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IOS Gateway clocking options with Multiple PRIs

I have a configuration with a 3845 that has a total of 14 PRIs. This gateway will be front-ending A PBX for all PSTN access. 7 PRIs come in from the PSTN to the 3845 and then 7 from the Gateway to the PBX. 3 of the PRI's are from one Carrier (LD) and 4 are from another Carrier (Local). There ar 7 PRI modules that are the 2 port VWIC2-MFT2. I understand that these modules must share a single clock source.

Does anyone have any insights as to the best we to clock this configuration?


Re: IOS Gateway clocking options with Multiple PRIs

You have to select a clock source which will clock all voice T1s. Pick one of your carriers as the primary clock source, the other as the secondary. The PBX will need to be set to clock off the T1s from the 3845. All carriers have extremely accurate clocks synched to a stratum 1 source, so you should see no slips even though one source will clock T1s from both.

To set primary source network-clock-select 1 t1 X/X/X

Seconday source network-clock-select 2 t1 X/X/X

All other T1 ports network-clock-participate t1 X/X/X

A good doc:

Please rate helpful posts.

New Member

Re: IOS Gateway clocking options with Multiple PRIs

There is another thread going on on this same topic (from a co-worker of mine). The solution proposed there is different than yours in that they are taking clock from all circuits connecting to the PSTN.

I'd be interested in your thoughts.

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