As the distance between locations increases over the WAN, especially for remote international sites with low-speed transport services, or where there are long backhauls, application performance degrades. This has less to do with the available bandwidth, and more to do with the time it takes to send and receive data packets over distance, data receipt acknowledgements required by some protocols before sending the next segment of data, and the number of times data must be retransmitted due to packet loss.
To counter such challenges, enterprises deploy WAN optimisation solutions. A common misconception persists that SD-WAN reduces or eliminates the need for WAN optimisation techniques. The reality is that SD-WAN and WAN optimisation solve fundamentally different problems, and they are complementary when deployed in unison.
Geographically distributed enterprises
with locations worldwide can experience impaired application performance for
critical, latency-sensitive TCP/IP applications such as transaction processing
or data backup caused by excessive round-trip delays. Network latency is
primarily caused by geographical distance between sites, and additional
bandwidth does not change the laws of physics.
According to Warren Gordon, ARUBA/HPE Business Unit Manager at Duxbury Networking (local distributors of ARUBA/HPE technology): “Geographically spread-out companies face a common problem: their computer systems slow down when they try to work together from different locations worldwide. This happens because the data takes a longer time to travel over long distances, leading to delays and sometimes even losing some data along the way. To solve this issue, businesses use two helpful tools. Firstly, SD-WAN helps them connect their systems securely and quickly. Secondly, WAN optimisation ensures that their applications work faster and more efficiently.
“Duxbury understands these challenges.
That’s why we offer an SD-WAN solution that not only ensures a smooth
connection but also works hand-in-hand with WAN optimisation to ensure
everything runs seamlessly, no matter where you are in the world. With this
solution, our customers can enjoy better performance and smoother operations
across their company's locations.”
By
deploying a virtual instance of Aruba EdgeConnect Enterprise SD-WAN appliance
in the public cloud, and enabling Aruba WAN Boost optimisation, enterprises can
overcome application and network latency performance problems, and accelerate
cloud-hosted applications and data transmission to the cloud from anywhere.
As
enterprises migrate more and more in-house applications to public cloud
environments, they need to address the network latency limitations encountered
while connecting to IaaS workloads. In cloud environments, the physical
location of the company’s server and the IP address or subnet might change at
any time.
With
Aruba WAN Boost, enabled on a virtual instance of the Aruba EdgeConnect
Enterprise SD-WAN edge platform, enterprises can leverage the WAN optimisation
techniques to ensure seamless public cloud integration, even if the server IP
address or subnets change, allowing enterprises to take full advantage of the
flexibility of the cloud, without any concern for application performance.
Aruba WAN Boost accelerates
data movement between data centres, branch offices, and the cloud. It uses real-time
optimisation techniques to overcome network quality, capacity, and distance
challenges, resulting in fast and reliable access to information, anywhere in
the world. Aruba WAN Boost key WAN optimisation features include:
1.
Latency mitigation via TCP protocol
acceleration techniques that improve application response times over distance.
2.
Data reduction techniques that include
compression and data deduplication mechanisms to reduce the amount of data that
traverses over WAN links.
TCP Protocol acceleration can improve
the performance of latency-sensitive applications, and data reduction
techniques provide benefits when transferring large data sets, especially
between geographically distributed locations.
Aruba
WAN Boost is integrated with Aruba EdgeConnect Enterprise and is not a separate
VNF for the sole purpose of supporting WAN optimisation. The flexible Aruba WAN
Boost consumption model provides WAN optimisation for applications where and
when it is needed.
Aruba WAN Boost is enabled in the business intent overlay configuration for classes of critical applications that benefit from it, and it is usually not enabled for applications that do not require WAN optimisation such as less latency-sensitive or real-time applications like voice and video conferencing.
TCP
protocol acceleration techniques
TCP
is a connection-oriented and rate-limiting protocol, which is widely used in
data networking and on the internet (for example, HTTP, HTTPS, SCP/FTP and
SMTP) and plays an integral role in determining overall network performance.
TCP
maintains a window that dictates how much traffic can flow over a connection.
The TCP window is the amount of data a sender can send on a path before an
acknowledgment is sent back from the receiver. TCP starts with a small window
size and gradually increases the window size until an acknowledgment isn’t
received within a specified time period. When this occurs, TCP assumes network
congestion and packet loss. The protocol responds by re-transmitting the lost
data packet and decreasing the window size.
Typically,
TCP has a 16-bit window field that is used by the receiver to inform to the
sender how many bytes of data the receiver is willing to accept. In standard
TCP implementation, the window field is limited to 16 bits, supporting a
maximum window size of 65,535 bytes.
Aruba
WAN Boost WAN optmisation software supports a window scaling feature that
delivers window sizes as large as 1GB, overcoming the throughput limitation
imposed by the standard 64KB TCP window size. This allows users to send more
data per flow, making most of the available bandwidth.
Round-trip
time (RTT) is the duration in milliseconds (ms) it takes for a data packet to
go from a starting point to a destination and back again to the starting point.
Aruba Boost employs a round-trip measurement scheme that enables more efficient
RTT calculation for more accurate RTO (retransmission timeout) measurements to
improve network throughput.
The
TCP acknowledgment system can’t handle multiple lost segments; it only
acknowledges the last successfully received segment leading to the
retransmission of data that was already received by the receiver. To counter
this, Aruba WAN Boost supports a Selective Acknowledgment (SACK) mechanism in
which only the necessary packets, that never reached the receiver, are resent.
This drastically improves network performance as fewer packets are
retransmitted, and results in efficient use of bandwidth.
Aruba
WAN Boost offers high-speed TCP, a modification to the standard TCP congestion
control technique. In high-speed TCP, the TCP congestion control alters how the
congestion window, which regulates the times at which the segments are sent
into the network, is opened on each round trip, and closed on congestion events
for better performance in high-bandwidth, high-latency environments.
Aruba
WAN Boost optimisation delivers the technology needed to improve WAN
performance and offers end users a LAN-like experience. Data reduction
techniques allow enterprises to achieve superior application performance over a
hybrid WAN comprising MPLS, internet and 4G/5G/ LTE connections. The data
reduction techniques include data compression and deduplication that eliminate
the transmission of any redundant data, thereby improving WAN performance.
The
WAN is no longer just a pipe that connects point A to point B; it has become a
strategic asset that enables employees to be more productive, businesses to be
more competitive, respond more quickly to customer and industry demands, and
serve as a foundation for whatever innovations might evolve next. The challenge
of delivering applications to users at branch offices and data centre sites
with high performance has not gone away. The rise of cloud networking, SaaS
applications, and IaaS workloads has made the issue more complicated. Aruba
EdgeConnect Enterprise with Aruba WAN Boost can improve the connectivity to
cloud-based applications, accelerate performance, and optimise bandwidth
utilisation between branch offices, enterprise data centres, and public cloud
environments.
“We
work closely with our customers to understand their specific needs and
challenges. Aruba EdgeConnect is our top recommendation for SD-WAN because it
effectively addresses the performance issues of geographically distributed
enterprises. Its application-driven approach prioritises critical applications,
while WAN optimisation further enhances network efficiency, resulting in
improved performance and productivity across the entire network,” says Gordon.