As your company grows, so does the number of users on your
network, and you may find yourself needing more bandwidth on your connection to
the Internet or your dedicated leased line connections to remote offices. But
you might not have grown quite enough, budget-wise, to move up to the next
level of connectivity, such as replacing your T-1 with a T-3. Instead, with
today’s bandwidth aggregation technology you may be able to purchase multiple
low-cost lines and combine them to give you the bandwidth you need, allowing
you to expand further (and gradually) as usage continues to grow.

How does bandwidth aggregation work?

Bandwidth aggregation is simple in concept: you simply
combine the bandwidth of two or more connections to provide a single
connection. Implementation can be simple or complex and can include load
balancing and failover.  Bandwidth aggregation
can be done via software, a dedicated appliance, or built into a broadband or
T-1 router. Consequently, bandwidth aggregation solutions vary in price from a
few hundred dollars to tens of thousands.

Combining multiple Internet connections to get more
bandwidth is not a new concept. In fact, Windows Multilink is a feature that’s
been around since NT and still exists in Windows XP and, at the time of this
writing, the Windows Vista beta. It only works with dialup modem connections,
but lets you attach two modems and phone lines to a computer (or a two-channel
ISDN line and adapter) and combine the bandwidth of both–if your ISP’s dialup
server is configured to support Multilink. You can even configure conditions
under which extra lines are used or disconnected to allocate bandwidth only as

A form of bandwidth aggregation commonly performed at the
ISP level is often referred to as channel bundling or link bonding. Many ISPs
offer “bonded T-1 lines, which is two or more lines aggregated to give you more bandwidth. Bonded
T-1s use Multilink Point-to-Point Protocol (MPPP), the same protocol used for
dialup Multilink. MPPP is a non-proprietary Internet standard that’s defined in
RFC 1990.

A different way of aggregating bandwidth is called
connection teaming, which establishes and maintains individual TCP/IP sessions
on multiple links instead of bonding the links. This involves a teaming server
on your local network that allocates TCP sessions to the available connections
to distribute Internet traffic smoothly across all the links. It allows you to
mix connection types (for example, analog modem and DSL or cable connections).

Saving money by aggregating broadband connections

Most businesses and home users in urban and suburban areas
today have abandoned dialup service for much faster broadband and/or much more
reliable dedicated leased lines. T-carrier lines have come down significantly
in price over the last several years, but a T-1 still costs an average of $400
per month or more. This is a cost that many small businesses can’t afford, so
they go with a broadband solution such as DSL, cable or new high speed options
like Verizon’sFiOS fiber
optic for Internet connectivity.

Broadband companies often offer “business level” packages
that give you static and additional IP addresses, symmetric downstream and
upstream transfer rates, terms of service that allow you to host servers, and
sometimes even service level agreements guaranteeing bandwidth speed and
uptime, at much lower prices than a T-1.

For example, Verizon has three FiOS business Internet packages ranging from 15/2 Mbps for
$59.95/month with a dynamic IP address to 30/5 Mbps for $389.95/month with up
to 5 static IP addresses. Comcast Cable has business Internet packages in some
areas ranging from $60/month for 4 Mbps/384 Kbps to $160/month for 8/1 Mbps.

A small business, if located in an area where they’re
available, can purchase both a mid-level FiOS
connection and a mid-level cable connection for around $100/month each and save
$200/month over a T-1. By aggregating the bandwidth, you get a much faster
connection, around 20 Mbps downstream and 3 Mbps upstream in comparison with
the 1.5 Mbps up and down for the T-1. And you have a backup connection if one
goes down. No wonder bandwidth aggregation is growing in popularity.

Bandwidth aggregation solution

There are a number of companies offering aggregation
solutions, usually in the form of a “load balancing router” or other network
appliance. There’s an appliance out there to fit every company’s budget. Some
examples include:

D-Link DI-LB604 Load Balancing Router

This is a good solution for small offices,
this broadband router includes two WAN ports to double your bandwidth capacity
and a built-in four port switch. It also includes Quality of Service (QoS), a built-in stateful packet
inspection firewall and integrated VPN gateway that supports
PPTP and IPsec pass-through. You can add more
switches as the network grows. It costs $179.00.

AstrocomPowerlink Pro

Multilink IP concentrators that provide load balancing and
failover that allows you to bundle up to three different broadband connections
for a total of 5 Mbps of aggregated bandwidth with the Pro 55 and over 100 Mbps
with the Pro 100. There
are several models
, costing from $1295 to $3995.

Symantec Gateway Security appliances

Firewall/VPN appliances that include intrusion
detection/prevention, anti-virus policy enforcement and Internet content
filtering. Some models, such as the 360/360R, have dual WAN ports for bandwidth
aggregation and load balancing. Costs $649 (model 360) to
$849 (model 360R).


This router clustering technology aggregates any combination
of T-1, T-3, DSL, ISDN and/or wireless over multiple ISPs and backbone networks
for up to 50 Mbps aggregated bandwidth. Provides load
balancing and automatic failover.

The future of bandwidth aggregation

Aggregating bandwidth doesn’t have to be limited to traditional
wired Internet connections. There are products that can aggregate wireless
connections, and more planned for the future. In fact, some amazing things are
being done with the bandwidth aggregation concept today. Microsoft IP Ventures
has made available for licensing something called Mobile Bandwidth Aggregation,
which combines bandwidth from multiple cell phone signals, even those from
different carriers and network types, to create one high-bandwidth Internet

For a company that’s looking for scalability in connecting
to the Internet, bandwidth aggregation can allow you to grow your bandwidth as
your bandwidth needs grow.