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New Member

BRI fluctuatiing

Hi,

I am trying to configure a Cisco 3845 with a BRI but the link fluctuates, up and down. I am running 12.4.3. Not sure what it is... A little guidance will be much appreciated..

Thanks

5 REPLIES
Silver

Re: BRI fluctuatiing

This is normal with Net3 switch type - the PSTN drops layer 1 after an idle period (around 30 seconds) when there are no calls going through the BRI. You can see this from the debug ISDN Q921 logs.

Make sure the config includes the command/s -

network-clock-select 1 bri slot/0/0

network-clock-select 2 bri slot/0/1

this tells the router to sync the clocking to the clock source coming in from the PSTN.

New Member

Re: BRI fluctuatiing

The is configured. The flap is every 5 seconds. It does not let the the link to settle, therefore I cannot make any calls through it.

thanks

Hall of Fame Super Gold

Re: BRI fluctuatiing

Hi, can you check your cabling ? Are you using static or dynamic TEI? Is there anything that you can see from "debug isdn q931" ?

pacameron: exactly because euro switches drop layer1 with short timeout, I do not suggest setting clock preference to BRI. Too many clock changes are also clutering syslog. My installations are fine with clock internal.

What is very useful instead with such switches, is the option "tei preserve".

New Member

Re: BRI fluctuatiing

my bri config and errors attached. still no good

Apr 9 11:40:59.677: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0/3/1, TEI 69 changed to up

Apr 9 11:41:14.589: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0/3/1, TEI 69 changed to down

Apr 9 11:41:14.681: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0/3/1, TEI 69 changed to up

Apr 9 11:41:29.593: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0/3/1, TEI 69 changed to down

Apr 9 11:41:29.685: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0/3/1, TEI 69 changed to up

interface BRI0/3/1

no ip address

isdn switch-type basic-net3

isdn tei-negotiation preserve

isdn point-to-point-setup

isdn incoming-voice voice

isdn bind-l3 ccm-manager service mgcp

isdn skipsend-idverify

Hall of Fame Super Gold

Re: BRI fluctuatiing

I see, it appears as we mentioned before that the switch deactivates L1 and l2 after 15 seconds. Then MGCP/CCM are apparently trying to bring it back up.

Could you try removing all MGCP related command, configure a dial-peer and you try calling with "csim start ". If it works better, you may consider switching your config to h.323,

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