When a telecommunications operator advertises an ADSL or fibre offer, what is presented is the nominal speed that can be achieved in theory but that rarely corresponds to the actual, often lower, performance.

For some time now there has been nothing but talk of fiber connectivity (FTTC or FTTH) but, overall, the areas of Italy where only an ADSL connection can be activated remain those in greater numbers.

Subscribing to ADSL offers therefore remains the only way to activate a broadband Internet connection for a large number of Italian users, both private and business.

In the case of Telecom Italia (TIM) connectivity, by visiting this page and going to the paragraph Compare the measured speed with the minimum value for your line you will find the complete list of offers marketed by the former monopolist.

By clicking on the commercial offer activated on your line, you can check the download and upload speeds guaranteed by TIM.

The most important data are those listed next to the items Minimum data transmission speed (minimum bandwidth) and Data transmission delay.

The minimum data transmission speed or minimum band) is the data transfer speed that TIM contractually undertakes to provide; data transmission delay is instead the time in milliseconds that elapses between a request sent to the first TIM hop and the subscriber.

In the article Internet Speed, how to verify it and what to do if the contract is not respected, we have presented all the best tools to verify the functioning of the connection; all the tools are used for an ADSL TIM test.

Here they are briefly presented:

  • speed test, check the speed of the connection quickly
  • reliable speed test: Google brings its own also to Italy
  • speedtest Fast.com
  • among the most famous instruments, of course, the OOKLA Speed test is still in vogue.

The only software tool that “trusts” to start a possible dispute against the provider is Ne.Me.Sys, developed by AGCOM in collaboration with Fondazione Ugo Bordoni (also presented in the above mentioned article).

If, after the ADSL TIM test, the connection is slower than contractually declared, the subscriber has the right to withdraw from the contract without the application of any penalty.

What Can Slow Down the ADSL Connection?

As we saw in the article From ADSL to fiber: what changes and what VDSL and vectoring mean, if the results of the test were not encouraging, the causes of a poorly performing ADSL connection are attributable to several factors:

Distance from the central unit. While for the FTTC fiber connections a scheme is used that foresees the use of the secondary copper network only in the last stretch, that is between the cabinet and the modem router of the user, in the case of traditional ADSLs the copper telephone pair reaches the central.

A particularly long cable, in addition to the “physiological” attenuation due to the distance, is more subject to the negative influences caused by interference along the way.

Line parameters such as attenuation and SNR significantly affect performance: as signal attenuation increases and SNR drops, download and upload speeds will decrease.

Signal-to-noise ratio (SNR). SNR relates the power of the useful signal to the noise present on the transmission medium, as we have seen in the article SNR: what it is, how to increase it and why it lowers on ADSL and VDSL.

Telecommunication providers generally use an SNR target of 6 dB: this means that we will try to establish a broadband connection as fast as possible by connecting higher carriers.

In many cases the Internet provider prefers to activate more conservative 12 dB profiles: the idea is to avoid that crosstalk or other impulsive interferences, therefore not continuously present on the cable, can cause disconnections due to a sudden reduction of the SNR.

If, examining the parameters of the modem router (usually found in the Status page of the configuration panel), a stable SNR at 12 dB is detected, you can try to ask the operator to enable the 6 dB profile in order to try the connection with a better carrier.

In the case of ADSL TIM 20 Mbps, for example, the profiles called i141 and F141 allow you to configure the line (ADSL2+ 22240/1215 kbps) with SNR 6 dB targets, respectively, in interleaved and fastpath.

The activation must be requested from the assistance of the telephone operator bearing in mind that the fastpath profile is used almost exclusively by those who love online video games and in particular multiplayer titles.

Poor quality system. To verify the real parameters of the ADSL line you should always use a modem router connected directly to the twisted pair that comes from the telephone exchange.

Carrying out an ADSL TIM test and comparing the values measured upstream with those found downstream of the system, you can see how much the wiring and connections inside the building help to slow down the connection.

The presence of noise introduced locally on the system will force the modem router to negotiate a lower carrier with the operator’s DSLAM.

And what are the first “suspects”? Certainly low quality telephone cables, poor telephone sockets, unshielded electrical cables in the vicinity, use of appliances that interfere with the signal transmitted on the telephone cable.

All elements that contribute to reduce, often drastically, the SNR value detected on the line.

Congestion on the output node. If the local network is “unloaded” (the connected users are not making data transfers either in download or in upload; no process in execution is occupying the network bandwidth) but there are evident slowdowns, especially at certain times of the day (at night everything seems to be very fast…), it is likely that the exit node of the telecommunications operator is particularly congested.

Unfortunately, TIM has recently disabled the possibility of launching the ping command on its IPs 192.168.100.1 and 192.168.200.1.

Even if not formally correct, we suggest to open the Windows command prompt (press the Windows+R key combination then type cmd) and then write:

tracert www.google.it

The first hop corresponds to the modem router in use while the Request expired at IP 192.168.100.1 or 192.168.200.1 that no longer responds to ICMP requests (neither Ping nor Traceroute). The other IPs within the TIM network (172.x.x.x) will also not respond to the ping command. The only solution is to query the first host outside the Telecom network: for example, the Seabone, the first node at the Italian MIX or the first IP address not included in the following ranges:

10.0.0.0 – 10.255.255.255

100.64.0.0 – 100.127.255.255

172.16.0.0 – 172.31.255.255

192.0.0.0 – 192.0.0.255

192.168.0.0 – 192.168.255.255

198.18.0.0 – 198.19.255.255

By typing ping -t followed by the previously noted IP, you can check the response time. If this is stable above 100 ms (especially if on average above 300 ms) in the absence of other data transfers, it is highly conceivable that there will be congestion at the output node level.

The advice is to contact the telecommunications operator and report high latency in the absence of data transfers.

To support your assertions, you can use the tool Ne.Me.Sys already mentioned above so as to certify unequivocally the performance of your ADSL connection.

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