Framing errors

Hey Guys/Girls

Can someone please explain to me what a “framing error” is and how to detect it and what to do to fix it?


Are you running into trouble with a Digium T1/E1 card?

No, but what difference dose it make? What about framing errors in general… (theory)

A digital circuit such as a T-1 or E-1 is a bunch of bits being transmitted serially down a pair of wires. In order for the receiving end to understand the sending end, the bits have to be arranged into certain patterns that encapsulate the actual data. These patterns are known as frames. The frames are crucial to the proper operation of the circuit. The frame is made of several distinct sections that define the start/end of frames, signalling and data segments.

Any two devices that communicate need to know the correct framing for the circuit, there are several variations and if the framing is not correct, the circuit will not operate.

A framing error indicates that the received frame does not match what the device was configured to expect.

Dale … r1915.html Table 15.5 suggests that framing error on ISDN specifically relates to the common channel signalling, and indicates that a signalling message was not a round number of bytes. It also lists a lot of possible causes, all related to hardware or the configuration of the network hardware.

Given the other questions, it could well be the consequence of timing slips.

As you appear to have hardware problems, and they are with non-Digium hardware, I’m sure Malcolm’s advice would be to seek support from the hardware vendor. If it were Digium hardware, he would point you to Digium’s commercial support channels.

Thanks David and dalenoll. :smile:

+1 to both of you for putting time into explaining what framing is.

beachboy: the difference is no one (I don’t, anyway) wants to spend any time writing an explanation of framing or pointing you to a resource if what you’re really after is a solution to a specific problem you’re having. If you’re just curious about framing for digital lines, Google and Wikipedia (and David55 and dalenoll) provide excellent results. :smile: