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When designing source-route bridging (SRB) internetworks featuring routers and IBM Systems Network Architecture (SNA) entities, you must carefully consider the configuration of SNA nodes as well as routing nodes. This appendix provides examples that focus on three specific SNA devices:
Figure C-1 illustrates a typical environment. Table C-1 through Table C-6 presents the definition parameters for the devices shown in Figure C-1.
The parameters listed in Table C-1 through Table C-6 illustrate input to the Network Control Program (NCP) system generation process that runs in the host processor using the Network Definition Facility (NDF). The NDF is part of the ACF/NCP/System Support Program utility. The output produced by the generation process is a load module that runs in an FEP. Its typical size can be slightly under 1 MB to more than 3 MB. The ACF/NCP/System Support Program utility is also used for loading and dumping an FEP.
The following tables outline relevant parameters for generating Token Ring resources. For more specific information, refer to IBM manual SC30-3448, NCP/SSP Resource Definition Reference.
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| LOCALTO | 1.5 | Local ring acknowledgment timer (seconds). |
| REMOTTO | 2.5 | Remote ring acknowledgment timer (seconds). |
| MAXSESS | 5000 | Maximum amount of sessions for all attached resources. |
| MXRLINE | None | Maximum number of NTRI physical connections (Version 5.2.1 and earlier only). |
| MXVLINE | None | Maximum number of NTRI logical connections (Version 5.2.1 and earlier only). |
| T2TIMER | (localt2, remott2, N3) | (Version 5.R4 and later only.) Parameters specify a receiver acknowledgement/timer(T2) for local and remote Token Rings whether from peripheral or subarea nodes. Acceptable values: localt2 range is 0 to 2.0 seconds; remott2 range is 0 to 2.0 seconds; N3 range is 1 to 127 (default is 2). The values for localt2 and remott2 should be 10.0% of the value of the adjacent stations's T1 timer. N3 specifies the maximum number of I-frames received without sending an acknowledgment for subarea connections. |
The LUDRPOOL definition shown in Table C-2 specifies the number of peripheral resources required for the correct amount of control block storage to be reserved for new connections.
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| NUMTYP2 | None | Maximum is 16000 |
| NUMILU | None | Required for LU Type 2.1 devices (independent LUs) |
The GROUP definition shown in Table C-3 specifies group definition parameters.
The LINE definition shown in Table C-4 specifies line definition parameters.
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| ADAPTER | TIC1
TIC2 | 4-MB Token Ring interface
4- or 16-MB Token Ring interface |
| ADDRESS | 1088 to1095 | Range of valid addresses for TICs; only one specified per LINE definition |
| BEACTO | 52 | Time in seconds the ring can beacon before TIC considers it down; maximum is 600 |
| LOCADD | 4000abbbbbbb | Locally administered TIC address, where a is any value from 0 to 7; and b is any integer value from 0 to 9 |
| LOCALTO | 1.5 | V5R4; same as in BUILD, but only for PU 4 (LOGICAL, SUBAREA) devices; allows granularity for individual TICs for SUBAREA connections |
| REMOTTO | 2.5 | V5R4 parameter; same as LOCALTO; see BUILD parameters in Table C-1 |
| T2TIMER | localt2, remott2, N3 | V5.4 parameter; see BUILD parameters in Table C-1; can be defined in LINE definition only if a subarea node was defined in GROUP definition |
| MAXTSL | 2044 to 16732 | Specifies maximum data in bytes that NTRI can transmit.; TIC1 maximum is 2044; TIC2 maximum at TRSPEED16 is 16732 |
| PORTADD | Number | For association of physical to logical ECLTYPEs; matches physical or logical ECLTYPE specification |
| RETRIES | m, t, n, ml | Where m = number of retries for remote ring sessions, t = pause between retry sequence, n = number of retry sequences, and ml = number of retries in a sequence for local ring sessions |
| TRSPEED | 4 or 16 | TIC speed |
Table C-5 specifies physical unit (PU) definition parameters.
Table C-6 specifies logical unit (LU) definition parameres.
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| LOCADDR | 0 | Specify this response only |
Devices that are attached to Token Ring and communicate with an IBM host application must be defined via the VTAM access method associated with the host. These devices are seen as dial-in resources from the host side and are defined in a configuration component named Switched Major Node. Some common definitions used in network configurations are outlined in Table C-7 through Table C-9.
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| TYPE | SWNET | Specifies a type of resource for VTAM; SWNET indicates switched major node type |
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| IDBLK | 017 | Typical values:
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IDNUM | xxxxx | Unique number identifying a device |
| MAXOUT | 1 to 7 | Number of I-frames sent before acknowledgment is required |
| MAXDATA | 265 | Indicates maximum number of bytes a PU 2 device can receive; ignored for PU 2.1, as this value is negotiable
Default for 3174 is 521 |
| PUTYPE | 2 | Only valid value |
| XID | YES or NO | YES should be used for PU 2.1 devices
NO should be specified for any other device |
Parameter | Example, Parameter Value, or Range | Parameter Description and Implementation Notes |
|---|---|---|
| LOCADDR | 2 through FF | Logical unit (LU) addresses attached to a PU |
The following configuration was taken from 3174-13R cluster controller serial number 45362 connected to a Token Ring. These entries were used with a specific 3174 running on a 4-Mbps Token Ring. The configuration of this 3174-13R involved three specific configuration screens. Table C-10 through Table C-12 list the configuration line numbers, entries used, and descriptions of the configuration line. Where applicable, extended descriptions are included for configuration entries that are relevant to the requirements of the routed internetwork.
| Configuration Line Number | Sample Value | Parameter Description and Implementation Notes |
|---|---|---|
| 98 | Online test password | |
| 99 | TKNRNG | Description field |
| 100 | 13R | Model number |
| 101 | 7 | Host attachment type |
| Configuration Line Number | Sample Value | Parameter Description and Implementation Notes |
|---|---|---|
| 500 | 0 | CSCM unique |
| 501 | TOSFNID | Network identifier |
| 503 | TOSFCTLR | LU name |
SNA end stations implement Logical Link Control type 2 (LLC2) when attached to a local-area network (LAN). LLC2 implements the following:
Figure C-2 illustrates how the T1 reply timer and error recovery operates for a 3174. Assume that the link between the two routers just failed. The following sequence characterizes the error recovery process illustrated in Figure C-2:
This operation is retried a total of seven times. The total elapsed time to disconnect the session is calculated as follows:
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