Path: utzoo!attcan!uunet!husc6!bloom-beacon!apple!rutgers!att!mtuxo!mtgzz!drutx!druco!stanwyck From: stanwyck@druco.ATT.COM (D. Stanwyck) Newsgroups: comp.protocols.iso Subject: Re: ISDN, Layer 3 Message-ID: <3080@druco.ATT.COM> Date: 22 Aug 88 15:05:42 GMT References: <4091@pdn.UUCP> Organization: AT&T, Denver, CO Lines: 67 in article <4091@pdn.UUCP>, larry@pdn.UUCP (Larry Swift) says: > 1) I'm having difficulty understanding the term "user-to-user signalling" > which seems to be used in opposition to circuit-switching and packet > switching. These three service type seem to make up the Layer 3 offering, > but the difference between the first two escapes me. User-user signalling is a service where the two "users" (hint- user <> end-system) may send information between themselves in the call control messages. This comes is several varieties - some associated with a circuit-switched call, and at least one not associated with any other communication path. This latter is the type you mention above. For this connection type, the network is told that all you want is to relay messages between the users without establishing a related communication path for e.g., a voice call. You could (correctly) call this using the CCS7 network or whatever the network's internal common channel signalling fabric is based on as a packet-switching network. As a result, not all network providers are jumping eagerly into this service, as the user data flows could potentially (and likely) block call-related signalling information. > 2) Where and how is leased circuit support accomplished? I see an > occasional reference to it, but no clear descriptions. Leased circuits are not dealt with in the Recommendations. At this time (though not necessarily in the future) they are strictly administrative items between you and the networks involved. No signalling related to them is defined. > 3) What is the difference between "Release Request" and "Disconnect > Request" in the call control states described in Section 2 of Q.931? This is a specific technical point - probably better dealt with by mail or phone. The brief answer is that Disconnect Request does not require the termination of all communication - i.e., you could potentially keep some type of user-user signalling up, while release request occurs some messages later and implies a total release of communications. > 4) What is "Suspend" used for (same section)? Nothing in the US. Suspend/Resume is used in some (one) European network for an desired ability for you to take your ISDN set, tell the other party to hang on, unplug your phone, walk down the street a few houses, plug it in there, and resume the conversation that was in progress at the other location. Of course, if you happen to walk across the boundary between exchanges, or take longer than , the call will collapse and you won't be able to resume. > 5) What are the terms "overlap sending/receiving" and "overlap mode" > descriptive of (same section)? Overlap sending/receiving and overlap modes relate to whether the address information is all carried in one message or is sent piecemeal to/from the exchange. Both are possibilities. > Larry Swift UUCP: {peora,uunet}!pdn!larry > Paradyne Corp., LF-207 Phone: (813) 530-8605 You really should get a copy of the current draft proposed American National Standard (DpANS) based on Q.931. It should be out for ballot by the end of this year. Otherwise, join T1S1 and attend T1S1.2 or see your company representative who does attend (Paradyne's mailing list member is Wayne Moore at MS LF104, 813-530-8262). -- AT&T o o 303-538-5004 Don Stanwyck || druco!stanwyck Denver, CO USA \__/ Telecom Standards