TYPICAL REQUEST UNIT SEQUENCES FOR ACTIVATING AND DEACTIVATING RESOURCES

resolution table that contains entries for the appropriate resources.

This table is created during NCP generation as a result of the system programmer coding GROUP, LINE, PU and LU macros for the appropriate resources.

The system programmer specifies the initial activation status of an SNA resource via the ACTIV operand of the TERNINAL macro that defines the resource.

The network operator may use the Activate SNA Resource and Deactivate SNA Resource basic operator commands to alter the activation status of an SNA resource.

TYPICAL REQUEST UNIT SEQUENCES FOR ACTIVATING AND DEACTIVATING RESOURCES

Figure 2-8 through Figure 2-19 present typical request unit sequences for activating and deactivating various portions of the network shown in Figure 2-1. (Figure 2-7 on page 2-23 gives the meaning of each of the symbols and abbreviations appearing in these request unit sequences.) Though they do not cover all possible activation and deactivation scenarios, these sequences should give a general idea of the way in which activation and deactivation occur in an SNA network.

Typical request unit sequences for initiating and terminating LU-LU sessions are given in Chapter 5, "Using LU-LU Sessions to Transmit Data between End Users."

2-22 SNA Technical Overview

- - - - J > Request Unit

<f- - - Response Unit

•••...••••• J> SDLC Command or Response

Channel

SDLC Link

ER Host Link LS LU NCP PNODE PU PUCP SA SSCP TG VR

Explicit Route Host Processor Data Link Link Station Logical Unit

Network Control Program Peripheral Node

Physical Unit

Physicai Unit Controi Point Subarea

System Services Control Point Transmission Group

Virtual Route

Figure 2-7. Symbols and Abbreviations Appearing in Sequence Diagrams of Chapter 2

Chapter 2. Managing SNA Network Resources 2-23

HOST1 NCP2

NC Explicit Route Operative

I ^II I

NC Explicit Route Operative

I I receive data link control commands and responses for the link. HOST1, including the maximum number of bytes that HOST1 will accept

SA1 SA2 operative but inactive explicit route is initiated when the route is needed numbers--one for each direciton.) PU2.0 indicates to PU 1.0 that the identified by explicit route numbers 1 (in the host-to-NCP direction) and 2 (in the reverse direciton). An inactive virtual route is activated when it is needed to satisfy a session activation request.

Figure 2-9. Activating Explicit and Virtual Routes between Adjacent Subarea Nodes

Chapter 2. Managing SNA Network Resources 2-25

HOST1

I

^SSCP1.1

PU1.0

TG1

HOST1

SSCP1.1

II

Activate Physical Unit

<1--

-Start Data Traffic

II

<1--

-Set Control Vector

II

<1--

-..

Activate Link (L1 N K2.1)

<1--

-II

Activate Link (L1NK2.4)

<I-

-

-J

I

NCP2 PU2.0

J>

-

-J>

-I>

-

-I>

-

-I>

-

-PNODE2.2 L1NK2.1

~

^{__I '}

^PNODE2051

1. SSCP1.1 identifies itself to PU2.0 and assumes control of NCP2 by acti-vating an SSCP-PU session with PU2.0.

2. SSCP1.1 enables the flow of FMD mes-sage units over the SSCP-PU session with PU2.0.

3. SSCP1.1 sends PU2.0 the current date and time.

4. SSCP1.1 tells PU2.0 to activate LI N K2.1 and to prepare to issue data link control commands for the link.

5. SSCP1.1 tells PU2.0 to activate LI NK2.4 and to prepare to issue data link control commands for the link.

(Figure 2-7 gives the meanings of the symbols and abbreviations that appear in this figure.)

Figure 2-10. Activating a Channel-Attached Subarea Node and Attached Links

2-26 SNA Technical Overview

PNODE2.2

HOST1

I

^SSCP1.1

~

TG1

HOST1 NCP2

SSCP1.1 Connect Out or Activate

..

^PU2.0

Connect In (LlNK2.4)

---~

I

^II

I

Request Contact (LSf)

~---I

II

I

Set Control Vector (LSf)

<i=---~

I

cont! (LSf)

I

<l---~

I

Cont!ed (LSf)

I

~---~----NCP2

I

^PU2.0

I

PNOOE2.5

LSe LSf PU2.5

Exchange 10 II

...•... J>

I

Exchange ID

I

<I ...•...

Set Normal Response Mode II

····I···i~

I

I I

:y~?:':?

__

~~~_~~":'.II~?~mlent

Activate Physical Unit

---~

<1--,-.-- I

Request Network Address Assignment

<1---~

set

l

Control Vector I (LU2.6)

c---~~

PNOOE2.2

I

^PU2.2

I

PNOOE2.5

I

^PU2.5

I

LU2.6

<l-

-1- --- ^{-1- -}

Activate logical Un.

---~---~---~---~---~~~

<1- - - ' .... -_-_-__ --'-_-'

(Figure 2-7 gives the meanings of the symbols and abbreviations that appear in this figure.)

[ill

^2.3

~

^2.6

Figure 2-12 (Part 1 of 2). Activating a Peripheral Node Attached Via a Switched SDLC Link

2-28 SNA Technical Overview

1. SSCP1.1 either tells PU2.0 to establish a connection over switched link LlNK2.4 or tells PU2.0 to enable switched link LlNK2.4 to accept incoming calls.

2. Once a connection over a switched link has been established, PU2.S informs PU2.0 about its physical unit and node including its identity, node type and characteristics, and the maximum acceptable message unit size for PNOOE2.S.

3. PU2.0 informs SSCP1.1 that a connection has been established to link sta-tion LSf. The representation of LSf in NCP2 has a network address of 2.5.

4. SSCP1.1 sends PU2.0 information related to link station LSf, including the local SOLC address of LSf.

5. SSCP1.1 tells PU2.0 to contact link station LSf.

6. PU2.0 causes local link station LSe to initiate data link control proce-dures to contact link station LSf. LSe tells LSf to go into normal re-sponse mode for information transfer. LSf responds affirmatively to this request.

7. PU2.0 informs SSCP1.1 that link station LSf is ready to receive and send message units.

8. SSCP1.1 identifies itself to PU2.S and assumes control of PNOOE2.5 by activating an SSCP-PU session with PU2.S.

9. SSCP1.1 sends PU2.0 the appropriate local addresses for LUs associated with node PNODE2.5. PU2.0 returns network addresses for the LUs to SSCP1.1. SSCP1.1 then sends PU2.0 control information about each LU associated with PNOOE2.S.

10. SSCP1.1 identifies itself to LU2.6 and assumes control of LU2.6 by activating an SSCP-LU session.

Figure 2-12 (Part 2 of 2). Activating a Peripheral Node Attached Via a Switched SDLC Link

Chapter 2. Managing SNA Network Resources 2-29

HOST1 HOST4 LSh an identification sequence. LSh rejects this sequence because its communication controller has not yet been loaded with NCP3.

Link station LSg tells link station LSh to go into normal response mode for information transfer. LSh replies that its communication controller needs to be loaded.

PU2.0 informs SSCP1.1 that the communi-cation controller containing link station LSh needs to be loaded.

Im Dokument Network Architecture Technical (Seite 48-56)