LLC1(4D) Devices LLC1(4D)

NAME

llc1 - Logical Link Control Protocol Class 1 Driver

SYNOPSIS

#include <sys/stropts.h>


#include <sys/ethernet.h>


#include <sys/dlpi.h>


#include <sys/llc1.h>

DESCRIPTION

The llc1 driver is a multi-threaded, loadable, clonable, STREAMS
multiplexing driver supporting the connectionless Data Link Provider
Interface, dlpi(4P), implementing IEEE 802.2 Logical Link Control
Protocol Class 1 over a STREAM to a MAC level driver. Multiple MAC
level interfaces installed within the system can be supported by the
driver. The llc1 driver provides basic support for the LLC1
protocol. Functions provided include frame transmit and receive, XID,
and TEST, multicast support, and error recovery and reporting.


The cloning, character-special device, /dev/llc1, is used to access
all LLC1 controllers configured under llc1.


The llc1 driver is a "Style 2" Data Link Service provider. All
messages of types M_PROTO and M_PCPROTO are interpreted as DLPI
primitives. An explicit DL_ATTACH_REQ message by the user is
required to associate the opened stream with a particular device
(ppa). The ppa ID is interpreted as an unsigned long and indicates
the corresponding device instance (unit) number. An error
(DL_ERROR_ACK) is returned by the driver if the ppa field value does
not correspond to a valid device instance number for this system.


The values returned by the driver in the DL_INFO_ACK primitive in
response to the DL_INFO_REQ from the user are as follows:

o The maximum Service Data UNIT (SDU) is derived from the
MAC layer linked below the driver. In the case of an
Ethernet driver, the SDU will be 1497.

o The minimum SDU is 0.

o The MAC type is DL_CSMACD or DL_TPR as determined by the
driver linked under llc1. If the driver reports that it is
DL_ETHER, it will be changed to DL_CSMACD; otherwise the
type is the same as the MAC type.

o The sap length value is -1, meaning the physical address
component is followed immediately by a 1-octet sap
component within the DLSAP address.

o The service mode is DL_CLDLS.

o The MAC type is DL_CSMACD or DL_TPR as determined by the
driver linked under llc1. If the driver reports that it is
DL_ETHER, it will be changed to DL_CSMACD; otherwise the
type is the same as the MAC type.

o The dlsap address length is 7.

o No optional quality of service (QOS) support is included
at present, so the QOS fields should be initialized to 0.

o The DLPI version is DL_VERSION_2.

o The provider style is DL_STYLE2.

o The broadcast address value is the broadcast address
returned from the lower level driver.


Once in the DL_ATTACHED state, the user must send a DL_BIND_REQ to
associate a particular Service Access Point (SAP) with the stream.
The llc1 driver interprets the sap field within the DL_BIND_REQ as
an IEEE 802.2 "SAP," therefore valid values for the sap field are in
the [0-0xFF] range with only even values being legal.


The llc1 driver DLSAP address format consists of the 6-octet
physical (e.g., Ethernet) address component followed immediately by
the 1-octet sap (type) component producing a 7-octet DLSAP address.
Applications should not hard-code to this particular implementation-
specific DLSAP address format, but use information returned in the
DL_INFO_ACK primitive to compose and decompose DLSAP addresses. The
sap length, full DLSAP length, and sap/physical ordering are included
within the DL_INFO_ACK. The physical address length can be computed
by subtracting the absolute value of the sap length from the full
DLSAP address length or by issuing the DL_PHYS_ADDR_REQ to obtain
the current physical address associated with the stream.


Once in the DL_BOUND state, the user may transmit frames on the LAN
by sending DL_UNITDATA_REQ messages to the llc1 driver. The llc1
driver will route received frames up all open and bound streams
having a sap which matches the IEEE 802.2 DSAP as DL_UNITDATA_IND
messages. Received frames are duplicated and routed up multiple open
streams if necessary. The DLSAP address contained within the
DL_UNITDATA_REQ and DL_UNITDATA_IND messages consists of both the sap
(type) and physical (Ethernet) components.


In addition to the mandatory, connectionless DLPI message set, the
driver additionally supports the following primitives:


The DL_ENABMULTI_REQ and DL_DISABMULTI_REQ primitives enable/disable
reception of specific multicast group addresses. A set of multicast
addresses may be iteratively created and modified on a per-stream
basis using these primitives. These primitives are accepted by the
driver in any driver state that is valid while still being attached
to the ppa.


The DL_PHYS_ADDR_REQ primitive returns the 6-octet physical address
currently associated (attached) to the stream in the
DL_PHYS_ADDR_ACK primitive. This primitive is valid only in states
following a successful DL_ATTACH_REQ.


The DL_SET_PHYS_ADDR_REQ primitive changes the 6-octet physical
address currently associated (attached) to this stream. Once changed,
all streams subsequently opened and attached to this device will
obtain this new physical address. Once changed, the physical address
will remain set until this primitive is used to change the physical
address again or the system is rebooted, whichever occurs first.


The DL_XID_REQ/DL_TEST_REQ primitives provide the means for a user to
issue an LLC XID or TEST request message. A response to one of these
messages will be in the form of a DL_XID_CON/DL_TEST_CON message.


The DL_XID_RES/DL_TEST_RES primitives provide a way for the user to
respond to the receipt of an XID or TEST message that was received
as a DL_XID_IND/DL_TEST_IND message.


XID and TEST will be automatically processed by llc1 if the
DL_AUTO_XID/DL_AUTO_TEST bits are set in the DL_BIND_REQ.

FILES

/dev/llc1
cloning, character-special device

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|Architecture | x86 |
+---------------+-----------------+

SEE ALSO

dlpi(4P), attributes(7)

February 13, 1997 LLC1(4D)