IBM’s tele-cottage experiment suggested that in
order for companies to cut overheads it was not vital for everyone to work from their
office desk. Some companies today operate a process of ‘hot-desking’ - whereby a
worker could go to any ‘free’ desk in the company, plug their laptop into the
corporate LAN with access to all documents, data and peripherals on the LAN. The
tele-cottage principal proposed that it could be done from a series of shared smaller
office buildings within an easy, short commute from home.But how is this possible?
The in-house RAS solution
The options are a closed box proprietary hardware and software, or an ‘open’
solution based on existing industry-standard hardware and o/s software such as NT. With
Windows NT Server 4.0, RAS allows multi-link channel aggregation, enabling desktop clients
dialling in (on an ISDN Basic Rate line) to combine two or more ISDN B channels to achieve
speeds of 128kbps or greater. NT Server 4.0 also contains Point-to-Point Tunnelling
Protocol (PPTP), allowing users the cheaper choice of using the Internet as a virtual
private network (VPN) to reduce erstwhile expensive long-distance dial-up calls to cheap
local calls. RAS is a sub-set of RRAS (RRAS adds routing to RAS).
It is also possible to provide remote access for a number of employees and possibly also
certain business partners, customers or suppliers with a proprietary RAS ‘box’
or an ‘open’ RAS solution.
Proprietary RAS box vs. open RAS solution?
As with any proprietary vs. open solution, you have to carefully consider whether the
in-house IT/IS expertise and resources are sufficient to cope with setting up your own
in-house RAS solution – or whether you would rather buy in a turnkey bespoke
proprietary solution. Of course historically, with specialist exceptions, the IT world has
moved away from proprietary ‘locked-in’ solutions, to ‘open’
future-proofed solutions. Cost considerations include looking carefully at the cost of
initial installation and the total cost of ownership (TCO). This should include any
external consultancy costs and on-going service or maintenance contracts over time. Of
course if you already have competent NT-qualified staff, then they should be able to
rapidly and cost effectively exploit the RAS benefits of NT. You should also consider a
tightly defined corporate policy on remote LAN access and information access.
Those who will benefit are organisations with staff who need access to the central
HQ’s LAN resources and data from regional offices, from a small-office-home-office
(SOHO), from a hotel during travels, and suppliers or strategic partners. These include
laptop users wanting GSM cellular phone connection to their HQ LAN, V.90 modem SOHO
workers, and RRAS routers or proprietary ISDN routers for connecting at 64Kbps. Often a
key driver for RAS is merely the ability for remote or travelling staff to access their
emails - and faxes if you have a network fax server - off the corporate LAN. This improves
customer service and responsiveness.
Deciding factors
Issues to consider when choosing a proprietary vs. ‘open’ RAS solution include:
cost of initial purchase, total cost of ownership, support cost, ease of installation,
ease of configuration, staff training, speed and size of scalability, performance
improvement opportunities, manageability and integration with other ‘open’
software applications (for management, security authentication, modem pooling etc). Open
RAS also offers the advantage of using complementary off-the-shelf software such as Citrix
WinFrame and MetaFrame, Lansource WinPort for modem pooling, Spartacom MPNT, and RADIUS
(Remote Authentication Dial-In User Service) security packages.
Possibly the very first consideration should be whether the number of remote access users
is likely to be consistently less than or greater than 256 ports on one RRAS server or 48
demand-dial users. Above these numbers and you’ll probably benefit more from a
proprietary RAS ‘hotbox’ that could give your RAS service slightly greater
security and management flexibility. Cisco and 3Com are such solution suppliers.
However, below these numbers and with a WindowsNT 4.0 server and in-house NT skills, you
are more likely to benefit most from using the indigenous NT RAS or RRAS service. Why buck
the industry trend to open systems with all its flexibility, cost effectiveness and
independence? RAS is based on open PC systems for maximum LAN/WAN interface choice.
Other benefits
Ease of use - While proprietary systems are usually plug’n’play to install,
they may take more system management time once up and running. IS staff familiar with NT
configurations and management are more likely to make installation, configuration and
management in their stride longer term.
Scalability - Proprietary systems such as those used by large enterprises and ISPs or
the new generations of ASPs (Application Service Providers) and RASPs (Remote Access
Service Providers) can offer several hundreds of RAS ports. Open RAS solutions are good at
offering a rapid start of a remote access service to corporate users with existing
hardware and software, and with the system expansion speed and flexibility using good
multi-port digital/analogue modem cards.
A NT-based RAS system can start with one analogue modem on your COM1 port to take calls
from the PSTN (Public Switched Telephone Network). This can be rapidly scaled up to a
maximum of 256 ports per RRAS server, or for 48 demand-dial users, simply by adding more
multi-line intelligent RAS cards. Smarter users will opt for high-density multi-port
intelligent RAS (modem) cards such as those offered by Brooktrout Technology, instead of
adding 4- or 8-port serial cards and more external modems. For example, Brooktrout’s
‘Instant-RAS’ IRAS-30 card offers any combination of up to 30 simultaneous
analogue or digital channels with its intelligent ‘AnyCall’ technology.
A RAS system based on such multi-line RAS server modem boards often cost (port-for-port)
30-60% less than proprietary modular hotbox RAS solution, depending on whose research you
read. IRAS cards offer unassailable speed of scalability - simply installing multiple
cards in a single RAS server can take you from two to a couple hundred ports in minutes --
DIY-style. Proprietary RAS boxes often scale more slowly in 4-port increments.
Flexibility - Using an open approach to your RAS challenge can enable you to exploit
existing IT infrastructure. For example, you can easily add RAS cards to an NT server that
hosts other network services, though you can’t get a hot-swap ability for RAS cards
(but do you need it?). Fault tolerance is typically an advantage of a hotbox RAS solution,
but some lack a redundant power supply, while a RAS service based on NT-servers could be
configured using several RAS servers spread throughout the enterprise (or country) for
added resilience.
Services - Open RAS or IRAS card solutions link into NT’s own services for
security and management, including callback security, NT user authentication, multi-line
connectivity and encryption - such as Password Authentication Protocol (PAP) and Challenge
Handshake Authentication Protocol (CHAP).
Security - Within an Open RAS solution, WindowsNT’s RRAS includes the fixed
dial-back security function, enabling your HQ’s RRAS server to dial back the specific
phone number that dialled it and only then complete the network logon. This is in addition
to a number of different encryption and authentication settings.
Speed - Depending on the number of anticipated simultaneous dial-in users and their
file transfer sizes, ensure that your RRAS server has sufficient bandwidth. While you
could get away with a 10MB Network Interface Card (NIC) for perhaps, two or three users
accessing files of a few hundred kilobytes, you probably need a 100MB NIC and an ISDN
adapter for dozens of remote users simultaneously sending and receiving files of several
megabytes each. Also consider then, the IRAS card which can handle both digital and
analogue calls simultaneously and automatically, since you won’t always know which
users or how many will be using which modem type. Also remember that unless one end of
your connection (usually that at your HQ) has a digital (ISDN) adapter installed, your
remote users will never get a faster analogue connection than 33.6Kbps - even if they do
have the latest V.90 56k modem.
However, RRAS includes a Multi-link PPP feature that enables the multiplexing of two lines
to achieve enough bandwidth to transform a 33.6Kbps (one-line analogue) connection into a
67Kbps (two-line analogue) connection. This is configured on the RRAS server. SOHO remote
workers in the UK should ensure that BT has not put a DACS box on their domestic
phone line - this multiplexes two domestic phone numbers onto one line, which limits
connection speed of even a fast 56k V.90 modem to a mere 33.6Kbps or less.
This brings us to compression and connection costs. Microsoft’s Point-to-Point
Compression (MPPC) provides file compression within RRAS. Independent tests have shown
MPPC to double the file throughput of a WindowsRRAS-server-to-WindowsRAS client
connection, when compared with a proprietary RAS solution. MPPC is the RRAS default
compression algorithm, offering the automatic benefit of reduced call charges and
increased file transfer speeds.
Tunnel your costs - Tunnelling enables you create your own private connection using
the Internet and to pay only a local call charge for long-distance connections. Using the
same Point-of-Presence (POP) connection between your remote SOHO to ISP, it then entails
changing your call connection protocol between your ISP to your RAS server using PPTP/VPN
(Virtual Private Network). This then becomes a secure, encrypted ‘tunnel’
connection to your corporate RRAS server. This can be anywhere in the world - but it must
have a leased line Internet connection. It also gives you the power of the Internet’s
redundancy and universality.
This article was contributed by ComCat, High Wycombe-based supplier of Instant RAS boards,
voice/ fax boards, Keyboard-Video-Mouse (KVM) switching and Computer Telephony Integration
(CTI) products. www.comcat.co.uk and info@techland.co.uk
IRAS - Instant RAS; RAS - Remote Access Server
RRAS - Routing & Remote Access Service
RASP - Remote Access Service Provider.
