Highly Effective Bandwidth Management Using Dynamic Load Balancing

boardpushyΠολεοδομικά Έργα

8 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

484 εμφανίσεις

WHI TE PAPER
Highly Effective Bandwidth Management
Using Dynamic Load Balancing





ii
Highly Effective Bandwidth Management Using Dynamic Load Balancing

CONTENTS

The Need For Dynami c Load Bal anci ng 3

Conf i gur i ng Dynami c Load Bal anci ng 4

Opt i mi zi ng Dynami c Load Bal anci ng 6

Advanced Spect r um Management and Dynami c Load Bal anci ng 6

Dynami c Load Bal anci ng and Channel Bondi ng 7

Summary 7









3
Highly Effective Bandwidth Management Using Dynamic Load Balancing

The Motorola Broadband Services Router
64000 (BSR 64000) supports dynamic load
balancing, which can enable a cable operator to
balance the cable modem traffic across
multiple upstream receiver ports and
downstream channels. Operators can benefit
from more satisfied users as well as better
bandwidth utilization, which allows them to
support more voice customers and higher data
speeds.
THE NEED FOR DYNAMIC LOAD
BALANCING
Evenly distributing voice, video, and data traffic
across upstream and downstream channels is a
major challenge faced by many cable operators.
There are currently three methods of load
balancing available:
• Manual load balancing
• Static load balancing
• Dynamic load balancing
By reviewing each of these alternatives, it
becomes clear that dynamic load balancing is
the preferred method because it automates
load balancing and improves network traffic
management and utilization.
MANUAL LOAD BALANCING
Operations personnel can manually move a
cable modem to a different upstream channel
within its same spectrum group and MAC
domain. The cable modem can be moved after
registration to balance the number of cable
modems evenly among the upstream channels
of the Cable Modem Termination System
(CMTS) module so that the entire upstream
bandwidth can be used more efficiently.
The underlying DOCSIS
®
commands used for
load balancing are DOCSIS Upstream Channel
Change (UCC), which allows an operator to
manually move a DOCSIS 1.0 cable modem to
a different upstream channel, and DOCSIS
Dynamic Channel Change (DCC), which allows
an operator to move a DOCSIS 1.1 or 2.0 cable
modem to a different upstream or downstream
channel.
Cable modems can be moved after registration
to balance the number of cable modems evenly
among the upstream channels of the CMTS
module so that the entire bandwidth can be
used more efficiently. Manual load balancing is
a labor-intensive process and provides limited
ability to support constantly changing loads on
CMTS interfaces.
STATIC LOAD BALANCING
This approach evenly distributes cable modems
across multiple upstream channels serving the
same geographic community or spectrum
group. The term “static” means that the CMTS
will only attempt to move a cable modem to
another upstream channel after the registration
process is complete.
When enabled, static upstream load balancing
occurs automatically to move a newly
registered cable modem to the least-loaded
upstream channel. Static upstream load
balancing is based solely on the cable modem
count on each upstream channel. It does not
take into consideration parameters such as:
• Whether the cable modem is a DOCSIS 1.0,
DOCSIS 1.1, or DOCSIS 2.0 modem
• Channel traffic utilization
• Upstream channel physical parameters; such
as channel type, channel width, modulation
profile, or mini slot size
• Reserved bandwidth for each service flow
• Channel quality
Cable operators need the ability to balance bandwidth on
multiple upstream or downstream ports accessible by diverse
populations of cable modems so that voice, video, and data
traffic is not adversely affected by a single downstream or
upstream port being over utilized.
Motorola BSR 64000 Cable Modem
Termination System/Edge Router








4
Highly Effective Bandwidth Management Using Dynamic Load Balancing

DYNAMIC LOAD BALANCING
Cable operators can evenly distribute traffic
across both upstream and downstream
channels within a defined load balance group
using dynamic load balancing. Cable modems
are moved from a channel with the highest
utilization to a channel with the lowest
utilization based on the actual bandwidth
utilization and cable operator-defined triggers.
The algorithm takes into account:
• The actual bandwidth utilization of each
channel that is configured for the load
balance group
• The actual bandwidth utilized by each
modem on the highest utilized channel
• The utilization thresholds
Successful deployment of dynamic load
balancing requires a CMTS/edge router that
delivers the intelligence needed to dynamically
balance loads based on diverse parameters.
Cable operators want to minimize the amount
of user movement between various channels—
but they also want to optimize bandwidth
efficiency. The ability to manage dynamic load
balancing according to clearly defined policies
can give cable operators the power and control
necessary to maximize bandwidth efficiency,
meet the real-time requirements of voice and
video traffic, and automate load balancing
despite constantly changing traffic conditions.
While static, upstream-only load balancing is
based solely upon the number of cable
modems, dynamic load balancing can be
implemented on both the upstream and the
downstream based upon bandwidth utilization
so that cable operators can most efficiently
utilize existing bandwidth.
CONFIGURING DYNAMIC LOAD
BALANCING
Each cable modem is connected to and uses a
specific port on a CMTS. The problem that
must be solved occurs when the bandwidth
usage between the multiple ports becomes
skewed so that one port is carrying a greater
load. Operators also have to address the
condition that occurs in instances when the
bandwidth is not skewed but the number of
subscribers on one port is much greater than
on the other ports.
The solution is to use dynamic upstream load
balancing on the BSR 64000. The DOCSIS 1.1
DCC command is used to adjust the load
between multiple upstream ports based upon
cable operator-specific policies. In addition,
MSOs can also balance DOCSIS 1.0 cable
modems using the DOCSIS UCC command.
Dynamic load balancing is implemented by the
BSR 64000 based on policies defined by the
cable operator. The BSR 64000 implements
dynamic load balancing by relying on the
DOCSIS specifications and adding
sophisticated algorithms that allow cable
operators to balance cable modem traffic
across multiple upstream or downstream ports.
A load balancing group is a cluster of either
downstream or upstream channels among
which cable modems can be autonomously
load balanced. The BSR 64000 assigns a cable
modem to a load balancing group upon
successful registration if the cable modem’s
channel is associated with that load balancing
group. MSOs must define load balancing
groups to be consistent with the physical plant
topology. Load balancing groups can also be
defined to support a restricted group of cable
modems that do not move.
The BSR 64000 implements dynamic load balancing by relying on the DOCSIS
specifications and adding sophisticated algorithms that allow cable operators to
balance cable modem traffic across multiple upstream or downstream ports.








5
Highly Effective Bandwidth Management Using Dynamic Load Balancing

For example, enterprise customers could be
assigned to receive a different class of service
than residential customers. Each enterprise
customer could be provided with DOCSIS 2.0
cable modems and they could be provided with
enterprise-class services with higher order
modulations. Residential subscribers sharing an
upstream channel with enterprise customers
can be moved to other channels. This allows
the operator to provide enterprise-class service
levels without disrupting services.
When the BSR 64000 is configured for dynamic
load balancing, select cable modems are
moved from a channel with the highest
utilization to a channel with the lowest
utilization based on the actual bandwidth used
and operator-defined utilization thresholds. The
algorithm takes into account the actual
bandwidth utilization of each channel that is
configured for the load balance group, the
actual bandwidth used by each modem on the
highest utilization channel, and the utilization
thresholds. The DOCSIS UCC command is
used to move DOCSIS 1.0 cable modems
between upstreams, but there are no
downstream moves possible for DOCSIS 1.0
cable modems. The DOCSIS DCC command is
used to move DOCSIS 1.1 and DOCSIS 2.0
cable modems across upstream and
downstream channels.
DEFINING LOAD BALANCING GROUPS
The BSR 64000 will assign cable modems to a
general load balancing group based on the
upstream channel on which they register.
Operators can also establish a restricted list of
cable modems which are used to
accommodate a topology-specific or
provisioning-specific restriction. For example,
an operator could establish topology-specific
restrictions, such as limiting the channels
available to cable modems that have to go
through many cascaded amplifiers because
they are unlikely to operate at higher
modulation schemes. Operators can also
accommodate provisioning-specific restrictions.
For example, a restricted list of customers that
would stay on their existing channels could be
established to accommodate business
customers or residential customers who have
been provisioned with voice services.
CONFIGURING LOAD BALANCING RULES
The BSR 64000 allows cable operators to
establish load balancing policies that provide
control over the autonomous load balancing
process on a per-cable modem basis. Each load
balancing policy is described by a set of rules
that govern the load balancing process. When a
load balancing policy is defined by multiple
rules all of the rules apply in combination. For
example, an operator could establish rules that
define the minimum thresholds for beginning
to rebalance load, the delta between channels
required, when to stop rebalancing load, and
the frequency with which these rules are
applied. Operators can reconfigure dynamic
load balancing rules via a Command Line
Interface (CLI).
Upstream modem count balancing—which
occurs upon modem registration— and channel
utilization balancing can work together, and
multiple rules can be applied to implement
dynamic load balancing. When modems come
online and register, the system will
automatically allocate modems so there is a
good balance of modems across the channels,
and the system can continuously implement
channel utilization balancing to rebalance cable
modems as needed to optimize the use of
each channel.
The system can continuously implement channel utilization balancing to
rebalance cable modems as needed to optimize the use of each channel.








6
Highly Effective Bandwidth Management Using Dynamic Load Balancing

OPTIMIZING DYNAMIC LOAD
BALANCING
Cable operators apply policies to load balancing
groups to optimize the use of bandwidth and
efficiently manage traffic on the Hybrid Fiber
Coax (HFC) network. Operations staff can
define the frequency with which dynamic load
balancing will be implemented and are
encouraged to minimize the number of load
balancing efforts required to avoid the risk of
service disruption. For example, the BSR 64000
will not move a cable modem that has been
moved consecutively during the last five load
balancing iterations to prevent a ”ping pong“
effect. By default, the BSR 64000 is designed
so that an eMTA will not be moved during an
active call. However, an operator can override
the default setting and configure the system so
an eMTA can be moved only when the highest
DCC technique can be used to eliminate the
remote possibility of impacting telephony
services.
The intelligent use of policies provides
maximum control over the implementation of
dynamic load balancing. For example, an
operator would want to implement dynamic
load balancing if one channel was operating at
70% and the other at 35%, but may not want
to implement dynamic load balancing if the
second channel was operating at 60% because
the delta would be too small. The BSR 64000
can provide great flexibility in defining the
triggers that initiate dynamic load balancing
according to policies.
Just as cable operators want to use load
balancing groups to define which cable
modems to dynamically balance, they will also
likely want to identify cable modems that they
would not like to balance. For example, a cable
operator will restrict business customers onto
channels that support higher-order modulation
schemes of DOCSIS 2.0 and higher
throughput. If the channels become over-
utilized, they will move residential subscribers
to other channels. The tremendous flexibility of
defining and enforcing policies can provide
cable operators with the ability to efficiently
balance the use of bandwidth for upstream and
downstream channels based on dynamically
changing traffic utilization load.
ADVANCED SPECTRUM
MANAGEMENT AND DYNAMIC LOAD
BALANCING
The BSR 64000 implements Advanced
Spectrum Management, an innovative feature
that provides cable operators with
sophisticated ingress noise cancellation, post-
equalization, sophisticated noise measurement,
and noise avoidance capabilities.
Motorola has architected a spare receiver—
RFSentry

—onto each DOCSIS CMTS module
to enable Advanced Spectrum Management.
An RFSentry receiver can monitor performance
of any one of the upstream ports without
impacting throughput. It can unobtrusively gain
access to all of the return nodes connected to
one of the receiver ports and perform tests on
any available modem on any one of the
receiver port’s supported nodes.
Advanced Spectrum Management monitors
cable modem performance and can be
programmed to establish a dynamic load
balancing session when necessary if RF
parameters degrade. For example, if the
upstream modulation profile is changed from
16 QAM to QPSK because of noise on that
specific upstream frequency, the bandwidth
automatically shrinks from 10.24 Mbps to
5.12 Mbps. In this case, it is ideal to rebalance
The BSR 64000 implements Advanced Spectrum Management, an innovative
feature that provides sophisticated ingress noise cancellation, post-equalization,
sophisticated noise measurement, and noise avoidance capabilities.








7
Highly Effective Bandwidth Management Using Dynamic Load Balancing

the load across multiple upstream channels so
that the cable modems on the affected
upstream are least affected by the imbalance in
the upstream spectrum. Advanced Spectrum
Management allows cable operators to swiftly
respond to spectral issues on the cable plant
and rebalance cable modems to support
evolving traffic requirements.
DYNAMIC LOAD BALANCING AND
CHANNEL BONDING
The emerging DOCSIS 3.0 specification will
include standards for channel bonding so that
operators can bond multiple physical channels
into a single, virtual, high-bandwidth channel.
This is achieved by statistical multiplexing of
multiple RF channels to create a single logical
channel.
Channel bonding enables increased throughput
between a cable modem and a BSR 64000 by
sending packets on multiple streams at the
same time. It uses a flexible, packet-based
algorithm for combining the capacity of multiple
upstream or downstream channels to achieve
the equivalent throughput of a wideband
channel, allowing cable operators to deliver
over 100 Mbps to individual cable modems.
Dynamic Load Balancing is complementary to
channel bonding. The real value of channel
bonding is that it allows operators to deliver
more bandwidth to an individual subscriber
than a single channel can deliver to a single
cable modem. The BSR 64000 includes support
for channel bonding and dynamic load
balancing, providing operators with maximum
flexibility in managing traffic load. While
channel bonding is ideal for servicing
subscribers who have requirements for very
high bandwidth applications—such as a
physician’s office that needs to share medical
imaging files—dynamic load balancing is ideal
for maximizing the use of existing channels and
moving cable modems when necessary to
continuously balance upstream and
downstream traffic.
SUMMARY
Cable operators can evenly distribute voice,
data, and video traffic across upstream and
downstream channels within operator-defined
load balance groups according to operator-
defined policies. The BSR 64000 offers robust
dynamic load balancing features that can give
cable operators the control necessary to
efficiently manage both upstream and
downstream traffic flows and avoid bottlenecks
and congestion.

The BSR 64000 can give cable operators the control necessary to avoid
bottlenecks and congestion.








Motorola, Inc.
101 Tournament Drive
Horsham, PA 19044 U.S.A.
www.motorola.com

MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. RFSentry is a trademark of Motorola, Inc. DOCSIS is a registered trademark of
Cable Television Laboratories, Inc. All other product or service names are the property of their respective owners.
©Motorola, Inc. 2006. All rights reserved..
534282-001-a
Voice and Data Solutions from Motorola
Dynamic load balancing is one of the many major features of the BSR 64000 that allow cable operators
to improve throughput, manage traffic, and deliver both residential and commercial services that can
provide the throughput and performance needed to reduce churn and capture customers.
For more information about the BSR 64000, please visit http://broadband.motorola.com.