Internetwork Design Guide -- SNA Host Configuration for SRB Networks

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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 article provides examples that focus on three specific SNA devices:
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 article provides examples that focus on three specific SNA devices:
* Front-end processors (FEPs)
* Front-end processors (FEPs)
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{{note|This material provides host-related configuration information pertinent to design material provided in [[Internetwork Design Guide  -- Designing SRB Internetworks#Designing SRB Internetworks|Designing SRB Internetworks]].}}
{{note|This material provides host-related configuration information pertinent to design material provided in [[Internetwork Design Guide  -- Designing SRB Internetworks#Designing SRB Internetworks|Designing SRB Internetworks]].}}
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{| align="right" border="1"
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|align="center"|'''Guide Contents'''
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|[[Internetwork Design Guide#Internetworking Design Basics|Internetworking Design Basics]]<br>[[Internetwork Design Guide#Designing various internetworks|Designing various internetworks]]<br>[[Internetwork Design Guide#Network Enhancements|Network Enhancements]]<br>[[Internetwork Design Guide#IP Routing Concepts|IP Routing Concepts]]<br>[[Internetwork Design Guide#UDP Broadcast Flooding|UDP Broadcast Flooding]]<br>[[ Internetwork Design Guide#Large-Scale H.323 Network Design for Service Providers|Large-Scale H.323 Network Design for Service Providers]]<br>[[Internetwork Design Guide#LAN Switching|LAN Switching]] <br>[[Internetwork Design Guide#Subnetting an IP Address Space|Subnetting an IP Address Space]] <br>[[Internetwork Design Guide#IBM Serial Link Implementation Notes|IBM Serial Link Implementation Notes]] <br>[[Internetwork Design Guide#References and Recommended Reading|References and Recommended Reading]]
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===== Figure: Typical SNA host environment=====
===== Figure: Typical SNA host environment=====

Latest revision as of 21:32, 16 October 2012

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 article provides examples that focus on three specific SNA devices:

  • Front-end processors (FEPs)
  • Virtual Telecommunications Access Method (VTAM)-switched major nodes
  • 3174 cluster controllers

Figure: Typical SNA host environment illustrates a typical environment. Table: BUILD Definition Parameters through Table: FEP Logical Unit (LU) Definition Parameter present the definition parameters for the devices shown in Figure: Typical SNA host environment.


Note Note: This material provides host-related configuration information pertinent to design material provided in Designing SRB Internetworks.


Guide Contents
Internetworking Design Basics
Designing various internetworks
Network Enhancements
IP Routing Concepts
UDP Broadcast Flooding
Large-Scale H.323 Network Design for Service Providers
LAN Switching
Subnetting an IP Address Space
IBM Serial Link Implementation Notes
References and Recommended Reading

Contents

Figure: Typical SNA host environment

Nd20c01.jpg

FEP Configuration

The parameters listed in Table: BUILD Definition Parameters through Table: FEP Logical Unit (LU) Definition Parameter 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 one MB to more than three 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.

Table: BUILD Definition Parameters
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 percent 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: LUDRPOOL Definition Parameters specifies the number of peripheral resources required for the correct amount of control block storage to be reserved for new connections.

Table: LUDRPOOL Definition Parameters
Parameter Example, Parameter Value, or Range Parameter Description and Implementation Notes

NUMTYP2

None

Maximum is 16,000.

NUMILU

None

Required for LU Type 2.1 devices (independent LUs).

The GROUP definition shown in Table: GROUP Definition Parameters specifies group definition parameters.

Table: GROUP Definition Parameters
Parameter Example, Parameter Value, or Range Parameter Description and Implementation Notes

AUTOGEN

Number

Specifies the number of LINE/PU pairs for this group.

COMPOWN

Y

Twin FEP backup capable resource.

COMPSWP

Y

TIC portswap capable (hot backup).

COMPTAD

Y

TIC capable of IPL loading FEP.

DIAL

YES or NO

Applies to ECLTYPE parameter specifications.

YES required for (LOGICAL,PERIPHERAL); NO required for all other combinations indicated in ECLTYPE specification.

ECLTYPE

(PHYSICAL,ANY)

(PHYSICAL, PERIPHERAL)

(PHYSICAL, SUBAREA)

(LOGICAL, PERIPHERAL)

(LOGICAL, SUBAREA)

Allows PU 4 and PU 2 devices to attach.

Allows PU 2 devices only.

Allows PU 4 devices only.

Defines devices attaching as PU 2.

Defines devices attaching as PU 4.

LNCTL

SDLC

Required for NCP processing compatibility.

PHYPORT

None

Required for ECLTYPE LOGICAL only; links this to a ECLTYPE PHYSICAL.

TIMER

error, ras, stap, or lstap

Entry points for NTRI timer routines.

The LINE definition shown in Table: LINE Definition Parameters specifies line definition parameters.

Table: 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 [[Internetwork Design Guide -- SNA Host Configuration for SRB Networks#Table 1

T2TIMER

localt2, remott2, N3

V5.4 parameter; see BUILD parameters in [[Internetwork Design Guide -- SNA Host Configuration for SRB Networks#Table 1Table: ; 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: FEP Physical Unit (PU) Definition Parameters specifies physical unit (PU) definition parameters.

Table: FEP Physical Unit (PU) Definition Parameters
Parameter Example, Parameter Value, or Range Parameter Description and Implementation Notes

ADDR

aa4000bccccccc

Destination service access point (DSAP) and MAC address for the PU of the Token Ring device in the FEP, where aa = the DSAP and is a nonzero hexadecimal multiple of 4; >b = 0 to 7;

   

c = 0 to 9; enter 4000 as shown; only specified if ECLTYPE defined in GROUP definition is one of the following: (LOG,SUB), (PHY,SUB), (PHY,ANY)

PUTYPE

1, 2, or 4

Depends on ECLTYPE:

For NTRI LOGICAL resources, only PUTYPE=2 is valid; for NTRI PHYSICAL resources, only PUTYPE=1 is valid

For NTRI PHYSICAL/SUBAREA LINES and PHYSICAL PERIPHERAL LINES, only PUTYPE=1 is valid. For NTRI LOGICAL PERIPHERAL LINES, only PUTYPE=2 is valid

XID

YES or NO

Defines the capability of a PU to receive and respond to an XID while in normal disconnected mode; for NTRI LOGICAL LINES, only YES is valid; for NTRI PHYSICAL LINES, only NO is valid

Table: FEP Logical Unit (LU) Definition Parameter specifies logical unit (LU) definition parameters.

Table: FEP Logical Unit (LU) Definition Parameter
Parameter Example, Parameter Value, or Range Parameter Description and Implementation Notes

LOCADDR

0

Specify this response only


VTAM-Switched Major Node Definitions

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: VBUILD Definition Parameter through Table: VTAM LU Definition Parameter.

Table: VBUILD Definition Parameter
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


Table: VTAM PU Definition Parameters
Parameter Example, Parameter Value, or Range Parameter Description and Implementation Notes

IDBLK

017

Typical values:

017 = 3X74

05D = PC-base VTAM PU

0E2 = Cisco SDLLC (registered with IBM)

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

Table: VTAM LU Definition Parameter
Parameter Example, Parameter Value, or Range Parameter Description and Implementation Notes

LOCADDR

2 through FF

Logical unit (LU) addresses attached to a PU

3174 Cluster Controller Configuration Example

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: 3174-13R Screen 1 Configuration Details through Table: 3174-13R Screen 3 Configuration Details list the configuration line numbers, entries used, and descriptions of the configuration line. When applicable, extended descriptions are included for configuration entries that are relevant to the requirements of the routed internetwork.


Note Note: Of particular interest when configuring 3174 devices for a router-based SRB environment are configuration line items 106, 107, and 384 in configuration screen 2 (refer to Table: VTAM LU Definition Parameter). These specify the required addresses and relevant Token Ring type for the cluster controller.
Table: 3174-13R Screen 1 Configuration Details
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


Table: 3174-13R Screen 2 Configuration Details
Configuration Line Number Sample Value Parameter Description and Implementation Notes

106

4000 2222 4444 04

The first 12 hexadecimal digits form the source MAC address of the cluster controller (4000 2222 4444); the last two digits are the source SAP (SSAP) for LLC2 (0x04 = SNA).

107

4000 0037 4501 04

The first 12 hexadecimal digits form the destination MAC address of the FEP (4000 0037 4501); the last two digits are the DSAP for LLC2 (0x04 for SNA).

108

0045362

Serial number of the cluster controller

110

0

MLT storage support

116

0

Individual port assignment

121

01

Keyboard language

123

0

Country extended code page support

125

00000000

Miscellaneous options (A)

126

00000000

Miscellaneous options (B)

127

0 0

RTM definition

132

0000

Alternate base keyboard selection

136

0000

Standard keyboard layout

137

0000

Modified keyboard layout

138

0

Standard keypad layout

141

A

Magnetic character set

165

0

Compressed program symbols

166

A

Attribute select keypad

168

0

Additional extension; mode key definition

173

0000

DFT options

175

000000

DFT password

179

000

Local format storage

213

0

Between bracket printer sharing

215

45362

PU identification

222

0

Support for command retry

382

0521

Maximum ring I-frame size; range of values is 265 to 2057.

383

2

Maximum number of I-frames 3174 will transmit before awaiting an acknowledgment (transmit window size).

384

0

Ring speed of the Token Ring network:


0 = 4 Mbps


1 = 16 Mbps normal token release


2 = 16 Mbps early token release

Table: 3174-13R Screen 3 Configuration Details
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:

  • Timers
  • Sequencing
  • Error recovery
  • Windowing
  • Guaranteed delivery
  • Guaranteed connection

Figure: T1 timer and error recovery process for 3174 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: T1 timer and error recovery process for 3174:

  1. The 3174 sends a data frame and starts its T1 timer.
  2. The T1 timer expires after 1.6 seconds.
  3. The 3174 goes into error recovery.
  4. The 3174 sends an LLC request (a receiver ready with the poll bit on), which requests the 3745 to immediately acknowledge this frame.
  5. The 3174 starts its T1 timer.
  6. The T1 timer expires after 1.6 seconds.

This operation is retried a total of seven times. The total elapsed time to disconnect the session is calculated as follows:

The first attempt plus seven retries multiplied by 1.6 seconds:

= 8 x 1.6 seconds

= 12.8 seconds

Figure: T1 timer and error recovery process for 3174

Nd20c02.jpg

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