Use the OPTIONS statement to specify the call handling options for each link. Values specified on the OPTIONS statement apply to all outgoing calls on the LINK MCH, but can be overridden for individual destination addresses by the DEST statement. More than one OPTIONS statement can be coded after each LINK statement.
Restriction: Several parameters can be placed in a single OPTIONS statement, but cannot continue on the next line. If all the parameters do not fit on one line, use additional OPTIONS statements.
Syntax
.------------------------------------------------. V | >>---OPTIONS--+-ACCEPTFACILITIES --hex_facilities-+-+---------->< +-ACCEPTREVERSE---------------------+ +-REVERSE---------------------------+ +-PACKETSIZE --packet_size----------+ +-WINDOWSIZE --window_size----------+ +-GATE------------------------------+ +-CALLDATA --call_user_data---------+ '-FACILITIES --hex_facilities-------'
Parameters
- ACCEPTFACILITIES hex_facilities
- The X.25 facilities field to be used when accepting incoming calls. Specify this value as an even number of hexadecimal digits. The facilities length byte is calculated automatically and should not be coded here.
- ACCEPTREVERSE
- Causes incoming calls with the reverse charging facility to be accepted. The default action is to clear reverse charge calls.
- REVERSE
- Includes the reverse charging facility in all outgoing call request packets.
- PACKETSIZE packet_size
- The packet size to negotiate on switched virtual circuits, one of the values 32, 64, 128, 256, 512, 1 024, 2 048, or 4 096 bytes.
- WINDOWSIZE window_size
- The window size to negotiate on switched virtual circuits, in the range of 1 - 7 for a modulo-8 network, or 1 - 127 for a modulo-128 network.
- GATE
- Specified if the NPSI MCH is defined with GATE=GENERAL to permit sharing of an X.25 physical link with other services.
- CALLDATA call_user_data
- The call user data field to be used on outgoing X.25 calls, specified as an even number of hexadecimal digits. The standard value for IP traffic must begin with the protocol identifier CC.
- FACILITIES hex_facilities
- The X.25 facilities field to be used on outgoing calls for this destination. Specify this value as an even number of hexadecimal digits. The field is inserted in outgoing call packets following facilities generated from window or packet size negotiation or reverse charging. The facilities length byte is calculated automatically and should not be coded here.
Examples
The following example shows the
proper placement of the OPTIONS statements when using both LINK and
ALTLINK statements.
Link XU021 3110 23456789 2 128 16
FAST XU021
Options PacketSize 1024
AltLink XU022 3110 34567890 2 128 8
FAST XU022
Options PacketSize 1024
Options AcceptReverse
*Usage notes
- The OPTIONS statements must follow the LINK or ALTLINK statements to which they apply.
- Negotiation takes place on outgoing calls if the window size or packet size on the OPTIONS statement is different from the network defaults coded in the LINK statement.
- The max_packet_size, also called the maximum transmission unit (MTU), coded in the BUFFERS statement must be large enough to hold the largest IP datagram to be transmitted or received over the link. If the MTU is greater than the X.25 packet size, an IP datagram is sent as an X.25 packet sequence. The buffer size must be sufficient to hold the combined data of the sequence. The MTU for DDN networks is 1007. See RFC 877 for more information. information about how to obtain RFCs is included in z/OS Communications Server: IP Configuration Guide.