man pages section 7: Device and Network Interfaces

dlpi(7P)

Name

dlpi– Data Link Provider Interface

Synopsis

#include <sys/dlpi.h>

Description

SunOS STREAMS-based device drivers wishing to support the STREAMS TCP/IP and other STREAMS-based networking protocol suite implementations support Version 2 of the Data Link Provider Interface (DLPI). DLPI V2 enables a data link service user to access and use any of a variety of conforming data link service providers without special knowledge of the provider's protocol. Specifically, the interface is intended to support Ethernet, X.25 LAPB, SDLC, ISDN LAPD, CSMA/CD, FDDI, token ring, token bus, Bisync, and other datalink-level protocols.

The interface specifies access to the data link service provider in the form of M_PROTO and M_PCPROTO type STREAMS messages and does not define a specific protocol implementation. The interface defines the syntax and semantics of primitives exchanged between the data link user and the data link provider to attach a physical device with physical-level address to a stream, bind a datalink-level address to the stream, get implementation-specific information from the data link provider, exchange data with a peer data link user in one of three communication modes (connection, connectionless, acknowledged connectionless), enable/disable multicast group and promiscuous mode reception of datalink frames, get and set the physical address associated with a stream, and several other operations.

Solaris conforms to The Open Group Technical Standard for DLPI, Version 2. For free access to this specification, point your browser to www.opengroup.org/pubs/catalog/c811.htm. Solaris also provides extensions to the DLPI standard, as detailed in this man page.

SOLARIS-SPECIFIC DLPI EXTENSIONS

Notification Support

Enables DLPI consumers to register for notification when events of interest occur at the DLPI provider. The negotiation may be performed on any attached DLPI stream, and begins with the DLPI consumer, sending a DL_NOTIFY_REQ to the provider, which is an M_PROTO message with the following payload:

      typedef struct {
              t_uscalar_t     dl_primitive;
              uint32_t        dl_notifications;
              uint32_t        dl_timelimit;
      } dl_notify_req_t;

The dl_primitive field must be set to DL_NOTIFY_REQ; the dl_timelimit field is reserved for future use and must be set to zero. The dl_notifications field is a bitmask containing the event types the consumer is interested in receiving, and must be zero or more of:

DL_NOTE_LINK_DOWN         Notify when link has gone down
DL_NOTE_LINK_UP           Notify when link has come up
DL_NOTE_PHYS_ADDR         Notify when address changes 
DL_NOTE_SDU_SIZE          Notify when MTU changes
DL_NOTE_SPEED             Notify when speed changes 
DL_NOTE_PROMISC_ON_PHYS   Notify when DL_PROMISC_PHYS is set
DL_NOTE_PROMISC_OFF_PHYS  Notify when DL_PROMISC_PHYS is cleared

Consumers may find it useful to send a DL_NOTIFY_REQ message with no requested types to check if the DLPI provider supports the extension.

Upon receiving the DL_NOTIFY_REQ, the DLPI provider must generate a DL_NOTIFY_ACK, which is an M_PROTO message with the following payload:

      typedef struct {
              t_uscalar_t     dl_primitive;
              uint32_t        dl_notifications;
      } dl_notify_ack_t;

The dl_primitive field must be set to DL_NOTIFY_ACK. The dl_notifications field must include any requested notifications that the driver supports, along with any other unrequested notifications that the driver supports. However, regardless of the notifications the driver supports, it is restricted to sending only DL_NOTIFY_IND messages (see below) that were requested in the DL_NOTIFY_REQ.

Since there are additional notification types which are not yet available for public use, DLPI consumers and providers must take care when inspecting and setting the dl_notifications field. Specifically, consumers must be careful to only request the above notification types, and providers must be careful to not include any unrecognized notification types in the dl_notifications field when constructing the DL_NOTIFY_ACK. In addition, DL_NOTIFY_IND's that are received with undocumented dl_notification or dl_data values must be ignored.

DLPI consumers may receive a DL_ERROR_ACK message (with dl_primitive set to DL_NOTIFY_REQ) in response to the initial DL_NOTIFY_REQ message. This message indicates that the DLPI provider does not support the DLPI notification extension. Otherwise, the DLPI consumer will receive a DL_NOTIFY_ACK and should expect to receive DL_NOTIFY_IND messages for any types that it requested that were still set in it. The DL_NOTIFY_IND is an M_PROTO message with the following payload:

     typedef struct {
             t_uscalar_t     dl_primitive;
             uint32_t        dl_notification;
             uint32_t        dl_data;
             t_uscalar_t     dl_addr_length;
             t_uscalar_t     dl_addr_offset;
     } dl_notify_ind_t;

The dl_primitive field must be set to DL_NOTIFY_IND, and the dl_notification field must be set to the event type that has occurred (for example, DL_NOTE_LINK_DOWN). Only a single event type may be set in each DL_NOTIFY_IND.

For the DL_NOTE_SPEED event type, dl_data must be set to the current interface speed in kilobits per second. For the DL_NOTE_PHYS_ADDR event type, dl_data must be set to DL_CURR_PHYS_ADDR. For the DL_NOTE_SDU_SIZE event type, dl_data must be set to the current MTU in bytes. Otherwise, dl_data must be set to zero.

For the DL_NOTE_PHYS_ADDR event type, the dl_addr_length field must be set to the length of the address, and the dl_addr_offset field must be set to offset of the first byte of the address, relative to b_rptr (for example, if the address imediately follows the dl_notify_ind structure, dl_addr_offset is set to 'sizeof (dl_notify_ind)'). For all other event types, the dl_addr_length anddl_addr_offset fields must be set to zero by DLPI providers and ignored by DLPI consumers.

In addition to generating DL_NOTIFY_IND messages when a requested event has occurred, the DLPI provider must initially generate one or more DL_NOTIFY_IND messages to notify the DLPI consumer of the the current state of the interface. For instance, if the consumer has requested DL_NOTE_LINK_UP | DL_NOTE_LINK_DOWN, the provider must send a DL_NOTIFY_IND containing the current state of the link (either DL_NOTE_LINK_UP or DL_NOTE_LINK_DOWN) after sending the DL_NOTIFY_ACK.

For the initial DL_NOTIFY_IND message, the DLPI provider is strongly recommended against sending DL_NOTE_LINK_DOWN, even if the interface is still initializing and is not yet ready to send or receive packets. Instead, either delaying the DL_NOTIFY_IND message until the interface is ready or optimistically reporting DL_NOTIFY_LINK_UP and subsequently reporting DL_NOTE_LINK_DOWN if the negotation fails is strongly preferred. This prevents DL_NOTIFY_IND consumers from needlessly triggering network failover operations and logging error messages during network interface initialization.

The DLPI provider must continue to generate DL_NOTIFY_IND messages until it receives a new DL_NOTIFY_REQ message or the DLPI stream is detached (or closed). Further, a DLPI style 2 driver must keep track of the requested events after a DL_DETACH_REQ operation, and if a subsequent DL_ATTACH_REQ is received, it must send gratuitous DL_NOTIFY_IND messages to notify the consumer of the current state of the device, since the state may have changed while detached (or the consumer may have simply discarded its previous state).

Passive Consumers of Aggregated Links

Solaris link aggregations as configured by dladm(1M) export DLPI nodes for both the link aggregation, and individual links that comprises the aggregation, to allow observability of the aggregated links. To allow applications such as snoop(1M) to open those individual aggregated links while disallowing other consumers such as ip(7P), DL_PASSIVE_REQ (a DLPI primitive), must be issued by snoop(1M) and similar applications.

The DL_PASSIVE_REQ primitive is an M_PROTO message containing the following payload:

typedef struct {
        t_uscalar_t     dl_primitive;
} dl_passive_req_t;

Issuing this primitive allows the consumer of a DLPI link to coexist with a link aggregation that also uses the link. Such a consumer is considered passive.

Consumers that don't use this primitive while an aggregation is using the link receive DL_SYSERR/EBUSY when issuing the following DLPI primitives:

DL_BIND_REQ
DL_ENABMULTI_REQ
DL_PROMISCON_REQ
DL_AGGR_REQ
DL_UNAGGR_REQ                
DL_CONTROL_REQ
DL_SET_PHYS_ADDR_REQ

A consumer that has not issued a DL_PASSIVE_REQ and has successfully issued one of the above primitives is considered active.

The creation of a link aggregation using dladm(1M) fails if one of the links included in the aggregation has an active consumer, but succeeds if the links do not have any DLPI consumers or only passive consumers.

QoS Support

The IEEE 802.1Q standard defines eight classes of priority values used by QoS traffic control of Ethernet packets. Although the priority values are encoded in the 802.1Q tags, they can be used independently from VLANs. In particular, a special priority tagged packet (with VLAN ID zero but priority bits non-zero) does not belong to any VLAN.

The priority value can be set on either a per-stream or per-packet basis. DLPI consumers can specify the per-stream priority using the DL_UDQOS_REQ request (the priority value remains unchanged until the next DL_UDQOS_REQ) and also specify the per-packet priority value using the b_band field of a M_DATA message or the dl_priority field of a DL_UNITDATA_REQ.

Raw Mode

The DLIOCRAW ioctl function is used by some DLPI applications, most notably the snoop(1M) command. The DLIOCRAW command puts the stream into a raw mode, which, upon receive, causes the the full MAC-level packet to be sent upstream in an M_DATA message instead of it being transformed into the DL_UNITDATA_IND form normally used for reporting incoming packets. Packet SAP filtering is still performed on streams that are in raw mode. If a stream user wants to receive all incoming packets it must also select the appropriate promiscuous modes. After successfully selecting raw mode, the application is also allowed to send fully formatted packets to the driver as M_DATA messages for transmission. DLIOCRAW takes no arguments. Once enabled, the stream remains in this mode until closed.

Files

Files in or under /dev.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability (Notification support/Passive mode behavior)	Evolving

Notes

A Solaris DLPI link name consists of a DLPI provider name followed by a numeric PPA (physical point of attachment).

The DLPI provider name must be between 1 and 16 characters in length, though names between 3 and 8 characters are preferred. The DLPI provider name can consist of any alphanumeric character (a-z, A-Z, 0-9), and the underscore (_). The first and last character of the DLPI provider name cannot be a digit.

The PPA must be a number between 0 and 4294967294 inclusive. Leading zeroes are not permitted.

SunOS 5.10 Last Revised 7 Jun 2010