OLC XIO Information Field Byte
o
1 2-517
Bit 0-3
Content
Format of XID I-field:
X 10 1 fixed format: only bytes 0 - 5 are included
X 111 variable format (for T112.0 to T415 node exchanges): bytes O-p are included
X I 2 I reserved
X 13 1 variable format (for T2.1 to T2.1/BF and T2.0 to T5 node exchanges):
bytes O-p are included
X 18 I - X I F I defined for external standards organizations 4 -7 Type of the XID-sending node:
XI11 T1 X ' 21 T2 X 13 1 reserved
X '41 subarea node (T4 or T5)
Length, in binary, of variable-format XID I-field (bytes O-p); reserved for fixed-format XID I-field
Node Identification
2 - 5 0 -11 Block number: an IBM product specific number; see the individual product specifications for the specific values used
Note: The values all O's and all 1's indicate that bytes 2 - 5 do not contain a unique node identifier.
12 - 31 10 number: a binary value that, together with the block number, identifies a specific station uniquely within a customer network installation; the 10 number can be assigned in various ways, depending on the product; see the individual product specifications for details
End of Format 0
Note: When the Block Number field does not contain all O's or all 1's, a value of all O's in the 10 number indicates that no 10 number has been assigned.
Note: For XID format 3, the contents of bytes 2 - 5 of the node identification field are used in some instances as a role-negotiation-value to resolve contention in protocol roles of nodes, e.g., primary/secondary DLC roles or the ODAI value to be appended to the (OAF', OAF') values assigned at a node. When a role-negotiation value is needed and the node does not supply a unique node iden-tification value, it supplies a random value in the 10 number field.
Chapter 2. XID Information Fields 2-1
OLC XID Information Field
Link Station and Connection Protocol Flags Reserved
Link-station role of XID sender:
o
sender is a secondary link station (nonnegotiable) 1 sender is a primary link station (nonnegotiable) ReservedLink-station transmit-receive capability:
X'O' two-way alternating X'1' two-way simultaneous
Characteristics of the node of the XID sender:
Reserved
Segment assembly capability of the path control element of the node:
00 the Mapping field is ignored and PIUs are forwarded unchanged
Short-hold capability of the XID sender:
o
short-hold mode not supported 1 short-hold mode supportedMaximum I-field length that the XID sender can receive:
Format flag:
Obits 1-15 contain the maximum I-field length (only value defined) Maximum I-field length, in binary
Reserved
SDLC command/response profile:
X'O' SNA link profile (only value defined)
Note: These profiles refer to the mandatory command/response support on an SDLC link, as follows:
OLC XIO Information Field point-to-point or multipoint configuration (determined from system definition), the support required is: config-uration (determined from system definition), the support required is:
Commands
SDLC initialization mode options:
o
SIM and RIM not supportedDLC XID Information Field
SDLC Address Assignment Field
Length (p minus 18), in binary, of the SDLC address to be assigned Secondary station address to be assigned
For byte 9, bit 7 = 1 (short-hold mode supported)
Short-Hold Mode Dependent Parameters Reserved
Characteristics of the node of the XID sender:
INIT-SELF support:
a
INIT-SELF may be sent to the XID senderNote: If the XID sender does not contain an SSCP, it forwards any INIT-SELF received to the proper node for processing, which returns the response to the originator of the request.
1 INIT-SELF (and character-coded logon) cannot be sent to the XID sender
OLC XID Information Field
00 exchange state indicators not supported (set only by implementations not at the current level of SNA)
X '02' System/370 channel to controller DLC DLC Dependent Section
Length, in binary, of the DLC Dependent Section field (Length field includes itself in the length specified.)
Link Station and Connection Protocol Flags Reserved
ABM support indicator:
o
XID sender cannot be an ABM combined station 1 XID sender can be an ABM combined stationOLC XIO Information Field
00 sender is a secondary link station (nonnegotiable) 01 sender is a primary link station (nonnegotiable) 10 reserved
11 negotiable (primary or secondary capability)
Note: For ABM stations, the value of bits 2 - 3 is used only for the purposes of OAF'-DAF' assignment and deciding which node sends the Set Mode command.
4-5 Reserved
6 -7 Link-station transmit-receive capability:
0
Note: These profiles refer to the mandatory command/response support on an SDLC link, as follows:
• For an SDLC link in normal response mode (NRM/NRME), having a point-to-point or multipoint configuration (determined from system definition), the support required is:
OLC XIO Information Field config-uration (determined from system definition), the support required is:
Commands the Link-Station Role of XID Sender field). having a point-to-point configura-tion, the support required is: format (extended control field).
Note 2: Frame Reject is not required to be transmitted; receive capability is required.
Reserved
SOLC initialization mode options:
o
SIM and RIM not supportedOLC XIO Information Field
Byte Bit Content
For Channel DLC (CDLC): System/370 Channel between T4 and T2.1 nodes
19-20
Note: The System/370 node always contains the primary link station for COLC;
the controller always contains the secondary station.
Indicators:
1 Attention time-out support (set by the secondary; reserved for the primary):
o
not supportedBuffer pre-fetch: number of buffers suggested for the secondary to pre-allocate each time the secondary reads LPIUs from the primary
Number of Read commands: number of Read CCWs the primary must include in every read channel program used to read LPIUs
Buffer size: for .the primary, the size of the input area associated with each Read CCW in channel programs used to read LPIUs; for the secondary, the approximate number of bytes available for LPIU storage in each buffer used for accepting LPIUs from the primary
Blocking delay: maximum interval that the secondary delays between the time it has an LPIU to send to the primary and the time it presents an Attention to the primary
Attention time-out (ATO): maximum interval that a secondary awaits a read channel program after presenting an Attention to the primary; if the time-out expires, a secondary-detected inoperative station condition is declared. This time-out value is also used for idle detection (1/2 ATO is used), second-chance Attention (1/2 ATO is used). and primary-detected inoperative station (3/2 ATO is used)
Note: The secondary has the option of presenting a second Attention, called a second-chance Attention, to handle the case of loss of the first Attention.
Previous number of Read commands: set by the secondary in an XIO sent in reply to a change-COLC-parameters nonactivation XID to specify the number-of-Read-commands parameter (see bytes 24 - 25) that was active prior to the change; otherwise, reserved
2-8 SNA Formats
OLC XID Information Field
Byte Bit
34-35
36(
=
n)n+1-p
Content
Previous primary buffer size: set by the secondary in an XID sent in reply to a change-CDLC-parameters non activation XID to specify the primary-buffer-size parameter (see bytes 26 - 27) that was active prior to the change; otherwise reserved
Time units used for Attention time-out and blocking delay:
X 100 I 100-millisecond time units X 1011 1-millisecond time units
End of DLC Dependent Section for Channel DLC
Control vectors, as described in "Control Vectors" on page 8-4 Note: The following control vectors may be included:
X'OE I PU Name control vector: type X I F1 1, not network-qualified PU name (maximum of 8 bytes may be sent from a T4/T5 node)
X IDE I Network Name control vector: type X I F4 1, network-qualified CP name (always present; the network identifier is always used, i.e., valid lengths of the CP name are 3 to 17 bytes with an imbedded period) X 110 I Product Set 10 control vector (always present)
Note: When included in XID, the product set 10 is limited to 60 bytes or less in length.
X ' 221 XID Negotiation Error control vector (present when an error during XID negotiation is detected; more than one may be present)
2-10 SNA Formats