[cisco-voip] what is: "cablelength long 0db"

[Lelio Fulgenzi]

Thanks. I'll have to review that doc.

…
Don't look at me, my iPod maid that spilling mistake.

On 2010-08-23, at 6:21 PM, Nikola Stojsin <nikolas at networkmakers.com>  
wrote:

> Hello Lelio:
>
>
>
> If I remember correctly, SPServices adds SSH/SSL, ATM, VoATM, and  
> MPLS to IP Voice (which itself adds voice to the data-only IP Base)  
> etc.
>
>
> This white paper might be useful (especially ‘Cisco Image Packaging  
> section’, somewhere in the middle):
>
> http://www.cisco.com/web/about/security/intelligence/ios-ref.html
>
>
>
> As for the cablelength long 0db, that command does two things: (1)  
> compensates for the reception loss due to the cable length by  
> increasing the pulse of a signal at the receiver (26dB is the  
> default), and (2) tries to controls far-end crosstalk (in other  
> words, by attenuating the signal from the transmitter - 0dB here – i 
> t tries to keep sending and receiving signal within 7.5dB of each ot 
> her). To quote Cisco:  “Line build-out attenuates the stronger signa 
> l from the customer installation transmitter so that the transmittin 
> g and receiving signals have similar amplitudes. A signal difference 
>  of less than 7.5 dB is ideal.” In other words, you are amplifying w 
> hat you receive and reducing what you send in an attempt to reduce t 
> he difference in sending and receiving signal levels below 7.5dB, al 
> l in order to prevent crosstalk. Etc. Etc.
>
>
>
> If you do a quick sh controller t1 0/0/0 and see the following line: 
>  “Cablelength is long gain26 0db”, that means pulse increase of  
> 26dB of what the interface receives and 0db attenuation (no attenuat 
> ion) of what the interface sends. Your mileage may vary here, but I  
> have yet to see this command being needed at the normal PRI cable le 
> ngths; conversely, it can be a lifesaver if the cable is long (or –  
> more commonly! – provider signal is challenged).
>
>
>
> HTH,
>
> Nikola
>
>
>
>
>
>
>
> -------------------------------------------
>
> Nikola Stojsin
>
> PhD CCIE #12888
>
> President
>
> Network Makers LLC
>
> 110 Wall Street, 11th Floor
>
> New York, NY 10005
>
> (212) 709-8201
>
> (212) 706-2986 (fax)
>
> nikolas at networkmakers.com
>
> http://www.networkmakers.com
>
> -------------------------------------------
>
>
>
> From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip- 
> bounces at puck.nether.net] On Behalf Of Lelio Fulgenzi
> Sent: Monday, August 23, 2010 5:26 PM
> To: voyp list
> Subject: [cisco-voip] what is: "cablelength long 0db"
>
>
>
> I've got this on my new 3845, but it's not on my other one.
>
> controller T1 0/0/0
>  cablelength long 0db
> !
> controller T1 0/1/0
>  cablelength long 0db
>
>
>
> And another thing, why am I running "(C3845-SPSERVICESK9-M), Version  
> 15.0(1)M2"
>
> isn't SP mean ServiceProvider? I'm sure I didn't ask for this.
>
> What are people normally running on their branch voice routers ???
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
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