Slow PTCL DSL Solution during Submarine Cable Cut

Many internet users in Pakistan, particularly those using PTCL Broadband were left in extreme agony last night when their internet lines started failing—connections timing out, websites not loading and the refresh button getting abused!

It was due to a submarine fiber optic cable fault, one of those high-speed undersea cables through which PTCL runs its traffic. The particular culprit was SEA-ME-WE-4, also called SMW4. It’s not the first time that PTCL users had to bear this torture of slow internet due to a cable fault, last time it occurred was in 2013 and that too was a fault in SMW4.

Thankfully, though, Pakistan doesn’t rely on only one cable to connect to the outside world. It has multiple submarine cable links like TW1 (which is operated by Transworld Associates) and SEAMEWE3.


During cable outages, which mostly occur on SMW cables affecting PTCL users, the ISPs using Transworld Associates’ fiber optic cable (TW1) are usually able to provide their services at full capacity without any degradation. This is exactly what happened yesterday too; PTCL users were suffering because the outgoing links were degraded. However, those ISPs routing their traffic via TW1 were spared from the disaster.

The one I use is Zong. Yes, I was using Zong’s 3G service and its service quality was great. On the other hand, I was struggling to load even a single 800 kB page on my PTCL broadband connection.

Here’s how you can identify through what cable your ISP routes traffic. I’m posting a traceroute to, which shows that packets leave the country through TW1 while on Zong:

Zong TW1 submarine cut

As you can see, on the 6th hop, my packets are being routed via TW1 cable.

This was for Zong—I’m not sure what other ISPs use for their internet connectivity. Can anybody shed some light on Telenor, Ufone, Warid and Mobilink?

Any traces would be great! The command you put in Windows’ command prompt is tracert while on Linux it is traceroute.

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Ehtisham Siddiqui

Blogger and a techie. WordPress, cricket and aviation freak. Love traveling!

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