From: [email protected] (Lars Poulsen) Greetings to fellow TREG'ers ...
Two weeks ago, I asked a question about ISDN point-to-point operation in the ETSI regime. I have not heard any feedback, so I wonder if it got lost in transmission. I have tried to clarify the question, and hope to hear from someone who has faced this issue and resolved it. In the design of a CPE with multiple BRI ports (for the purposes of this discussion, think of it as a small PBX with a handful of BRI ports to the central office), we would like to derive timing for our device's internal TDM bus from an arbitrarily selected BRI port. With the ISDN circuits we are using, we find that when we select slave mode timing for the other BRI ports (meaning they get timing from the bus in the box rather than from the BRI line), they become unable to do D channel contention. The lack of D-channel contention is not functionally crippling, it just limits the device to point-to-point operation per ETS 300125 Annex A. I am, however concerned that approval of equipment with such a restriction may require a waiver that may not be portable across the EU. Has anyone else encountered this problem ? Would you be willing to discuss how you solved it ? (The obvious workaround would be to put a FIFO between the BRI port and the TDM bus, and tell each BRI he's the master; but that seems like a potentially large kludge.) -- / Lars Poulsen Internet E-mail: [email protected] OSICOM Technologies (Internet Business Unit, formerly RNS) 7402 Hollister Avenue Telefax: +1-805-968-8256 Santa Barbara, CA 93117 Telephone: +1-805-562-3158
