This variable allows associating a certain protocol type to the connector. In reading, this variable shows if the last allocation attempt were in success (2, ok), in error (3) or if still any attempt has not been carried out to assign a protocol to a connector (4, indefinite). In writing, it is only permitted to do a set to some of the values allowed like possible protocols associated to the connectors. To LAN lines, the protocol type is determined by the device hardware (Ethernet or TokenRing), reason why they do not admit Set operations that try to modify this protocol. Possible values for WAN lines are: fr (61), ppp (59), pppas (55), sdlc (63), x25 (61444), x28 (11), atppp-dial (31). ISDN lines can have two B channels, and its possible values are: B1 channel: chb1-dial-fr (40), chb1-dial-ppp (41), chb1-dial-x25 (61442) B2 channel: chb2-dial-fr (240), chb2-dial-ppp (241), chb2-dial-x25 (261442) An interface MultiLink PPP can also be assigned to ISDN lines, independently of the type of B channel, since these interfaces are not associated to any specific connector, nor physical line. ch-mppp (75) When doing the allocation, the dial-fr and dial-ppp will always go first and the MPPP after. The INTERNAL interface can take the value xst (61445), associated to index 30. There can be another INTERNAL interface with the value int-270 (61446), associated to the index 33. This is the only way to assign the values, and any interrelation different from the associations above indicated cannot be done. When a atppp-dial (null, value 31) is assigned to one of the WAN lines by first time, two interfaces (one after the other) are added: one for the ATI of the B channel type: X.25(value 18), and another for the particular DIAL (PPP). The allocation of the DIAL interfaces (X25-DIAL, FR-DIAL, PPP-DIAL) is complex. In general, the allocation is done starting for the connector 1 and after with the connector 2. In general, chb1 will be assigned first and chb2 after. If it is tried to generate a chb2 in a connector which doesn't have chb1, it returns error. In case a same connector has FR-dial and/or PPP-dial in a B channel and X25-dial in the other B channel, FR-dial and / or PPP-dial will be assigned to chb1. I. If the device has an only basic access (ISDN) and can carry two B channels, then these will be chb1 and chb2. They are always present and are modified individually. II. If the device has two basic access and can carry two B channels, there are three possibilities: that they are associate one to each basic access, that two B channels are associate to one of the accesses and the other one is empty, and the inverse thing to the previous thing. A. CHB1 ALLOCATION: *If a chb1-x25 is assigned to a connector, two things can occur: - There is chb1 for that connector: If it is chb1-x25 nothing is done. If it is chb1-rdsi-base, it is changed to chb1-x25 and chb1-rdsi-base is eliminated. The PPP-DIAL or FR-DIAL which it has associate are eliminated if there is no another RDSI-BASE in that connector, otherwise they stay associated to that RDSI-BASE. - There isn't chb1 for that connector: In this case, the other connector has two B channels, chb1 and chb2. Therefore chb2 of the other connector is modified. If it is ch2-x25, it is associated to it to the chb1 of the initial connector. If it is chb2-rdsi-base, it is changed to chb1-x25 of the initial connector and chb2-rdsi-base is eliminated from its connector. The PPP-DIAL or FR-DIAL which it has associate, are eliminated if there is no another RDSI-BASE in its connector, otherwise they stay associated to that RDSI-BASE. *If a chb1-rdsi-base is assigned to a connector, two things can occur: - There is chb1 for that connector: If it is chb1-x25, it is changed to chb1-rdsi-base. If it is chb1-rdsi-base, PPP-DIAL or FR-DIAL is added to that chb1-rdsi-base. - There isn't chb1 for that connector: In this case, the other connector has two B channels, chb1 and chb2. Therefore chb2 of the other connector is modified. If it is chb2-x25, it is changed to chb1-rdsi-base. of the initial connector. If it is chb2-rdsi-base, it is changed to chb1-rdsi-base of the initial connector and chb2-rdsi-base is eliminated from its connector. The PPP-DIAL or FR-DIAL which it has associate, are eliminated if there is no another RDSI-BASE in its connector, otherwise they stay associated to that RDSI-BASE. B. CHB2 ALLOCATION: *If a chb2-x25 is assigned to a connector (this is always done after having associated the chb1 to that connector), two things can occur: - There is chb2 for that connector: If it is chb2-x25 nothing is done. If it is chb2-rdsi-base, it is changed to chb2-x25 and chb2-rdsi-base is eliminated. The PPP-DIAL or FR-DIAL which it has associate are eliminated if there is no another RDSI-BASE in that connector, otherwise they stay associated to that RDSI-BASE. - There isn't chb2 for that connector: In this case, the other connector has a B channel (chb1), therefore chb1 of the other connector is modified. If it is ch1-x25, it is associated to it to the chb2 of the initial connector. If it is chb1-rdsi-base, it is changed to chb2-x25 of the initial connector and chb1-rdsi-base is eliminated from its connector. The PPP-DIAL or FR-DIAL which it has associate, are eliminated if there is no another RDSI-BASE in its connector, otherwise they stay associated to that RDSI-BASE. *If a chb2-rdsi-base is assigned to a connector (this is always done after having associated the chb1 to that connector), two things can occur: - There is chb1 for that connector: If it is chb2-x25, it is changed to chb2-rdsi-base. If it is chb2-rdsi-base, PPP-DIAL or FR-DIAL is added to that chb2-rdsi-base. - There isn't chb2 for that connector: In this case, the other connector has a B channel (chb1), therefore the chb1 of the other connector is modified. If it is chb1-x25, it is changed to chb2-rdsi-base. of the initial connector. If it is chb1-rdsi-base, it is changed to chb2-rdsi-base of the initial connector and chb1-rdsi-base is eliminated from its connector. The PPP-DIAL or FR-DIAL which it has associate, are eliminated if there is no another RDSI-BASE in its connector, otherwise they stay associated to that RDSI-BASE. III. If the device has two basic accesses and can carry 4 B channels, they will be chb1 and chb2 for the RDSI1, and chb1 and chb2 for the RDSI2. They are always present and are modified individually. When a FR-DIAL or PPP-DIAL is assigned to one of the ISDN lines by first time, two interfaces are added: one for the ISDN and another for the particular DIAL (FR or PPP). A X25-DIAL by each ISDN basic access can only be assigned. There can be several FR-DIAL and PPP-DIAL in a same ISDN basic access. X25-dial cannot coexist with FR-dial nor PPP-dial in a same ISDN basic access. For that reason, when assigning a X25-dial to an ISDN connector, the ISDN-base is eliminated, and if there is no another RDSI-base associated to that connector, possible PPP-dial and FR-dial are also eliminated; the same happens if there is a X25-dial in a basic access and it is tried to add a FR-dial or a PPP-dial: then the X25-DIAL is eliminated. The maximum number of interfaces that the device can have is 40. In addition, there can be 6 DIAL in total between the two basic accesses, for each ISDN basic access.