| Document revision date: 30 March 2001 | |
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The IO$M_SENSE_MAC qualifier, when used with IO$_SENSEMODE, returns the parameters specified in Section 1.16.3.6. In addition to the set mac parameters, Table 1-22 shows the returns of the following parameters:
1.16.4.2 IO$M_SHOW_MAP Functional Modifier to IO$_SENSMODE (Alpha Only)
On Alpha systems using Token Ring only, the IO$M_SHOW_MAP qualifier, when used with IO$_SENSEMODE, returns the current setting of the mapping table. The P2 buffer is filled with the current multicast to functional address mapping information. The entries are 16 bytes long and are in the format shown in Figure 1-28. This QIO requires PHY_IO privilege.
Figure 1-28 Format of IO$M_SHOW_MAP P2 Buffer (Alpha Only)
The multicast address and functional address mask are returned in canonical format (that is, not bit-reversed). The following errors may occur:
On Alpha systems with Token Ring only, the IO$M_SHOW_ROUTE qualifier, when used with IO$_SENSEMODE, returns the current value of the source routing cache table. Each entry is 64 bytes long. Figure 1-29 shows the format of the returned P2 buffer:
Figure 1-29 Format of IO$M_SHOW_ROUTE P2 Buffer (Alpha Only)
Table 1-23 shows possible states of the entry.
The LAN address is returned in canonical format (that is, not bit-reversed). The timers are recorded as seconds before expiration. The transmit and receive timers are initialized from the NMA$C_PCLI_A_TIM parameter, the discovery timer is initialized from the NMA$C_PCLI_ROUTEDIS parameter, and the stale timer is initialized to 10 minutes (600 seconds). The following errors may occur:
The I/O status block (IOSB) for all LAN driver functions is shown in Figure 1-30. <REFERENCE>(io_func_codes_2_app_a) lists the completion status returns for these functions. (The OpenVMS system messages documentation provides explanations and suggested user actions for these returns.)
Figure 1-30 IOSB Contents
The first longword of the IOSB returns, in addition to the completion
status, either the size (in bytes) of the data transfer or the size (in
bytes) of the attribute buffer (P2) returned by a sense mode function.
The second longword returns the unit and line status bits listed in
Table 1_9 and the error summary bits listed in Table 1-10.
1.18 Application Programming Notes
This section contains information to assist you in writing application
programs that use the LAN device drivers. Section 1.18.1 discusses the
additional rules required for application programs that you intend to
run in promiscuous mode. Section 1.18.2 describe the Ethernet and 802
sample programs.
1.18.1 Promiscuous Mode
The LAN drivers allow only one port per controller to start with promiscuous mode enabled (NMA$C_PCLI_PRM specified as NMA$C_STATE_ON). Any port running in promiscuous mode usually places an additional load on the CPU because the LAN driver processes every packet on the LAN for the promiscuous user. If there is no promiscuous port on a controller, the controller performs most of the filtering required for the packets on the line.
Table 1-24 details additional rules for ports running in promiscuous mode.
1.18.2 Local Area Network Programming Examples
The VAX MACRO program LANETH.MAR (Example 1-3 shows the typical use of QIO functions in driver operations such as establishing the protocol type, starting the port, and transmitting and receiving data. The program sends a LOOPBACK packet and waits for the packet to be returned.
The DEC C program LAN802E.C (Example 1-4) shows how to initialize an 802E port and how to send and receive packets on that port. This program sends a LOOPBACK packet and waits for the packet to be returned.
| Example 1-3 LANETH.MAR Local Area Network Programming Example | ||
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| Example 1-4 LAN802.C Local Area Network Programming Example | ||
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