It identifies the port number of the input port for which
the connection state is being reported.
Sequence Number
In the case that the requested connection state cannot be
reported in a single success response message, each
successive success response message in reply to the same
request message must increment the Sequence Number. The
Sequence Number of the first success response message, in
response to a new request message, must be zero.
Connection Records
Each success response message must contain one or more
Connection Records. Each Connection Record specifies a
single point-to-point or point-to-multipoint virtual path
connection or virtual channel connection. The number of
Connection Records in a single Report Connection State
success response must not cause the packet length to exceed
the maximum transmission unit defined by the encapsulation.
If the requested connection state cannot be reported in a
single success response message, multiple success response
messages must be sent. All success response messages that
are sent in response to the same request message must have
the same Input Port and Transaction Identifier fields as
the request message. A single Connection Record must not be
split across multiple success response messages. The More
flag of the last Connection Record in a success response
message indicates whether the response to the request has
been completed or whether one or more further success
response messages should be expected in response to the
same request message.
Each Connection Record has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|V|P|M| Input VPI | Input VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Output Branch Records ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flags
A: All Connections
V: VPI/VCI
For the first Connection Record in each success response
message the All Connections and the VPI/VCI flags must be
the same as those of the request message. For successive
Connection Records in the same success response message
these flags are not used.
P: VPC
The VPC flag, if set, indicates that the Connection Record
refers to a virtual path connection. If zero, it indicates
that the Connection Record refers to a virtual channel
connection.
M: More
If the More flag is set, it indicates that another
Connection Record, in response to the same request message,
will follow either in the same success response message or
in a successive success response message. If the More flag
is zero it indicates that this is the last Connection
record in this success response message and that no further
success response messages will be sent in response to the
current request message. It indicates that the response to
the request message is now complete.
Input VPI
Input VCI
The input VPI and VCI of the connection specified in this
Connection Record. If this Connection Record specifies a
virtual path connection (the VPC flag is set) the Input VCI
field is unused.
Output Branch Records
Each Connection Record must contain one or more Output
Branch Records. Each Output Branch Record specifies a
single output branch belonging to the connection identified
by the Input VPI and Input VCI fields of the Connection
Record. A point-to-point connection will require only a
single Output Branch Record. A point-to-multipoint
connection will require multiple Output Branch Records. The
last Output Branch Record of each Connection Record is
indicated by the Last Branch flag of the Output Branch
Record. If a point-to-multipoint connection has more output
branches than can fit in a single Connection Record
contained within a single success response message, that
connection may be reported using multiple Connection
Records in multiple success response messages.
Each Output Branch Record has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Output Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L|x x x| Output VPI | Output VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Output Port
The output port of the switch to which this output branch
is routed.
Flags
L: Last Branch
The Last Branch flag, if set, indicates that this is the
last Output Branch Record of this Connection Record. If
zero, it indicates that one or more further Output Branch
Records are to follow. If this is the last Output Branch
Record in the message and the Last Branch flag is zero,
further output branches belonging to the same connection
will be given in another Connection Record. This Connection
Record will be the first Connection Record in the next
success response message. This Connection Record must have
the same Input VPI and Input VCI values as the current
Connection Record.
x: Unused.
Output VPI
Output VCI
The output VPI and VCI of the output branch specified in
this Output Branch Record. If this Output Branch Record is
part of a Connection Record that specifies a virtual path
connection (the VPC flag is set) the Output VCI field is
unused.
A Report Connection State request message may be issued regardless of
the Port Status or the Line Status of the target switch port.
If the Input Port of the request message is valid, and the All
Connections flag is set, but there are no connections established on
that port, a failure response message must be returned with the code
field set to, "Failure specific to the particular message type." For
the Report Connection State message, this failure code indicates that
no connections matching the request message were found. This failure
message should also be returned if the Input Port of the request
message is valid, the All Connections flag is zero, and no
connections are found on that port matching the specified virtual
path connection, virtual path, or virtual channel connection.
7. Configuration Messages
The configuration messages permit the controller to discover the
capabilities of the switch. Three configuration request messages have
been defined: Switch, Port, and All Ports.
All configuration request messages have the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.1 Switch Configuration Message
The Switch Configuration message requests the global (non port-
specific) configuration for the switch. The Switch Configuration
message is:
Message Type = 64
The Port field is not used in the request message.
The Switch Configuration success response message has the following
format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Firmware Version Number | Window Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Switch Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| Switch Name |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Firmware Version Number
The version number of the switch control firmware
installed.
Window Size
The maximum number of unacknowledged request messages that
may be transmitted by the controller without the
possibility of loss. This field is used to prevent request
messages being lost in the switch because of overflow in
the receive buffer. The field is a hint to the controller.
If desired, the controller may experiment with higher and
lower window sizes to determine heuristically the best
window size.
Switch Type
A 16-bit field allocated by the manufacturer of the switch.
(For these purposes the manufacturer of the switch is
assumed to be the organization identified by the OUI in the
Switch Name field.) The Switch Type identifies the product.
When the Switch Type is combined with the OUI from the
Switch Name the product is uniquely identified. Network
Management may use this identification to obtain product
related information from a database.
Switch Name
A 48-bit quantity that is unique within the operational
context of the device. A 48-bit IEEE 802 MAC address, if
available, may be used as the Switch Name. The most
significant 24 bits of the Switch Name must be an
Organizationally Unique Identifier (OUI) that identifies
the manufacturer of the switch.
7.2 Port Configuration Message
The Port Configuration message requests the switch for the
configuration information of a single switch port. The Port field in
the request message specifies the port for which the configuration is
requested. The Port Configuration message is:
Message Type = 65.
The Port Configuration success response message has the following
format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V|M|L|R| Min VPI |Q|x x x| Max VPI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min VCI | Max VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Cell Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Cell Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Status | Port Type | Line Status | Priorities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Physical Slot Number | Physical Port Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Port
The switch port to which the configuration information
refers. Configuration information relating to both the
input and the output sides of the switch port is given.
Port numbers are 32 bits wide and allocated by the switch.
The switch may choose to structure the 32 bits into
subfields that have meaning to the physical structure of
the switch hardware (e.g. physical slot and port). This
structure may be indicated in the Physical Slot Number and
Physical Port Number fields.
Flags
V: VP Switching
The VP Switching flag, if set, indicates that this input
port is capable of supporting virtual path switching. Else,
if zero, it indicates that this input port is only capable
of virtual channel switching.
M: Multicast Labels
The Multicast Labels flag, if set, indicates that this
output port is capable of labelling each output branch of a
point-to-multipoint tree with a different label. If zero,
it indicates that this output port is not able to label
each output branch of a point-to-multipoint tree with a
different label.
L: Logical Multicast
The Logical Multicast flag, if set, indicates that this
output port is capable of supporting more than a single
branch from any point-to-multipoint connection. This
capability is often referred to as logical multicast. If
zero, it indicates that this output port can only support a
single output branch from each point-to-multipoint
connection.
R: Label Range
The Label Range flag, if set, indicates that this switch
port is capable of reallocating its VPI label range or its
VCI label range and therefore accepts the Label Range
message. Else, if zero, it indicates that this port does
not accept Label Range messages.
Q: QoS
The QoS flag, if set, indicates that this switch port is
capable of handling the Quality of Service messages defined
in section 9 of this specification. Else, if zero, it
indicates that this port does not accept the Quality of
Service messages.
x: Unused
Min VPI
The default minimum value of dynamically assigned incoming
VPI that the connection table on the input port supports
and that may be controlled by GSMP. This value is not
changed as a result of the Label Range message.
Max VPI
The default maximum value of dynamically assigned incoming
VPI that the connection table on the input port supports
and that may be controlled by GSMP. This value is not
changed as a result of the Label Range message.
At power-on, after a hardware reset, and after the Reset
Input Port function of the Port Management message, the
input port must handle all values of VPI within the range
Min VPI to Max VPI inclusive and GSMP must be able to
control all values within this range. It should be noted
that the range Min VPI to Max VPI refers only to the
incoming VPI range that can be supported by the associated
port. No restriction is placed on the values of outgoing
VPIs that may be written into the cell header. If the
switch does not support virtual paths it is acceptable for
both Min VPI and Max VPI to specify the same value, most
likely zero.
Use of the Label Range message allows the range of VPIs
supported by the port to be changed. However, the Min VPI
and Max VPI fields in the Port Configuration and All Ports
Configuration messages always report the same default
values regardless of the operation of the Label Range
message.
Min VCI
The default minimum value of dynamically assigned incoming
VCI that the connection table on the input port can support
and may be controlled by GSMP. This value is not changed as
a result of the Label Range message.
Max VCI
The default maximum value of dynamically assigned incoming
VCI that the connection table on the input port can support
and may be controlled by GSMP. This value is not changed as
a result of the Label Range message.
At power-on, after a hardware reset, and after the Reset
Input Port function of the Port Management message, the
input port must handle all values of VCI within the range
Min VCI to Max VCI inclusive, for each of the virtual paths
in the range Min VPI to Max VPI inclusive, and GSMP must be
able to control all values within this range. It should be
noted that the range Min VCI to Max VCI refers only to the
incoming VCI range that can be supported by the associated
port on each of the virtual paths in the range Min VPI to
Max VPI. No restriction is placed on the values of outgoing
VCIs that may be written into the cell header.
Use of the Label Range message allows the range of VCIs to
be changed on each VPI supported by the port. However, the
Min VCI and Max VCI fields in the Port Configuration and
All Ports Configuration messages always report the same
default values regardless of the operation of the Label
Range message.
For a port over which the GSMP protocol is operating, the
VCI of the GSMP control channel may or may not be reported
as lying within the range Min VCI to Max VCI. A switch
should honor a connection request message that specifies
the VCI value of the GSMP control channel even if it lies
outside the range Min VCI to Max VCI.
Receive Cell Rate
The maximum rate of cells that may arrive at the input port
in cells/s.
Transmit Cell Rate
The maximum rate of cells that may depart from the output
port in cells/s. (The transmit cell rate of the output port
may be changed by the Set Transmit Cell Rate function of
the Port Management message.)
Port Status
Gives the administrative state of the port. The defined
values of the Port Status field are:
Available:
Port Status = 1. The port is available to both send
and receive cells. When a port changes to the
Available state from any other administrative state,
all dynamically assigned virtual connections must be
cleared and a new Port Session Number must be
generated.
Unavailable:
Port Status = 2. The port has intentionally been taken
out of service. No cells will be transmitted from this
port. No cells will be received by this port.
Internal Loopback:
Port Status = 3. The port has intentionally been taken
out of service and is in internal loopback: cells
arriving at the output port from the switch fabric are
looped through to the input port to return to the
switch fabric. All of the ATM functions of the input
port above the physical layer, e.g. header
translation, are performed upon the looped back cells.
External Loopback:
Port Status = 4. The port has intentionally been taken
out of service and is in external loopback: cells
arriving at the input port from the external
communications link are immediately looped back to the
communications link at the physical layer without
entering the input port. None of the ATM functions of
the input port above the physical layer are performed
upon the looped back cells.
Bothway Loopback:
Port Status = 5. The port has intentionally been taken
out of service and is in both internal and external
loopback.
The Port Status of the port over which the GSMP session
controlling the switch is running, must be declared
Available. The controller will ignore any other Port status
for this port. The Port Status of switch ports after
power-on initialization is not defined by GSMP.
Port Type
The type of physical transmission interface for this port.
The values for this field are defined by the atmIfType
object specified in the Ipsilon IP Switch MIB [IpsilonMIB].
Line Status
The status of the physical transmission medium connected to
the port. The defined values of the Line Status field are:
Up:
Line Status = 1. The line is able to both send and
receive cells. When the Line Status changes to Up
from either the Down or Test states, a new Port
Session Number must be generated.
Down:
Line Status = 2. The line is unable either to send or
receive cells or both.
Test:
Line Status = 3. The port or line is in a test mode,
for example, power-on test.
Priorities
The number of different priority levels that this output
port can assign to virtual connections. Zero is invalid in
this field. If an output port is able to support "Q"
priorities, the highest priority is numbered zero and the
lowest priority is numbered "Q-1". The ability to offer
different qualities of service to different connections
based upon their priority is assumed to be a property of
the output port of the switch. It may be assumed that for
connections that share the same output port, an ATM cell on
a connection with a higher priority is much more likely to
exit the switch before an ATM cell on a connection with a
lower priority if they are both in the switch at the same
time.
Physical Slot Number
The physical location of the slot in which the port is
located. It is an unsigned 16-bit integer that can take any
value except 0xFFFF. The value 0xFFFF is used to indicate
"unknown." The Physical Slot Number is not used by the GSMP
protocol. It is provided to assist network management in
functions such as logging, port naming, and graphical
representation.
Physical Port Number
The physical location of the port within the slot in which
the port is located. It is an unsigned 16-bit integer that
can take any value except 0xFFFF. The value 0xFFFF is used
to indicate "unknown." The Physical Port Number is not used
by the GSMP protocol. It is provided to assist network
management in functions such as logging, port naming, and
graphical representation.
There must be a one to one mapping between Port Number and
the Physical Slot Number and Physical Port Number
combination. Two different Port Numbers must not yield the
same Physical Slot Number and Physical Port Number
combination. The same Port Number must yield the same
Physical Slot Number and Physical Port Number within a
single GSMP session. If both Physical Slot Number and
Physical Port Number indicate "unknown" the physical
location of switch ports may be discovered by looking up
the product identity in a database to reveal the physical
interpretation of the 32-bit Port Number.
7.3 All Ports Configuration Message
The All Ports Configuration message requests the switch for the
configuration information of all of its ports. The All Ports
Configuration message is:
Message Type = 66
The Port field is not used in the request message.
The All Ports Configuration success response message has the
following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Records | Port Record Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Port Records ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Number of Records
Field gives the total number of Port Records to be returned
in response to the All Ports Configuration request message.
The number of port records in a single All Ports
Configuration success response must not cause the packet
length to exceed the maximum transmission unit defined by
the encapsulation. If a switch has more ports than can be
sent in a single success response message it must send
multiple success response messages. All success response
messages that are sent in response to the same request
message must have the same Transaction Identifier as the
request message and the same value in the Number of Records
field. All success response messages that are sent in
response to the same request message, except for the last
message, must have the result field set to "More." The last
message, or a single success response message, must have
the result field set to "Success." All Port records within
a success response message must be complete, i.e. a single
Port record must not be split across multiple success
response messages.
Port Record Length
Field gives the length of each port record in bytes. This
is currently 32 but the Port Record Length field allows for
the future definition of further fields at the end of the
port record while preserving compatibility with earlier
versions of the protocol.
Port Records
Follow in the remainder of the message. Each port record
has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V|M|L|R| Min VPI |Q|x x x| Max VPI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min VCI | Max VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Cell Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Cell Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Status | Port Type | Line Status | Priorities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Physical Slot Number | Physical Port Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The definition of the fields in the Port Record is exactly the same
as that of the Port Configuration message.
8. Event Messages
Event messages allow the switch to inform the controller of certain
asynchronous events. Event messages are not acknowledged. The Result
field and the Code field in the message header are not used and
should be set to zero. Event messages are not sent during
initialization. Event messages have the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Event Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| zero | VPI | VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Event Sequence Number
The current value of the Event Sequence Number for the
specified port. The Event Sequence Number is set to zero
when the port is initialized. It is incremented by one each
time the port detects an asynchronous event that the switch
would normally report via an Event message. The Event
Sequence Number must be incremented each time an event
occurs even if the switch is prevented from sending an
Event message due to the action of the flow control.
VPI/VCI
Field gives the VPI/VCI to which the event message refers.
If this field is not required by the event message it is
set to zero.
Each switch port must maintain an Event Sequence Number and a set of
Event Flags, one Event Flag for each type of Event message. When a
switch port sends an Event message it must set the Event Flag on that
port corresponding to the type of the event. The port is not
permitted to send another Event message of the same type until the
Event Flag has been reset. Event Flags are reset by the "Reset Event
Flags" function of the Port Management message. This is a simple flow
control preventing the switch from flooding the controller with event
messages. The Event Sequence Number of the port must be incremented
every time an event is detected on that port even if the port is
prevented from reporting the event due to the action of the flow
control. This allows the controller to detect that it has not been
informed of some events that have occurred on the port due to the
action of the flow control.
8.1 Port Up Message
The Port Up message informs the controller that the Line Status of a
port has changed from either the Down or Test state to the Up state.
When the Line Status of a switch port changes to the Up state from
either the Down or Test state a new Port Session Number must be
generated, preferably using some form of random number. The new Port
Session Number is given in the Port Session Number field. The VPI/VCI
field is not used and is set to zero. The Port Up message is:
Message Type = 80
8.2 Port Down Message
The Port Down message informs the controller that the Line Status of
a port has changed from the Up state to the Down state. This message
will be sent to report link failure if the switch is capable of
detecting link failure. The port session number that was valid before
the port went down is reported in the Port Session Number field. The
VPI/VCI field is not used and is set to zero. The Port Down message
is:
Message Type = 81
8.3 Invalid VPI/VCI Message
The Invalid VPI/VCI message is sent to inform the controller that one
or more cells have arrived at an input port with a VPI/VCI that is
currently not allocated to an assigned connection. The input port is
indicated in the Port field, and the VPI/VCI in the VPI/VCI field.
The Invalid VPI/VCI message is:
Message Type = 82
8.4 New Port Message
The New Port message informs the controller that a new port has been
added to the switch. The port number of the new port is given in the
Port field. A new Port Session Number must be assigned, preferably
using some form of random number. The new Port Session Number is
given in the Port Session Number field. The state of the new port is
undefined so the VPI/VCI field is not used and is set to zero. The
New Port message is:
Message Type = 83
8.5 Dead Port Message
The Dead Port message informs the controller that a port has been
removed from the switch. The port number of the port is given in the
Port field. The Port Session Number that was valid before the port
was removed is reported in the Port Session Number field. The
VPI/VCI fields are not used and are set to zero. The Dead Port
message is:
Message Type = 84
9. Quality of Service Messages
The GSMP Quality of Service (QoS) messages allow a controller to
group virtual path connections and virtual channel connections into
QoS classes, and to allocate QoS resources to both QoS classes and to
individual connections. At initialization, the switch describes its
QoS capabilities to the controller, in terms of the abstract switch
model, using the QoS Configuration message. The controller issues
Scheduler Establishment messages to configure the scheduler on each
switch output port. It also issues QoS Class Establishment messages
to configure QoS classes. Connections may be added to, or deleted
from, a QoS class using the QoS Connection Management message. QoS
resources may also be assigned to individual connections using the
QoS Connection Management message. Connections that only require the
scheduler may use the simple connection management messages defined
in Section 3, "Connection Management Messages."
9.1 Abstract Switch Model
The abstract switch model, fig. 1, is the means by which a switch can
describe its fundamental QoS capabilities to a controller. It
consists of four main functions: a policer, a classifier, a
regulator, and a scheduler. The classifier groups multiple
connections (VPCs or VCCs) together into a QoS class such that QoS
resources may be shared by the QoS class as a whole. Within a QoS
class there is no differentiation between members of the class in
terms of QoS resources received. However, the ordering of cells
within each constituent VPC or VCC must be preserved on exit from the
switch. Connections are not required to be aggregated into a QoS
class with other connections; they may be allocated individual QoS
resources.
VPC/VCCs Policer Classifier Regulator Scheduler
+--+ +----+ +--------+
-------->| |---->| | | |
+--+ | | | |
| | | |
+--+ | | +----+ | |
-------->| |---->| | | |--------->| |
+--+ | | | |conforming| |
| |------>| | | |
+--+ | | QoS | | | |
-------->| |---->| | Class | |--------->| |
+--+ | | +----+ excess | |
| | | |
+--+ | | | |
-------->| |---->| | | |
+--+ +----+ | |
| |
| | Output
| | Port
| |---------->
| |
| |
+--+ +----+ | |
-------->| |---->| | | |
+--+ | | | |
| | | |
+--+ | | +----+ | |
-------->| |---->| | | |--------->| |
+--+ | | | |conforming| |
| |------>| | | |
+--+ | | QoS | | | |
-------->| |---->| | Class | |--------->| |
+--+ | | +----+ excess | |
| | | |
+--+ | | | |
-------->| |---->| | | |
+--+ +----+ | |
+--------+
Fig. 1: Abstract Switch Model
The policer is a single input, single output device that can discard
or tag cells. A policer may be applied to police each individual
connection. A policer may also be applied to police the aggregate
traffic of a QoS class. The policer is used to enforce an upper
bound on the traffic on a connection or on a QoS class.
The regulator follows the policer and classifier. It offers either a
policing function or a shaping function. The policing function
evaluates cells as conforming to the rate specified by the regulator
parameters or as being in excess of that rate. One of three actions
can be specified to be taken for each cell as a result of this
evaluation: tagging, discard or differentiated scheduling. Tagging
sets the CLP bit of cells deemed to be in excess of the rate defined
by the regulator parameters. The discard function discards excess
cells. The differentiated scheduling function allows conforming cells
and excess cells to be scheduled for service at different points in
the scheduler. This would allow conforming cells, for example, to
receive service with a QoS guarantee, whereas excess cells receive
best-effort service. The implementation of differentiated
scheduling, however, is complicated by the requirement not to reorder
cells within each connection.
The shaping function of the regulator paces cells out, on each QoS
class or individual connection, at the rate specified by the
regulator parameters. No jitter requirement may be specified, nor is
any specific guarantee of jitter given. If traffic arrives on any QoS
class or individual connection at a greater rate than the output rate
specified, that traffic will be delayed. If the delayed traffic for
any QoS class or individual connection exceeds a bound, discard will
occur. Differentiated scheduling is supported by the shaper but its
application to shaping is somewhat different than its application to
policing. Conforming traffic is that traffic which leaves the shaper
as a result of the shaping process. The conforming pointer specifies
the point in the scheduler structure where such traffic is scheduled
for output. (This is typically the highest priority of the scheduler
but the GSMP specification permits other priorities to be specified.)
If an excess pointer is also enabled for a particular QoS class or
individual connection, traffic in excess of the rate specified by the
shaper may also be transmitted. The position of the excess pointer
in the scheduler structure determines the undefined amount of
additional traffic that will be supported. The excess traffic may be
tagged if required, if tagging is supported. The excess pointer will
receive the same share of bandwidth that a best-effort class or
connection would receive at the same location in the scheduler
structure.
The location of the classifier and regulator functions in the switch
is important. If the classifier is located on an input port, only
virtual connections that arrive at that input port may be aggregated
into a QoS class. If the classifier is centralized, or located on an
output port, virtual connections that arrive at any input port may be
aggregated into the same QoS class. If the regulator is located on an
output port all virtual connections within a QoS class passing
through that regulator must exit the switch at that output port.
However, if the regulator is centralized, or located on an input
port, virtual connections that are part of the same QoS class may be
switched to different output ports. Each switch port must specify
the location of its classifier and regulator functions.
The scheduler is located on the output port, fig. 2. It distributes
the bandwidth of the output link between the QoS classes and
individual connections. It is a two-level scheduler: a priority
scheduler at one level and a FIFO or a weighted scheduler at the
other. Up to 255 strict priority levels may be supported. Traffic in
any specific priority level may only be transmitted if no traffic is
queued for transmission in any higher priority level. Within each
priority level a weighted scheduler may be defined. Each leaf of the
scheduler tree is connected to a waiting room. The waiting room has
two functions. When it receives service from the scheduler, it must
select a QoS class or individual connection for transmission. When it
is notified of traffic arrival on a QoS class or connection, it must
decide whether there is enough room left in the waiting room to
accept the traffic, else that traffic must be discarded. The waiting
room has a size parameter indicating how much traffic may be
accepted. Other queueing parameters may be attached to the waiting
room. Multiple conforming and excess pointers from the regulators may
point to each waiting room. Within a waiting room, the scheduling of
multiple connections sharing that waiting room may support weighted
sharing between the connections.
From Waiting FIFO/Weighted Priority
Regulator Room Scheduler Scheduler
Net +---+
+------+ Weight | |
---------->| |-%-------->| 0 |------\
+------+ | | \
+---+ \
---------->+------+ |
| |-%--\ +---+ |
---------->+------+ \---->| | |
| 1 |---\ |
+------+ /---->| | \ \
---------->| |-%--/ +---+ \ \ +---+
+------+ \ \-->| |
\----->| |--------->
---------->+------+ /-->| | Output
---------->| |-%-\ / +---+ Port
---------->+------+ \ /
\ +---+ /
+------+ \--->| | /
---------->| |-%-------->| 2 |-----/
+------+ /--->| |
/ +---+
+------+ /
---------->| |-%-/
+------+
Fig. 2: The Scheduler
9.2 QoS Configuration Message
The QoS Configuration message permits the controller to discover the
QoS capabilities of each switch port in terms of the abstract switch
model. The QoS Configuration message is:
Message Type = 96
The QoS Configuration request message has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The QoS Configuration success response message has the following
format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scheduler Flags | Regulator Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Excess Capabilities | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hi Sharing | Lo Sharing | Max Classes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Default Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Default Discard Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max Buffer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max Shaper Buffer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scaling Factor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Port
The switch port to which the QoS configuration information
refers. QoS configuration information relating to both the
input and the output sides of the switch port is given.
Scheduler Flags
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|W|Q|S|G|D|F|M|B|I|x x x x x x x|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
W: Weighted Connections
Bit 0 of the Scheduler Flags field, if set, indicates that
a weighted service algorithm (such as weighted round-robin)
is available for allocation of service to individual
connections within at least some waiting rooms. It means
that a Connection Weight parameter can be attached to a QoS
Connection Management message. Not all waiting rooms at all
priority levels may be able to support this function.
Whether a particular waiting room can support this function
will be discovered when a QoS Connection Management message
is issued.
Q: Weighted QoS Classes
Bit 1 of the Scheduler Flags field, if set, indicates that
a weighted service algorithm (such as weighted round-robin)
is available for allocation of service to QoS classes
within at least some waiting rooms. It means that a QoS
Class Weight parameter can be attached to a QoS Class
Establishment message. Not all waiting rooms at all
priority levels may be able to support this function.
Whether a particular waiting room can support this function
will be discovered when a QoS Class Establishment message
is issued.
S: Shared Waiting Room
Bit 2 of the Scheduler Flags field, if set, indicates that
multiple QoS classes and multiple connections may be
scheduled within a single waiting room. This is expected to
be the normal case. If Bit 2 of the Scheduler Flags field
is zero, it indicates that only a single QoS class or a
single connection may be directed to any single waiting
room.
G: Global Max Classes
Bit 3 of the Scheduler Flags field, if set, indicates that
the Max Classes field gives the maximum number of QoS
classes that may be supported by the entire switch. If
zero, it indicates that the Max Classes field gives the
maximum number of QoS classes that may be supported by this
switch port.
D: Packet Discard
Bit 4 of the Scheduler Flags field, if set, indicates that
the scheduler on this output port is capable of packet
discard. Packet discard indicates a discard algorithm that
is aware of AAL-5 packet boundaries and attempts to discard
whole packets. No specific algorithm is indicated though
Early Packet Discard (EPD) is likely to be the most common.
Other algorithms such as "push from front" schemes, dynamic
threshold, or Random Early Detection (RED) are also
examples of possible packet discard algorithms. The only
parameters available to the packet discard algorithm, via
GSMP, are the Size and Discard Threshold of the waiting
room.
F: Frame-Based Scheduling
Bit 5 of the Scheduler Flags field, if set, indicates that
the scheduler on this output port is capable of frame-based
scheduling. In frame-based scheduling, a connection is only
scheduled for transmission when a complete AAL-5 packet is
available. When a connection is scheduled for
transmission, all cells belonging to one or more complete
packets from that connection will be transmitted without
being interleaved with any other cells on that output port
(regardless of their priority). Frame-based scheduling is
a property of the waiting room and is requested in the
Scheduler Establishment message. A QoS class may be routed
through a waiting room configured with frame-based
scheduling. In this case each component connection of the
QoS class will receive frame based scheduling. For correct
distribution of bandwidth, each QoS class that requires
frame-based scheduling should have its own waiting room.
M: VC Merging
Bit 6 of the Scheduler Flags field, if set, indicates that
the scheduler on this output port is capable of VC merging
by a mechanism other than frame-based scheduling. VC
merging indicates that the switch is capable of the
multipoint-to-point merging of two or more incoming virtual
connections onto a single outgoing virtual connection
without interleaving cells from different AAL-5 packets
that bear the same VPI/VCI. VC merging differs from frame-
based scheduling in that cells with a different VPI/VCI may
be interleaved with those of a multipoint-to-point VC
merging connection. Thus, higher priority cells may be
interleaved during the transmission of a packet on a lower
priority VC merging connection. Most switches achieve VC
merging by using frame-based scheduling. VC merging is a
property of the waiting room and is requested in the
Scheduler Establishment message. A QoS class may be routed
through a waiting room configured with VC merging. In this
case each component connection of the QoS class will
receive VC merging.
B: Shared Buffer
Bit 7 of the Scheduler Flags field, if set, indicates that
at least some of the buffer space specified by the Max
Buffer field is shared with other ports. If zero, it
indicates that the buffer space specified by the Max Buffer
field is not shared with other ports.
I: Identical Ports
Bit 8 of the Scheduler Flags field, if set, indicates that
all ports of the switch have identical QoS capabilities. If
this bit is set the controller does not have to request the
QoS configuration of each port individually as all ports
have the same capability.
x: Bits 9--15 of the Scheduler Flags field are not used.
Regulator Flags
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|C|Q|I O|P|S|H|M|x x x x x x x x|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
C: Connection Policing
Bit 0 of the Regulator Flags field indicates that this
input port supports the policing of individual incoming
connections. The parameters for the policer are specified
in the QoS Connection Management message when the
connection is established.
Q: QoS Class Policing
If bit 1 of the Regulator Flags field is set, a policer
function is available to police each QoS class on output
from the classifier. The parameters for this policer are
specified in the QoS Class Establishment message. If this
bit is zero, no policer function is available to police a
QoS class.
IO: QoS Class Location
Bits 2 and 3 of the Regulator Flags field specify the
location of the classifier and regulator functions. If both
bits 2 and 3 of the Regulator Flags field are zero, no
classifier or regulator function is available to this port.
If bit 2 of the Regulator Flags field is set and bit 3 is
zero, the classifier and regulator functions are available
on the input port. This implies that only virtual
connections arriving at this input port may be grouped into
QoS classes by this classifier. However, connections in a
QoS class output from this regulator may be switched to any
output port.
If bit 2 of the Regulator Flags field is zero and bit 3 is
set, the classifier and regulator functions are available
on the output port. This implies that virtual connections
arriving at any input port may be grouped into QoS classes
by this classifier. However, all connections in any QoS
class output from this regulator may only be switched to
this output port.
If both bits 2 and 3 of the Regulator Flags field are set,
this switch port has access to centralized classifier and
regulator functions. This implies that virtual connections
arriving at any input port may be grouped into a QoS class
by this classifier. Also, connections in a QoS class output
from this regulator may be switched to any output port.
Regulator Function
P: If bit 4 of the Regulator Flags field is set, the regulator
is able to support the policing function.
S: If bit 5 of the Regulator Flags field is set, the regulator
is able to support the shaping function on all priority
levels of the scheduler.
H: If bit 5 of the Regulator Flags field is zero and bit 6 is
set, the regulator is able to support the shaping function
but only on the highest priority level of the scheduler.
All connections and QoS classes using this regulator must
be routed to a waiting room at the highest priority level
of the scheduler.
M: QoS Multicast
If bit 7 of the Regulator Flags field is set, any point-
to-multipoint connection arriving on this input port, with
QoS parameters established by the GSMP Quality of Service
messages, must use the same QoS parameters for all output
branches.
x: Bits 8--15 of the Regulator Flags field are not used.
Excess Capabilities
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|T|S|A|B|x x x x x x x x x x x|