[c-nsp] Re: DS3 framing: M13 vs. C-bit

[ringwyrm27]

C-Bit has a channel in overhead called the MDL (maintenance data link) that 
allows for the passing of FEAC codes like the FDL does on a T1.  It also 
allows for the passing of G.832 type messages (error counts and so on).

C-bit/MDL allows telco to perform remote testing on the DS-3 by logging into 
a mux and just shooting the loop up/down codes down the MDL.  I don't 
believe that M13 allows for this.

----- Original Message ----- 
From: "John Neiberger" <John.Neiberger at efirstbank.com>
To: <cisco-nsp at puck.nether.net>
Sent: Tuesday, January 18, 2005 12:40 PM
Subject: [c-nsp] DS3 framing: M13 vs. C-bit


>I don't have  a lot of experience with DS3s and I have a minor problem
> that I need some help with. We have a point-to-point DS3 with both
> endpoints set to M13 framing (Cisco 7513 PA-T3+ and a Kentrox IDSU).
> This link involves two service providers. Qwest says that we are
> provisioned for M13, as well. However, Time Warner at the other end of
> the link seems to think we're provisioned for C-bit. My question is
> this: does that matter?
>
> We see a highly intermittent burst of errors from time to time but
> other than that we don't see a problem. It can run for days or weeks
> without a single error and then we'll see a blip of a couple thousand
> errors, after which it runs cleanly again. Is it possible that this
> problem is caused because of c-bit being used on the Time Warner side of
> that part of the link?
>
> We have three potential courses of action:
>
> 1. Get Time Warner to switch to M13
> 2. Get Qwest to switch to c-bit and change our end devices to c-bit
> 3. Do nothing since the errors are brief and infrequent
>
> What do you think? Could the framing mismatch cause a problem, perhaps
> similar to an AMI/B8ZS mismatch in the DS1 world?
>
> Thanks,
> John
> --
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