- Rockwell 2200 SNAP Streams Driver
The sxp (also known as the SNAP ) driver is a loadable, clonable, STREAMS driver that supports the connectionless Data Link Provider Interface ( dlpi(7P)) over one or more FDDI adapters (Rockwell 2200 Series). The cloning character-special devices (/dev/sxp, /dev/snap, /dev/llc, /dev/mac) are used to access the 2200 Series adapter(s). The /dev/sxp device is equivalent to /dev/snap. /dev/sxp is used so that the name SXP will show up in ifconfig. All messages transmitted on a SNAP device have the 802.2 LLC and Sub-Network Access Protocol (SNAP) and the FDDI MAC headers ( RFC -1188) prepended. For an LLC device, the LLC and MAC headers are prepended, and for a MAC device only the MAC header is prepended. Received FDDI frames are delivered to the appropriate open device. In response to a DL_INFO_REQ, the SNAP driver returns the following values in the DL_INFO_ACK primitive:
The maximum SDU is 4500.
The minimum SDU is 0.
The DLSAP address length is 8 (always true in the Solaris environment).
The address offset is 0 (prior to being attached).
The MAC type is DL_FDDI.
The sap length value is -2, which indicates that within the DLSAP address, the physical address component is followed immediately by a 2-byte service access point ( SAP ) component.
The service mode is DL_CLDLS.
The quality of service (QOS) fields are 0, because optional QOS is not supported.
The provider style is DL_STYLE2.
The broadcast address value is the IEEE broadcast address (FF:FF:FF:FF:FF:FF).
Because the SNAP driver is a "style 2" Data Link Service provider, an explicit DL_ATTACH_REQ message from the user is required to associate the opened stream with a particular network device (that is, ppa). The dl_ppa field within the DL_ATTACH_REQ indicates the instance (unit) number of the network device. If no currently attached ppa has the same instance number and there are no unattached ppas available, the driver returns an error (DL_ERROR_ACK). Once in the DL_ATTACHED state, a DL_BIND_REQ is required to associate a particular SAP with the stream.
Once in the DL_ATTACHED state, a DL_BIND_REQ is required to associate a particular Service Access Point ( SAP ) with the stream. For the sap field within the DL_BIND_REQ, valid values are in the range [0-0xFFFF]. Values for 0-0xFF will give LLC 802.2 service without SNAP encapsulation, unless a later DL_HIERARCHIAL_BIND DL_SUBS_BIND_REQ is made. Values from 0x100-0xFFFF will give LLC 802.2 with SNAP encapsulation without the need for a DL_SUBS_BIND_REQ. Note that DL_HIERARCHIAL_BIND class DL_SUBS_BIND_REQs are only supported on streams bound to the 0xAA SAP. After successful completion of the DL_BIND_REQ, the ppa is initialized and the stream is ready for use. In addition to the DL_HIERARCHIAL_BIND class of DL_SUBS_BUD_REQ, the DL_PEER_BIND class can be used to bind multiple SAP s with a stream.
Frames may be transmitted on the FDDI ring by sending DL_UNITDATA_REQ messages to the SNAP driver. The DLSAP address contained within the DL_UNITDATA_REQ must consist of both the SAP and physical (FDDI) components. For a SNAP device, the SAP portion of the DLSAP address is placed in the EtherType field of the 802.2 SNAP header. The DSAP and SSAP fields of the 802.2 LLC header are both set to the value 170, indicating a SNAP message and a MAC frame_type of LLC. For an LLC device, the SAP portion of the DLSAP address is placed in the DSAP field of the 802.2 LLC header. The SSAP field is set to the SAP bound to the stream. The MAC frame_type is LLC. For a MAC device, the SAP portion of the DLSAP address is placed in the frame_control field of the MAC header. Received FDDI frames are routed up the correct stream(s) as DL_UNITDATA_IND messages (containing the DLSAP address). The stream(s) are found by:
Comparing the EtherType field of the SNAP header with the bound SAP of all of the SNAP streams
Comparing the DSAP field of the LLC header with the bound SAP of all the LLC streams
Comparing the frame_control field of the MAC header with the bound SAP of all the MAC streams.
If necessary, messages are duplicated. In addition to the mandatory connectionless DLPI message set, the driver also supports the following primitives: DL_ENABMULTI_REQ, DL_DISABMULTI_REQ, DL_PROMISCON_REQ, DL_PROMISCOFF_REQ, DL_PHYS_ADDR_REQ.
The DL_ENABMULTI_REQ and DL_DISABMULTI_REQ primitives enable or disable reception of individual multicast group addresses. Using these primitives, a set of multicast group addresses may be iteratively created and modified on a per-stream basis. These primitives are accepted by the driver in any state following a successful DL_ATTACH_REQ. The DL_PROMISCON_REQ and DL_PROMISCOFF_REQ primitives (with the DL_PROMISC_PHYS flag set in the dl_levelfield) enable or disable reception of all (promiscuous mode) frames on the media, including frames generated by the local host. When used with the DL_PROMISC_SAP flag (set), this enables or disables reception of all sap values. When used with the DL_PROMISC_MULTI flag (set), this enables or disables reception of all multicast group addresses. The affect of each primitive is always on a per-stream basis, and is independent of the other sap and physical level configurations on this stream (or other streams). In the DL_PHYS_ADDR_ACK message, the DL_PHYS_ADDR_REQ primitive returns the 6-octet FDDI address (in canonical form) currently associated with the stream. This primitive is valid only in states following a successful DL_ATTACH_REQ. The driver also supports the following ioctls (I/O controls): DLIOCRAW, SL_RAW, SL_DATA_ENABLE, SL_DATA_DISABLE, and DRV_CONFIG. As defined by Solaris, the DLIOCRAW ioctl puts the stream into raw mode, which causes the driver to send the full MAC -level packet up the stream in an M_DATA message, instead of transforming it to the DL_UNITDATA_IND form. On this stream, the driver will also accept formatted M_DATA messages for transmission. To disable raw mode, the stream must be closed. The DLIOCRAW ioctl requires no arguments. As defined by Rockwell, the SL_RAW ioctl puts the stream into raw mode, similar to the DLIOCRAW ioctl except that the frame-type field of the MAC header is considered to be a long word instead of a byte, preserving alignment. The SL_RAW ioctl requires no arguments. As defined by Rockwell, the SL_DATA_ENABLE and SL_DATA_DISABLE ioctls enable or disable the transmission of data on the stream. By default, transmission is enabled. The SL_DATA_ENABLE and SL_DATA_DISABLE ioctls require no arguments.
SXP special character device
SXP loadable module
SXP configuration file
See attributes(5) for descriptions of the following attributes: