4. METODOLOGÍA
4.6. Procedimiento de ejecución del estudio
The program logs all network traffic and gives daily, weekly and monthly traffic reports. For simple calculations the free download version of the Broadband Monitor is available at
-http://www.bwmonitor.com/index.htm.
Ping is a general tool available in Windows to check destination availability.
The following destinations should be calculated,
- ISP site - the website of the service provider
- National site - well-known sites within the country - preferably hosted by some other ISP
- Global site - well-known global sites such as Google and Yahoo which are hosted outside the country.
The indicators should be calculated at different times. The time periods are selected in a manner that enables the analysis of quality from a low usage period to a heavily used period.
5.2.1 Broadband Download Speed (Kbps/Mbps) Definition
One of the key advertised metrics in broadband services is the download speed, which defines the maximum traffic a subscriber can receive. The performance of many residential applications such as Web-browsing and downloading content also depends on this metric. Attempts should be made to measure the actual download speed available to the subscriber.
Comments
The download speed is measured by downloading a 10MB file from the mail attachment using a standard Web browser, and by calculating the average download bandwidth using network measuring tools like Bandwidth Monitor.
Normally the downloading software will indicate the download speed, but this does not include TCP/IP header and other overheads. Therefore, tools such as Bandwidth Monitor are used, as they measure the bandwidth by snooping the raw packets that are getting transferred. (Note: The download speed advertised by the operator is a raw bandwidth).
5.2.2 Broadband Upload Speed (Kbps/Mbps) Definition
This is the upstream speed for a broadband Internet connection. This metrics defines the speed at which the subscriber can send traffic to the Internet. Upload speeds plays a significant role in responsiveness and real-time applications such as VoIP.
Comments
Proposed Methodology
Prerequisites:
The respective E-Mail accounts on the ISP, National and Global sites are expected to have free space to upload a 5 MB attachment file.
Test Procedure:
With a stand-alone application, the upload speed can be measured by uploading a 5-MB file to a YAHOO Mail application, and by calculating the average upload bandwidth using standard measuring tools such as Bandwidth Monitor.
Standard tools such as Bandwidth Monitor are used, as they measure the bandwidth by snooping packets. The reasons for doing this are explained in 5.1 on Download Speed.
5.2.3 RTT (Round Trip Delay) - Milli-Seconds Definition
This is the time taken for traffic to reach a particular destination and return. The round-trip delay time is significant in systems that require two-way interactive communication, such as voice telephony, or ACK/NAK data systems, where the round-trip time directly affects the throughput rate, such as the Transmission Control Protocol (TCP).
Comments
The initial Ping packet will also take more RTT, for reasons such as a delay due to ARP
resolutions. However, considering the speed of the Internet and the sampling base, this error will be insignificant.
5.2.4 Jitter (Milli-Seconds) Definition
Jitter is the fluctuation/variation of an end-to-end delay from one packet to the next packet within the same packet stream/connection/flow. Jitter experienced by the packets is more relevant for real-time traffic such as VoIP.
For example - radio quality voice requires less than 1 ms Jitter, toll-quality voice requires less than 20 ms jitter, normal VoIP requires jitter to be less than 30 ms. Beyond 30 ms, the VoIP performance will be low.
(Source:
Ensure that the Ping traffic to the test-sites is not blocked by a local firewall, and that the sites are reachable.
Test Procedure:
Use the same result as that received for RTT using Ping. The result of the Ping output is saved in a file. M = ARTT is the average RTT, derived out of 1000 samples. If r1, r2 … r1000 are the RTT for individual packets, then the Jitter is derived using the formula given below.
k = 1000
∑ | M – r
k| / 1000
k = 1
In the above formula, rk is extracted from the Ping result stored in the file.
5.2.5 Packet- Loss (as a Percentage)
Definition
This is the number of packets (as a percentage) which do not reach their destination. Packet-loss can result in highly noticeable performance issues with Streaming Technologies, VOIP,
videoconferencing and so on, and will affect all other network applications to a degree.
Comments
Proposed Methodology
Prerequisites:
Ensure that the Ping traffic to the test-sites is not blocked by a local firewall, and that the sites are reachable.
Test Procedure:
Ping software is also used to calculate packet-loss. After having calculated RTT and Jitter, Ping provides a summary of the total number of packets transmitted, packets received and the packets lost in terms of percentages.
5.2.6 Broadband Availability (as a Percentage) Definition
This indicates the number of times broadband services can be accessed. Network non-availability can happen due to various reasons like line failure, AAA failure, backhaul failure etc.
This metrics indicates the reliability of the broadband service. During testing if T attempts are made to connect to the Internet, and if F times the attempt failed, then:
Availability = (1–F/T) x 100!%
An attempt is declared as a failure if a connection to the Internet cannot be obtained within 30 seconds.
Comments
Proposed Methodology
Network availability is measured by checking accessibility to the Internet. The experiment should be run on each ISP/Packages 6 times a day (if the Internet is not reachable, the number of attempts may need to be extended). Hence if T is the total number of times the experiment is conducted for an ISP/Package, and F is the number of times the Internet is unreachable, then the availability for that ISP/Package is calculated as follows.
(1–F/T) x 100%