+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Policer:
D: If bit 0 of the Excess Capabilities field is set, the policer
function of the regulator is able to support discard.
T: If bit 1 of the Excess Capabilities field is set, the policer
function of the regulator is able to support tagging.
S: If bit 2 of the Excess Capabilities field is set, the policer
function of the regulator is able to support differentiated
scheduling.
Shaper:
A: If bit 3 of the Excess Capabilities field is set, the shaper
function of the regulator is able to support tagging.
B: If bit 4 of the Excess Capabilities field is set, the shaper
function of the regulator is able to support differentiated
scheduling.
x: Bits 5--15 of the Excess Capabilities field are not used.
Hi Sharing
Lo Sharing
Defines a range of priority levels that support weighted
sharing. Each priority level in the range Lo Sharing to Hi
Sharing inclusive, supports weighted sharing. A priority
level that supports weighted sharing offers a weighted
sharing algorithm (for example, weighted round-robin)
between waiting rooms within that priority level. This
permits the output link bandwidth available at that
priority level, to be shared between the waiting rooms
allocated to that priority level, according to the Net
Weight parameter of each waiting room. The value 0xFF for
both parameters indicates that this output port does not
support weighted sharing in any priority level.
Max Classes
If bit 3 of the Scheduler Flags field is zero, Max Classes
gives the maximum number of QoS classes that may be
supported by this switch port. In this case the maximum
number of QoS classes that may be supported by this switch
port is not affected by the number of QoS classes in use by
other switch ports. If bit 3 of the Scheduler Flags field
is set, Max Classes gives the maximum number of QoS classes
that may be supported by the entire switch. In this case it
is assumed that use of these QoS classes may be distributed
among the various switch ports.
Default Size
The size of waiting room that this output port allocates by
default. The actual size of waiting room may be specified
in the Scheduler Establishment message. The size of a
waiting room specifies the maximum number of cells
permitted to wait for transmission via that waiting room.
Any further cells arriving at that waiting room beyond this
number will be discarded.
Default Discard Threshold
The value of discard threshold that this output port
allocates by default. The actual value of discard threshold
may be specified in the Scheduler Establishment message.
The discard threshold specifies the number of cells waiting
for transmission via a waiting room after which further
arriving cells will be subject to a discard mechanism.
Max Buffer
The maximum amount of buffer space, measured in cells,
available to this port. If bit 7 of the Scheduler Flags
field is zero this, buffer space is not shared with other
ports. If bit 7 of the Scheduler Flags field is set, at
least some of this buffer space is shared with other ports.
Max Shaper Buffer
The maximum amount of buffer space, measured in cells,
available to a QoS connection or a QoS class within the
shaper function of the regulator. This shaper buffer space
is likely to be shared among all QoS classes and QoS
connections using the shaper, so there is no guarantee that
the amount of buffer space defined by the Max Shaper Buffer
field will be available to any particular QoS class or QoS
connection.
Scaling Factor
The QoS Class Establishment and QoS Connection Management
messages require parameters that describe cell rates in
cells per second or their reciprocal, cell interarrival
periods, in seconds per cell. In order that these
parameters may be specified with a 32-bit unsigned integer,
the switch defines a Scaling Factor to be used in defining
such parameters. By appropriate choice of the Scaling
Factor the switch can select the range and granularity of
rate or time that can be specified with the 32-bit unsigned
integer. Further details are given in the discussion of
the UPC Parameters field of the QoS Connection Management
message.
9.3 Scheduler Establishment Message
The Scheduler Establishment message is used to configure the
scheduler on a specified output port. It is used to configure a
waiting room, attach it to a leaf of the scheduler tree, and return a
Scheduler Identifier to reference the waiting room. The Scheduler
Establishment message may also be used to modify the parameters of an
already established waiting room.
Scheduler Identifiers in the range 0--255 represent default values.
They are used for the priority levels that may be specified in the
Class of Service field of Connection Management messages without
requiring explicit establishment via a Scheduler Establishment
message. Each of these default values specifies a single waiting
room with default parameters, configured as a FIFO queue, on each of
the valid scheduler priority levels. (This permits Connection
Management messages to continue to specify QoS requirements as a
priority without requiring the use of any of the QoS messages.) The
number of priority levels available to the scheduler is specified in
the Priorities field of the Port Configuration and All Ports
Configuration messages.
The Scheduler Establishment Message is:
Message Type = 97
The Scheduler Establishment request and success response 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scheduler Identifier | Net Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |D|F|M|W|x x x x| Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Waiting Room Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discard Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Scheduler Identifier
The Scheduler Identifier is selected by the controller. It
is used to identify the waiting room being established or
modified in future messages. The Scheduler Identifier is
taken from a namespace that is local to the switch port. A
Scheduler Identifier in the Scheduler Establishment message
must be greater than 0x00FF but less than 0xFFFF. The
values 0 -- 0x00FF are reserved for use as default values.
The default values of the Scheduler Identifier are used to
specify the default settings for the scheduler. Each of the
default values maps directly to one of the scheduler
priority levels. The value 0xFFFF is reserved for use in
the QoS Connection Management message.
Net Weight
The Net Weight specifies the share of the bandwidth
available to the priority level, specified by the Priority
field, that should be given to this waiting room. The Net
Weight parameter is only valid if the priority level
specified by the Priority field supports weighted sharing.
The Net Weight is an unsigned 16-bit field specifying a
binary fraction. I.e. the bandwidth share, as a fraction
of the bandwidth available to the priority level, is given
by:
Bandwidth share = Net Weight * 2**(-16)
A Net Weight of zero indicates equal sharing between all
waiting rooms sharing this priority level that request a
Net Weight of zero. While a 16-bit field is used to
specify the Net Weight it is understood that the accuracy
of the bandwidth sharing is hardware dependent and is not
specified.
If weighted sharing is not required at a particular
priority level, a waiting room with a Net Weight value of
0xFFFF must be specified for that priority level. A
priority level that does not support weighted sharing can
only support a single waiting room.
Flags
D: Packet Discard
Bit 0 of the Flags field, if set, indicates that packet
discard is required on all connections and QoS classes
routed through this waiting room.
F: Frame-Based Scheduling
Bit 1 of the Flags field, if set, indicates that frame-
based scheduling is required on all connections and QoS
classes routed through this waiting room. 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. 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 2 of the Scheduler Flags field, if set, indicates that
VC merging is required on all connections and QoS classes
routed through this waiting room. VC merging enables 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. Most switches achieve VC merging by
using frame-based scheduling. 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.
W: Weighted Scheduling
Bit 3 of the Flags field, if set, indicates that weighted
scheduling is required on all connections and QoS classes
routed through this waiting room. All connections and QoS
classes routed through this waiting room will require a
Connection Weight or a QoS Class Weight respectively. The
Connection Weight is specified in the QoS Connection
Management message. The QoS Class Weight is specified in
the QoS Class Establishment message. If weighted scheduling
within this waiting room is unavailable, a failure response
message must be returned indicating, "Weighted scheduling
within this waiting room is unavailable."
Bit 3 of the Flags field, if zero, indicates that this
waiting room should be configured as a single FIFO queue.
All cells arriving at this waiting room will receive
first-in-first-out service. If Frame-Based Scheduling or VC
Merging are also selected, the strict first-in-first-out
service discipline will be modified by the requirement to
support Frame-Based Scheduling or VC Merging.
x: Bits 4--7 of the Flags field are not used.
Priority
Specifies the priority level in the scheduler to which the
waiting room should be attached. Priorities are numbered
from zero, with priority level zero being the highest
priority.
Waiting Room Size
The required size of the waiting room. The size of a
waiting room specifies the maximum number of cells
permitted to wait for transmission via that waiting room.
Any further cells arriving at that waiting room beyond this
number will be discarded. If the switch is unable to grant
the size requested in the Scheduler Establishment request
message it may reply with the actual size allocated to the
waiting room in the Waiting Room Size field of the success
response message. A value of zero for the Waiting Room
Size indicates that the default value should be used.
Discard Threshold
The required value of the discard threshold. The discard
threshold specifies the number of cells waiting for
transmission via a waiting room after which further
arriving cells will be subject to a discard mechanism. The
value of the Discard Threshold must be less than or equal
to the value of the Waiting Room Size parameter for any
given waiting room. If the switch is unable to grant the
value of discard threshold requested in the Scheduler
Establishment request message it may reply with the actual
value of discard threshold allocated to the waiting room in
the Discard Threshold field of the success response
message. A value of zero for the Discard Threshold
indicates that the default value should be used.
9.4 QoS Class Establishment Message
The QoS Class Establishment message is used to configure a QoS class
on a specified port or to modify the parameters of an already
established QoS class. It configures the classifier and the
regulator functions for the QoS class. It also configures the QoS
class policer if a policing function is available for QoS classes.
Two styles of QoS class are available. In one style each component
connection of the QoS class may be routed independently to an output
port and waiting room specified in its connection management message.
In this case the Scheduler Identifier, and if required, the Excess
Scheduler Id, are specified in the QoS Connection Management message
that references this style of QoS class. In the alternative style of
QoS class, all component connections in the QoS class are routed to
the same waiting room on the same output port. In this case the
Output Port, the Scheduler Identifier, and if required, the Excess
Scheduler Id, are specified in the QoS Class Establishment message.
The classifier and regulator functions must be located together,
either on an input port, on an output port, or centralized. Each port
declares the location of its classifier and regulator functions at
initialization using the QoS Configuration message. If the classifier
and regulator functions are located on an input port, only
connections that arrive at that input port may join a QoS class
established on that port. However, each connection that is part of a
QoS class established on that port may be switched to a different
output port. If the classifier and regulator functions are located on
an output port, connections that arrive at any input port may join a
QoS class established on that port. However, all connections within a
QoS class established on that port must be switched to that output
port. For a centralized classifier and regulator function, there is
no restriction on the input ports on which connections in a QoS class
must arrive, or on the output ports to which connections in a QoS
class must be switched. (For the case of a centralized classifier
and regulator the actual port specified in the QoS Class
Establishment message is used only for administrative purposes. Any
valid value of Port and Port Session Number, that specifies a
centralized classifier and regulator function, may be used.)
The QoS Class Establishment message is:
Message Type = 98
The QoS Class Establishment request and success response 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Regulator | Excess Action | QoS Class Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scheduler Identifier | Excess Scheduler Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Output Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ QoS Class Policer Parameters ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ QoS Class Regulator Parameters ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
QoS Class Identifier
The QoS Class Identifier is selected by the controller. It
is used to identify the QoS class being established or
modified, in future QoS Connection Management and QoS Class
Establishment messages. It is taken from a namespace that
is global across the entire switch. No two QoS classes may
have the same QoS Class Identifier regardless of the switch
ports on which they are defined. A QoS Class Identifier in
a QoS Class Establishment message must be greater than 0
and less than 0xFFFFFFFF.
Regulator
The Regulator field specifies which function is required of
the regulator. Three possible functions are currently
defined: none, policing, and shaping.
None: Regulator = 1
Policing: Regulator = 2
Shaping: Regulator = 3
If the Regulator function is specified as none, no
operations are performed by the regulator on the cells
output from the classifier. Cells output from the
classifier are transferred directly to the waiting room
specified by the Scheduler Identifier.
If policing is specified, a token bucket policer will be
applied to the QoS class. The policer determines which
cells conform to the specified policer traffic parameters
and which do not. Conforming cells are transferred directly
to the waiting room specified by the Scheduler Identifier.
The action to be taken by the policer on the excess traffic
is specified by the Excess Action field. The policer
traffic parameters are specified in the QoS Class Regulator
Parameters fields.
If shaping is specified, traffic shaping will be applied to
the QoS class. Cells in a QoS class should leave the
regulator spaced evenly apart at a rate defined by the QoS
Class Regulator Parameters fields. These cells are
transferred directly to the waiting room specified by the
Scheduler Identifier. The jitter on the conforming cell
stream on exit from the shaping function of the regulator
is not specified.
Excess Action
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|T|D|S|x x x x x|
+-+-+-+-+-+-+-+-+
T: Tagging
If bit 0 of the Excess Action field is set, all cells
transferred to the waiting room specified by the Excess
Scheduler Id will have their CLP bit set. If bit 0 of the
Excess Action field is zero, the CLP bit of cells
transferred to the waiting room specified by the Excess
Scheduler Id will remain unchanged.
D: Discard
This function is only available if policing is selected as
the regulator function. If the Regulator field specifies
Policing, and bit 1 of the Excess Action field is set, all
cells determined by the policer to be in excess of the
traffic parameters must be discarded. In this case the
Excess Scheduler Id is not used and bit 0 of the Excess
Action field should be ignored.
S: Differentiated Scheduling
This function operates differently according to whether
policing or shaping is selected as the regulator function.
If the Regulator field specifies Policing, and bit 1 of the
Excess Action field is zero, and bit 2 of the Excess Action
field is set, all cells determined by the policer to be in
excess of the traffic parameters must be transferred to the
waiting room specified by the Excess Scheduler Id. In this
case care must be taken in the implementation to ensure
that within each virtual path connection or virtual channel
connection, cells depart in the same order that they
arrived. If the Regulator field specifies Policing, and
bit 1 of the Excess Action field is zero, and bit 2 of the
Excess Action field is zero, all cells determined by the
policer to be in excess of the traffic parameters must be
transferred to the waiting room specified by the Scheduler
Identifier. In this case the Excess Scheduler Id is not
used.
If the Regulator field specifies Shaping, and bit 2 of the
Excess Action field is zero, cells will be transferred from
the QoS class to the waiting room pointed to by the
Scheduler Identifier at a rate defined by the QoS Class
Regulator Parameters. In this case the Excess Scheduler Id
is not used. If the Regulator field specifies Shaping, and
bit 2 of the Excess Action field is set, additional cells
will be scheduled for transmission by the waiting room
pointed to by the Excess Scheduler Id. This permits a
minimum cell rate to be allocated to the QoS class using
the QoS Class Regulator Parameters and additional bandwidth
to be shared by the QoS class. The additional share of
bandwidth is determined according to the parameters of the
waiting room pointed to by the Excess Scheduler Id. If the
Excess Scheduler Id is specified in the QoS Class
Establishment message, the additional bandwidth will be
shared by the entire QoS class. If the Excess Scheduler Id
is specified in each individual QoS Connection Management
message, the additional bandwidth is specific to that
connection and not shared by the entire QoS class. Care
must be taken in the implementation to ensure that within
each virtual path connection or virtual channel connection,
cells depart in the same order that they arrived.
x: Bits 3--7 of the Excess Action field are not used.
QoS Class Weight
If bit 1 of the Scheduler Flags field of the QoS
Configuration message indicates that weighted service may
be applied to a QoS class, the QoS Class Weight parameter
specifies the share of the bandwidth available to the
waiting room that should be given to this QoS class.
The QoS Class Weight is an unsigned 16-bit field specifying
a binary fraction. I.e. the bandwidth share, as a fraction
of the bandwidth available to the waiting room, is given
by:
Bandwidth share = QoS Class Weight * 2**(-16)
A QoS Class Weight of zero indicates equal sharing between
all QoS classes sharing this waiting room that request a
QoS Class Weight of zero. While a 16-bit field is used to
specify the QoS Class Weight it is understood that the
accuracy of the bandwidth sharing is hardware dependent and
is not specified.
If the Regulator field of the QoS Class Establishment
message indicates None, or Policer, the QoS Class Weight
should be applied to the waiting room pointed to by the
Scheduler Identifier. If the Regulator field of the QoS
Class Establishment message indicates Shaper, the QoS Class
Weight should be applied to the waiting room pointed to by
the Excess Scheduler Id.
If the specified waiting room is unable to offer weighted
sharing for a QoS class, a failure response message should
be returned with the failure code indicating: "This waiting
room is unable to offer weighted sharing for a QoS class."
Scheduler Identifier
If all conforming traffic from this QoS class is directed
to the same waiting room, on the same output port, this
field specifies the Scheduler Identifier for the entire QoS
class. The Scheduler Identifier points to the waiting room,
on the output port specified by the Output Port field, to
which all conforming traffic should be sent. If this field
is not used it should be set to 0xFFFF. If each component
connection of the QoS class specifies its own output port
and waiting room, the Scheduler Identifier must be
specified in the QoS Connection Management message and this
field must be set to 0xFFFF.
Excess Scheduler Id
If all conforming traffic from this QoS class is directed
to the same waiting room, on the same output port, this
field specifies the Excess Scheduler Id for the entire QoS
class. The Excess Scheduler Id points to the waiting room,
on the output port specified by the Output Port field, to
which all excess traffic should be sent. If this field is
not used it should be set to 0xFFFF. If each component
connection of the QoS class specifies its own output port
and waiting room, the Excess Scheduler Id must be specified
in the QoS Connection Management message and this field
must be set to 0xFFFF. If the Scheduler Id is specified in
the QoS Class Establishment message, the Excess Scheduler
Id must also be specified in the QoS Class Establishment
message (or not used). If the Scheduler Id is specified in
the QoS Connection Management message, the Excess Scheduler
Id must also be specified in the QoS Connection Management
message (or not used). The Excess Scheduler Id must not
point to the same waiting room on the same output port as
the Scheduler Identifier.
Output Port
If the Scheduler Identifier field in the QoS Establishment
message is not 0xFFFF the Output Port field specifies the
Output Port to which traffic from this QoS class should be
routed. If the Scheduler Identifier field in the QoS
Establishment message is 0xFFFF, this field is not used.
QoS Class Policer Parameters
A policer function may be applied to a QoS class on output
from the classifier independently of the regulator
function. The QoS class policer function is identical to
the connection policer function defined in the QoS
Connection Management message with the exception that it
applies to all cells that belong to the QoS class rather
than just cells that belong to a single connection.
The QoS Class Policer Parameters 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Increment-1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Limit-1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Increment-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Limit-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |C|A|x x x x x x|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The definition of these fields is given in the UPC
Parameters section of the QoS Connection Management
message.
QoS Class Regulator Parameters
The QoS class regulator function is identical to the
regulator function defined in the QoS Connection Management
message with the exception that it applies to all cells
that belong to the QoS class rather than just cells that
belong to a single connection.
The QoS Class Regulator Parameters 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Regulator Increment |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Regulator Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The definition of these fields is given in the Regulator
Parameters section of the QoS Connection Management
message.
9.5 QoS Release Message
The QoS Release message is used to delete a Scheduler Identifier or a
QoS Class Identifier and to release all resources associated with it.
The QoS Release message is:
Message Type = 99
The QoS Release request and success response 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Scheduler Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Port
If the QoS Release message contains a Scheduler Identifier,
the Port field must contain the Port Number of the switch
output port to which the Scheduler Identifier applies. If
the QoS Release message contains a QoS Class Identifier,
any valid Port number may be used. (The QoS Class
Identifier has a global namespace.)
Port Session Number
The current Port Session Number for the port specified in
the Port field.
Scheduler Identifier
If the Scheduler Identifier contains the value 0xFFFF the
QoS Class Identifier specified in the QoS Class Identifier
field should be released. Else, if the value of the
Scheduler Identifier lies in the range 0x0100 -- 0xFFFE
inclusive, the Scheduler Identifier specified by the
Scheduler Identifier field should be released. A Scheduler
Identifier with a value less than 0x0100 is invalid in a
QoS Release message. (It specifies a default value which
may not be released.)
QoS Class Identifier
If the Scheduler Identifier contains the value 0xFFFF the
QoS Class Identifier field specifies the QoS Class
Identifier to be released.
If the QoS Release message requests that a Scheduler Identifier be
released, and the Scheduler Identifier is still in use by one or more
established connections, a failure response must be returned with the
failure code indicating: "Scheduler Identifier still in use." If the
QoS Release message requests that a QoS Class Identifier be released,
and the QoS Class Identifier is still in use by one or more
established connections, a failure response must be returned with the
failure code indicating: "QoS Class Identifier still in use."
9.6 QoS Connection Management Message
The QoS Connection Management message is used by the controller to
establish and modify virtual channel connections and virtual path
connections across the switch which require QoS parameters to be
specified. The functionality of the QoS Connection Management message
is identical to that of the Add Branch connection management message
with the additional specification of QoS parameters. No specific QoS
connection release messages are defined. QoS connections may be
released with the Delete Tree, Delete All, and Delete Branches
messages defined in Section 4, "Connection Management Messages." When
a QoS connection is released, all associated QoS resources are
released.
There are three styles of connection with specified QoS parameters:
QoS Connection:
This connection style specifies its own individual QoS parameters
and is routed independently to the waiting room and output port
specified in the QoS Connection Management message. It is not a
member of a QoS class. Each output branch of a point-to-multipoint
QoS connection may specify its own QoS parameters which may be
different from all other output branches of that point-to-
multipoint QoS connection, if the switch supports this capability.
However, all output branches must specify identical connection
policer parameters. A QoS Connection Management message requesting
this style of connection is identified by a QoS Class Identifier
with the value 0xFFFFFFFF.
QoS Class Connection:
This connection style does not specify its own individual QoS
parameters. It is a member of a QoS class, and the QoS parameters
are specified by the QoS class. It is, however, routed
independently to the waiting room and output port specified in the
QoS Connection Management message. Each output branch of a
point-to-multipoint QoS Class Connection must use the same QoS
parameters. A QoS Connection Management message requesting this
style of connection will have a valid QoS Class Identifier and a
valid Scheduler Identifier.
QoS Class Member:
This connection style does not specify its own individual QoS
parameters. It is a member of a QoS class, and the QoS parameters
are specified by the QoS class. The QoS class also specifies the
waiting room and output port to which all members of the class are
routed. This style of connection does not support point-to-
multipoint connections. A QoS Connection Management message
requesting this style of connection will have a valid QoS Class
Identifier and a Scheduler Identifier with the value 0xFFFF.
To request a virtual channel connection with specified QoS
parameters, the Virtual Channel Connection (VCC) QoS Connection
Management message is:
Message Type = 100.
To request a virtual path connection with specified QoS parameters,
the Virtual Path Connection (VPC) QoS Connection Management message
is:
Message Type = 101.
The QoS Connection Management message has the following format for
both request and response messages:
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 Session Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Input Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|Q|B|C| Input VPI | Input VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Output Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x x x x| Output VPI | Output VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Branches | Scheduler Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Regulator | Excess Action | Connection Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|A|x x x x x x| Reserved | Excess Scheduler Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ UPC Parameters ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Regulator Parameters ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Port Session Number
Input Port
Input VPI
Input VCI
Output Port
Output VPI
Output VCI
Number of Branches
The definition of these fields is exactly the same as
defined for the Add Branch message in Section 4.1,
"Connection Management Messages."
M B C Flags
The definition of the M, B, and C flags is exactly the same
as defined in Section 4, "Connection Management Messages."
They apply to the QoS Connection Management message exactly
as defined for the Add Branch message.
Q: QoS Profile Flag The QoS Profile flag is not used in the QoS
Connection Management message.
Scheduler Identifier
For QoS Connection and QoS Class Connection styles, the
Scheduler Identifier points to the waiting room, on the
output port specified by the Output Port field, to which
all conforming traffic on the connection should be routed.
The values 0 -- 255 specify the default settings for the
scheduler. Each of the default values maps directly to one
of the scheduler priority levels. A Scheduler Identifier in
the range 0 -- 255 may be used without first being
established by a Scheduler Establishment message. All
Scheduler Identifiers in the range 0x0100 to 0xFFFE must
first be established by a Scheduler Establishment message.
A Scheduler Identifier with a value of 0xFFFF indicates
that a QoS Class Member connection style is being
requested. In this connection style, the waiting room and
output port are specified by reference to the QoS class
specified by the QoS Class Identifier field. In this case
the QoS Class Identifier field must contain a valid QoS
Class Identifier.
QoS Class Identifier
For QoS Class Connection and QoS Class Member connection
styles, the QoS Class Identifier specifies the QoS Class to
which the connection belongs. It must first be established
by a QoS Class Establishment message and must have a value
greater than 0 and less than 0xFFFFFFFF.
A QoS Class Identifier with a value of 0xFFFFFFFF indicates
that a connection of style "QoS Connection" is being
requested. In this connection style, the connection does
not belong to a QoS class. All QoS parameters are specified
by the QoS Connection Management message and apply only to
the specified connection.
Regulator
Excess Action
The Regulator and Excess Action parameters are only used in
connection requests of style "QoS Connection." The
definition of these fields in the QoS Connection Management
message is exactly the same as defined for the QoS Class
Establishment message with the exception that they apply to
an individual connection rather than to an entire QoS
class.
Connection Weight
This field is only used in connections of style "QoS
Connection" and "QoS Class Connection." For QoS Class
Member style connections, the QoS Class Weight parameter of
the QoS Class Establishment message should be used to
assign a weight to the QoS Class.
If bit 0 of the Scheduler Flags field of the QoS
Configuration message indicates that weighted service may
be applied to a connection, the Connection Weight parameter
specifies the share of the bandwidth available to the
waiting room that should be given to this connection.
The Connection Weight is an unsigned 16-bit field
specifying a binary fraction. I.e. the bandwidth share, as
a fraction of the bandwidth available to the waiting room,
is given by:
Bandwidth share = Connection Weight * 2**(-16)
A Connection Weight of zero indicates equal sharing between
all connections in this waiting room that request a
Connection Weight of zero. While a 16-bit field is used to
specify the Connection Weight it is understood that the
accuracy of the bandwidth sharing is hardware dependent and
is not specified.
For connections of style "QoS Class Connection," if the
Regulator function of the QoS Class is specified as None,
or Policer, the Connection Weight should be applied to the
waiting room pointed to by the Scheduler Identifier field
in the QoS Connection Management message. If the Regulator
function of the QoS Class is specified as Shaper, the
Connection Weight should be applied to the waiting room
pointed to by the Excess Scheduler Id field in the QoS
Connection Management message.
For connections of style "QoS Connection," if the Regulator
field of the QoS Connection Management message specifies
None, or Policer, the Connection Weight should be applied
to the waiting room pointed to by the Scheduler Identifier
field. If the Regulator field of the QoS Connection
Management message specifies Shaper, the Connection Weight
should be applied to the waiting room pointed to by the
Excess Scheduler Id field.
If the specified waiting room is unable to offer weighted
sharing for a connection, a failure response message should
be returned with the failure code indicating: "this waiting
room is unable to offer weighted sharing for a connection."
QoS Flags
S: Selective Discard
If the Selective Discard flag is set, only cells with the
Cell Loss Priority (CLP) bit set will be subject to the
discard mechanism when the number of cells in the waiting
room exceeds the Discard Threshold. If the Selective
Discard flag is zero, all cells (CLP=0 and CLP=1) will be
subject to the discard mechanism when the number of cells
in the waiting room exceeds the Discard Threshold.
Selective discard can be combined with packet discard. In
this case only packets in which at least one cell has the
CLP bit set will be subject to the discard mechanism.
A: All Branches
For a QoS Connection Management message that specifies a
point-to-multipoint connection, if the All Branches flag is
set, all branches of the point-to-multipoint connection
must be set to the QoS parameters specified in the message.
If the All Branches flag is zero, only the single output
branch specified in the message should be set to the QoS
parameters specified in the message. For a QoS Connection
Management message that specifies a point-to-point
connection, the All Branches flag is not used.
x: Unused
Excess Scheduler Id
For connections of style "QoS Connection" and "QoS Class
Connection," the Excess Scheduler Id points to the waiting
room, on the output port specified by the Output Port
field, to which all excess traffic should be routed. The
values 0 -- 255 specify the default settings for the
scheduler. Each of the default values maps directly to one
of the scheduler priority levels. An Excess Scheduler Id in
the range 0 -- 255 may be used without first being
established by a Scheduler Establishment message. All
values of Excess Scheduler Id in the range 0x0100 to 0xFFFE
must first be established by a Scheduler Establishment
message.
If this field is not used it should be set to 0xFFFF. The
Excess Scheduler Id must not point to the same waiting room
on the same output port as the Scheduler Identifier.
UPC Parameters
All connection styles may be subject to a Usage Parameter
Control (UPC) function, also known as a connection policer.
The policing function is applied to each individual
connection before it is combined with other connections
into a QoS class by the classifier function. A policing
function applied to an entire QoS class is defined in the
QoS Class Establishment message.
The connection policer is defined by reference to the
Generic Cell Rate Algorithm (GCRA) defined by the ATM Forum
[af-tm-0056], although any equivalent policing algorithm
may be used. The GCRA takes two parameters, the increment
(I) and the limit (L). The reciprocal of the increment
(1/I) specifies the rate being policed. The limit specifies
the burst tolerance. (For comparison with the token bucket
policer discussed in [Partridge], the size of the token
bucket is given by L/I.)
Two policers in series may be specified to permit the
policing of both peak rate and average rate (also called
sustainable rate). The parameters for the first policer are
Increment-1 and Limit-1. For comparison with the ATM Forum
specification these would be used to police the Peak Cell
Rate (PCR) and Cell Delay Variation Tolerance (CDVT)
respectively. The parameters for the second policer are
Increment-2 and Limit-2. For comparison with the ATM Forum
specification these would be used to police the Sustainable
Cell Rate (SCR), and Burst Tolerance. (The Burst Tolerance
may be computed from the Maximum Burst Size [af-tm-0056].)
There are two configurations in which the two policers may
be connected in series. In the All Cells configuration,
all cells (cells with the Cell Loss Priority (CLP) bit set
to zero and cells with the CLP bit set to one) are subject
to the policing action of both policers in series. In the
CLP Selective configuration, all cells, both CLP=0 and
CLP=1, are policed by the first policer; but only cells
with CLP=0 are subject to policing by the second policer.
Either tagging or discard may be specified for each of the
policer configurations.
The values of the parameters Increment and Limit in the UPC
Parameters fields are given in terms of a time unit
specified by the switch in the QoS Configuration Parameters
message. The time unit is specified by the switch as a
rate, the Scaling Factor, which gives the rate in cells per
second that would result from an Increment parameter value
of one. Thus to determine the value of the Increment
parameter from the desired policed rate given in cells per
second:
Increment parameter = (Scaling_Factor)/(policed_rate)
To determine the value of the Limit parameter from the
desired Cell Delay Variation Tolerance (CDVT) given in
seconds:
Limit parameter = CDVT * Scaling_Factor
To determine the value of the Limit parameter from the
desired Burst Tolerance (BT) given in seconds:
Limit parameter = BT * Scaling_Factor
The Increment and Limit parameters are specified as 32-bit
unsigned integers; so the choice of the Scaling Factor
allows the switch to select the range and granularity of
the policer parameters with respect to the line rate of the
switch port. For example, a SONET STS-3c (155.52 Mbps)
switch port has a line rate of approximately 353 kcells/s.
With a Scaling Factor value of 353,000,000 we can specify a
policed rate slightly less than the line rate with a
granularity of 0.1%. For a policed rate of 1 kbps we can
still support a bucket size of 31 cells.
The UPC Parameters 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Increment-1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Limit-1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Increment-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Limit-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |C|A|x x x x x x|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Increment-1
The increment parameter for the first policer, specified as
a 32-bit unsigned integer. A value of zero for the
Increment-1 parameter is used to disable the first policer.
In this case all cells will be considered to conform to the
traffic parameters of the first policer.
Limit-1
The limit parameter for the first policer, specified as a
32-bit unsigned integer.
Increment-2
The increment parameter for the second policer, specified
as a 32-bit unsigned integer. A value of zero for the
Increment-2 parameter is used to disable the second
policer. In this case all cells will be considered to
conform to the traffic parameters of the second policer.
Limit-2
The limit parameter for the second policer, specified as a
32-bit unsigned integer.
Flags
C: Configuration
If the Configuration flag is set, the policer should be set
to the All Cells configuration. If the Configuration flag
is zero, the policer should be set to the CLP Selective
configuration.
In the All Cells configuration, all cells (both CLP=0 and
CLP=1) are subject to the policing action of both policers
in series. In the CLP Selective configuration, all cells,
both CLP=0 and CLP=1, are policed by the first policer; but
only cells with CLP=0 are subject to policing by the second
policer. Either tagging or discard may be specified for
each of the policer configurations.
A: Action
If the Action flag is zero, discard is required as the
policing action. If the Action flag is set, tagging is
required as the policing action.
If tagging is selected in the All Cells configuration, any
cell with CLP=0 in either policer, that the policer
determines to be in excess of the specified policer
parameters, will be changed to CLP=1. If discard is
selected in the All Cells configuration, any cell (CLP=0 or
CLP=1) in either policer, that the policer determines to be
in excess of the specified policer parameters, will be
discarded.
In the CLP Selective configuration, the first policer is
always set to discard any cell (CLP=0 or CLP=1) that it
determines to be in excess of its specified policer
parameters. If tagging is selected in the CLP Selective
configuration, the second policer will change the CLP bit
to CLP=1 of any cell that it determines to be in excess of
its specified parameters. If discard is selected in the CLP
Selective configuration, the second policer will discard
any cell that it determines to be in excess of its
specified parameters.
To configure the policer for the conformance definitions
specified by the ATM Forum [af-tm-0056] the following
configurations are suggested:
CBR.1: One policer, All Cells, Discard
VBR.1: Two policers, All Cells, Discard