test

Solstice X.25 9.2 Developer's Guide

7.8 N_linkconfig--Configure the wlcfg Database

This ioctl is used to configure the wlcfg database for a link. The wlcfg database appropriate to a link is carried as the M_DATA part of the ioctl N_linkconfig. The U_LINK_ID member of the wlcfg structure specifies the link to be configured. The wlcfg database structure is defined in the /usr/include/netx25/x25_control.h file.

Note -

This ioctl affects currently open connections and could therefore disrupt users significantly. For this reason it can only be used by root.

The wlcfg database structure contains the members described below:

U_LINK_ID

The upper level link identifier which is quoted by upper level software in the xaddrf address structure to specify which link a call is to be sent on. It is also used to identify which link an incoming call arrived on.

NET_MODE

This determines the characteristics of the network protocol Possible values are:

Table 7-18 NET_MODE values

String 

Value 

Network, X.25 Type, or Country 

X25_LLC

1 

X.25(84/88)/LLC2 

X25_88

2 

X.25(88) 

X25_84

3 

X.25(84) 

X25_80

4 

X.25(80) 

GNS

5 

UK 

AUSTPAC

6 

Australia 

DATAPAC

7 

Canada 

DDN

8 

USA 

TELENET

9 

USA 

TRANSPAC

10 

France 

TYMNET

11 

USA 

DATEX_P

12 

Germany 

DDX_P

13 

Japan 

VENUS_P

14 

Japan 

ACCUNET

15 

USA 

ITAPAC

16 

Italy 

DATAPAK

17 

Sweden 

DATANET

18 

Holland 

DCS

19 

Belgium 

TELEPAC

20 

Switzerland 

F_DATAPAC

21 

Finland 

FINPAC

22 

Finland 

PACNET

23 

New Zealand 

LUXPAC

24 

Luxembourg 

X25_Circuit

25 

dialup call 

X25_VSN

This determines the version of the X.25 protocol used over the network. Allowed values are:

Setting NET_MODE to X25_LLC overrides an X.25 (80) value.

L3PLPMODE

Indicates whether the link is DTE or DCE. Allowed values are:

LPC to HPC

Logical channel range assigned to PVCs.

LIC to HIC

Logical channel range assigned to one way incoming logical channels.

LTC to HTC

Logical channel range assigned to two-way logical channels.

LOC to HOC

Logical channel range assigned to one-way outgoing logical channels.

Note -

In a DTE/DTE environment, one of the interacting pairs views these ranges as a DCE, for example, LIC to HIC are viewed as one-way outgoing. HxC = LxC = 0 denotes no channels in that grouping.

NPCchannels, NICchannels, NTCchannels, NOCchannels and Nochnls

The number of logical channels assigned. This is calculated from the logical channel ranges and can only be changed only by altering these ranges.

THISGFI

0x10 indicates Modulo 8. 0x20 indicates Modulo 128 sequence numbering operates on the network.

LOCMAXPKTSIZE

The maximum acceptable size of local to remote data packets, expressed as a power of 2.

REMMAXPKTSIZE

The maximum acceptable size of remote to local data packets expressed as a power of 2.

LOCDEFPKTSIZE

The default local-to-remote packet size expressed as a power of 2.

REMDEFPKTSIZE

The default remote-to-local packet size on a particular link, expressed as a power of 2.

LOCMAXWSIZE

The maximum acceptable local to remote X.25 window size.

REMMAXWSIZE

The maximum acceptable remote to local X.25 window size.

LOCDEFWSIZE

The local-to-remote default window size.

REMDEFWSIZE

The remote-to-local default window size.

MAXNSDULEN

The default maximum length beyond which concatenation is stopped and the data currently held is passed to the NS-user. This parameter can be overridden on a per-circuit basis using the nsdulimit parameter on N-CONNECT requests and N-CONNECT responses.

ACKDELAY

The maximum delay in ticks (0.1 second units) over which a pending acknowledgement will be withheld. The default value is 5, the permitted range 1--32000.

T20value

The length of DTE timer T20, the Restart Request Response Timer, in ticks (0.1 second units). The default value is 1800. The permitted range is 0--32000.

T21value

The length of DTE timer T21, the Call Request Response Timer, in ticks (0.1 second units). The default value is 2000. The permitted range is 0--32000.

T22value

The length of DTE timer T22, the Reset Request Response Timer, in ticks (0.1 second units). The default value is 1800. The permitted range is 0--32000.

T23value

The length of DTE timer T20, the Clear Request Response Timer, in ticks (0.1 second units). The default value is 1800. The permitted range is 0--32000.

Tvalue

The maximum time over which acknowledgments of data received from the remote transmitter will be withheld. After this timer expires any withheld acknowledgments are carried by a Receive Not Ready (RNR) packet. This timer ensures that non-receipt of acknowledgment by the remote transmitter does not cause resets within the virtual circuit. This timer does not cause transmission of window status every Tvalue ticks (0.1 second units). The default value is 750. The permitted range is 0--32000.

T25value

The length of DTE timer T25, the Window Rotation Timer, in ticks (0.1 second units). The default value is 1500, as specified in ISO 8208. The permitted range is 0--32000.

The code may be configured to be lenient in the case of flow control inhibition (see Section 11.2 of ISO 8208). That is, a decision has to be made in order to cater for the case when the remote station does not rotate the window fast enough to prevent expiration of T25. ISO 8208 recommends strongly that high level protocols be used to effect recovery, to achieve this, set T25 to either zero (implying infinite) or a very large value.

The timer Tvalue, should be set to a value approximately half T25value, in order to prevent the remote PLP from resetting on T25 expiration. The timer ACKDELAY should be approximately 0.5 seconds, although this recommendation may change after evaluation and experience is gained.

Finally, the idlevalue timer may be set according to how quickly the LAN administration wishes the resource to be reclaimed, while connectvalue should be about three times the T20 value.

Note also that ISO 8208 recommends that the retry values R20, R22 and R23 should never be set to zero in order to cater for the possibility of collisions (see footnote to Figure 6, ISO 8208).

T26value

The length of DTE timer T26, the Interrupt Response Timer, in ticks (0.1 second units). The default value is 1800. The permitted range is 0--32000.

T28value

The length of DTE timer T28, the Registration Request Timer, in ticks (0.1 second units). The default value is 1800. The permitted range is 0--32000.

idlevalue

The number of ticks (0.1 second units) over which a link-level connection associated with no connections is maintained. This timer is meaningful on a LAN or on a dial-up WAN connection. The default value is 600. The permitted range is 0--32000.

connectvalue

The number of ticks (0.1 second units) over which the DTE/DCE resolution phase must be complete. On expiration of this timer, the link connection is disconnected and all pending connections are aborted. The default value is 2000. The permitted range is 0--32000.

R20value

The DTE Restart Request Retransmission Count. The default value is 1. The permitted range is 1--255.

R22value

The DTE Restart Request Retransmission Count. The default value is 1. The permitted range is 1--255.

R23value

The DTE Restart Request Retransmission Count. The default value is 1. The permitted range is 1--255.

localdelay and accessdelay

In milliseconds, the values of the transit delay attributed to internal processing and the effect of the line transmission rate. These values are used to check whether any maximum acceptable end-to-end transit delay specified in an N-CONNECT request or an N-CONNECT indication is in fact available.

locmaxthclass

The maximum value of the throughput class quality of service parameter in the local-to-remote direction which is supported. According to ISO 8208 this parameter is bounded in the range 3 and <= 12 corresponding to a range 75 to 48000 bits/second.

remmaxthclass

The maximum value of the throughput class quality of service parameter in the remote-to-local direction which is supported. According to ISO 8208 this parameter is bounded in the range 3 and <= 12 corresponding to a range 75 to 48000 bits/second.

locdefthclass

In some PSDNs, for example, TELENET, negotiation of throughput class is constrained to be towards a configured default throughput class. In such cases the flag thclass_neg_to_def (see below) is non-zero and locdefthclass is the default for the local-to-remote direction. In other PSDNs, locdefthclass should be set equal to the value of locmaxthclass (see above).

Note that locmaxthclass must be greater than or equal to locdefthclass.

remdefthclass

In some PSDNs, for example, TELENET, negotiation of throughput class is constrained to be towards a configured default throughput class. In such cases the flag thclass_neg_to_def is non-zero and remdefthclass is the default for the remote-to-local direction. In other PSDNs, set remdefthclass equal to the value of remmaxthclass (see above).

Note that remmaxthclass must be greater than or equal to remdefthclass.

locminthclass

According to ISO 8208, the throughput class parameter must be greater than or equal to 3 and less than or equal to 12. Some PSDNs may provide a different mapping, in which case locminthclass is the minimum value in the local-to-remote direction. Note that locmaxthclass must be less than or equal to locdefthclass which must be greater than or equal to locminthclass.

remminthclass

According to ISO 8208, the throughput class parameter is defined in the range 3 and 12. Some PSDNs may provide a different mapping, in which case remminthclass is the minimum value in the remote-to-local direction. Note that remmaxthclass must be greater than or equal to remdefthclass which must be greater than or equal to remminthclass.

CUG_CONTROL

This member controls Closed User Group actions in two ways. Firstly, it describes the type, if any, of Closed User Group facilities subscribed to. This is used to choose the appropriate encoding for any closed user group facilities in N-CONNECT requests. Secondly, it specifies the action to be taken if the Closed User Group optional facility is present in an incoming call. It is a bit map where the bits have the following meanings:

Table 7-19 bit map summary

Bit 

Description 

0 

subscription to CUGs with no Outgoing or Incoming Access 

1 

subscription to Preferential CUG 

2 

subscription to CUGs with Outgoing Access  

3 

subscription to CUGs with Incoming Access (For Information Only) 

4 

subscription to Basic Format CUGs 

5 

subscription to Extended format CUGs 

6 

reject incoming calls containing any Closed User Group facility 

7 

reserved 

Bits 0 and 2 are mutually exclusive as are bits 4 and 5.

SUB_MODES

This member is a bit map, which contains information on the various subscription options for a particular PSDN link. The entries mean:

Table 7-20 SUB_MODES summary

Entry 

Description 

SUB_EXTENDED

Subscribe to extended call packets. This permits the use of extended CALL REQUEST and CALL ACCEPT packets.

BAR_EXTENDED

Treat incoming extended call packets as a procedure error.The use of extended call packets allows window and packet size negotiation. Not setting the BAR_EXTENDED member permits the use of extended INCOMING CALL and CALL CONFIRM packets.

SUB_FSELECT

Subscribe to fast select with no restriction on response. This permits the use of fast select on INCOMING CALL packets.

SUB_FSRRESP

Subscribe to fast select with restriction on response. This permits the use of fast select with restricted response on INCOMING CALL packets.

SUB_REVCHARGE

Subscribe to reverse charging. This permits the use of reverse charges on INCOMING CALL packets.

SUB_LOC_CHG_PREV

Subscribe to local charging prevention. If set, this member has two effects. It prevents the use of reverse charges on INCOMING CALL packets regardless of the setting of SUB_REVCHARGE, and any CALL REQUEST packet will have the reverse charges facility automatically inserted.

SUB_TOA_NPI_FMT

Subscribe to using TOA/NPI address format. This specifies that all call set-up and clearing packets transmitted will always use the TOA/NPI address format.

BAR_TOA_NPI_FMT

Treat incoming TOA/NPI address formats as a procedure error. The BAR_TOA_NPI_FMT entry if set specifies that any call set-up and clearing packets received employing the TOA/NPI address format will be treated as a procedure error.

BAR_CALL_X32_REG

Refuse to accept incoming calls while X.32 registration is incomplete. 

SUB_NUI_OVERRIDE

Subscribe to NUI override.The SUB_NUI_OVERRIDE entry if set specifies that when an NUI is provided in a CALL REQUEST, then any associated subscription time options override the facilities which apply to the interface, for the duration of that particular call.

BAR_INCALL

Bar incoming calls.

BAR_OUTCALL

Bar outgoing calls.

Some PSDNs require certain procedures to be followed which are not standard for all X.25 networks. The structure psdn_local contains the flags used to tune the actions of the X.25 driver to the requirements of the particular network to which the configuration refers. The entries and values taken by the psdn_local structure are described below.

PSDN_MODES

This is used to tune the various options for a particular PSDN link. It is a bit map in which the various entries when set imply:

Table 7-21 PSDN Modes

Mode 

Description 

ACC_NODIAG

Allow the omission of the diagnostic byte in incoming RESTART, CLEAR and RESET INDICATION.

USE_DIAG

Use diagnostic packets.  

CCITT_CLEAR_LEN

Restrict the length of a CLEAR INDICATION to 5 bytes and a CLEAR CONFIRM to 3 bytes.  

BAR_DIAG

Disallow diagnostic packets. 

DISC_NZ_DIAG

Discard diagnostic packets on a non-zero LCN. 

ACC_HEX_ADD

Allow DTE addresses to contain hexadecimal digits. 

BAR_NONPRIV_LISTEN

Disallow a non-privileged user (that is, one without superuser privilege) from listening for incoming calls.  

INTL_PRIO

Prioritize international calls. 

DATAPAC_PRIORITY

Use DATAPAC (1976) priority rules. 

ISO_8882_MODE

Use strict ISO8882 conformance. 

X121_MAC_OUT

Keep X.121 address in call packets to LAN. 

X121_MAC_IN

Put X.121 address in call packets from LAN. 

The BAR_DIAG and DISC_NZ_DIAG entries specify the treatment of incoming diagnostic packets. When BAR_DIAG is set, incoming diagnostic packets are handled as follows. If USE_DIAG is set, and the link is configured as a DCE, then a diagnostic packet is sent to the DTE. Otherwise, the incoming diagnostic packet is simply discarded. When DISC_NZ_DIAG is set, diagnostic packets will be discarded when received on non-zero logical channel numbers. If ACC_HEX_ADD is set, DTE addresses are not restricted to containing only BCD digits.

intl_addr_recogn

The main use of this feature is in conjunction with the intl_prioritised member discussed below. Possible values are:

Table 7-22 Intl_addr_recogn summary

Value 

Description 

0 

International calls are not distinguished. 

1 

The DNIC of the called DTE address is examined and compared to that held in psdn_local members dnic1 and dnic2. A mismatch implies an international call.

2 

International calls are distinguished by having a "1" prefix on the called DTE address; for example, DATAPAC has this feature. 

3 

International calls are distinguished by having a "0" prefix on the called DTE address. 

dnic1, dnic2

The first four BCD digits of the DNIC and is only used when intl_addr_recogn has the value one.

intl_prioritised

This determines whether some prioritization method is to be used for international calls, and is used in conjunction with prty_encode_control and prty_pkt_forced_value.

intl_prioritised has two values: zero implying no priority, while non-zero implies an attempt to prioritize according to ptry_encode_control.

intl_addr_recogn has the value one.

prty_encode_control

This describes how the priority request is to be encoded for this PSDN. Values are:

Table 7-23 prty_encode_control values

Value 

Description 

0 

The priority is encoded according to section 3.3.3 of Annex G, Blue Book Volume VIII, Fascicle VIII.3 (CCITT, 1988). 

1 

Encode the priority request using the DATAPAC Priority Bit (1976 version).

2 

Encode the priority request using the DATAPAC Traffic Class (1980 version which uses the Calling Network facility marker).

prty_pkt_forced_value

If this entry is non-zero then it implies that all priority call requests and incoming calls should have the associated packet size parameter forced to this value (note that the actual packet size is two to the power of this parameter; for example, 7 implies 128 byte packets). A zero value implies no special action on packet size is required.

src_addr_control

This provides the means to override or set the calling address in outgoing call requests for this PSDN. It takes the following values:

Table 7-24 src_addr_control values

Value 

Description 

0 

No special action. Calling DTE addresses are encoded as and if provided by the network service user. 

1 

Force omission of the calling DTE address, even if the network service user supplied one. 

2 

If the network service user does not supply a DTE address, use the configured DTE address (local_address) for this PSDN (which can, of course, be NULL).

3 

Force the calling DTE address to that contained in local_address, even if the network service user supplied one.

dbit_control

This member specifies the action to be taken:

Actions which may be specified during the call setup phase are:

Actions which may be specified during the data transfer phase are:

thclass_neg_to_def

This accommodates certain network procedures which dictate that negotiation of throughput class must be towards the default value (for example, TELENET), the default value being configured into the member defthclass. A non-zero value in this member requests use of this option, zero implies non-use.

thclass_type

This provides the means by which throughput class encodings can be used to assign window and packet sizes (according to the arrays thclass_wmap and thclass_pmap described below). It should be noted that some implementations of X.25 do not use the X.25 packet and window negotiation but instead rely on mapping the throughput class to these parameters (see thclass_type 1,2 and 3). Thclass_type should be used on such PSDNs. Note also that the values of locmaxthclass and remmaxthclass may have an effect on what is achieved through the mapping.

The values assigned to thclass_type to indicate the mapping are:

Table 7-25 thclass_type values

Value 

Description 

0 

No special action is to be taken on throughput class. 

1 

Use only the low nibble of the throughput class parameter to map window and packet size for both directions and encode the high nibble as zero. Note that the window and packet sizes are intended to be asserted by the throughput class parameter. 

2 

Use only the high nibble of the throughput class parameter to map window and packet size for both directions and encode the low nibble as zero. Note that the window and packet sizes are intended to be asserted by the throughput class parameter. 

3 

Use both nibbles of the throughput class to map window and packet size for the appropriate directions. Note that the window and packet sizes are intended to be asserted by the throughput class parameter. 

Values 1, 2 and 3 are intended for use on non-standard X.25 PSDN implementations. Note the following.

For the special values 1 and 2:

For the value 3, window and packet sizes can be negotiated by the network service user only through the throughput class parameter. Negotiations through the flow negotiation parameters when subscribing to the extended facility option are overridden. However, as for values 1 and 2, this value is intended only for cases where this is the only means of negotiating window and packet sizes.

Since window and packet sizes can be mapped using these three values without the use of window and packet negotiation facilities, it is important that the map (thclass_wmap and thclass_pmap) is correct for the PSDN, in order to ensure that both called and calling parties agree on the values associated with a particular throughput class.

thclass_wmap, thclass_pmap

The mapping between the value of the throughput class (a number 0 to 15) and a window and packet parameter. Zero in this table indicates that the currently set or default value be used.

local_address

Holds the local DTE address for this X.25 link in a byte array, local_address.lsap_add, with an associated length byte local_address.lsap_len.