|
Limiting the Impact of Top Talkers on a
Budget
Employing restrictions of subscriber bandwidth usage without packet shaping.
By: Bruce Bahlmann - Contributing Author (your
feedback
is important to us!)
Created: March
31, 2003
This paper is the product of
Broadband Market Research which is available from Birds-Eye Network Services.
Second in a series of monthly
technology columns I've agreed to write for Broadband Properties...
There are three known ways to manage subscriber use of bandwidth.
They are modifying subscriber demand (take rate, price, usage patterns, etc.), managing
the access point (connection speed, burst, priority, etc.), and restricting the flow of
subscriber traffic using packet shaping. While all these methods are certainly effective
in restricting the bandwidth consumed by your top bandwidth users, cost ultimately
dictates the best possible solution. As many of you manage smaller private cable systems,
universities, and apartments this article will help you more effectively use resources you
already have to significantly reduce the impact of top talkers on your system.
One of the key recommendations in this article is for cable operators
to belay the purchase of packet shaping hardware until they have exhausted other, more
affordable, measures of restricting bandwidth usage. While this in no way means packet
shaping is not effective or attractive, it does mean that employing packet shaping is the
most expensive and intrusive means of limiting subscriber bandwidth. It also means that
packet shaping is not equipped nor designed to address the source of the bandwidth issue:
individual subscriber demand. For more information about managing subscriber demand for
bandwidth refer to “Impact of Content & Demand on Bandwidth Management”
article in Broadband Properties July 2002 or go to Birds-Eye.Net’s website to review
an online copy of this article.
Managing Subscriber Demand
There are many different pricing models for Internet service. Some
based on flat rate, some on bundling with other services, as well as a heightened interest
in usage based models. While the primary goal of investigating such pricing models is to
determine profitability, cost, and margins for services, an equally important goal should
be to appropriately manage subscriber demand (expectation) of such a service.
In a one size-fits-all scenario, a single service attempts to cater
to the needs of everyone from novice users to power users. Unfortunately every subscriber
views the service in a different way. On one end of the spectrum you have novice users who
view the service as being “extremely fast” and a convenience over dial-up
service. On the other end of the spectrum you have power users who view the service as a
“value” and likes the reliability of an always-on means of accessing the
Internet. With such diversity in users, it is difficult to offer one product that
economically satisfies this range of users. Similarly to cable programming packages, every
subscriber has different preferences, wants, needs, and price points so they are willing
to accept less if it fits more within their budget.
Using tiered service offerings to manage top takers is hands-down the
most cost effective means of restricting bandwidth use because you regulate use at its
very source (demand) by providing subscribers with a choice in price and performance.
While higher priced services will still require more bandwidth to satisfy, they will also
command higher price points to offset the expense of supporting them. A successful tiered
offering of services should look like a bell curve in terms of subscribers it supports. On
the extremes (max/min service speeds) you will see only small numbers of subscribers where
as in the middle you will see a majority of your subscribers.
Managing Access Point
Creating an effective tiered service line-up will greatly depend on
your ability to effectively manage the access point: the cable modem. The cable modem has
several great features that when combined with a tiered service offering provides cable
operators with tremendous flexibility (albeit largely unused for this purpose) to restrict
top talkers. Among these features include the following:
- Up/Down Stream Bandwidth Settings
– Allows cable operator to set the effective upstream and downstream throughput on
the cable modem. These settings are typically the extent of most service offerings.
- Burst Traffic Settings – Allows
cable operators to permit (or deny) subscribers to exceed their current bandwidth settings
by some amount for short durations of time.
- Priority – Allows cable
operators to assign each cable modem with a traffic priority. The higher the priority, the
more likely the subscriber using that cable modem will be able to leverage the full extent
of their bandwidth settings. When every subscriber has the same priority they all compete
equally for the opportunity to send/receive traffic. When priorities are mixed, those with
a higher priority have precedence over those with lower priority.
Manipulating these three settings can significantly reduce top talker
traffic demand. The two key settings here being burst and priority. When cable operators
set burst at zero and then combine priority with their tiered offering the result will be
significant gains in their progress towards limiting the impact of top talkers. It is
recommended that cable operators tier their service in the following way. Rather than
following the current practice where all subscribers are allocated bandwidth services with
the highest priority (7), give higher bandwidth subscribers a much lower priority 1-3.
Lower bandwidth services should be allocated higher priority (5-6) so as to prevent them
from being squeezed out. Finally, middle tier services should be assigned a priority
between 3 and 5. Regardless, no service
should be given the highest priority level and the priority given for any service follows
the practice that the higher the assigned bandwidth the lower the assigned priority –
follow this practice within tiers.
The goal in manipulating bandwidth, burst, and priority is to enable
each service some acceptable operational level without giving all the jewels away to the
high bandwidth services – we all know what happens when we do this. When high
bandwidth subscribers must compete with lower bandwidth subscribers (with higher priority)
for the same bandwidth the higher bandwidth subscribers will get throttled. Effectively
accomplishing the same results as packet shaping for a mere fraction of the cost. During
high usage times when nearly all your subscribers are online, the lower priority settings
for higher bandwidth services will keep their extreme usage in check.
Experiment with priority until you find the point where priority
parity among service tiers successfully limits your high bandwidth services. In addition,
you may want to initially experiment with your top bandwidth users by giving them lower
priority access and watch how this impacts their bandwidth consumption. Note during this
time your still giving them the same bandwidth service as before, only your giving them
fewer opportunities to exploit it. You should see fairly immediate results.
In cases where there is not much contention for
bandwidth on a top talker?s network segment, limiting priority will have
little (if any impact). However, if this is the case, you have much bigger
problems then top talkers - subscriber acquisition.
Check out these other Birds-Eye.Net papers/products regarding
this article:
Can Birds-Eye.Net help you or your Company?
Receive your Birds-Eye.Net articles and white
papers hot off
the presses by adding our RSS feed to your reader.
|