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If you have any questions about the Nexus Watch service please see the sections below. If you still cannot find the answer, please email enquiries@nexuswatch.com and we will be happy to be of assistance.

Please choose a section:

General Questions
Free Trial
Nexus Watch Pricing
Tests
Events and Alerts

GENERAL QUESTIONS
I already have a network management system. Why should I use Nexus Watch?

Most network management systems are designed to monitor network equipment (hubs, switches, routers etc) from inside your network. Just because your network and servers are working, it doesn't necessarily follow that your customers can get to your site or that they are getting acceptable performance to keep them there.

Nexus Watch monitors your Internet services (DNS, HTTP, FTP, etc), over the Internet just as if it were an electronic customer connecting to your site from their home or office. It reports the true customer experience by measuring the end-to-end system, including the Internet itself.

What's all this business with multiple ISP's?
When you configure Nexus Watch to perform a test (eg: download a page from a web server), the test is performed through more than one ISP (Internet Service Provider) at the same time. The Nexus Watch pollers, which perform the tests, are each connected to the Internet via different ISPs. When a test is performed, the pollers are triggered to perform the same test at exactly the same time, but through different paths along the Internet.

This is a vital part of the test, and is one of the main differentiators between Nexus Watch and other services. If there is only one poller then we can never be sure whether performance or availability problems are that of the ISP or of the test subject. By examining results obtained through different ISPs we can obtain a much better picture of where performance issues lie. Using multiple ISPs also means that the Nexus Watch service is more resilient to Internet failures near the pollers.

Where are the Nexus Watch pollers located?
At the present time there are two Nexus Watch pollers, each installed in facilities in London’s Docklands and connected to different ISPs. There are plans to extend the service with more Nexus Watch pollers connected to multiple ISPs across the world. This will provide our customers with a view of the performance of their Internet based services from all around the world.

If you have an interest in seeing statistics obtained through a particular ISP, or from a particular geographical location please contact enquiries@nexuswatch.com. We are able to make special arrangements to suit your needs.

Does Nexus Watch require any hardware or software to be installed on my systems?
No. This is one of the key advantages. Nexus Watch acts just as if it were one of your customers. It accesses all of your services in the same way that they do, but can still obtain a large amount of important information.

Because no special hardware or software needs to be installed at your site, Nexus Watch offers the following benefits:

Very quick to set up. Management can be achieved just minutes from now!
Requires no investment in technologies that will quickly become outdated and need replacing.
Requires no specialist knowledge of setting up management systems.
Requires no operations staff to monitor the management systems.
Requires no downtime of your systems.

Can Nexus Watch harm my systems?
Nexus Watch is very safe. It only uses services that you have made available on the Internet. Unlike with most network or systems management, there is no connection to your internal networks or computers.

To protect you from accidentally setting a polling interval so low that it could put adverse load upon your server, the minimum polling interval is set to 5 minutes by default. Nexus Watch is capable of polling more frequently, and one of our operations team will be happy to reduce your minimum allowed polling interval upon request.

Does availability of bandwidth affect the results of my tests?
We ensure that Nexus Watch has more than enough bandwidth available at each of the pollers to perform all of the tests that our customers configure. The bandwidth used is continually monitored and upgraded well in advance of reaching the maximum allowed by the connections. The web interface is connected separately to the Internet, so heavy use by users will not affect results.

You can be sure that the statistics gathered are not skewed by the performance of the Nexus Watch system or its connections to the Internet. Of course the performance of the rest of the Internet will affect your results, but that is the nature of the Internet and the same applies to your customers connecting to your site. This is why Nexus Watch reports the true customer experience.

Does the performance of the Nexus Watch hardware affect the results of my tests?
No. The Sun Microsystems hardware that Nexus Watch runs on has plenty of performance capacity built in. In addition, all system statistics are continually monitored to ensure that your tests are unaffected.

What other services can be purchased with Nexus Watch?
For an additional fee we can provide a consultancy service to examine your statistics and write a regular report giving interpretations and recommendations.

Nexus Watch is a service provided by Parallel. Parallel is a specialist network management company that has the expertise and experience to install custom-built network management systems to suit any requirement. For further information call Parallel on 08700 727255, email enquiries@parallel.ltd.uk, or visit www.parallel.ltd.uk.

FREE TRIAL
Why are you having a free trial?
There are two reasons for this. Nexus Watch has been fully tested by our staff, but the best way to test the service in a real-life scenario is to let our customers use it. We don’t think that it would be fair to ask for payment during this period, so are offering the service for free.

We are eager to ensure that the service is providing what our customers want, and at a price that they regard as fair. To help us do so, we ask participants in the free trial to fill in a short on-line questionnaire which should take no longer than 5 minutes.

What will happen at the end of the free trial?
Signed up users will be notified at least 7 days prior to the beta testing period ending. When the beta testing period ends, all accounts will be disabled unless subscriptions are purchased. There is no obligation to purchase a subscription, and you will not automatically be charged. In return, all we ask is for you to email any comments that you have about the service to nexuswatch@nexuswatch.com

Will there be any difference between the service provided during the free period, and the service provided afterwards?
Yes, there will be some improvements. During the free period, we only permit you to configure two tests of each type. For the subscription service, the upper limit will depend upon the level of service purchased.

During the free period, sending of pages or SMS messages as alerts has been disabled. This is because sending alerts of these types costs us money for each alert, and with potentially thousands of users all sending messages it would not be cost effective to run the service.

We are planning on having some other tests available immediately after the free trial, and will continue to add other tests when the service is running.

Of course, we will also be working to incorporate any improvements following any suggestions from the participants in the trial.

NEXUS WATCH PRICING
What will the cost of Nexus Watch be after the free trial?
The pricing structure of Nexus Watch has not yet been decided in detail. We are very keen to ensure that the service is extremely competitive, and some of the questions that we ask on the registration questionnaire are designed to help us define a fair pricing policy.

We will email registered customers with the pricing policy as soon as it has been defined. Customers participating in the free trial will benefit from a discount. As an additional thank you, customers who send us comments about the service will receive an extra discount on top!

TESTS
What services can Nexus Watch measure?
At present, Nexus Watch supports the following services: HTTP, HTTPS, FTP, DNS. These are described in more detail in the following sections.

What services will Nexus Watch support in the future?
Our aim is for Nexus Watch to support every Internet service that is in use today, and to provide some clever analysis tools. We can also develop special tests that are specific to your site – even using proprietary protocols. Contact us for more information.

Modules currently under development are:
Transaction monitor. This module will record step-by-step processes that customers go through on your web site. For example; doing a search, adding a product to a shopping basket, entering credit card details, and completing purchases.
SMTP test. This module will measure the availability and performance of Internet mail servers, and time taken for emails to traverse the Internet.
Pattern matcher. This module will look for text patterns in web pages, and can catch server side script errors, check for expected results etc.
HTML syntax checker. Having incorrect HTML syntax in your web pages can cause some browsers to not render the page properly. The HTML syntax checker will watch out for these types of problems in your web pages, and look for browser-specific peculiarities that could affect your customers.
Link checker. There is already some link checking in the existing HTTP test. This new link checker will crawl around your whole site, traversing links and checking for broken links.
Database test. This test will measure the performance of back-end databases using some clever inference that will not require any equipment installing on your site.
Fault correlator. We will be building in some extra intelligence to analyse the results of all of your tests to draw conclusions about root causes of problems

What is the HTTP Test, and how does it work?
The HTTP test is designed for monitoring your HTTP servers and web pages. Unlike services offered by other companies, our HTTP test does much more than just downloading a web page!

Getting a web page successfully over the Internet depends upon a number of factors. First, the client browser needs to know the IP address of the server, and will use DNS to perform the lookup. Poorly performing DNS servers will affect their overall experience. There’s also the question of whether DNS queries and web pages have been cached somewhere along the line. In-line objects (JPEG’s, Flash documents etc) can be stored on different servers and will also affect the overall page response.

Nexus Watch takes all of these points into consideration, and performs a number of tests. The DNS response time is first tested. To ensure that the results are consistent, the test is performed twice and the second result logged. This ensures that any DNS caching that may be configured to occur anywhere along the path is taken into account. We can never prevent an intermediary system from caching the requests (as they are beyond our and your control), but we can force caching to occur if it has been configured to do so by repeating the test. This is the only way to produce consistent results.

Next, the web page is downloaded twice (for the same reason of forcing any possible caching to occur). The HTTP connection time is logged separately from the download time of the page and all of its in-line objects. This helps you distinguish between a slow network (where connection time will be high), and a possible slow server (where transfer rate is low, but connection time is low).

When you configure a report for a HTTP test, you are able to see the results of these “sub-tests”.

Of course, as with all of the Nexus Watch tests, the HTTP test is performed simultaneously via multiple ISPs to help you distinguish between problems with you system and ISP problems.

The Nexus Watch HTTP test supports downloading of pages that require logins. Just enter the login name and password on the test configuration page.

Nexus Watch will repeat the test at intervals set by the Polling Interval field on the test configuration page.

You may configure error and threshold events to watch out for, and optionally have Nexus Watch send you an alert if it sees them.

What is the HTTPS Server Test, and how does it work?
The HTTPS Test is exactly the same as the HTTP test, except that it is for secure HTTP transactions that use SSL.

Like the HTTP Test, the HTTPS test also supports logins.

What is the DNS Server Test, and how does it work?
The DNS Server test has been designed to monitor the availability and performance of a particular DNS server.

When you configure the test, you are asked for the DNS server address. You can supply either the fully qualified hostname (eg: dns0.mydomain.com) or it’s IP address.

The test is performed by querying the DNS server for it’s own address, which it will always know without the need for consulting other servers.

Because DNS uses UDP as the transport protocol, there is no such thing as a “connection time”. However, at Nexus Watch we feel that it is important to try and distinguish between network response and server response as much as is possible. The DNS Server Test therefore has a sub-test that performs an ICMP echo (“ping”) of the DNS server at the same time. Because a ping packet will not involve any processing by DNS software (such as “Bind”), it gives a metric for the performance of the network between Nexus Watch and the server.

Please note however, that depending upon the configuration of the server and the network to it, ICMP packets may be given different priority or may even be blocked. This sub-test is therefore of most value when you know the network configuration by your DNS server.

The test configuration also allows you to specify what to do if you don’t get a response. The very nature of UDP as a transport protocol can mean that not getting a response first time is acceptable (as it is a connectionless protocol). You can configure the amount of time to wait for a DNS response (the “timeout”). You can also configure how many times to retry (the “retry” value), and how much to increase the timeout by between retries (the “timeout multiplier”). Only after retrying the specified amount of times will Nexus Watch generate an event if there is still no response.

Nexus Watch will repeat the test at intervals set by the Polling Interval field on the test configuration page.

You may configure error and threshold events to watch out for, and optionally have Nexus Watch send you an alert if it sees them.

What is the DNS Lookup Test, and how does it work?
The DNS Lookup Test measures the speed of looking up a particular address, using the DNS system.

DNS is a globally distributed system comprising many thousands of servers all sharing information. What is most important to many companies is the speed at which their web (or any other) address is looked up using the system as a whole, and not the performance of a particular DNS server (which is covered in the DNS Server Test).

All Internet addresses are defined on an authoritative server first of all. The authoritative server for a particular address is the only server that can say with 100% certainty what IP address a particular host name has or vice-versa. Other DNS servers will either take occasional copies of the authoritative server tables, or they will ask the authoritative server when they are themselves asked. Queries can move up a chain of DNS servers in order to find the answer. Servers will normally cache responses for a period (the “Time to Live”, or “TTL”).

When you configure the DNS Lookup Test, you are asked to specify the address to lookup. This can be a fully qualified hostname (for a forward lookup, to get the IP address), or the IP address (for a reverse lookup, to get the host name).

As with all tests, Nexus Watch performs the DNS Lookup Test simultaneously via multiple ISPs. The DNS server local to each of the Nexus Watch pollers is queried for the address. This is performed twice by each poller so that caching of results does not produce inconsistent and misleading results.

The test then establishes the authoritative server for the address provided, and queries it directly for the address. Results are shown individually in the DNS Lookup reports.

The test configuration also allows you to specify what to do if you don’t get a response. DNS uses UDP as a transport protocol. The very nature of UDP means that not getting a response first time is acceptable (as it is a connectionless protocol). You can configure the amount of time to wait for a DNS response (the “timeout”). You can also configure how many times to retry (the “retry” value), and how much to increase the timeout by between retries (the “timeout multiplier”). Only after retrying the specified amount of times will Nexus Watch generate an event if there is still no response.

Nexus Watch will repeat the test at intervals set by the Polling Interval field on the test configuration page.

You may configure error and threshold events to watch out for, and optionally have Nexus Watch send you an alert if it sees them.

What is the FTP Test, and how does it work?
As the name suggests, the FTP Test is designed for measuring the availability and performance of FTP servers. Passive and active FTP servers are supported.

To configure the FTP Test, enter the URL (web address) of the file (eg: ftp://myftpserver.mydomain.com/pub/myfile). You may then optionally enter a login ID and password. If you do not enter these, then an anonymous login is assumed, and your email address will be given as the password.

In a similar way to how the HTTP Test works, the FTP Test records three metrics – the DNS lookup time, the connection time, and the download time. Recording these separately gives a much better indication of exactly where performance problems are occurring.

Nexus Watch will perform downloads at intervals set by the Polling Interval field on the test configuration page.

You may configure error and threshold events to watch out for, and optionally have Nexus Watch send you an alert if it sees them.

EVENTS AND ALERTS
What is the difference between an event and an alert?
An event is triggered by an error (eg: site not responding), or a threshold breach (eg: transfer rate is less than 1kb/s). You can configure what events you want Nexus Watch to look out for by going to the Configure Test page for each of your tests.

An alert is Nexus Watch informing you that an event has been triggered. For example you may wish to be alerted by email, pager or SMS to the fact that an event has occurred. Not all events need to generate an alert. You can configure an event to log only, and view the log by creating and event report.

What is the difference between a rising and falling threshold?
A falling threshold is breached when the test results fall below the threshold. For example, imagine a test is measuring HTTP transfer rate. You may consider that an acceptable transfer rate is 3kb/s, and want to be informed if the test yields a transfer rate which is lower than this. In this case you would need to set a falling threshold of 3.

A rising threshold is the opposite. The event is triggered if the test results are higher than your threshold. You may use a rising event for tests such as HTTP download time.

What is a re-arm value?
Using re-arm values minimises repetition of events caused by a test that is yielding results that are fluctuating around a threshold.

In the example above of a falling threshold of 3, imagine that the results were fluctuating around this value (eg: 5.4, 3.2, 2.4, 3.1, 2.7 etc), but in normal circumstances were above 4.0. We would not necessarily want to generate an event every time we got a value of less than 3.0, as the problem is likely to be caused by the same condition. If we set a re-arm value of 4.0, then Nexus Watch will create an event the first time the test yields a value of less than 3.0, but will not create another until the test first returns a value of more than 4.0 and then drops below 3.0 again.

Falling thresholds should have a re-arm value that is higher than the threshold. Rising thresholds should have a re-arm value that is lower than the threshold.

We recommend that you start with re-arm values that are 10% apart from the threshold.

What is meant by clearing an event?
For error events, such as a site not resonding, the event is said to have been cleared if the test is performed again without yielding the error.

For threshold events, such as a transfer rate dropping below 3kb/s, the event is said to have been cleared if the test is performed again and the results yield a value that is beyond the re-arm value. For example, for a falling threshold of 3.0 with a re-arm value of 4.0, the event will be cleared if the test next returns a value of 4.0 or more.

I have received an alert and am now taking steps to fix the problem. How do I stop Nexus Watch from sending me new alerts for the same event while I attend to the problem?
Go to the Events Summary page by clicking the Events button in the menu to the left of the screen. Find the event in the Event Report at the bottom of the screen. In the Alerts column, click the suspend button which looks like this: You can resume the alerts by clicking the resume button which will have replaced the suspend button, and looks like this:

What types of alert are available?
Nexus Watch can send emails, pages and mobile phone SMS messages.

Please note however that during the free trial, only email alerts will be available.

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