Tech FAQ

how many e1in one stm1
how many e1 in one stm4
how many e1 in one stm16

By aminjan on Sep 8, 2009

As E1 is 2.048Mbps and Stm1 is 155.55mbps
so 155.55/2.048 should be the number of E1 in one stm1 it is logical according to my knowledge.

By Sultan Hussain on Nov 10, 2009

One STM-1 is 155.55 and one E1 is 2.048 if we just divide 155.55 by 2.048 we get 75.9 E1s which is not correct. the thing is that we are dividing in decimal where one kilo is 1000 but but when we say kilo byte then this kilo is 1024(binary) not 1000. That’s why we get less E1s and that is 63

By Zahid on Nov 20, 2009

To Zahid: Well Answered

By Arsalan on Nov 28, 2009

Hi Sultan, m not agree wid your ans becos both side having same unit(mbps/mbps), so it will not effect the overall result so how u can say that? cud u expln to me?

By Atul sharma on Feb 5, 2010

so there is one question..why STM-1 is not= 63E1 =155.52 Mbps

By Ziad on Aug 22, 2010

hi zahid i m not agree with ur answer bcoz even one E1 is 2Mbps and Stm-1 is 155.52 Mbps then deviding 155.52Mbps by 2.048Mbps we get 75.9 only u should check it.

By vivek jadhav on Sep 17, 2010

1E1=2.048Mbps

STM1=63 E1…

AND STM4=4*STM1=63*4E1s

bUT ITS NOT THAT EASY…
In SDH there is a lot of header data…

By Syed Khyzer Ali Abidi on Nov 8, 2010

dearsm

1 stm1 is 63e1 because there is some header should add, it means 1 stm1=63e1+header

By farhad on Nov 29, 2010

what is Diffrence Between 1STM and STM1
and also STM electrical what Mbps..

By zameer on Dec 9, 2010

i agree with mr. farhad
his answer in correct.

By izhar kazmi on Mar 19, 2011

Calculation of number of E1 in an STMN frame are not the result of the simple division of total STM capacity into E1 capacity, because you need to remove ALL the different headers (MSOH, RSOH, POH) and pointers… that’s what makes SDH so different from PDH, the additional data you put into the frame so that it can be extracted without decomposing the whole frame, but just taking the E1 that you need.
In summary:
STM1 = 63 E1s
STM4 = 4×63 E1s
STM16 = 16×63 E1s… and so on.
Good day.

By Richard M. on Nov 27, 2011

There are total 64 E-1’s in one STM-1 card,
from which
1 is used as header
and remaining 63 are world wide known,

Higher levels go up by a factor of 4 at a time: the other currently supported levels are STM-4, STM-16, STM-64 and STM-256. Beyond this we have wavelength-division multiplexing (WDM) commonly used in submarine cabling.

Hope you all got your answers.

By D on Dec 24, 2011