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Community Member

STM1

Hi,

I am bit confused with STM1 Standard,

is it 155 mbps or 126 mbps ? plz explain

(63E1 = 2 *63 = 126 mbps)

What is exact speed of STM1 ?

KS

15 REPLIES
Community Member

STM1

Hi,

This link is not sufficient to understand....anybody can explain in brief.

KS

Gold

STM1

try this one:

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

Don't conflate speed with capacity.

Community Member

STM1

What is difference between Speed and capacity in STM1 ?

Gold

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.

Community Member

STM1

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

Super Bronze

Re: STM1

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

STM1's bandwidth is about 155 Mbps.  STM1 has about 6 Mbps of overhead leaving about 149 Mbps for payload.

When you mux E1s into STM1, you introduce additional bandwidth overhead.

Also an E1 is rated at 2.048 Mbps, and there's a +/- allowance so the bandwidth consumption can be a little higher than your calculated 126 Mbps.

You can search the Internet for STM1 E1 muxes (for additional information).

Community Member

STM1

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

Super Bronze

Re: STM1

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

155

Community Member

STM1

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.........

Community Member

STM1

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

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

Cisco Employee

STM1

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,

Community Member

STM1

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

Community Member

STM1

Dear Kuldip,

  In STM there are 63 channels , each of 2mbps , so max bandwidth we can use is 63*2mb=126 Mb(129.024 Mb). So you can connect only 63 offices, each having 2 mb link or E1 line.Actual bandwidth of STM1 is 155mbps difference is utilised for signaling purpose.

Community Member

STM1

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. ?

Gold

STM1

that 29mbps is spread over all seperate channels. There is nothing to "configure" in this regard it is a standard.

The overhead is built in as part of the Synchronous Digital Hierarchy.

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