[cisco-voip] network-clock-participate???

[Jason Aarons (US)]

Usually if you have one long distance voice PRI from AT&T and another
voice PRI for local calls with Verizon on same VWIC2-2MFT-T1 card you
have timing issues due to the single PLL design. Best bet would be to
separate into two VWIC2-1MFT-T1 cards if in doubt.  If both PRIs were
from same carrier you are less likely to have different timing. 

 

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Derick
Winkworth
Sent: Monday, August 25, 2008 11:40 AM
To: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] network-clock-participate???

 

In telco-land, there is the idea that all network switches are
synchronized to the same clock.  This is achieved by planning how a
clock is distributed through your network.  The idea is that there is
one clock device in a network switch, called a PLL (phase-lock loop).
The PLL will receive/recover the master clock on one of its bearer
ports, or on a dedicated clock port called a BITS port.

 

All other ports on that switch/device will be timed using this master
clock.

 

Cisco's ISRs were built using this model.  There is one PLL on the
motherboard, called the network-clock.  Modules on your router may
participate in this clocking scheme or not.  Some have to, because they
don't have their own PLLs/clocks on-board.  When you need/want a module
to participate in the network clock, you use the network-clock-select
command.  You select the master clock with the network-clock-select
command.  You can choose multiple master clocks and order them by
priority.  Only one is active at a time.

 

The implication here is that if you connect to multiple carriers (and
thus multiple clock domains), you may/will end up with clock slips on
one of the ports.  Otherwise, you would set the telco port as the master
clock and then time the rest of your private ports off of this.  You may
need to do this if you want the ISR to do TDM switching, for instance.

 

 

 

 

 

 

 

 

 

 

 

 

----- Original Message ----
From: "Carter, Bill" <bcarter at sentinel.com>
To: john edwards <voicenerd at googlemail.com>; cisco-voip at puck.nether.net
Sent: Sunday, August 24, 2008 7:45:32 PM
Subject: Re: [cisco-voip] network-clock-participate???

http://www.cisco.com/en/US/docs/ios/voice/voiceport/configuration/guide/
vp_cfg_digital_vps_ps6441_TSD_Products_Configuration_Guide_Chapter.html#
wp1009559

"The network-clock-participate command allows the router to use the
clock from the line via the specified slot/WIC/AIM and synchronize the
onboard clock to the same reference."




-----Original Message-----
From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of john edwards
Sent: Sunday, August 24, 2008 5:53 PM
To: cisco-voip at puck.nether.net
Subject: [cisco-voip] network-clock-participate???

Hi everyone,

I wonder if anyone knows where I can find a thorough explanation of
the 'network-clock-participate' and 'network-clock-select' commands?

I have trawled through multiple references, but I am still confused :-(

Thanks very much in advance.

Voicenerd
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