put into the trunk. So I have complete control, and all the management of
the network resides on site."