1 osi =title OSI TRANSPORT This module implements the OSI Connection-Oriented Transport Protocol specification International Standard ISO 8073; and for DEC OSF/1, the Connectionless-Mode Transport Service Protocol International Standard ISO 8602. These protocols implement the OSI Reference Model Transport Layer 4. These protocols, as well as the NSP protocol, implement the transport protocols in the Digital Network Architecture. The entities that constitute the OSI Transport module are listed below. The indention indicates the hierarchical relationships between the entities. OSI Transport Application Port Template Local NSAP Remote NSAP The Connection-Oriented Transport Service COTS provides transparent and reliable transfer of data between Transport Service users. It operates over the Network layer, and employs end-to-end protocols that enhance the inherent characteristics of the underlying network service. The protocol is structured to produce protocol classes that minimize the possible incompatibilities and implementation costs. A protocol class is selected for a particular transport connection, based on the characteristics of the network service to be used, the requirements of the Transport Service user, and the availability of classes at the remote Transport Service provider. This module implements class 0, class 2, and class 4 of the COTS protocol. Class 0 is the simplest class. It sets up a network connection for each transport connection requested, and assumes that the network connection does not make errors. The transport protocol does neither sequencing nor flow control, as it relies on the underlying network layer to perform everything correctly. Class 2, like class 0, is designed to be used over reliable networks. It differs from class 0 in that two or more transport connections may be multiplexed over the same network connection. Class 4, the most complex of the protocols, is designed to work over unreliable Network Services. It can handle the error detection and recovery of lost transport packets. These packets are called TPDUs Transport Protocol Data Units. Class 4 runs over either CLNS or CONS. Classes 0 and 2 run only over CONS. The Routing module provides a connectionless network service CLNS; for more information, refer to the Routing chapter. The X.25 Access module, if configured into the system, provides a reliable connection-oriented network service CONS. The OSI Transport entity is the top-level entity in the hierarchy of entities belonging to the OSI Transport module. 2 character =title Characteristics Attributes ! CLNS CLASSES SUPPORTED ! Default: Class {4} Value: Bit-set ! ! Set of protocol classes supported on the Connectionless Network ! Service CLNS. You cannot modify this characteristic. ! ! CONGESTION AVOIDANCE Default: True Value: Boolean Enables the use of the automatic congestion avoidance mechanism to reduce the transport window size in response to an indication from the Network layer when operating on the Connectionless Network Service CLNS. ! CONS CLASSES SUPPORTED ! Default: Classes {0,2,4} Value: Bit-set ! ! Set of protocol classes supported on the Connection-Oriented Network ! Service CONS. You cannot modify this characteristic. See ! kernel_config for more information. ! ! ! CONS FILTERS ! Default: {} Value: set of simple names ! ! The names of X.25 Access module filters used to determine which inbound ! network connection requests should be directed to the transport entity. ! You can modify this characteristic only when the entity is disabled. ! ! For each cons filter, there must be a corresponding x25 access ! template with the same name. One or more of these filters must be ! specified in order to run COTS over CONS. The X.25 access filter osi ! transport is typically used. ! ! ! CONS NSAP ADDRESSES ! Default: {} Value: Set of NSAP Addresses ! ! The set of valid NSAP addresses for use with CONS. One or more NSAPs ! must be specified to run COTS over CONS. ! ! DELAY FACTOR Default: 4 Value: 2-15 Factor by which to multiply the current value of the round-trip delay estimate status attribute in order to set a value for the retransmission timer. This attribute works with protocol class 4 only. DELAY WEIGHT Default: 5 Value: 0-255 Relative weighting to apply to the current estimate and to a new sample when estimating round-trip delay. This attribute works with protocol class 4 only. DISCONNECT HOLDBACK Default: 0 Value: 0 - ( 2 to the 23 ) When operating over the Connection-Oriented Network Service CONS, the length of the time to maintain a network connection for possible reuse after all transport connections multiplexed upon it have been disconnected. Specified in seconds. This characteristic may not be changed while the transport entity is enabled. ISO VERSION Version number of ISO 8073 to which the implementation conforms. You cannot modify this characteristic. MAXIMUM MULTIPLEXING Default: 2 to the 23rd Value: 1 - ( 2 to the 23rd) Maximum number of transport connections that can be multiplexed on a single network connection operating over the cons. You can modify this characteristic to a lower value only when the entity is disabled. This attribute applies only if X.25 has been configured in the kernel. MAXIMUM NETWORK CONNECTIONS Default: 2000 Value: 1 - ( 2 to the 23rd) Maximum number of concurrent network connections that the OSI transport protocol can use when operating over the cons. You can modify this characteristic to a lower value only when the entity is disabled. MAXIMUM MULTIPLEXING When operating over the Connection-Oriented Network Service CONS, the maximum number of transport connections that can be multiplexed on any single network connection. This characteristic can be increased only when the transport entity is enabled. You can modify this characteristic to a lower value only when the entity is disabled. MAXIMUM NETWORK CONNECTIONS When operating over the Connection-Oriented Network Service CONS, the maximum number of network connections which can be in use concurrently by DNA OSI Transport. This characteristic can be increased only when the transport entity is enabled. MAXIMUM RECEIVE BUFFERS Maximum number of receive buffers that can store received DT transport PDUs. You can modify this characteristic only when the entity is disabled. Also, you can only increase the characteristic value. MAXIMUM REMOTE NSAPS Maximum number of remote NSAPs that can exist concurrently. This value must be greater than the current value of maximum transport connections. You can modify this characteristic to a lower value only when the entity is disabled. This characteristic can be increased when enabled. MAXIMUM TRANSPORT CONNECTIONS Maximum number of active transport connections allowed at one time. Must be less than the current value of maximum remote nsaps. You can modify this characteristic to a lower value only when the entity is disabled. MAXIMUM WINDOW Default: 8 Value: 1-65535 Maximum credit window that can be granted on a transport connection. This is used for control of the number of data segments PDUs allowed to be transmitted over a particular transport connection before at least one acknowledgment must be returned from the destination system. If the number of PDUs already transmitted equals the maximum window and no corresponding acknowledgments have been received, transport stops sending PDUs over the transport connection and waits for an acknowledgment message. You can modify this characteristic to a lower value only when the entity is disabled. NSAP SELECTOR Default: 33 Value: 0-255 The NSAP selector to use for the Connection-Oriented Transport Service COTS when running over CLNS. If 0 or 1, COTS over CLNS is not enabled. This attribute cannot be set to 32, which is the value of the NSP NSAP selector. Or, on DEC OSF/1, to the current setting of the osi transport attribute cltp nsap selector if it is other than 0 or 1. This attribute cannot be modified when transport is enabled. SUPPORT MAP Default: None Value; False Specifies whether the implementation supports the MAP manufacturing automation protocol entity. You cannot modify this characteristic. VERSION Version number of the DNA OSI Transport architecture specification to which the implementation conforms. You cannot modify this characteristic. 2 status =title Status Attributes CURRENTLY ACTIVE CONNECTIONS Number of active transport connections. STATE Status of the osi transport entity. ON - The OSI transport entity is enabled. OFF - The OSI transport entity is disabled. 2 app =title OSI TRANSPORT APPLICATION An OSI Transport Application entity stores information about an end user that is activated for receipt of an incoming connection request when the request contains that end user's name in its Destination Name field. 3 character =title Characteristic Attributes CALLED TSELS Default: No tsap Value: Hex-string Transport Service Access Point TSAP for which the image specified by the image name characteristic accepts connections. This characteristic, which is similar to the addresses characteristic, is used by applications that do not use the DNA session control protocol for example, VOTS applications. FILE NAME Default: No File Name Value: Filename File name of the program to be invoked upon receipt of a connect request containing a TSEL matching the Called TSELS attribute of the application entity. ! OUTGOING ALIAS ! Specifies whether the application uses the alias node identifier in its ! outgoing connection requests. If this attribute is set to DISABLED, ! the application must not use the alias node address in its outgoing ! connection requests. ! ! OUTGOING PRIVILEGE REQUIRED ! Specifies whether the object must be privileged in order to initiate a ! connection to the remote application. If this attribute is set to ! DISABLED, no privileges are required. ! ! OUTGOING PROXY ! Specifies whether to invoke a proxy on outgoing connection requests ! when the user does not explicitly specify to do so. If this attribute ! is set to DISABLED, no proxy is invoked. The setting of this ! characteristic overrides the setting of the SESSION CONTROL OUTGOING ! PROXY characteristic for the specified application. ! ! REQUEST VERIFY ! Specifies whether the application automatically verifies the source ! node name on non-proxy requests. If False, the application must ! request verification when required. The node name is always verified ! for proxy access, regardless of this attribute's setting. ! ! USERNAME Default: No user Name Value: Username User name portion of the access control information that identifies the account under which the application is to run. If invalid information or no user name is specified, system defaults are used to select the user. 2 local_nsap =title OSI TRANSPORT LOCAL NSAP An OSI Transport Local NSAP entity is automatically created for each NSAP address used by the OSI transport entity. Local NSAPs are used primarily to group together remote NSAPs see the OSI transport local NSAP remote NSAP entity. DELETED REMOTE NSAPS Number of times a remote NSAP has been deleted in order to reclaim the resources. NETWORK SERVICE Type of network service being used. NSAP ADDRESS NSAP address corresponding to entity. 2 local_rmt =title OSI TRANSPORT LOCAL NSAP REMOTE NSAP An OSI transport local nsap remote nsap entity maintains the transport counters and generates events resulting from interactions between its superior local NSAP and a remote transport service. 3 counters =title Counter Attributes CONNECTS RECEIVED Total number of CR TPDUs, regardless of their disposition, that the local NSAP has received from the remote NSAP. CONNECTS SENT Total number of CR TPDUs sent by the local NSAP to the remote NSAP, including retransmissions. DUPLICATE PDUS RECEIVED Total number of all types of detected duplicate TPDUs received from the remote NSAP. FAILED CHECKSUMS Number of checksum failure events detected. LOCAL PROTOCOL ERRORS Number of reported local protocol error events. This event is generated whenever an ER error TPDU is received from the remote NSAP. PDUS RECEIVED Total number of all types of TPDUs received from the remote NSAP excluding detected duplicates. PDUS SENT Total number of all types of TPDUs sent to the remote NSAP excluding retransmissions. REJECTS RECEIVED Number of detected reject received events. REJECTS SENT Number of detected reject sent events. REMOTE PROTOCOL ERRORS Number of reported invalid tpdu received events. This event is generated whenever the remote NSAP violates the Transport Protocol. RETRANSMITTED PDUS Total number of all types of retransmitted TPDUs sent to the remote NSAP. TOTAL OCTETS RECEIVED Total number of octets of all types of TPDUs received from the remote NSAP, regardless of their disposition. This count includes detected duplicates. TOTAL OCTETS SENT Total number of octets of all types of TPDUs sent to the remote NSAP, including retransmissions. USER OCTETS RECEIVED Total number of user data octets received from the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include duplicates such as data retransmitted by the remote NSAP. USER OCTETS SENT Total number of user data octets sent to the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include data retransmitted by the local NSAP. USER PDUS DISCARDED Number of PDUs received from the remote NSAP that were discarded because of insufficient buffer space. USER PDUS RECEIVED Total number of TPDUs containing user data received from the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include duplicates such as TPDUs retransmitted by the remote NSAP. USER PDUS SENT Total number of TPDUs containing user data sent to the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include retransmitted TPDUs. ! !2 status !=title Status Attributes ! ! ! NSAP ADDRESS ! ! Address assigned to the local NSAP when it is created. ! ! ! ! ! 2 port =title OSI TRANSPORT PORT An OSI transport port entity represents one end of a transport connection and maintains status information about that connection. Although the connectionless transport protocol does not create transport connections, ports are still used to maintain status information. 3 Counters =title Counter Attributes DUPLICATE PDUS RECEIVED Total number of all types of detected duplicate TPDUs received from the remote NSAP. This attribute applies only to COTS. FAILED CHECKSUM Number of checksum failure events detected. PDUS RECEIVED Total number of all types of TPDUs received from the remote NSAP excluding detected duplicates. PDUS SENT Total number of all types of TPDUs sent to the remote NSAP excluding retransmissions. RETRANSMITTED PDUS Total number of all types of retransmitted TPDUs sent to the remote NSAP. TOTAL OCTETS RECEIVED Total number of octets of all types of TPDUs received from the remote NSAP, regardless of their disposition. This count includes detected duplicates. TOTAL OCTETS SENT Total number of octets of all types of TPDUs sent to the remote NSAP, including retransmissions. USER OCTETS RECEIVED Total number of user data octets received from the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include duplicates such as data retransmitted by the remote NSAP. USER OCTETS SENT Total number of user data octets sent to the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include data retransmitted by the local NSAP. USER PDUS RECEIVED Total number of PDUs containing user data received from the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include duplicates such as TPDUs retransmitted by the remote NSAP. USER PDUS SENT Total number of TPDUs containing user data sent to the remote NSAP, including normal, expedited, connect, accept, and disconnect data. This count does not include retransmitted TPDUs. 3 status =title Status Attributes ACKNOWLEDGMENT DELAY TIME Maximum amount of time, in seconds, that an AK TPDU is to be withheld. This attribute applies to protocol class 4 only. CHECKSUMS Indicates whether checksums are in use on the transport connection. This attribute is supported only for class 4 protocol. CLIENT Name designated by the port user when the port was opened. If DNA session control is being used, this is the name of the session control port being used. ! CLNS INACTIVE AREA ADDRESS ! ! Specifies the inactive area address used by the transport template ! associated with this port. ! ! CONS TEMPLATE When operating over the CONS, the name of the X.25 Access module's template specified when establishing the underlying network connection. CR TIMEOUT Amount of time, in seconds, to wait for a response to a CR TPDU before assuming that the remote transport service provider will not respond. This attribute is valid for protocol classes 0 and 2 only. DIRECTION Indicates whether the port is open to initiate an outgoing connection, to receive an incoming connection, or is listening for incoming connection requests. INCOMING - Transport connection initiated by remote transport service. LISTENING - Listening for incoming connection requests. OUTGOING - Transport connection initiated by this transport service. UNKNOWN - Port direction is not known. ER TIMEOUT Amount of time, in seconds, to wait for a response to an ER TPDU before disconnecting the network connection. This attribute is valid for protocol classes 0 and 2 only. EXPEDITED DATA Indicates whether the expedited data option is in use for the transport connection. This attribute is supported only for class 2 and class 4 protocols. EXTENDED FORMAT Indicates whether the use of extended formats should be negotiated for a transport connection which operates the class 2 or 4 protocol. INACTIVITY TIME Time, in seconds, being used for the inactivity timer. This value is the product of multiplying the keepalive time by the inactivity factor architectural constant = 4. This attribute is valid for protocol class 4 only. INITIAL RETRANSMIT TIME Time, in seconds, used for the retransmission timer when sending the first TPDU on the transport connection. The value of this attribute is derived from the template used when the port was initialized. This attribute applies to COTS only. KEEPALIVE TIME Time, in seconds, being used for the window timer. The value of this attribute is derived from the template used when the port was initialized. This attribute is valid for protocol class 4 only. LOCAL NSAP Local NSAP address being used for the transport connection. LOCAL REFERENCE Unique reference number assigned to the transport connection by the local transport service provider. This attribute applies to COTS only. LOCAL TRANSPORT SELECTOR Local transport selector for this port. MAXIMUM NSDU SIZE When operating over the CONS, the maximum NSDU size for transmitting and receiving buffers. Expressed as a number of octets. This attribute is valid for CONS only. NEGOTIATED TPDU SIZE The TPDU size which was negotiated for this transport connection. This attribute applies to COTS only. NETWORK PORT Name of the network service port being used. NETWORK SERVICE Type of network service over which the transport connection is operating. Attribute value derived from the template used when the port was initialized. PROTOCOL CLASS Protocol class operating on the transport connection. This attribute is not valid for CLTS. REMOTE IDENTIFIER Implementation identity and version of the remote NSAP. When present, this value is received in the identification of implementation parameter of the CR or CC TPDU. This attribute applies to COTS only. REMOTE NSAP Remote NSAP address being used for the transport connection. This attribute applies to COTS only. REMOTE REFERENCE Reference number assigned to the transport connection by the remote transport service provider. The value will be 0 if the transport connection is operating the class 0 protocol. This attribute applies to COTS only. REMOTE TRANSPORT SELECTOR Remote transport selector that identifies the remote transport service user. This attribute applies to COTS only. REQUEST ACKNOWLEDGMENT Indicates whether request acknowledgment was negotiated for this transport connection. This attribute is valid for class 4 protocol only. RETRANSMIT THRESHOLD Number of times a TPDU requiring acknowledgment is to be retransmitted without acknowledgment before the transmission completes with an error. This attribute is valid for class 4 protocol only. ROUND-TRIP DELAY ESTIMATE Current estimate, in milliseconds, of the round-trip delay on the transport connection. This attribute is valid for protocol class 4 only. SEND IMPLEMENTATION ID Indicates whether the implementation id will be sent in the CR. It is always returned in the CC if it is present in the CR. SEND PREFERRED MAXIMUM tpdu SIZE Indicates whether the preferred maximum TPDU size parameter was sent in the CR or CC TPDU. SEND REQUEST ACKNOWLEDGMENT Indicates whether the request acknowledgment parameter was sent in the CR or CC TPDU. TYPE Indicates that the port is being used for the connection-oriented CO Transport protocol. CL - Connectionless transport service. CO - Connection-Oriented transport service. USE CLNS ERROR REPORTS When operating over CLNS, indicates whether the network Routing layer's error reporting facility should be used when performing connection establishment. This attribute applies to COTS only. 2 template =title OSI TRANSPORT TEMPLATE An OSI transport template entity provides a collection of characteristics that supply default values for certain parameters that influence the operation of a port on a transport connection. One template, with the reserved identifier default, is automatically created when the osi transport entity is created. This template is used by default when a user does not specify a template identifier in a call to establish a connection. The default template is automatically deleted when the osi transport entity is deleted. Similarly, the initial values of the attributes in a template are the same as the current values in the default template. 3 character =title Characteristics Attributes ACKNOWLEDGMENT DELAY TIME Default: 1 Value: 0-65 Maximum amount of time, in seconds, that an AK TPDU is to be withheld. This attribute is valid for protocol class 4 only. CHECKSUMS Default: False Value: Boolean Specifies whether the use of checksums should be negotiated for a transport connection. This attribute is valid for protocol class 4 only. ! CLASSES ! Default: {4} Value: Bit-set ! ! Set of protocol classes that can be negotiated for use on a transport ! connection. If the value of the network service attribute is CLNS, the ! class must be a subset of the classes supported by the OSI transport ! attribute clns classes supported. If the value is CONS, the classes ! must be a subset of the classes supported by the OSI transport ! attribute cons classes supported. If the value of the network ! service attribute is ANY, the classes must be a subset of the combined ! classes in the clns classes supported and cons classes supported ! attributes. ! ! ! CLNS INACTIVE AREA ADDRESS ! Default: Empty Set Value: Set of Area_address ! ! Specifies the inactive area address to be used by transport connections ! that use this template. This characteristic is relevant only for ! connections that use CLNS with Null Internet. The set must contain no ! more than one area address. ! ! CONS TEMPLATE Default: OSI Transport Value: Simple-name Name of the X.25 Access module template to be used when establishing a network connection over the CONS. Used only when the value of the network service attribute is cons. CR TIMEOUT Default: 30 Value: 1 - ( 2 to the 23rd) During connection establishment, the amount of time, in seconds, to wait for a response to a CR TPDU before assuming that the remote transport service provider will not respond. This attribute is valid for protocol classes 0 and 2 only. ER TIMEOUT Default: 30 Value: 1 - ( 2 to the 23rd) The amount of time, in seconds, to wait for a response to an ER TPDU before disconnecting the network connection. This attribute is used for protocol classes 0 and 2 only. EXPEDITED DATA Default: True Value: Boolean Specifies whether use of the expedited data option should be negotiated for the transport connections. This attribute is not valid for protocol class 0. EXTENDED FORMAT Default: None Value: Boolean Specifies whether the use of extended TPDU format should be negotiated for the transport connections. Normal format gives 7-bit sequence numbers and 4-bit credit fields; extended format gives 31-bit sequence numbers and 16-bit credit fields. This attribute is supported only for class 2 and class 4 protocols. INBOUND Default: True Value: Boolean Indicates whether this template may be used as the template for an inbound transport connection. The algorithm of selection of the inbound template is different depending on the type of network service over which the transport connection is made. If an inbound template cannot be found for an inbound transport connection, then the template called default will be selected as the default. For the CLNS network service, the inbound template selected is the first template found that has the Inbound attribute set to true, the Network Service attribute set to CLNS, and the CLNS Inactive Area Address attribute set to empty set. For the CLNS network service using the inactive subset, that is, null internet, the incoming template selected is the first template found that has the Inbound attribute set to True, the Network Service attribute set to CLNS and the CLNS Inactive Area Address attribute matches the Inactive Area Address attribute of the Routing Circuit entity that the transport connection is using. For the CONS network service, the inbound template selected is the first template found that has the inbound attribute set to true, the network service attribute set to CONS and the CONS template attribute that is, an X.25 Access template name matches the name of the X.25 Access filter that was used to accept the inbound network connection. INITIAL RETRANSMIT TIME Default: 5 Value: 1 - ( 2 to the 23rd ) Amount of time, in seconds, to wait for an acknowledgment before retransmitting the first TPDU over the transport connection. KEEPALIVE TIME Default: 60 Value: 1 - 6383 Time, in seconds, to be used for the window timer. When the transport service provider has no TPDUs to send over a transport connection, it retransmits the last AK TPDU at the specified frequency to prevent expiration of the remote NSAP's inactivity timer. This attribute is valid for protocol class 4 only. LOCAL NSAP Default: system dependent Value: NSAP address A local NSAP address to be used by default if one is not supplied across the service interface. ! LOOPBACK ! Default: False Value: Boolean ! ! Specifies whether transport connections using this template are looped ! back locally in the transport layer. ! ! MAXIMUM NSDU SIZE Default: 2048 Value: 2048 When operating over the CONS, the maximum NSDU size to use for transmit and receive buffers. Expressed as a number of octets. NETWORK SERVICE Default: CLNS Value: any, CLNS, or CONS Type of network service. The network service chosen must be compatible with the value of the protocol class attribute. ANY - Either. CLNS - Connectionless Network Service. CONS - Connection-Oriented Network Service. RETRANSMIT THRESHOLD Default: 8 Value: 0 - ( 2 to the 23rd ) Number of times a TPDU requiring acknowledgment is to be retransmitted before it is assumed that network connectivity has failed. This attribute is valid for protocol class 4 only. SECURITY Default: Null Value Value: Octet String An octet string to be transmitted in the security parameter of a CR or CC TPDU. A null value causes the security parameter to be omitted from the TPDU. For security reasons, this attribute cannot be displayed. SEND IMPLEMENTATION ID Default: True Value: Boolean Indicates whether the implementation id should be sent in the CR if the proposed protocol class is 2 or 4. It is always returned in the CC if it is present in the CR. SEND PREFERRED MAXIMUM TPDU SIZE Default: True Value: Boolean Indicates whether the preferred maximum TPDU size parameter should be sent in the CR TPDU. If the preferred maximum TPDU size parameter was present in the CR TPDU, then it indicates whether the preferred maximum TPDU size parameter should be sent in the CC TPDU. The default value of this characteristic should not be changed unless the remote implementation does not conform to ISO 8073. SEND REQUEST ACKNOWLEDGMENT Default: True Value: Boolean Indicates whether the request acknowledgment parameter should be sent in the CR TPDU. If the request acknowledgment parameter was present in the CR TPDU, then it indicates whether the request acknowledgment parameter should be sent in the CC TPDU. The default of this characteristic should not be changed unless the remote implementation does not conform to ISO 8073. USE CLNS ERROR REPORTS Default: False Value: Boolean Indicates whether the network Routing layer's error report facility should be used when performing connection establishment. If set to true, this may result in faster detection of an unreachable node at the time of connection establishment. This characteristic should not be set to true on an end system that is either dual-railed or connected to a network that has a high probability of duplication. This is valid only if network service equals CLNS.