Fresh Telecom Algorithms Interview Questions & Answers:

1. How to calculate signaling threshold? I mean to say that how much traffic it can sustain. If it overloaded then what will happen? How can we decide there are requirement of another signaling link in the same Trunk Group?

it is depends on type of links we are using(Ethernet,
STM1,STM2,STM4 etc.) so we can deside the threshold of the
link,we can also check the links traffic.
if links overload than it will drops the pakets. we have to
upgrads the links.

2. Tell me Why the STMs in multiple of 1,4,16,64?

I think you have to study SDH network to understand the answer of this question.I am giving the formulae by which the STM-N is generated.

STM-64: 64 VC-4 or 16 VC-4-4c or 4 VC-4-16c or 1 VC-4-64c
STM-16: 16 VC-4 or 4 VC-4-4c or 1 VC-4-16c
STM-4: 4 VC-4 or 1 VC-4-4c
STM-1: 1 VC-4


Higher-level STM-N frames can be simplistically perceived as *4 multiples of a basic STM-1. An STM-4 is constructed by byte-interleaved multiplexing of 4 STM-1s into a frame that is 9 rows by 1080 columns wide. The STM-4 signal has a line rate of 622.080 Mbps (4 * 155.520 Mbps). The four STM-1s (STM-1(1), STM-1(2), STM-1(3), and STM-1(4)) are frame aligned before multiplexing. Frame alignment is achieved by ensuring that the first 12 bytes of the STM-4 signal are A1 framing bytes drawn from STM-1(1), the next 3 from STM-1(2), then 3 from STM-1(3), and finally 3 from STM-1(4). The 12 A1 framing bytes are followed by 12 A2 framing bytes that are obtained from the 4 STM-1s in a process, similar to the way that the A1 bytes were obtained.