LLC1(4D) LLC1(4D)


llc1 - Logical Link Control Protocol Class 1 Driver


#include <sys/stropts.h>

#include <sys/ethernet.h>

#include <sys/dlpi.h>

#include <sys/llc1.h>


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

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

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.


cloning, character-special device


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

|Architecture | x86 |


dlpi(4P), attributes(7)

February 13, 1997 LLC1(4D)