|MAC(9E)||Driver Entry Points||MAC(9E)|
The main interface with MAC is through a series of callbacks defined in a mac_callbacks(9S) structure. These callbacks control all the aspects of the device. They range from sending data, getting and setting of properties, controlling mac address filters, and also managing promiscuous mode.
The MAC framework takes care of many aspects of the device driver's management. A device that uses the MAC framework does not have to worry about creating device nodes or implementing open(9E) or close(9E) routines. In addition, all of the work to interact with dlpi(4P) is taken care of automatically and transparently.
When sending frames, the MAC framework always calls functions registered in the mac_callbacks(9S) structure to have the driver transmit frames on hardware. When receiving frames, the driver will generally receive an interrupt which will cause it to check for incoming data and deliver it to the MAC framework.
Configuration of a device, such as whether auto-negotiation should be enabled, the speeds that the device supports, the MTU (maximum transmission unit), and the generation of pause frames are all driven by properties. The functions to get, set, and obtain information about properties are defined through callback functions specified in the mac_callbacks(9S) structure. The full list of properties and a description of the relevant callbacks can be found in the PROPERTIES section.
The MAC framework is designed to take advantage of various modern features provided by hardware, such as checksumming, segmentation offload, and hardware filtering. The MAC framework assumes none of these advanced features are present and allows device drivers to negotiate them through a capability system. Drivers can declare that they support various capabilities by implementing the optional mc_getcapab(9E) entry point. Each capability has its associated entry points and structures to fill out. The capabilities are detailed in the CAPABILITIES section.
The following sections describe the flow of a basic device driver. For advanced device drivers, the flow is generally the same. The primary distinction is in how frames are sent and received.
All device drivers have to define a dev_ops(9S) structure which is pointed to by a modldrv(9S) structure and the corresponding NULL-terminated modlinkage(9S) structure. The dev_ops(9S) structure should have a cb_ops(9S) structure defined for it; however, it does not need to implement any of the standard cb_ops(9S) entry points.
Normally, in a driver's _init(9E) entry point, it passes its modlinkage(9S) structure directly to mod_install(9F). To properly register with MAC, the driver must call mac_init_ops(9F) before it calls mod_install(9F). If for some reason the mod_install(9F) function fails, then the driver must be removed by a call to mac_fini_ops(9F).
Conversely, in the driver's _fini(9E) routine, it should call mac_fini_ops(9F) after it successfully calls mod_remove(9F). For an example of how to use the mac_init_ops(9F) and mac_fini_ops(9F) functions, see the examples section in mac_init_ops(9F).
These steps should all be taken during a device's attach(9E) entry point. It is recommended that the driver perform this sequence of steps after the device has finished its initialization of the chipset and interrupts, though interrupts should not be enabled at that point. After it calls mac_register(9F) it will start receiving callbacks from the MAC framework.
To allocate the registration structure, the driver should call
mac_alloc(9F). Device drivers
should generally always pass the symbol
as the argument to mac_alloc(9F).
Upon successful completion, the driver will receive a
mac_register_t structure which it should fill in. The
structure and its members are documented in
The mac_callbacks(9S) structure is not allocated as a part of the mac_register(9S) structure. In general, device drivers declare this statically. See the MAC Callbacks section for more information on how to fill it out.
Once the structure has been filled in, the driver should call mac_register(9F) to register itself with MAC. The handle that it uses to register with should be part of the driver's soft state. It will be used in various other support functions and callbacks.
If the call is successful, then the device driver should enable
interrupts and finish any other initialization required. If the call to
mac_register(9F) failed, then
it should unwind its initialization and should return
DDI_FAILURE from its
The driver does not need to hold onto an allocated mac_register(9S) structure after it has called the mac_register(9F) function. Whether the mac_register(9F) function returns successfully or not, the driver may free its mac_register(9S) structure by calling the mac_free(9F) function.
A device driver should make no assumptions about when the various callbacks will be called and whether or not they will be called simultaneously. For example, a device driver may be asked to transmit data through a call to its mc_tx(9E) entry point while it is being asked to get a device property through a call to its mc_getprop(9E) entry point. As such, while some calls may be serialized to the device, such as setting properties, the device driver should always presume that all of its data needs to be protected with locks. While the device is holding locks, it is safe for it call the following MAC routines:
Any other MAC related routines should not be called with locks held, such as mac_link_update(9F) or mac_rx(9F). Other routines in the DDI may be called while locks are held; however, device driver writers should be careful about calling blocking routines while locks are held or in interrupt context, even when it is legal to do so as this may cause all other callers that need a given lock to back up behind such an operation.
During a single interrupt or poll request, a device driver should process a fixed number of frames. For each frame the device driver should:
Once all the frames have been processed and assembled, the device driver should deliver them to the rest of the operating system by calling mac_rx(9F). The device driver should try to give as many mblk_t structures to the system at once. It should not call mac_rx(9F) once for every assembled mblk_t.
The device driver must not hold any locks across the call to mac_rx(9F). When this function is called, received data will be pushed through the networking stack and some replies may be generated and given to the driver to send out.
It is not the device driver's responsibility to determine whether or not the system can keep up with a driver's delivery rate of frames. The rest of the networking stack will handle issues related to keeping up appropriately and ensure that kernel memory is not exhausted by packets that are not being processed.
If the device driver has negotiated the
MAC_CAPAB_RINGS capability (discussed in
mac_capab_rings(9E)) then it
should call mac_rx_ring(9F) and
not mac_rx(9F). A given interrupt may
correspond to more than one ring that needs to be checked. The set of rings
is likely to span different groups that were registered with MAC through the
mr_gget(9E) interface. In those
cases, the driver should follow the above procedure independently for each
ring. That means it will call
mac_rx_ring(9F) once for each
ring using the handle that it received from when MAC called the driver's
mr_rget(9E) entry point. When it is
looking at the rings, the driver will need to make sure that the ring has
not had interrupts disabled (due to a pending change to polling mode). This
is discussed in greater detail in the
mri_poll(9E) manual pages.
Finally, the device driver should make sure that any other housekeeping activities required for the ring are taken care of such that more data can be received.
At some point in the future when resources have become available again, for example after an interrupt indicating that some portion of the transmit ring has been sent, then the device driver must notify the system that it can continue transmission. To do this, the driver should call mac_tx_update(9F). After that point, the driver will receive calls to its mc_tx(9E) entry point again. As mentioned in the section on callbacks, the device driver should avoid holding any particular locks across the call to mac_tx_update(9F).
As long as a device driver implements the needed entry points, then there is nothing else that it needs to do to take advantage of polling. A driver should not attempt to spin up its own threads, task queues, or creatively use timeouts, to try to simulate polling for received packets.
If the hardware supports more than one unicast filter then the
device driver should consider implementing the
MAC_CAPAB_RINGS capability, which exposes a means
for multiple unicast MAC address filters to be used by the broader system.
It is still useful to implement this on hardware which only has a single
mac_capab_rings(9E) for more
MAC_CAPAB_RINGScapability and see mac_capab_rings(9E) for more information.
Logically, there are two different sets of things that the device driver needs to keep track of while it's operating:
By default, when a link first comes up, the device driver should generally configure the link to support the common set of speeds and perform auto-negotiation.
A user can control what speeds a device advertises via auto-negotiation and whether or not it performs auto-negotiation at all by using a series of properties that have _EN_ in the name. These are read/write properties and there is one for each speed supported in the operating system. For a full list of them, see the PROPERTIES section.
In addition to these properties, there is a corresponding set of properties with _ADV_ in the name. These are similar to the _EN_ family of properties, but they are read-only and indicate what the device has actually negotiated. While they are generally similar to the _EN_ family of properties, they may change depending on power settings. See the Ethernet Link Properties section in dladm(8) for more information.
It's worth discussing how these different values get used throughout the different entry points. The first entry point to consider is the mc_propinfo(9E) entry point. For a given speed, the driver should consult whether or not the hardware supports this speed. If it does, it should fill in the default value that the hardware takes and whether or not the property is writable. The properties should also be updated to indicate whether or not it is writable. This holds for both the _EN_ and _ADV_ family of properties.
The next entry point is
mc_getprop(9E). Here, the device
should first consult whether the given speed is supported. If it is not,
then the driver should return
ENOTSUP. If it does,
then it should return the current value of the property.
The last property endpoint is the
mc_setprop(9E) entry point. Here,
the same logic applies. Before the driver considers whether or not the
property is writable, it should first check whether or not it's a supported
property. If it's not, then it should return
ENOTSUP. Otherwise, it should proceed to check
whether the property is writable, and if it is and a valid value, then it
should update the property and restart the link's negotiation.
Finally, there is the mc_getstat(9E) entry point. Several of the statistics that are queried relate to auto-negotiation and hardware capabilities. When a statistic relates to the hardware supporting a given speed, the _EN_ properties should be ignored. The only thing that should be consulted is what the hardware itself supports. Otherwise, the statistics should look at what is currently being advertised by the device.
The MAC framework will query a device for support of a capability
through the mc_getcapab(9E)
function. Each capability has its own constant and may have corresponding
data that goes along with it and a specific structure that the device is
required to fill in. Note, the set of capabilities changes over time and
there are also private capabilities in the system. Several of the
capabilities are used in the implementation of the MAC framework. Others,
MAC_CAPAB_RINGS, represent feature that have
not been stabilized and thus both API and binary compatibility for them is
not guaranteed. It is important that the device driver handles unknown
capabilities correctly. For more information, see
The following capabilities are stable and defined in the system:
MAC_CAPAB_HCKSUMcapability indicates to the system that the device driver supports some amount of checksumming. The specific data for this capability is a pointer to a uint32_t. To indicate no support for any kind of checksumming, the driver should either set this value to zero or simply return that it doesn't support the capability.
Note, the values that the driver declares in this capability indicate what it can do when it transmits data. If the driver can only verify checksums when receiving data, then it should not indicate that it supports this capability. The following set of flags may be combined through a bitwise inclusive OR:
When in a driver's transmit function, the driver will be processing a single frame. It should call mac_hcksum_get(9F) to see what checksum flags are set on it. Note that the flags that are set on it are different from the ones described above and are documented in its manual page. These flags indicate how the driver is expected to program the hardware and what checksumming is required. Not all frames will require hardware checksumming or will ask the hardware to checksum it.
If a driver supports offloading the receive checksum and verification, it should check to see what the hardware indicated was verified. The driver should then call mac_hcksum_set(9F). The flags used are different from the ones above and are discussed in detail in the mac_hcksum_set(9F) manual page. If there is no checksum information available or the driver does not support checksumming, then it should simply not call mac_hcksum_set(9F).
Note that the checksum flags should be set on the first mblk_t that makes up a given message. In other words, if multiple mblk_t structures are linked together by the b_cont member to describe a single frame, then it should only be called on the first mblk_t of that set. However, each distinct message should have the checksum bits set on it, if applicable. In other words, each mblk_t that is linked together by the b_next pointer may have checksum flags set.
It is recommended that device drivers provide a private property or driver.conf(5) property to control whether or not checksumming is enabled for both rx and tx; however, the default disposition is recommended to be enabled for both. This way if hardware bugs are found in the checksumming implementation, they can be disabled without requiring software updates. The transmit property should be checked when determining how to reply to mc_getcapab(9E) and the receive property should be checked in the context of the receive function.
MAC_CAPAB_LSOcapability indicates that the driver supports various forms of large send offload (LSO). The private data is a pointer to a mac_capab_lso_t structure. The system currently supports offloading TCP packets over both IPv4 and IPv6. This structure has the following members which are used to indicate various types of LSO support.
t_uscalar_t lso_flags; lso_basic_tcp_ivr4_t lso_basic_tcp_ipv4; lso_basic_tcp_ipv6_t lso_basic_tcp_ipv6;
The lso_flags member is used to indicate which members are valid and should be considered. Each flag represents a different form of LSO. The member should be set to the bitwise inclusive OR of the following values:
The lso_basic_tcp_ipv4 member is a structure with the following members:
The lso_basic_tcp_ipv6 member is a structure with the following members:
Like with checksumming, it is recommended that driver writers provide a means for disabling the support of LSO even if it is enabled by default. This deals with the case where issues that pop up for LSO may be worked around without requiring additional driver work.
MAC_CAPAB_RINGScapability is very important for implementing a high-performing device driver. Networking hardware structures the queues of packets to be sent and received into a ring. Each entry in this ring has a descriptor, which describes the address and options for a packet which is going to be transmitted or received. While simple networking devices only have a single ring, most high-speed networking devices have support for many rings.
Rings are used for two important purposes. The first is receive side scaling (RSS), which is the ability to have the hardware hash the contents of a packet based on some of the protocol headers, and send it to one of several rings. These different rings may each have their own interrupt associated with them, allowing the card to receive traffic in parallel. Similar logic can be performed when sending traffic, to leverage multiple hardware resources, thus increasing capacity.
The second use of rings is to group them together and apply filtering rules. For example, if a packet matches a specific VLAN or MAC address, then it can be sent to a specific ring or a specific group of rings. This is especially useful when there are multiple different virtual NICs or zones in play as the operating system will be able to use the hardware classificaiton features to already know where a given packet needs to be delivered internally rather than having to determine that for each packet.
From the MAC framework's perspective, a driver can have one or more groups. A group consists of the following:
The details around how a device driver changes when rings are employed, the data structures that a driver must implement, and more are available in mac_capab_rings(9E).
MAC_CAPAB_TRANSCEIVERcapability provides a means of discovering the number of transceivers, their types, and reading the data from a transceiver. This allows administrators and users to determine if devices are present, if the hardware can use them, and in many cases, detailed information about the device ranging from its manufacturer and serial numbers to specific information about its health. Implementing this capability will lead to the operating system being able to discover and display transceivers as part of its fault management topology.
See mac_capab_transceiver(9E) for more details on the capability structure and the various function entry points that come along with it.
MAC_CAPAB_LEDcapability provides a means to access and control the LEDs on a network interface card. This is then made available to the broader operating system and consumed by facilities such as the Fault Management Architecture. See mac_capab_led(9E) for more details on the structure and requirements of the capability.
Many of the properties listed below are read-only. Each property indicates whether it's read-only or it's read/write. However, driver writers may not implement the ability to set all writable properties. Many of these depend on the card itself. In particular, all properties that relate to auto-negotiation and are read/write may not be updated if the hardware in question does not support toggling what link speeds are auto-negotiated. While copper Ethernet often does not have this restriction, it often exists with various fiber standards and phys.
The following properties are the subset of MAC framework properties that driver writers should be aware of and handle. While other properties exist in the system, driver writers should always return an error when a property not listed below is encountered. See mc_getprop(9E) and mc_setprop(9E) for more information on how to handle them.
MAC_PROP_DUPLEX property is used
to indicate whether or not the link is duplex. A duplex link may have
traffic flowing in both directions at the same time. The
link_duplex_t is an enumeration which may be set
to any of the following values:
MAC_PROP_SPEED property stores the
current link speed in bits per second. A link that is running at 100
MBit/s would store the value 100000000ULL. A link that is running at 40
Gbit/s would store the value 40000000000ULL.
MAC_PROP_STATUS property is used
to indicate the current state of the link. It indicates whether the link
is up or down. The link_state_t is an enumeration
which may be set to any of the following values:
indicates whether or not the device is currently configured to perform
auto-negotiation. A value of 0 indicates that
auto-negotiation is disabled. A non-zero value
indicates that auto-negotiation is enabled. Devices should generally
default to enabling auto-negotiation.
When getting this property, the device driver should return the current state. When setting this property, if the device supports operating in the requested mode, then the device driver should reset the link to negotiate to the new speed after updating any internal registers.
MAC_PROP_MTU property determines
the maximum transmission unit (MTU). This indicates the maximum size
packet that the device can transmit, ignoring its own headers. For an
Ethernet device, this would exclude the size of the Ethernet header and
any VLAN headers that would be placed. It is up to the driver to ensure
that any MTU values that it accepts when adding in its margin and header
sizes does not exceed its maximum frame size.
By default, drivers for Ethernet should initialize this value and the MTU to 1500. When getting this property, the driver should return its current recorded MTU. When setting this property, the driver should first validate that it is within the device's valid range and then it must call mac_maxsdu_update(9F). Note that the call may fail. If the call completes successfully, the driver should update the hardware with the new value of the MTU and perform any other work needed to handle it.
If the device does not support changing the MTU after the
device's mc_start(9E) entry
point has been called, then driver writers should return
MAC_PROP_FLOWCTRL property manages
the configuration of pause frames as part of Ethernet flow control.
Note, this only describes what this device will advertise. What is
actually enabled may be different and is subject to the rules of
auto-negotiation. The link_flowctrl_t is an
enumeration that may be set to one of the following values:
When getting this property, the device driver should return the way that it has configured the device, not what the device has actually negotiated. When setting the property, it should update the hardware and allow the link to potentially perform auto-negotiation again.
indicates which Forward Error Correction (FEC) code is advertised by the
The link_fec_t is an enumeration that may be a combination of the following bit values:
LINK_FEC_AUTOcannot be set along with any of the other values. This is the default setting the device driver should use.
When setting the property, it should update the hardware with
the requested, or combination of requested codings. If a particular
combination of codings is not supported by the hardware, the device
driver should return
EINVAL. When retrieving
this property, the device driver should return the current value of the
MAC_PROP_ADV_FEC_CAP has the same
MAC_PROP_EN_FEC_CAP. The property
indicates which Forward Error Correction (FEC) code has been negotiated
over the link.
The remaining properties are all about various auto-negotiation link speeds. They fall into two different buckets: properties with _ADV_ in the name and properties with _EN_ in the name. For any given supported speed, there is one of each. The _EN_ set of properties are read/write properties that control what should be advertised by the device. When these are retrieved, they should return the current value of the property. When they are set, they should change how the hardware advertises the specific speed and trigger any kind of link reset and auto-negotiation, if enabled, to occur.
The _ADV_ set of properties are read-only properties. They are meant to reflect what has actually been negotiated. These may be different from the _EN_ family of properties, especially when different power management settings are at play.
See the Link Speed and Auto-negotiation section for more information.
The properties are ordered in increasing link speed:
describes whether or not 10 Mbit/s half-duplex support is
describes whether or not 10 Mbit/s half-duplex support is enabled.
describes whether or not 10 Mbit/s full-duplex support is
describes whether or not 10 Mbit/s full-duplex support is enabled.
describes whether or not 100 Mbit/s half-duplex support is
describes whether or not 100 Mbit/s half-duplex support is enabled.
describes whether or not 100 Mbit/s full-duplex support is
describes whether or not 100 Mbit/s full-duplex support is enabled.
describes whether or not 100 Mbit/s Ethernet using the 100BASE-T4
standard is advertised.
The MAC_PROP_ADV_100T4_CAP property describes whether or not 100 Mbit/s Ethernet using the 100BASE-T4 standard is enabled.
describes whether or not 1 Gbit/s half-duplex support is advertised.
describes whether or not 1 Gbit/s half-duplex support is enabled.
describes whether or not 1 Gbit/s full-duplex support is advertised.
describes whether or not 1 Gbit/s full-duplex support is enabled.
describes whether or not 2.5 Gbit/s full-duplex support is
describes whether or not 2.5 Gbit/s full-duplex support is enabled.
describes whether or not 5.0 Gbit/s full-duplex support is
describes whether or not 5.0 Gbit/s full-duplex support is enabled.
describes whether or not 10 Gbit/s full-duplex support is
describes whether or not 10 Gbit/s full-duplex support is enabled.
describes whether or not 40 Gbit/s full-duplex support is
describes whether or not 40 Gbit/s full-duplex support is enabled.
describes whether or not 100 Gbit/s full-duplex support is
describes whether or not 100 Gbit/s full-duplex support is enabled.
MAC_PROP_PRIVATE. Properties are distinguished by a name, which is a character string. The list of such private properties is defined when registering with mac in the m_priv_props member of the mac_register(9S) structure.
The driver may define whatever semantics it wants for these private properties. They will not be listed when running dladm(8), unless explicitly requested by name. All such properties should start with a leading underscore character and then consist of alphanumeric ASCII characters and additional underscores or hyphens.
Properties of type
show up in all three property related entry points:
mc_setprop(9E). Device drivers
should tell the different properties apart by using the
strcmp(9F) function to compare it to
the set of properties that it knows about. When encountering properties that
it doesn't know, it should treat them like all other unknown properties.
In general, if the device is not keeping track of these statistics, then it is recommended that the driver store these values as a uint64_t to ensure that overflow does not occur.
If a device does not support a specific statistic, then it is fine to return that it is not supported. The same should be used for unrecognized statistics. See mc_getstat(9E) for more information on the proper way to handle these.
As a solution to this, the driver should program the device to start placing the received Ethernet frame at two bytes off of the start of the DMA buffer. This will make sure that no matter whether or not VLAN tags are present, that the IP header will be 4-byte aligned.
The Fault Management Architecture (FMA) provides facilities for detecting and reporting various classes of defects and faults. Specifically for networking device drivers, issues that should be detected and reported include:
All such errors fall into three primary categories:
DDI_FM_EREPORT_CAPABLEso as to allow the driver to report issues that it detects.
Drivers should wire themselves to receive notifications when these events occur. The means and capabilities will vary from device to device. For example, some devices will generate information about these notifications through special interrupts. Other devices may have a register that software can poll. In the cases where polling is required, driver writers should try not to poll too frequently and should generally only poll when the device is actively being used, e.g. between calls to the mc_start(9E) and mc_stop(9E) entry points.
Many devices do not have such a communication mechanism. However, whenever there is some activity where the device driver must wait, then it should be prepared for the fact that the device may never get back to it and react appropriately by performing some kind of device reset.
When a non-fatal error occurs, then the device driver should
submit an ereport and should optionally mark the device degraded using
DDI_SERVICE_DEGRADED value depending on the
nature of the problem that has occurred.
Device drivers should never make the decision to remove a device from service based on errors that have occurred nor should they panic the system. Rather, the device driver should always try to notify the operating system with various ereports and allow its policy decisions to occur. The decision to retire a device lies in the hands of the fault management architecture. It knows more about the operator's intent and the surrounding system's state than the device driver itself does and it will make the call to offline and retire the device if it is required.
One wrinkle with device resets is that many networking cards show up as multiple PCI functions on a single device, for example, each port may show up as a separate function and thus have a separate instance of the device driver attached. When resetting a function, device driver writers should carefully read the device programming manuals and verify whether or not a reset impacts only the stalled function or if it impacts all function across the device.
If the only way to reset a given function is through the device, then this may require more coordination and work on the part of the device driver to ensure that all the other instances are correctly restored. In cases where this occurs, some devices offer ways of injecting interrupts onto those other functions to notify them that this is occurring.
In this case, a driver will use bcopy(9F) to copy memory between the two distinct regions. When transmitting a packet, it will copy the memory from the mblk_t to the DMA region. When receiving memory, it will allocate a mblk_t through the allocb(9F) routine, copy the memory across with bcopy(9F), and then increment the mblk_t's b_wptr structure.
If, when receiving, memory is not available for a new message block, then the frame should be skipped and effectively dropped. A kstat should be bumped when such an occasion occurs.
When transmitting a device driver has an mblk_t and needs to call the ddi_dma_addr_bind_handle(9F) function to bind it to an already existing DMA handle. At that point, it will receive various DMA cookies that it can use to obtain the addresses to program the device with for transmitting data. Once the transmit is done, the driver must then make sure to call freemsg(9F) to release the data. It must not call freemsg(9F) before it receives an interrupt from the device indicating that the data has been transmitted, otherwise it risks sending arbitrary kernel memory.
When receiving data, the device can perform a similar operation. First, it must bind the DMA memory into the kernel's virtual memory address space through a call to the ddi_dma_addr_bind_handle(9F) function if it has not already. Once it has, it must then call desballoc(9F) to try and create a new mblk_t which leverages the associated memory. It can then pass that mblk_t up to the stack.
The first thing to remember is that DMA resources may be finite on a given platform. Consider the case of receiving data. A device driver that binds one of its receive descriptors may not get it back for quite some time as it may be used by the kernel until an application actually consumes it. Device drivers that try to bind memory for receive, often work with the constraint that they must be able to replace that DMA memory with another DMA descriptor. If they were not replaced, then eventually the device would not be able to receive additional data into the ring.
On the other hand, particularly for larger frames, copying every packet from one buffer to another can be a source of additional latency and memory waste in the system. For larger copies, the cost of copying may dwarf any potential cost of performing DMA binding.
For device driver authors that are unsure of what to do, they should first employ the copying method to simplify the act of writing the device driver. The copying method is simpler and also allows the device driver author not to worry about allocated DMA memory that is still outstanding when it is asked to unload.
If device driver writers are worried about the cost, it is recommended to make the decision as to whether or not to copy or bind DMA data a separate private property for both transmitting and receiving. That private property should indicate the size of the received frame at which to switch from one format to the other. This way, data can be gathered to determine what the impact of each method is on a given platform.
McCloghrie, K. and Rose, M., RFC 1213 Management Information Base for Network Management of, TCP/IP-based internets: MIB-II, March 1991.
McCloghrie, K. and Kastenholz, F., RFC 1573 Evolution of the Interfaces Group of MIB-II, January 1994.
Kastenholz, F., RFC 1643 Definitions of Managed Objects for the Ethernet-like, Interface Types.
|July 2, 2022||OmniOS|