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Inside Macintosh: Networking /

Chapter 11 - Ethernet, Token Ring, and Fiber Distributed Data Interface / Ethernet, Token Ring, and FDDI Reference

Routines / Adding and Removing Ethernet Multicast Addresses

EAddMulti

The EAddMulti function adds a multicast address or a functional address to the node that is running your application.

FUNCTION EAddMulti (thePBptr: EParamBlkPtr; 
                     async: Boolean): OSErr;

thePBptr

A pointer to a parameter block of type EParamBlock.

async

A Boolean value that specifies whether the function should be
executed asynchronously or synchronously. Specify TRUE for asynchronous execution.

-->	ioCompletion	ProcPtr	A pointer to completion routine.
<--	ioResult	OSErr	Result code.
-->	ioRefNum	Integer	Driver reference number.
-->	csCode	Integer	Always ENetAddMulti for this function.
-->	eMultiAddr	6-byte array	Multicast address.

Field Description

eMultiAddr

The multicast address that you want to add and use.

DESCRIPTION

You use the EAddMulti function to add a multicast address for Ethernet or FDDI to
the node that is running your application so that the hardware device driver for that network type will accept packets delivered to that address. You can also use this function to add a functional address that serves the same purpose for token ring.

Each time a client of a hardware device driver calls the EAddMulti function for a particular multicast address, the driver increments a counter for that multicast address. Each time a client of the hardware device driver calls the EDelMulti function, the driver decrements the counter for that address. As long as the count for a multicast address is equal to or greater than 1, the hardware device driver accepts packets directed to that multicast address. Therefore, if any client of the hardware device driver in the node has called the EAddMulti function for a particular multicast address, the driver receives packets delivered to that address. This process also applies to token ring for functional addresses. For information on how to specify multicast and functional addresses, see Inside AppleTalk, second edition. Be careful not to use the broadcast address, which is also described in Inside AppleTalk, as a functional address.

TOKEN RING AND FDDI CONSIDERATIONS

If your token ring application requires a functional address, use the EAddMulti function to register a functional address. Functional addresses are the token ring equivalent of Ethernet and FDDI multicast addresses. If your FDDI application requires a multicast address, use the EAddMulti function to register a multicast address.

ASSEMBLY-LANGUAGE INFORMATION

To execute the EAddMulti function from assembly language, call the _Control
trap macro with a value of ENetAddMulti in the csCode field of the parameter
block. To execute the _Control trap asynchronously, include the value ,ASYNC in
the operand field.

RESULT CODES

noErr	0	No error
eMultiErr	-91	Invalid address or table is full