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NAME
ng_atm — netgraph ATM node type
SYNOPSIS
#include <sys/types.h>
#include <net/if_atm.h>
#include <netgraph.h>
#include <netgraph/atm/ng_atm.h>
DESCRIPTION
The atm netgraph node type allows natm(4) ATM drivers to be connected to the netgraph(4) networking
subsystem. When the ng_atm module is loaded a node is automatically created for each natm(4) ATM
interface. The nodes are named with the same name as the interface. Nodes are also created if a driver
for an ATM card is loaded after ng_atm was loaded.
The atm nodes are persistent. They are removed when the interface is removed. NGM_SHUTDOWN messages are
ignored by the node.
HOOKS
Four special hooks with fixed names and an unlimited number of hooks with user defined names are
supported. Three of the fixed hooks are attached to strategic points in the information flow in the
natm(4) system and support only reading. The fourth fixed hook behaves like the other user hooks, but a
number of management messages are sent along the hook. The other hooks can be attached to VCIs
dynamically by means of control messages to the atm node and can be written and read.
The four fixed hooks are:
input This is a connection to the raw input stream from the network. If this hook is connected, all
incoming packets are delivered out to this hook. Note that this redirects ALL input. Neither
natm(4) nor the user hooks will see any input if input is connected. An atm_pseudohdr (see
natm(4)) is prepended to the actual data.
output This is a connection to the raw output stream to the network device. If this hook is connected,
all outgoing packets are handed over to the netgraph system and delivered to the hook instead of
being delivered to the ATM driver. An atm_pseudohdr (see natm(4)) is prepended to the actual
data.
orphans This hook receives all packets that are unrecognized, i.e., do not belong to either a natm(4)
socket, a ng_atm VCI or natm(4) IP. Because ATM is connection oriented and packets are received
on a given VCI only when someone initiates this VCI, packets should never be orphaned. There is
however one exception: if you use natm(4) IP with LLC/SNAP encapsulation packets with do not
have the IP protocol indicated in the packet header are delivered out of this hook. An
atm_pseudohdr (see natm(4)) is prepended to the actual data send out to the hook.
manage This hook behaves exactly like a normal user hook (see below) except that the node at the other
hand will receive management messages.
Hooks for dynamically initiated VCIs can have whatever name is allowed by netgraph(4) as long as the name
does not collide with one of the three predefined names.
To initiate packet sending and receiving on a dynamic hook, one has to issue a NGM_ATM_CPCS_INIT control
message. To terminate sending and receiving one must send a NGM_ATM_CPCS_TERM message (see “CONTROL
MESSAGES”). The data sent and received on these hooks has no additional headers.
CONTROL MESSAGES
This node type supports the generic messages plus the following:
NGM_ATM_GET_IFNAME
Return the name of the interface as a NUL-terminated string. This is normally the same name as
that of the node.
NGM_ATM_GET_CONFIG
Returns a structure defining the configuration of the interface:
struct ng_atm_config {
uint32_t pcr; /* peak cell rate */
uint32_t maxvpi; /* maximum vpi */
uint32_t maxvci; /* maximum vci */
uint32_t max_vpcs; /* maximum number of VPCs */
uint32_t max_vccs; /* maximum number of VCCs */
};
NGM_ATM_GET_VCCS
Returns the table of open VCCs from the driver. This table consists of a header and a variable
sized array of entries, one for each open VCC:
struct atmio_vcctable {
uint32_t count; /* number of vccs */
struct atmio_vcc vccs[0]; /* array of VCCs */
};
struct atmio_vcc {
uint16_t flags; /* flags */
uint16_t vpi; /* VPI */
uint16_t vci; /* VCI */
uint16_t rmtu; /* Receive maximum CPCS size */
uint16_t tmtu; /* Transmit maximum CPCS size */
uint8_t aal; /* aal type */
uint8_t traffic; /* traffic type */
struct atmio_tparam tparam; /* traffic parameters */
};
struct atmio_tparam {
uint32_t pcr; /* 24bit: Peak Cell Rate */
uint32_t scr; /* 24bit: VBR Sustainable Cell Rate */
uint32_t mbs; /* 24bit: VBR Maximum burst size */
uint32_t mcr; /* 24bit: MCR */
uint32_t icr; /* 24bit: ABR ICR */
uint32_t tbe; /* 24bit: ABR TBE (1...2^24-1) */
uint8_t nrm; /* 3bit: ABR Nrm */
uint8_t trm; /* 3bit: ABR Trm */
uint16_t adtf; /* 10bit: ABR ADTF */
uint8_t rif; /* 4bit: ABR RIF */
uint8_t rdf; /* 4bit: ABR RDF */
uint8_t cdf; /* 3bit: ABR CDF */
};
Note that this is the driver's table, so all VCCs opened via natm(4) sockets and IP are also shown.
They can, however, be distinguished by their flags. The flags field contains the following flags:
ATM_PH_AAL5 use AAL5 instead of AAL0
ATM_PH_LLCSNAP if AAL5 use LLC SNAP encapsulation
ATM_FLAG_NG this is a netgraph VCC
ATM_FLAG_HARP this is a HARP VCC
ATM_FLAG_NORX transmit only VCC
ATM_FLAG_NOTX receive only VCC
ATMIO_FLAG_PVC treat channel as a PVC
If the ATM_FLAG_NG flag is set, then traffic and tparam contain meaningful information.
The aal field contains one of the following values:
ATMIO_AAL_0 AAL 0 (raw cells)
ATMIO_AAL_34 AAL 3 or AAL 4
ATMIO_AAL_5 AAL 5
ATMIO_AAL_RAW device specific raw cells
The traffic field can have one of the following values (not all drivers support all traffic types
however):
ATMIO_TRAFFIC_UBR
ATMIO_TRAFFIC_CBR
ATMIO_TRAFFIC_ABR
ATMIO_TRAFFIC_VBR
NGM_ATM_CPCS_INIT
Initialize a VCC for sending and receiving. The argument is a structure:
struct ng_atm_cpcs_init {
char name[NG_HOOKSIZ];
uint32_t flags; /* flags. (if_natmio.h) */
uint16_t vci; /* VCI to open */
uint16_t vpi; /* VPI to open */
uint16_t rmtu; /* receive maximum PDU */
uint16_t tmtu; /* transmit maximum PDU */
uint8_t aal; /* AAL type (if_natmio.h) */
uint8_t traffic; /* traffic type (if_natmio.h) */
uint32_t pcr; /* Peak cell rate */
uint32_t scr; /* Sustainable cell rate */
uint32_t mbs; /* Maximum burst size */
uint32_t mcr; /* Minimum cell rate */
uint32_t icr; /* ABR: Initial cell rate */
uint32_t tbe; /* ABR: Transmit buffer exposure */
uint8_t nrm; /* ABR: Nrm */
uint8_t trm; /* ABR: Trm */
uint16_t adtf; /* ABR: ADTF */
uint8_t rif; /* ABR: RIF */
uint8_t rdf; /* ABR: RDF */
uint8_t cdf; /* ABR: CDF */
};
The name field is the name of the hook for which sending and receiving should be enabled. This
hook must already be connected. The vpi and vci fields are the respective VPI and VCI values to
use for the ATM cells. They must be within the range, given by the maxvpi and maxvci fields of the
ng_atm_config structure. The flags field contains the flags (see above) and the other fields
describe the type of traffic.
NGM_ATM_CPCS_TERM
Stop sending and receiving on the indicated hook. The argument is a
struct ng_atm_cpcs_term {
char name[NG_HOOKSIZ];
};
MANAGEMENT MESSAGES
If the manage hook is connected, certain messages are sent along the hook. They are received by the peer
node with a cookie of NG_ATM_COOKIE.
NGM_ATM_CARRIER_CHANGE
The carrier state of the ATM physical interface has changed. The message has the following
structure:
struct ng_atm_carrier_change {
uint32_t node;
uint32_t state;
};
The node field is the node ID of the ATM node. This can be used by the managing entity (for
example ilmid(8)) to manage several interfaces at the same time through the same node. The state
field is 1 if the carrier was detected, and 0 if it was lost.
NGM_ATM_VCC_CHANGE
A permanent VCC has been added, deleted or changed. This is used by ilmid(8) to generate the
appropriate ILMI traps. The structure of the message is:
struct ng_atm_vcc_change {
uint32_t node;
uint16_t vci;
uint8_t vpi;
uint8_t state;
};
Where state is 0 if the PVC was deleted, and 1 if it was added or modified.
FLOW CONTROL
If the hardware driver supports it, the node can emit flow control messages along a user hook. The
format of these messages is described in <netgraph/ng_message.h>. The atm node may generate
NGM_HIGH_WATER_PASSED and NGM_LOW_WATER_PASSED messages. The first one indicates that the hardware
driver has stopped output on the channel and drops new packets, the second one reports that output was
reenabled. Currently, the structures are not filled with information.
SHUTDOWN
The nodes are persistent as long as the corresponding interface exists. Upon receipt of a NGM_SHUTDOWN
messages, all hooks are disconnected and the node is reinitialized. All VCCs opened via netgraph(4) are
closed. When the ATM interface is unloaded, the node disappears. If the node is compiled with
NGATM_DEBUG there is a sysctl net.graph.atm.allow_shutdown which, when set to a non-zero value, allows
the nodes to shut down. Note that this is intended for development only and may lead to kernel panics if
set.
SEE ALSO
natm(4), netgraph(4), ng_ether(4), ngctl(8)
AUTHORS
Harti Brandt <harti@FreeBSD.org>
Debian June 24, 2003 NG_ATM(4)