[c-nsp] 2821 VWIC2-2MFT-T1/E1 clocking issue

[sthaug at nethelp.no]

> Second E-1 on the WIC shows slips.  It appears that "clock source line" 
> doesn't do what it should, or somehow the first E-1 is clocking both 
> circuits.  Physically disconnecting the first E-1 fixes the slips on the 
> second.
> 
> Bug?  Misconfiguration?  Hardware limitation?

When I was working with the previous generation of the WICs on 1700
routers (several years ago), this was indeed a hardware limitation,
and was also documented.

However, for the VWIC2-2MFT-T1/E1 the documentation, for instance at

http://www.cisco.com/en/US/products/hw/modules/ps2617/products_configuration_example09186a008052c920.shtml

explicitly says "The 2-port MFT VWIC2s can enable each port to be
clocked from independent clock sources for data applications." Note
the "can", and also note that it says this is not supported for voice
applications. It also mentions that you need to use the "independent" 
keyword, and that only 1 channel-group is supported.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no