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ATT DEFINITY Communications System Generic 3 Instructions Manual
ATT DEFINITY Communications System Generic 3 Instructions Manual
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Generalized Route Selection (GRS) Issue 3 March 1996 3-747 The GRS capability will recognize one or more of the following five BCCs for each trunk group preference in the routing pattern (DCP/DMI mode is explained later). : Table 3-58. BCC Assignment EndpointVoice/ Data Mode BCC Comments Voice Terminal Voice 0 Data Line Circuit Pack 2 2 Voice Data Set 2 2 Modular Processor Data Module0,1,2 1,2,4 See Note Modular Processor Data Mo dule-M11 1 For ACCUNET Switched 56 kbps Service Modular Trunk Data Module22 Digital Terminal Data Module22 510D Personal Terminal 2 2 Digital Communications Protocol Interface 0,2,3 2,3,4 See Note 7400A Data Mo dule 2 2 3270T Data Module 3 3 3270C Data Module 3 3 3270A Data Mo dule 2,3 2,3 See Note Legend BCC Type DCP/DMI Mode 0 Voice-Grade Data and Voice None 1 56 kbps Data (Mode 1) 1 2 64 kbps Data (Mode 2) 2 3 64 kbps Data (Mode 3) 3 4 64 kbps Data (Mode 0) 0
Feature Descriptions 3-748Issue 3 March 1996 NOTE: For all endpoints, the switch automatically determines its current operating mode when the data mo dule originates. Before any call is originated, the default is Mode 2. Since call origination from a data mo dule d etermines the mo de to be used on the call, it is recommended that the data module user press the Originate/Disconnect button once after changing data options. This way, the right mo de is sure to be assigned to the next call. ISDN-PRI BCC Parameters The ISDN-PRI BCC Parameters are: nInformation Transfer Capability nLow-Layer Compatibility nDCP/DMI Mod e Information Transfer Capability The information to be transferred (or type of call) requires different transmission facilities. For example, transmission needs for voice calls and data calls are generally different. Voice and voice-grade data calls can be sent over analog trunks, while high speed data calls require digital trunks. The Information Transfer Capability parameter in the Bearer Capability Information Element (BC IE) and Low-Layer Information Element (LLC IE) have the following four values: nVoice (speech) nVoice-grade data (3.1 kHz transmission) nUnrestricted digital transmission nRestricted digital transmission. With data calls, the switch distinguishes the information transfer capability (restricted or unrestricted) of the originating data end p oint (trunk or terminal), and then uses the information transfer capability of the data endpoint to route the call onto the appropriate facility. For BRI and PRI originating data endpoints, the information transfer c a pability is c ontained in the ISDN SETUP m e s sa g e. Fo r non-ISDN data endpoints, the switch uses the information transfer capability specified by the system administrator. The default for the information transfer capability of an endpoint is restricted. The system administrator may change the information transfer c a pability to restricted or unrestricted for each non-ISDN originating endpoint.
Generalized Route Selection (GRS) Issue 3 March 1996 3-749 More than one Information Transfer Capability can be supported by one BCC. Low-Layer Compatibility The low-layer comp atibility information element provides remote compatibility checking. This element is used with the bearer capability element and determines the mode of the originating caller. The low-layer compatibility information element is optional and sent only in case of data calls. NOTE: DCP Mode 0 does not send an LLC IE. DCP/DMI Mode The Digital Communications Protocol (DCP) and the Digital Mulitplexed Interface (DMI) mo des are d ata parameters of the originating data facility. These modes are not a pplicable to voice. The mode values (0, 1, 2, and 3) are administered for d ata and Alternate Voice/Date (AVD) non-ISDN-PRI trunk groups. These mode values determine the BCC of the trunk groups. 1. Use BCC 4 for an unknown data mode that re quires a 64 kbps channel. Table 3-59. Assignment of BCC Based on Information Transfer Capability DCP/DMI MODEInformation Transfer Capability BCC Comments — Speech 3.1 kHz 0 Used for Voice/ Voice Grade Data. M1 Unrestricted/ Restricted Digital1 Used for Mode 1 Data (56 kbps). M2 Unrestricted/ Restricted Digital2 Used for Mode 2 Data (async data speed up to 19.2 k b ps). M3 Unrestricted/ Restricted Digital3 Used for Mode 3 Data (64 kbps). M0 Unrestricted/ Restricted Digital4 Used for Mode 0 Data 1 (64 k bps clear channel).
Feature Descriptions 3-750Issue 3 March 1996 Determination of BCC at Tandeming or Terminating System Determination of the BCC for an incoming call from a ISDN-PRI trunk to a tandem or terminating switch is based on the BCC parameters received on the signaling channel (D-channel) of the trunk. This includes the ITC (restricted or unrestricted) if the call is a data call. Determination of the BCC for an incoming call from a non-PRI trunk will be as follows: nIf the incoming trunk is a voice trunk, then the BCC is defaulted to 0. nIf the incoming trunk is a data, AVD, or RBAVD (robbed-b it AVD) trunk, then the BCC and ITC are administrable. GRS Operation The AAR/ARS routing pattern will contain an indication for each trunk group preference showing which BCC or BCCs can use that trunk group. A trunk group preference may have more than one BCC. GRS uses a look-ahead algorithm when determining which preference in a routing pattern to choose. GRS first attempts to find an exact match between the originator’s BCC and the corresponding allowed BCC for any of the preferences in the routing pattern. Therefore, if preference 1 does not have an exact match (even though there are available compatible members in preference 1), it will be skip p ed over if a subsequent preference in the same pattern has an allowed BCC that exactly matches the originator’s BCC. After matching the BCCs, G3i will then match the ITCs. The originator’s ITC is matched to the route preference ITC. Unrestricted (unre) matches on ‘‘unr’’ or ‘‘both.’’ Restricted (rest) matches on ‘‘rest’’ or ‘‘both.’’ NOTE: ITC matching only ap p lies to data calls (BCC 1 through 4). As an example of how GRS chooses a trunk group preference, assume preference 1 in a pattern has BCC 0 and BCC 2 set to yes, while preference 2 has BCC 1, BCC 3, and BCC 4 set to yes. A voice or Mode 2 d ata c all accessing this pattern will use the first preference, while a Mode 1, Mo de 3, or Mode 0 data call will use the second, independent of the availability of trunks in the first preference. When an exact match is not found in any of the routing p attern preferences, calls are treated as follows: nCalls With an Originating BCC of 0
Generalized Route Selection (GRS) Issue 3 March 1996 3-751 A BCC 0 originated call (such as voice or analog modem) will not b e denied routing by GRS, even if the routing pattern lacks a preference with BCC 0 set to yes. This allows the user to use voice transfer to data when making a data call, without the need for data preindication. If a BCC 0 originated call accesses a routing pattern for which no preference has BCC 0 set to yes, then GRS will choose a preference with BCC 2 set to yes, if one exists. If none exists, the next preferred ord er would be a preference with BCC 1 set to yes, followed by BCC 3, and finally, BCC 4. Since each preference must allow at least one BCC to be passed, a BCC 0 (voice) originated call will never b e blocked by GRS. The call is of course still subject to other restrictions, such as FRL restrictions. The ITC d oes not help select a preference. Since BCC 0 (voice) has no ITC, the switch selects an ITC from the routing pattern when a BCC 0 call is being routed as a data call. Table 3-60 shows how the ITC codepoint in the Bearer Capability IE is determined. nCalls With an Originating BCC of 2 If a BCC 2 originated call accesses a routing pattern for which no preference has BCC 2 set to yes, then GRS will choose a preference with BCC 0 set to yes, if one exists. If none exists, the call will be blocked with intercept treatment. nCalls With an Originating BCC of 1, 3, or 4 A DCP/DMI Mode 0 (BCC 4), Mo de 1 (BCC 1), or Mo de 3 (BCC 3) originated call requires an exact match on at least one preference in a routing pattern in order for GRS to allow the c all to c omplete. For examp le, a Mode 1 originated call will complete only if the accessed routing pattern has a preference with BCC 1 set to yes. The ITCs must also match. When an ISDN-PRI trunk group preference is accessed, the BCC information is encoded and sent in the outg oing ISDN SETUP m e ss a g e to the d istant-end as shown below. The BCC information sent to the far end is imp ortant, because the Table 3-60. Determination of ITC Codepoint Originating Endpoint’s ITC Routing Preference’s ITCITC codepoint in BC IE restricted unrestrictedboth endpointboth unrestricted voice x restricted voice x unrestricted voice x unrestricted voice x unrestricted
Feature Descriptions 3-752Issue 3 March 1996 BCC information that the far-end receives in the SETUP message will become the originating BCC for the far-end’s incoming trunk call. nIf an exact match of the originator’s BCC and ITC has been found, then that Bearer Cap a bility is encoded and sent in the ISDN SETUP message to the far-end. If the call is a data call, the system uses the ITC of the routing p attern to encode the SETUP message as shown in Table 3-61. nIf an exact match is not found, but the call is allowed to proceed, then the BCC encoded in the SETUP message sent to the far-end is that of the routing p attern. For example, if a BCC 2 (for example, DTDM) end p oint originates a call that accesses a pattern that has one preference with only BCC 0 set to yes, then the switch automatically inserts a modem pool for this call. In effect, the modem pool is converting BCC 2 to BCC 0. The far-end cannot distinguish this call from a BCC 0 originated call that has no modem pool inserted. Therefore, BCC 0 is sent in the SETUP message. This may in turn determine routing decisions by the far-end. Ad ditional routing d ecisions are ma de as shown in the following tables. 1. A voice originated call without d ata preindication that is routed to a routing pattern with data preferences only. Table 3-61. Encoding of Setup message Originating Endpoint’s ITCRouting Preference’s ITC ITC codepoint in BC IE restricted unrestrictedboth endpointboth unrestricted restricted x restricted restricted x restricted restricted x unrestricted unrestricted x unrestricted unrestricted x unrestricted unrestricted x unrestricted voice 1x restricted voice x unrestricted voice x unrestricted voice x unrestricted
Generalized Route Selection (GRS) Issue 3 March 1996 3-753 BCC and ITC Determination on Calls from Endpoints to ISDN-PRI Trunks Table 3-62. Calls from Endpoint to ISDN-PRI Trunks Originating Chosen BCC from the Routing Pattern BCC BCC 0 BCC 1 BCC 2 BCC 3 BCC 4 BC C 0 P PT PT PT PT BCC 1 BPBBB BCC 2 PMBPBB BCC 3 BBBPB BCC 4 BBBBP Legend B Block the call with intercept treatment P Allow the call and send the originating en d point’s BCC in the SETUP m essage. Use the ITC as shown in the following table PT Allow the call and send the BCC and ITC chosen from the routing pattern in the SETUP message PM Insert a pooled modem for the call and send the BCC and ITC chosen from the routing pattern in the SETUP message
Feature Descriptions 3-754Issue 3 March 1996 If BCC 1, 2, 3, or 4 is chosen from the preceding table, the following table is used to d etermine the a p propriate ITC. Table 3-63. Calls from Endpoints to ISDN-PRI Trunks Originating Chosen ITC from the Routing Pattern ITC unr rest both endpt both unr unrPBPPU restBPPPU Legend B Block the call with interc ept treatment P Allow the call and send the originating endpoint’s ITC in the SETUP message PU Allow the call and send ‘‘unrestricted’’ in the SETUP message
Generalized Route Selection (GRS) Issue 3 March 1996 3-755 BCC and ITC Determination on Calls from Trunks to ISDN-PRI Table 3-64. Calls from Trunks to ISDN-PRI Trunks Originating Chosen BCC from the Routing Pattern BCC BCC 0 BCC 1 BCC 2 BCC 3 BCC 4 B C C 0 P PT PT PT P T BCC 1 BPBBB BCC 2 PTBPBB BCC 3 BBBPB BCC 4 BBBBP Legend B Block the call with interc ept treatment P Allow the call and send the incoming trunk’s BCC in the SETUP message. Use the ITC as shown in the following table PT Allow the call and send the BCC and ITC chosen from the routing pattern in the SETUP me ss a ge
Feature Descriptions 3-756Issue 3 March 1996 If BCC 1, 2, 3, or 4 is chosen from the preceding table, the following table is used to d etermine the a p propriate ITC. The system does not insert pooled modem for any interworking trunk-to-ISDN-PRI trunk calls. The BCC and ITC of an incoming trunk is determined as follows: nISDN-PRI Trunk BCC and ITC are in the received SETUP m e s sa g e nAVD Trunk BCC and ITC are the BCC and ITC values administered on the trunk group form nRBAVD Trunk BCC and ITC are the BCC and ITC values ad ministered on the trunk group form nData Trunk BCC and ITC are the BCC and ITC values a dministered on the trunk group form nVoi ce T ru nk BCC is 0. Table 3-65. Calls from Trunks to ISDN-PRI Trunks Originating Chosen ITC from the Routing Pattern ITC unr rest both endpt both unr unr P B P PU rest B P P PU Legend B Block the call with interc ept treatment P Allow the call and send the incoming trunk’s ITC in the SETUP message PU Allow the call and send ‘‘unrestricted’’ in the SETUP message