Colocation &
Outsourcing
In an ideal world, businesses
should use diverse communication
links to wherever their
infrastructure is located, with both
links capable of carrying the full
load at peak time. The network
should switch between these links
seamlessly with users unaware a
failure has even occurred.
In this scenario, neither
customers nor employees would
notice any service impact in the
event of a failure. In practice,
fully redundant links are often
expensive, and businesses need
to understand both the risks
their infrastructure carries, the
potential costs of downtime and
the potential costs of the diverse
or redundant network solutions.
Armed with this information
management can then make an
informed choice of risk vs cost.
Risk and options
assessment
At the core of any organisation’s
network design is a set of
requirements and a risk
assessment. This should define
an organisation’s requirements
for uptime and connectivity, by
site and application and detail
the impact associated with loss
of services.
From these requirements a
set of options can be built, and
their associated costs determined.
Each option should detail the
risk involved or eliminated, and
crucially, any assumptions made.
This activity requires a significant
amount of due diligence and
pragmatism, for instance, it is
very common for carriers to lease
fibres or buy services from each
other. Significant work is required
to ensure fibre routes that are
intended to be diverse are as
resilient as they appear. It may be
necessary for an organisation to sub
contract this work to a third party.
Similarly, looking at the
performance and uptime record
of a service provider, especially
when things go wrong is critical.
There are many stories of floods or
power issues which can take many
hours to fix. One update received
from a well known carrier indicated
‘Engineers are in the vicinity of
the fibre break awaiting the fire
brigade to declare the area safe’.
That fault took well over 30 hours
to fix, but due to good network
design resulted in zero downtime
or business interruption.
Other network providers offer a
100% network uptime guarantee.
This is attractive on the surface,
but in practice, may be a marketing
ploy, with the provider factoring in
the cost of paying out on an SLA
when their performance falls short.
Cost of downtime
In order to decide on an
appropriate resilience option,
the true cost of downtime must
be understood. The basis of
this may be simple, for instance
loss of trade for an e-commerce
site is easily quantifiable. More
difficult are intangible costs
such as loss of reputation for a
website or service being down,
or an inability to provide a full
service to customers. The impact
of reputation damage can last
a great deal longer than any
network outage. Ideally the cost
of downtime of each critical
application should be calculated,
as different applications will have
different requirements in terms
of uptime and performance in the
event of failures.
Calculating this cost by
application may allow cheaper,
lower specification backup
connections to be used, in the
knowledge that only critical
traffic will be carried in the event
of failure.
Cost of solutions
‘In an ideal
world,
businesses
should use
diverse
communication
links to
wherever their
infrastructure
is located,’
Once the potential options have
been established, they must
be priced and ranked as to how
they address the business need.
For instance, one carrier may
provide sub second failover, whilst
another may provide a better
SLA guarantee in the event of
a fibre cut. Selecting a single
communications provider may
create a single point of failure
from a supplier perspective, but
it also ensures there is a one
point of contact for support and
management, which will increase
speed of response in the event
of failures and avoids the finger
pointing which can occur in a multi
supplier scenario. Selecting a
single Wide Area Network provider
is the most common route as an
organisation can leverage the
expertise of the selected supplier,
who should take responsibility for
delivering to agreed service levels.
In practice, combining all the
above trade-offs – probability of
failure, time to fix cost of the solution
and budget should lead to the most
appropriate solution. The cost of a
fully redundant solution can be a
hard sell to management, but best
practice dictates this cost should be
factored in to the initial colocation
or cloud project as a starting point.
The same management who wish
to keep costs low tend to be even
less accepting of downtime when it
occurs – even when identified as an
‘acceptable risk’.
In summary, centralising data
storage and processing offers a great
many advantages to organisations
both in terms of operations
and cost savings. Any project to
move services away from a site
increases reliability on the network
infrastructure. To deliver the full
range of benefits cloud and data
centre services offer the stability
and reliability of communications
infrastructure is key.
September 2017 | 23