tfUseScatIntfDriver

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#include <trsocket.h>

ttUserInterface tfUseScatIntfDriver	(
	ttCharPtr namePtr,
	ttUserLinkLayer linkLayerHandle,
	int TM_FAR * errorCodePtr
	);

Function Description

tfUseScatIntfDriver() adds a loopback driver below link layer using one scattered device driver send call and scattered device driver recv. tfUseIntfDriver() and tfUseScatIntfDriver() are very useful to debug a link layer. tfUseScatIntfDriver() avoids copying the data in the loopback driver. An example would be as follows:

 
ethernetLinkLayerHandle = tfUseEthernet();
myInterfaceHandle=tfUseScatIntfDriver("TEST1",
                                      etherLinkLayerHandle,
                                      &errorCode);
 

Note:

Both TM_USE_ONE_SCAT_DRV_SEND and TM_USE_DRV_SCAT_RECV need to be defined. If either one of these macros is not defined then tfUseScatIntfDriver() will revert to tfUseIntfDriver().

When using the loop back driver (scattered or non scattered version) some macro definitions and configurations are necessary to ensure that the loopback driver is used and not bypassed for a given destination IP address (peer IP address).

Peer IP Address	Steps to ensure that the loopback driver is used
Configured in the stack	Define TM_LOOP_TO_DRIVER or TM_SINGLE_INTERFACE_HOME.
Not configured in the stack	Define TM_DEV_IP_NO_CHECK. If the link layer is Ethernet then a proxy ARP entry should be added for the peer IP address.

Parameters

• namePtr

  The caller's name for the device (each call to tfUseScatIntfDriver() must use a unique name). The name length cannot exceed TM_MAX_DEVICE_NAME - 1 (13 bytes).

• linkLayerHandle

  The link layer (layer 2) protocol handle that this interface will use. This is returned by tfUseEthernet(), tfUseAsyncPpp(), or tfUseSlip().

• drvAddErrorPtr

  A pointer to an int that will contain an error (if one occured).

Returns

• interfaceHandle

  Success

• NULL

  Failure

Possible *drvAddErrorPtr Values

• TM_EINVAL

  One of the parameters is invalid.

• TM_EALREADY

  A device with the same name has already been added.

• TM_ENOBUFS

  Insufficient memory to allocate the device entry.

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