Mark Vernon draws a map to help architects find their way through
the network maze
Network architecture and integration expertise are more valuable
than most IT skills to modern online organisations. But a proven
ability to successfully couple the front end, notably the fancy Web
interface, to legacy and third-party systems is hard to find.
"These skills are vital but rare," says Julie Giera, vice-president
at Giga Information Group. "The problem is that architecture skills
are different from programming or application development, though
they are often passed off as the same."
This dearth of expertise is due in no small part to the
multiplicity of legacy network standards, Novell, Decnet IV and V,
IBM's Systems Network Architecture, Appletalk and so on. Architects
have not had the time to build up a solid body of work based on the
new Internet protocol (IP) standards. So what are the issues that
architects face and how can they navigate and negotiate the
standards maze?
The challenge to network architects always used to be handling the
variety of protocols found in enterprise networks. But IP is now
starting to dominate because it is about as close as can be to a
genuinely open and flexible network environment and proliferating
Internet-based applications demand Internet-based networks.
So, if we set aside the matter of integrating IP with its older
technologies, the IP issue increasingly seems to be whether to run
a separate voice and data infrastructure, or to combine them into
one IP infrastructure. The answer to this question breaks down into
two standards issues: voice over IP and quality of service (QoS).
The challenge here stems from the fact that the Internet is without
connections. It is an unswitched network, with information sent out
in numerous packets of data, each finding its own way and being
reassembled at the other end. For structured data, such as the
contents of a Web page, this works well. The problem with voice
data is that if it is not to sound like Klingon, the data packets
must arrive at the other end within about 20 milliseconds of each
other. If there is a delay, say of 250 milliseconds, the voice
transmission crashes.
Three standards are ready to rally IP on this forced march: H.323,
session initiation protocol (SIP), and media gateway control
protocol (MGCP).
"Sometimes they are complementary and sometimes they compete,"
explains Neil Dipple, IP development manager at Alcatel.
"MGCP, as its name implies, is used for gateways, typically between
wide area networks and IP, and interoperates with both SIP and
H.323. However H.323 and SIP are competing for the same market, to
control the end points such as IP handsets."
He adds that H.323 may have the upper hand at the moment, but
network purists see it as cumbersome, since it was originally
designed to support the even more rigorous requirements of video
applications. Many commentators believe that SIP, while holding a
small fraction of the market today, will increase in popularity as
it is simpler to scale and manage.
Which leads on to the matter of quality. According to Justin van
der Lande, marketing director at Granite Systems, there are various
methods of overcoming this issue:
1. Provide effective, infinite bandwidth
2. Run the IP services with QoS settings
3. Use tweaked IP.
The first option of adding more bandwidth breeds its own problems.
Tagging IP packets offers some guarantees of service since they can
then be prioritised, allowing voice packets, for example, to go to
the top of the queue. Tweaked IP takes this a stage further by
managing data packets not only at the end but right across the
network.
However, this involves another layer of standards to run, such as
multi-protocol label switching, which are largely proprietary. "The
problem then reappears when there is equipment from multiple
suppliers present," says van der Lande. If the dominance of IP
seems not to have simplified network standards, the physical
infrastructure issue has been settled.
"Today Ethernet is the de facto standard for local area networks.
The only debate is at what speed is it deployed, but large
companies have already installed 10/100 megabits per second to the
desktop with gigabit links from the wiring closet to the
datacentre," Dipple says.
Foundry Networks, a member of the 10 Gigabit Ethernet Alliance,
provides a good example of the work being done in the recent launch
of a complete suite of standards-compliant 10gbps Ethernet
products. The products tackle a number of Ethernet issues, notably
network infrastructure expansion, by magnifying the overall speed,
efficiency and performance of the technology. However, if speed is
on the up, the choice of cable remains open.
"Networking managers have two distinct choices to make when
planning for a multi-gigabit future: fibre-optic or copper-based.
The jury is still out on which will become the preferred option for
installers and end-users," says Steve Strange technical manager at
Anixter UK. "Fibre-based systems are an increasingly attractive
option. At present, it remains indisputable that fibre has a higher
bandwidth than any alternative medium available.
"Fibre can support higher data rates than copper and new
developments in next generation multimode fibre enable it to
transmit at 10gbps for up to 300m. Furthermore, fibre is steadily
dropping in price, has gigabits of headroom and a high level of
tolerance to electromagnetic interference."
So much for fibre. But why this talk of wires? Surely the future is
wireless? Wireless in the form of general packet radio services
will only reach six to eight times the current 9.6kbps by the end
of this year, according to Giga. So it is still only usable in
certain parts of the network, notably those that directly touch the
user.
But competition is high in this space too, notably between
Bluetooth and wireless Ethernet, which are particularly targeted at
the needs of wireless professionals, docking in laptops and roaming
on mobiles. Bluetooth has certain attractions, such as not
requiring additional IT resources.
"Yet, concerns have arisen regarding the potential interference
Bluetooth could create in certain office environments," says Peter
Grant of Gartner Dataquest. "Adoption in the office depends on how
quickly process drop and throughput performance improves." Or to
put it another way, the network standards maze seems as likely to
confuse network architects as ever.