Product Review
The Netropy N61
Apposite’s Netropy N61 Delivers
an Amazing Value Proposition
BY TMC LABS
M
any organizations today comprise several offices of
various sizes in disparate parts of the country and the
world, and these offices are typically interconnected
using WAN links obtained from telecommunication outfits.
network port of a laptop. Once the laptop
is configured for the same network address as the one pre-configured on the
appliance, the GUI management program
can be accessed over a browser.
So, how does one go about making sure
applications that work smoothly over a
LAN, also work within acceptable limits
over WAN lines? Enter WAN emulators,
such as those from Apposite Technologies. Apposite makes network emulator
appliances that can be utilized to simulate
a variety of WAN conditions for testing
network infrastructure and applications.
Documentation
The appliance was shipped with a quick
start guide card, which we found quite useful to get us started. The product overview,
hardware, and user’s guide are available
as PDF files online. The user’s guide is also
available from the N61’s GUI interface. We
found all documentation up-to-date and
very comprehensive. Apposite’s website
(www.apposite-tech.com) also provides a
demo video for the product, as well as a
guide to compare various Netropy models.
Apposite’s two main lines of products are
Linktropy and Netropy. While Linktropy is
used to simulate one WAN link, Netropy
can simulate up to 15 different WAN links
(paths), allowing for more robust and
realistic tests for larger organizations.
The Netropy N61 contains one emula-
tion engine between the two available
ports. To utilize the emulated WAN links
(paths), packets can be assigned to different links by IP address, range, VLAN, or
other packet identifiers.
Installation
The Netropy N61 is a 1U tall appliance,
so rack installation is simple and painless. Starting the appliance was as easy
as plugging it in to a power outlet. The
Netropy N61 provides two methods of
management. The first is through a CONSOLE port, using a null modem and SSH
terminal. The more modern way is via the
MGMT Ethernet auto-sense/auto-negotiate port, which can be connected to the
Testing
We set up two simple networks with
host1 and host2 using the same subnet
and connected them to port 1 and port 2
of the N61 respectively. We started an infinite ping between the hosts and observed
that packets were traveling without delay.
Next, we added a path (emulated WAN)
by changing various parameters to simulate real-world conditions and observing the effects on the traffic. For traffic
generation, we mainly utilized the ICMP
ping protocol and FTP file transfer.
In one test, we started the FTP file transfer with the path bandwidth at 10Mbps
and suddenly changed the bandwidth to
1Kbps. This caused an immediate packet
loss situation and network sluggishness.
22 INTERNET TELEPHONY®
March 2016
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Product Review
In another test, we introduced random
background traffic of 50 percent using the
background utilization feature of the N61
and observed commensurate packet loss
and slowness as well.
Continuing with our tests, we introduced
various forms of delay of 50-500 ms to
emulate latency and jitter. We observed
rising packet losses as we increased
delay time. We also simulated packet
loss of various kinds (random, burst, and
periodic) and various values and verified
instant loss of packets and network delay.
To measure packet loss and bandwidth
utilization, we also used other network
diagnostics applications such as PingPlotter and WinMTR. The figures here show
some of the results that we captured
during our emulation tests.
The N61 has many more configuration
options to fine-tune the path, and we
were able to test and verify the functions
of some of these additional settings.
As previously mentioned, N61 is capable of
supporting 15 separate emulated WANs.
To do that, packets can be classified using
a variety of methods, such as IPv4 or IPv6
addresses, VLAN, MPLS, MAC address, and
IP/port combinations. We used the first
method of IPv4 classification to establish a
new path and were able to verify its operation alongside our original path.
One of the extremely useful features of
Netropy emulators is the ability to simulate
real network conditions using a previously
recorded network session. To achieve
this goal, the operator uses the Netropy
Recorder utility on a Windows or Linux
host and saves a snapshot of the network
activity to a recording file, which can also
be altered manually. At a later time, the file
can be loaded into a Netropy emulator via
the GUI for playback within a path.
The figure atop page 25 shows the recording of a network session in our labs
over a period of time. We then saved the
session as a recording file and successfully loaded it into the N61 for playback.
Ease of Use
We found the GUI interface very intuitive
and self-explanatory. The N61 comes
with a comprehensive set of parameters
to configure the simulation properties.
While this makes it possible to simulate
a variety of conditions, it can also be
daunting to configure the parameters.
The user’s guide is a great reference to
decipher all the GUI options. However,
we wished context-sensitive help were
available within the various sections of
the GUI. That would be especially useful
for more novice users.
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March 2016
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Apposite does offer a second, simpler
line of emulators, its Linktropy offer, with
fewer features and an information button
for each parameter. The company says
it typically recommends novice users
consider the Linktropy products.
Support
All Netropy products include one year of
maintenance, including customer support
and firmware upgrades. Extended maintenance contracts are also available from
Apposite or local resellers.
Quality
Throughout the installation and testing
phases, we were pleased with the hardware, as well as the GUI of the N61. The
appliance boots up quickly and the GUI is
responsive. Configuration changes are in
real time and could be saved to a file on
the management PC for future playback.
Room for Improvement
N61 is a comprehensive and robust
appliance and, in our opinion, excels in
WAN emulation. Some improvements
would be more precise help and guidance for the various functionalities and
modes of operations. Also, it would be
nice if the appliance could remember its
settings if it were to suddenly lose power.
Such a recovery feature would allow the
device to be booted back up and resume
its operation without further need to
reconfigure the device to its last state.
Value
The Netropy N61 offers an amazing
value proposition for the work that it
does. Capable of supporting 15 different
emulated WANs with a variety of configurations, the N61 is an indispensable
tool for organizations to test and verify
their applications over a nearly unlimited variety of network conditions. The
N61’s entry-level appliance, at around
$10,000, supports bandwidth levels of
up to 100Mbps. Licensing with additional cost will be required to support 1Gbps
bandwidth, bringing the price to around
$15,000. For more powerful testing
and emulation, Apposite Technologies
offers more advanced Netropy models
to emulate bandwidths up to 40Gbps.
The previously mentioned Linktropy line
starts at under $2,000. IT
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RATINGS
MY SCORE
Ease of Install
Testing
Ease of Use
Quality
Value
Overall
March 2016
INTERNET TELEPHONY® 25