try this one:

http://www.wisegeek.com/what-is-stm-1.htm

Don't conflate speed with capacity.

What is difference between Speed and capacity in STM1 ?

the bandwidth measure is how much data in a given moment of time can be carried over a circuit.

In your case the maximum is 155mbps.

The speed will be a function of the sum of propagation delays, serialization, tcp window...and on and on.

http://broadband-nation.blogspot.com/2007/06/speed-vs-bandwidththe-age-old-question.html

thats one discussion, there are many more.

But maximum limit of STM1 is only 126 mbps then how can STM1 carry 155 mbps data over it.......

Hi Joseph,

Actually my client is asking this question many times and they want exact answer then what i will tell them  ?

126  or  155  Mbps ?

KS

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155

Can i connect 77 Branch office from head office where STM1 link terminated ? and

Each branch offices require 2 mbps pipe. As you stated that STM1 support 155 mbps

that means i can distribute or use  77 *2 = 154 mbps for all offices ?

Plz correct me if i am wrong.........

STM1 pipe uses which Medium :  Fibre or Copper or both ?

Can anybody explain STM1 with best explanation in terms of mbps ? 126 or 155 

STM-1 pipe can be used with copper media also but due to distace limitation we don't prefer it.

For STM-1 multiplexing from VC12 to STM-1, please check the doc:

http://www.cisco.com/en/US/docs/optical/15000r3_0/15305/install/guide/305R1C5.pdf

thanks,

Can anybody explain STM1 with best explanation in terms of mbps ? 126 or 155 

You mean to say that 155-126 = 29 mbps will be used for signalling, Payload, overhead and etc.

i think it is wastage of 29 mbps. we can use even less mbps for such purpose.

who is responsible for configuring 29 mbps,  ISP end or  Branch offices Router end. ?