E3 Clocking config

Unanswered Question


We currently have an E3 line configured between two of our office. That E3 line is up, but from time to time it goes down and after some loop testing with the provider it comes back up.

The E3 controllers of each routers are configured with the command clock source line.

However our provider say that he is not providing the clocking and that we have to configure one of the router to provide that clocking (routers configured in master slave).

We are not sure that this is even possible that the provider is not giving us the clocking since the line is up (and we heve the command clock source line on both end). Did somebody can confirm if the E3 line may be even up with that config?

We want to avoid providing the clocking if the provider is giving it also through the line.


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Overall Rating: 5 (1 ratings)
Giuseppe Larosa Thu, 07/24/2008 - 12:36
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Hello Marc,

the provider is carrying your E3 (that is PDH) inside an SDH infrastructure.

In this case the provider can say it is not providing a clock directly, but SDH has its own clocks that uses to sample the PDH E3 link.

You can try by issuing the following:

sh int ser x/y

if inside the input error counters you see frame errors this can point to a clocking problem.

If this is the case the two clocks are free running.

From time to time deviations become so big that SDH is not able to sample the PDH link and the line has to be reset and this is what happens with the loop test.

If on one side you set the clock internal you provide a reference to the other side and they are not free running anymore.

Hope to help



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