Solved: E1 PRI Clock Sourcing Question

Tobivan_Helden_2 · ‎05-27-2008

Hello,

I'm configuring the following scheme: CUCM <mgcp> 2821 <e1-pri> 2821 <fxs> analog phone.

Have a question about how to avoid different violations and errors (they are accumulated for now) on E1 controllers.

1. The first 2821 router I've configured the following way (among others):

- "External clock" in the endpoint configuration in CUCM Administration

- "network-clock-participate wic 1"

- "show controller e1" tells that 'Clock Source is Line'

- ISDN L2 is up, D-channel (CUCM controlled) is up

2. The second 2821 router I've configured the following way (among others):

- "network-clock-participate wic 1"

- "show controller e1" tells that 'Clock Source is Line'

- ISDN L2 is up, D-channel is up

As I see, the clock source can be only one.

I have no routers except these two.

So how can it be possible to regulate the clock between them ?

paolo bevilacqua · ‎05-27-2008

Hi, on both routers are "network-clock-select 1 E1 1/0".

Slips will cease and you will be fine.

Hope this helps, please rate post if it does!

View solution in original post

paolo bevilacqua · ‎05-27-2008

Hi, on both routers are "network-clock-select 1 E1 1/0".

Slips will cease and you will be fine.

Hope this helps, please rate post if it does!

Tobivan_Helden_2 · ‎05-27-2008

Paolo,

1.

As always you've driven the centre. That's great !

After reconfiguring the message occurs

"%MARS_NETCLK-3-CLK_TRANS: Network clock source transitioned from priority 10 to priority 1"

And controllers are fine now :)

2.

Could you please also explain the mechanism of the fix ?

As I've found in documentation, 'network-clock-select' just

prioritizes clock sources if there are more than one.

<< CITED BEGIN

{ network-clock-select

When an active clock source fails, the system chooses the next lower priority clock source specified by this command. When a higher-priority clock becomes available, the system automatically reselects the higher-priority clock source.

}

<< CITED END

Thus it doesn't absolutelty clear for me what has been happened :)

Both routers have had the same source, and the problem has been solved only after I had prioritized theirs sources. Hm...

paolo bevilacqua · ‎05-27-2008

Hi, what the manual doesn't say, is that the VWIC card MUST have the selected "network-clock" to be same circuit that is connected to, else slips will happen.

Slips are not a serious problem for data and voice, but cause fax and modem to fail.

Thanks for the appreciation and good luck!