I have a T1 point-to-point between the two sides. Each router 1760 has a WIC-1DSU-T1-V2. When I set both routers to slave mode - service-module t1 clock source line - ( which is wrong ) then the connection is up, and I can access the remote side, but the interface shows a high number of timing error.
When I set one router to master ( service-module t1 clock source internal ) then the connection is absolutely broken.
I called the telephone comany and they confirmed that my T1 is point-to-point and I must provide the clock from one router.
Well, it sounds like you understand how it's *supposed* to work. Which telephone company is involved?
Try troubleshooting the old-fasioned way: - put 1 side in internal - have the service provider give you a software loop pointing toward the internal side - send lots of pings from the router to the IP address of the serial interface (bounces off loop) - have service provider move loop to isolate
If necessary, have the service provider put a test-set on the line to verify the frequency of the ds1 at both sides of the ds1.
Some configuration issues to look at. Are both ends set the same for framing and line code Like ESF and B8ZS. This is what you would normally get from a telco. You must verify with your telco if they are giving you B8ZS or AMI. If these are provisioned incorrectly you will see errors on the span. On the T1 card are you using all time slots, 1-24, and is the speed set for
64k, this needs to be the same on both ends. And verify with your telco you are set for 64k and not 56k Clocking should have one end use it's internal clock, and the receiving end should be set to recover clocking from the line. T1 Configuration Commands service-module t1 clock source Syntax service-module t1 clock source {line | internal} Description The service-module t1 clock source command configures the T1 CSU/DSU module to accept the source of clock from the line (or network, in telco terminology) or to generate clocking internally. This command configures the CSU/DSU module, not the Cisco 2524-2525 interface to the CSU/DSU. The
2524-2525 interface is clocked from the CSU/DSU in either setting. In most applications, the CSU/DSU should be configured with the clock source line. For back-to-back configurations, one CSU/DSU should be configured with clock source internal and the other with clock source line. Application This command applies to the T1 CSU/DSU. Default line Example interface serial 0 service-module t1 clock source line
service-module t1 data-coding Syntax service-module t1 data-coding {normal | inverted} Description The service-module t1 data-coding command determines whether the user data is inverted by the CSU/DSU. Data inversion makes every one bit in the data stream into a zero and every zero bit into a one. Data inversion is used with bit-oriented protocols like HDLC, PPP, and LAPB to ensure density on a T1 line with Alternate Mark Inversion (AMI) encoding. These bit-oriented protocols perform zero insertions after every five "one" bits in the data stream. This has the effect of ensuring at least one zero in every eight bits. If the data stream is then inverted, it ensures at least one out of every eight bits is a one. This command cannot be used if the timeslots speed is set to 56.
More information can be found here
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From what you have described there is either a miscommunication between you and the telco about the T1 Verify from your telco that you have B8ZS or AMI
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