David Strom

Coping with Mixed Operating Systems: Strategies for Supporting Enterprise Heterogeneity

By David Strom

When it comes to supporting enterprise networks, heterogeneity has become a fact of life, and

this is especially true when it comes to supporting operating systems. For better or worse, the

networks of today have become a real mixed bag.

For years corporate support departments have urged their users to purchase the application

first, then platform and operating system second. It seems as finally these notions have been

accepted with a vengeance, with the result that networks are inevitably multi-client. Couple

this with the growing trend of mergers and LANs moving from departmental to enterprise

concerns, and the result is that the days of a single operating system per corporation are

firmly in the past.

So how to cope? It isn't easy. Getting rid of even part of this complex installed base doesn't

happen willingly, as each operating system has its own political faction and supporters. Tools

for managing mixed networking environments are poor to non-existent, and rarely work

across network operating systems. Client software that supports multiple protocols gives users

a fighting chance, but is complex to support and configure and sometimes difficult to keep

running. Even applications from a single vendor such as Microsoft have trouble interoperating

across multiple operating systems and platforms. 

Nevertheless some corporate network administrators and architects are trying to make the

transition to a simpler environment. "Anything that can save our users even an hour a year is

something we should consider," says Mike Ulvestad, a senior consultant at Hughes Aircraft in

Long Beach, California, who responsible for formulating corporate-wide microcomputing

standards. "With 35,000 users, that adds up to 15 man-years saved per hour."

Others have accepted that multiple solutions will exist within their domains for a long time to

come. "Although potential savings may happen, it is hard to pick a single vendor when the

three major LAN OS vendors -- Banyan, Novell, and Microsoft -- have products that only

have a ten percent functional spread among them," said Chris Stormont, who until recently

worked at the Bank of Boston and was responsible for implementing their electronic mail

strategy across multiple network operating systems. 

"Does one have a significant functional benefit over the other two? Not really."

Multiple network operating systems arise in several situations. "LANs originally came in the

back door at Hughes Aircraft," say Ulvestad. Thus each department chooses whatever is

appropriate, and corporate administrators are left trying to stitch things together after the fact.

Multiple systems also happen as a result of a merger between two corporations, which can

throw even the strictest standards-setting organizations into a tizzy. 

Another way that mixed networks arise is from demands by the users themselves. As

mentioned earlier, users' needs often dictate multiple client operating systems to support a

variety of applications.  "I've got one agency that wants to run Autocad on character-mode

DOS, ADABAS on OS/2 clients, and the usual office automation needs on Windows. And

that's just one agency," says Sam Blumenstyk, who supports a variety of city agencies in his

capacity as director of LAN consulting services for the Computer and Data Communications

Services Agency of the City of New York.

Most city agencies have standardized on one network operating system or another, "but there

is some strain and confusion when different agencies want to work together on a project,"

said Blumenstyk. "The city is just too diverse to standardize on one network operating system

especially at this point in time," said Pat Carragee, the assistant commissioner for network

systems in the city. "We are a service bureau, we continue to match needs and solutions on a

case by case basis."

Hughes has settled on NetWare as the "tactical" LAN operating system for now, and

attempted to put most of its new users on NetWare, even though "we've got pockets of

everything from LAN Manager to Vines around here," said Ulvestad. Indeed, one large

Banyan network within the company recently converted over to NetWare. 

The Bank of Boston also has a mixed bag, but management has been unable to win any

converts. "We have a lot of politics and religious zealots around here. We would like to move

to supporting a single LAN OS, but it is difficult to have a candid discussion about the

relative strengths and weaknesses of each one," says Stormont. 

All of the organizations interviewed stated that the mixed environment spells support trouble.

This is especially true when it comes to troubleshooting problems that cross networking

niches. "We had a corrupt cc:Mail database that took us three months to track down the cause

to some flaky software in our Wellfleet routers and a bad IBM Token Ring adapter," said

Stormont. "It took so much time because we had to convince 25 people to work together to

solve this problem. We didn't figure it out until everyone began talking to each other."

Another issue is printing. "We have printers that can serve only a single community," said

Ulvestad. "We've got Apple printers, mainframe printers, Unix printers, and NetWare and

Banyan printers, and often they are located right next to each other. We'd like to share them

across environments."

But there is hope. A number of tools and strategies are available to make dealing with mixed

environments easier. One of the best tools cited by network administrators is to run multiple

protocols on each desktop. This has the advantage of being able to connect to a wide variety

of network resources, such as NetWare and Unix servers, without the need to reboot machines

or disconnect from one network to use another. "Our standard is to provide a single network

connection, so we have steered clear of using multiple networking adapters in each desktop,"

says Ulvestad. "Instead, we are moving desktops with multi-protocol requriements to run

Novell's ODI (Open Datalink Interface)." 

ODI is Novell's preferred mechanism of running multiple protocols, such as IPX and IP, over

the same network adapter inside each desktop. And, ODI will be the sole mechanism for

clients that want to make use of upcoming NetWare 4.0's new services, according to Novell.

Alternatives to ODI that accomplish the same purpose include Microsoft and

Banyan-sponsored Network Driver Interface Specification (NDIS) and a shareware solution

called packet drivers that has popularity in the Unix community.

Another advantage of this approach is that it widens the availability of supported network

adapters and lowers purchase costs.  "It is a much better situation if we can buy an Ethernet

card for $125 and run NDIS drivers, rather than get a card for two or three times that with its

own native drivers," says Blumenstyk. "NDIS has been an important technology for Banyan

and the LAN Manager/Unix communities in terms of widening support for networking cards,"

he said.

However, the extra flexibility of ODI-like approaches has some disadvantages: using these

solutions require more expertise in configuring desktops and knowing which networking

adapters and protocols support which version of the specification. Plus, not all vendors have

applications that support these multi-protocol stacks. "We continually beat up on our vendors

to provide support for ODI drivers and stacks," says Ulvestad. One of the reasons Microsoft's

Workgroup for Windows software is not supported at Hughes is because it doesn't have ODI

network drivers. (It uses NDIS or the native IPX drivers instead.) 

Another disadvantage is that in many cases ODI-like solutions are less popular with end users

"because there is not enough RAM left to run most of your applications," said Stormont. 

A second strategy is to run multiple protocols on each network server. Hughes, with its large

percentage of Macs, runs Appletalk on most of its NetWare servers, and some servers also

run TCP/IP stacks as well. "We have stopped short of running OSI protocols because there

aren't alot of desktop applications that are driving that, but we think we will in the future,"

said Ulvestad. "The Apple/Novell stuff works particularly well," said Stormont.

But multiple protocols isn't the answer to everyone's problems. "I've got a NetWare LAN and

an application running on a VAX. Do I really want to load the entire protocol stack of the

VAX just to support terminal emulation? Not really," said Blumenstyk. "I'm looking for other

solutions where I can just put in a gateway to provide those terminal sessions."


Beyond accommodating multiple protocols on either desktops or servers, perhaps the ultimate

solution is to find a suite of applications that can interoperate across a mixed network. This is

still a sticky point with many of the corporate networkers interviewed.

One application that has the potential for unifying heterogeneous environments is electronic

mail. But its promise is still unrealized, according to several network administrators at large


Hughes uses Softswitch to connect together many email systems, but "we often have to go

with the lowest common denominator for services. For example, sending binary files across

email is a major pain in the neck. With some of our email systems, you can't even send

binaries. With others, you have to know what the receipient is running. Sending out a

spreadsheet to ten people using three different systems with all of them being able to read the

file can be a real challenge," said Ulvestad.

"You've got directory services that are being provided by Novell in release 4.0 and by

Banyan. How do you coordinate these things with an application like cc:Mail that has its own

directories? How can you be sure that the application will read each directory the same way?

You can't," says Stormont.

Still, there are some solutions for email babble. The City of New York uses Softswitch's

mainframe-based gateway products, and users are able to send files across the city with

relative ease. "(the city's implementation called) CityMail is one of our most popular

services," said Blumenstyk.

Another solution is Banyan's Enterprise Network Services, "although that is a one-way street

to providing Streetalk directory services for NetWare," says Stormont. 

Beyond email, the most frequent issue for applications interoperability is to  try to get

Macintosh and Windows users to work together, using applications software from the same

vendor. "We use a lot of  Microsoft applications at Hughes for their dual-platform abilities.

Most of their Mac applications lag at least several months behind their Windows counterparts,

and Microsoft comes out with a new version every 18 months. Even on something as

common as word processing, there are a lot of features that aren't the same between the two

platforms. We have to deal with everything from fonts to file naming conventions switching

between a Windows and a Mac user," said Ulvestad.

And in some cases, applications interoperability can drive organizations  purchase decisions.

"We have one agency who purchased Word Perfect for their Macs largely because they were

connecting them to a LAN that was already running Word Perfect products on PCs," said


One suite of applications which has worked well for Hughes has been Digital

Communications Associates' line of Irma workstation products. "None of them are the best of

the breed, but together they seem to work well across multiple operating systems and

attachment types. For instance, I can switch from a coax-connection to a gateway running

TN3270 over Ethernet, and the software looks the same, a lot of my scripts will still work,

and the file transfer software will work the same. That appeals to me," said Ulvestad.

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David Strom David Strom Port Washington, NY 11050 USA US TEL: 1 (516) 944-3407