NSIS X. Fu
B. Schloer
Internet-Draft Univ. Goettingen
Expiration Date: April 3, 2008 H. Tschofenig
T. Tsenov
Nokia Siemens Networks
October 4, 2007
QoS NSLP State Machine
draft-fu-nsis-qos-nslp-statemachine-06.txt
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document describes a state machine for the NSIS Signaling Layer
Protocol for Quality-of-Service signaling (QoS NSLP). A combined
state machine for QoS NSLP entities at different locations of a flow
path is presented in order to illustrate how QoS NSLP may be
implemented.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Notational conventions used in state diagrams . . . . . . . 3
4. State Machine Symbols . . . . . . . . . . . . . . . . . . . 5
5. Common Rules . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1 Common Procedures . . . . . . . . . . . . . . . . . . . . 7
5.2 Common Variables . . . . . . . . . . . . . . . . . . . . . 7
5.3 Events . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.4 Assumptions . . . . . . . . . . . . . . . . . . . . . . . 9
6. Basic State Machine Concept . . . . . . . . . . . . . . . . 11
6.1 The QoS NSLP Daemon . . . . . . . . . . . . . . . . . . . 11
6.2 States, Events and Callback Functions . . . . . . . . . . 12
6.3 Timer . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.4 The Toggle Flag . . . . . . . . . . . . . . . . . . . . . 13
7. State Machine for QoS NSLP nodes . . . . . . . . . . . . . . 13
7.1 State ST_IDLE . . . . . . . . . . . . . . . . . . . . . . 14
7.2 State ST_WR . . . . . . . . . . . . . . . . . . . . . . 16
7.3 State ST_INST . . . . . . . . . . . . . . . . . . . . . . 19
8 Actions and Transitions . . . . . . . . . . . . . . . . . . . 23
8.1 State ST_IDLE . . . . . . . . . . . . . . . . . . . . . . 23
8.2 State ST_WR . . . . . . . . . . . . . . . . . . . . . . 24
8.3 State ST_INST . . . . . . . . . . . . . . . . . . . . . . 26
9. Security Considerations . . . . . . . . . . . . . . . . . . 27
10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . 28
11. Change History . . . . . . . . . . . . . . . . . . . . . . 28
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 29
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
13.1 Normative References . . . . . . . . . . . . . . . . . . 30
13.2 Informative References . . . . . . . . . . . . . . . . . 30
Appendix A. ASCII versions of the state diagrams . . . . . . . . 31
A.1 State ST_IDLE . . . . . . . . . . . . . . . . . . . . . 31
A.2 State ST_WR . . . . . . . . . . . . . . . . . . . . . 33
A.3 State ST_INST . . . . . . . . . . . . . . . . . . . . . 36
A.4 Commonly used functions . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 47
Intellectual Property and Copyright Statements . . . . . . . 48
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1. Introduction
This document describes a state machine for QoS NSLP [1], trying to
show how QoS NSLP can be implemented to support its deployment. The
state machine described in this document is illustrative of how the
QoS NSLP protocol defined in [1] may be implemented for QoS NSLP
nodes in the flow path. Where there are differences [1] are
authoritative. The state machine diagrams are informative only.
Implementations may achieve the same results using different methods.
According to [1], there are several possibilities for QoS NSLP
signaling, at least including the following: - end-to-end signaling
vs. scoped signaling - sender-initiated signaling vs. receiver-
initiated signaling.
The messages used in the QoS NSLP protocol can be summarized as
follows:
Requesting message Responding message
------------------------+---------------------------
RESERVE |None or RESERVE or RESPONSE
QUERY |RESERVE or RESPONSE
RESPONSE |NONE
NOTIFY |NONE
------------------------+---------------------------
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [2].
3. Notational conventions used in state diagrams
The following text is reused from [3] and the state diagrams are
based on the conventions specified in [4], Section 8.2.1. Additional
state machine details are taken from [5].
The complete text is reproduced here:
State diagrams are used to represent the operation of the protocol by
a number of cooperating state machines each comprising a group of
connected, mutually exclusive states. Only one state of each machine
can be active at any given time.
All permissible transitions between states are represented by arrows,
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the arrowhead denoting the direction of the possible transition.
Labels attached to arrows denote the condition(s) that must be met in
order for the transition to take place. All conditions are
expressions that evaluate to TRUE or FALSE; if a condition evaluates
to TRUE, then the condition is met. The label UCT denotes an
unconditional transition (i.e., UCT always evaluates to TRUE). A
transition that is global in nature (i.e., a transition that occurs
from any of the possible states if the condition attached to the
arrow is met) is denoted by an open arrow; i.e., no specific state is
identified as the origin of the transition. When the condition
associated with a global transition is met, it supersedes all other
exit conditions including UCT. The special global condition BEGIN
supersedes all other global conditions, and once asserted remains
asserted until all state blocks have executed to the point that
variable assignments and other consequences of their execution remain
unchanged.
On entry to a state, the procedures defined for the state (if any)
are executed exactly once, in the order that they appear on the page.
Each action is deemed to be atomic; i.e., execution of a procedure
completes before the next sequential procedure starts to execute. No
procedures execute outside of a state block. The procedures in only
one state block execute at a time, even if the conditions for
execution of state blocks in different state machines are satisfied,
and all procedures in an executing state block complete execution
before the transition to and execution of any other state block
occurs, i.e., the execution of any state block appears to be atomic
with respect to the execution of any other state block and the
transition condition to that state from the previous state is TRUE
when execution commences. The order of execution of state blocks in
different state machines is undefined except as constrained by their
transition conditions. A variable that is set to a particular value
in a state block retains this value until a subsequent state block
executes a procedure that modifies the value.
On completion of all of the procedures within a state, all exit
conditions for the state (including all conditions associated with
global transitions) are evaluated continuously until one of the
conditions is met. The label ELSE denotes a transition that occurs if
none of the other conditions for transitions from the state are met
(i.e., ELSE evaluates to TRUE if all other possible exit conditions
from the state evaluate to FALSE). Where two or more exit conditions
with the same level of precedence become TRUE simultaneously, the
choice as to which exit condition causes the state transition to take
place is arbitrary.
In addition to the above notation, there are a couple of
clarifications specific to this document. First, all boolean
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variables are initialized to FALSE before the state machine execution
begins. Second, the following notational shorthand is specific to
this document:
<variable> = <expression1> | <expression2> | ...
Execution of a statement of this form will result in <variable>
having a value of exactly one of the expressions. The logic for
which of those expressions gets executed is outside of the state
machine and could be environmental, configurable, or based on
another state machine such as that of the method.
4. State Machine Symbols
( )
Used to force the precedence of operators in Boolean expressions
and to delimit the argument(s) of actions within state boxes.
;
Used as a terminating delimiter for actions within state boxes.
Where a state box contains multiple actions, the order of
execution follows the normal English language conventions for
reading text.
=
Assignment action. The value of the expression to the right of the
operator is assigned to the variable to the left of the operator.
Where this operator is used to define multiple assignments, e.g.,
a = b = X the action causes the value of the expression following
the right-most assignment operator to be assigned to all of the
variables that appear to the left of the right-most assignment
operator.
!
Logical NOT operator.
&&
Logical AND operator.
||
Logical OR operator.
if...then...
Conditional action. If the Boolean expression following the if
evaluates to TRUE, then the action following the then is executed.
{ statement 1, ... statement N }
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Compound statement. Braces are used to group statements that are
executed together as if they were a single statement.
!=
Inequality. Evaluates to TRUE if the expression to the left of the
operator is not equal in value to the expression to the right.
==
Equality. Evaluates to TRUE if the expression to the left of the
operator is equal in value to the expression to the right.
>
Greater than. Evaluates to TRUE if the value of the expression to
the left of the operator is greater than the value of the
expression to the right.
<=
Less than or equal to. Evaluates to TRUE if the value of the
expression to the left of the operator is either less than or
equal to the value of the expression to the right.
++
Increment the preceding integer operator by 1.
+
Arithmetic addition operator.
&
Bitwise AND operator.
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5. Common Rules
Throughout the document we use terms defined in the [1], such as flow
sender, flow receiver, QUERY, RESERVE or RESPONSE.
5.1 Common Procedures
tx_reserve():
Transmit RESERVE message
tx_response():
Transmit RESPONSE message
tx_query():
Transmit QUERY message
tx_notify():
Transmit NOTIFY message
install_qos_state():
Install the local QoS state.
delete_qos_state():
Delete the local QoS state.
send_info_to_app():
Report information to the application.
RMF():
Performs Resource Management Function and returns the following
values{AVAIL, NO_AVAIL}.
is_local(RII):
Checks the RII object of received RESPONSE message if it is
requested by current node or other upstream node. Returns values
{true, false}.
is_local(RSN):
Checks The RSN object of the received RESPONSE message if it is
requested by current node. Returns values {true, false}.
process_query():
Processes a Query message and provides the requested info
5.2 Common Variables
RII:
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Request Identification Information (RII) object.
RSN:
Reservation Sequence Number (RSN) object.
INFO:
Info_Spec object. Takes values:
- 0x02 - Success values
- 0x04 - Transient Failure values
QSPEC:
QoS specification object.
T-Flag:
Tear flag. Indicates to tear down reservation state. Takes values
{true, false}.
Q-Flag:
Request Reduced Refreshes flag of common message header. Takes
values {true, false}.
R-Flag:
Reserve-Init flag (QUERY) or Replace flag (RESERVE). Indicates a
Receiver Initiated Reservation request in a QUERY message or an
replacing RESERVE in a RESERVE message. Takes values {true,
false}.
S-Flag:
Scoping flag of common message header. Takes values
{true="Next_hop", false="Whole_path"}.
setRII:
If set a RII object will be included into the message. Takes
values {true, false}.
ReducedRefresh:
Keeps information if Reduced refresh method may be used for
refreshing a installed QoS state. Takes value {"On","Off"}.
FlowID:
Flow ID kept by the installed QoS state.
Nodepos:
Position of the QoS NSLP node. Takes values {"QNI", "QNE", "QNR"}.
Toggle:
Flag to indicate whether the direction of a new message has to be
changed compared to the direction of a received one. Takes values
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{true, false}.
Direction:
Direction, in which the message has to be sent. Takes values
{DOWNSTREAM, UPSTREAM}.
SII:
Source Identification Information entry. Takes values:
- CurrSII - SII entry stored for current installed QoS state.
(Assumed to be the one for the direction where the message comes
from e.g.Upstream/Downstream)
- newSII - SII of the received message is different from the SII
stored for the current installed QoS state.
5.3 Events
EV_TG_QUERY:
External trigger to send a QUERY message.
EV_RX_QUERY:
QUERY message received
EV_RX_NOTIFY:
NOTIFY message received
EV_TG_RESERVE:
External trigger to send a RESERVE message.
EV_RX_RESERVE:
RESERVE message received
EV_RX_RESPONSE:
RESPONSE message received
EV_TIMEOUT_RESPONSE:
Wait-Response interval timer expiration
EV_TIMEOUT_REFRESH:
Refresh interval timer expiration
EV_TIMEOUT_STATE_LIFETIME:
State lifetime timer expiration
5.4 Assumptions
- For simplification not all included objects in a message are shown.
Only those that are significant for the case are shown. The State
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Machine does not present handling of messages that are not
significant for management of the states such as certain NOTIFY
and QUERY messages.
- The State Machine represents handling of messages of the same
Session ID and with no protocol errors. Separate parallel
instances of the state machines should handle messages for
different Session IDs.
- Default message handling should be defined for messages with
different Session IDs that have impact on current session state
and error messages. This is not included in the current version.
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6 Basic State Machine Concept
6.1 The QoS NSLP Daemon
The QoS NSLP Daemon (qosd) listens for incoming messages from the
local application and for messages coming over the network from GIST.
For each new SessionID (SID) a new State Machine (FSM) is created as
shown in the diagram below.
Incoming messages from the client application are checked for the
type of the message (QUERY or RESERVE) and for the SID. A table is
searched for the given SID. If it is not found, a new FSM is created
and its address together with the SID is added to the table. If the
type of the message is a QUERY with set R-Bit, a Receiver Initiated
Reservation is requested and the node position is QNR, in all other
cases the node position is QNI. If the SID is found, the address of
the FSM is returned. Now the FSM is triggered with the corresponding
event of the message (EV_TG_QUERY, EV_TG_RESERVE). If the FSM returns
to the qosd in ST_IDLE, it is deleted together with its table entry.
For a message arriving from GIST, the procedure is almost the same.
The table is searched for the given SID. If it is not found, then the
IP-address of the MRI is compared to the local IP-address. If the
arriving message is requesting a Receiver Initiated Reservation and
the destination address is equal to the local address then the node
position is QNR. If the addresses are equal and no Receiver Initiated
Reservation is requested then the node position is QNI. If the
addresses are not the same, a new FSM for a QNE is created. Also
here, the corresponding FSM is triggered with the event according to
the arrived message and deleted when returning in ST_IDLE.
+-------+ +-------+ +-------+
| | | | | |
| FSM 1 | | FSM 2 | | FSM n |
| | | | | |
+-------+ +-------+ +-------+
\ | /
\ | /
\ | /
\ | /
\ | /
+-------+
| |
| qosd |
| |
+-------+
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Figure 1
6.2 States, Events and Callback Functions
Three States are defined: ST_IDLE, ST_WR and ST_INST. A new created
FSM is starting automatically in ST_IDLE. In this state no
reservation state is installed no responses to previously sent
messages are expected. In ST_WR the FSM is waiting for a response to
a previously sent message, but no reservation state is installed. In
ST_INST reservation state has been installed and incoming messages
are processed.
The following table provides to a given state and a triggered event
the function which has to be executed by the FSM. Example: when
EV_RX_QUERY is triggered in state ST_IDLE, the function
idle__rx_query is executed.
+-----------+----------------------------+-------------------------------+
| State | Event | Executed Function |
+-----------+----------------------------+-------------------------------+
| ST_IDLE | EV_RX_QUERY | idle__rx_query |
| ST_IDLE | EV_RX_NOTIFY | idle__rx_notify |
| ST_IDLE | EV_RX_RESERVE | idle__rx_reserve |
| ST_IDLE | EV_RX_RESPONSE | idle__rx_response |
| ST_IDLE | EV_RX_RMF_MSG | idle__rx_rmf_msg |
+-----------+----------------------------+-------------------------------+
| ST_WR | EV_RX_QUERY | wr__rx_query |
| ST_WR | EV_RX_NOTIFY | wr__rx_notify |
| ST_WR | EV_RX_RESERVE | wr__rx_reserve |
| ST_WR | EV_RX_RESPONSE | wr__rx_response |
| ST_WR | EV_RX_RMF_MSG | wr__rx_rmf_msg |
| ST_WR | EV_TIMEOUT_WAITRESP | wr__timeout_response |
| ST_WR | EV_TIMEOUT_STATELIFETIME | wr__timeout_statelifetime |
+-----------+----------------------------+-------------------------------+
| ST_INST | EV_RX_QUERY | inst__rx_query |
| ST_INST | EV_RX_NOTIFY | inst__rx_notify |
| ST_INST | EV_RX_RESERVE | inst__rx_reserve |
| ST_INST | EV_RX_RESPONSE | inst__rx_response |
| ST_INST | EV_RX_RMF_MSG | inst__rx_rmf_msg |
| ST_INST | EV_TIMEOUT_WAITRESP | inst__timeout_response |
| ST_INST | EV_TIMEOUT_REFRESH | inst__timeout_refresh |
| ST_INST | EV_TIMEOUT_STATELIFETIME | inst__timeout_statelifetime |
| ST_INST | EV_SII_CHANGED | inst__sii_changed |
| ST_INST | EV_NETWORK_NOTIFICATION | inst__network_notification |
+-----------+----------------------------+-------------------------------+
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Figure 2
6.3 Timer
The Response Timer at QNI and QNE is started when a RESPONSE message
is expected to a sent QUERY or RESERVE. When a reservation is set up,
the Refresh Timer are started at QNI and QNE and the StateLife Timer
are started at QNE and QNR. When the Refresh Timer times out, a
refreshing RESERVE is sent peer to peer towards the QNR and the
Response Timer are started because a confirmation is expected. On
arrival the StateLife Timer is restarted.
If the confirmation is not sent back, then the refreshing RESERVEs
are resent up to MAX_RETRY. After MAX_RETRY has been reached,
reservation state is removed and a RESERVE with set T-Flag is sent to
the QNR to remove reservation state along the path. When no
refreshing RESERVE arrive at QNE and QNR, then the StateLife Timer
expires and reservation state is also removed and a RESERVE with set
T-Flag is sent towards the QNR.
+-----------------+-------------------+-------------------+
| QNI | QNE | QNR |
+-----------------+-------------------+-------------------+
| Refresh Timer | Refresh Timer | StateLife Timer |
| Response Timer | Response Timer | |
| | StateLife Timer | |
+-----------------+-------------------+-------------------+
Figure 3
6.4 The Toggle Flag
The Toggle Flag manipulates the direction of the message. When set,
the message is sent in the opposite direction compared to the
received one. The boolean operation XOR is used. Example, where true
is the toggle flag: DOWNSTREAM XOR true = UPSTREAM (0 XOR 1 = 1).
7. State machine
The following section presents the state machine diagrams of QoS
NSLP. Please note that stateless nodes do not perform transitions to
other states than ST_IDLE. A C-like pseudo code example for
update_rsn() and for send_rmf() is presented in Appendix A.4. The
send_rmf function is located in the RMF code and update_rsn() is part
of the FSM code.
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7.1 State ST_IDLE
(see the .pdf version for missing diagram or
refer to Appendix A.1 if reading the .txt version)
Figure 4
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(see the .pdf version for missing diagram or
refer to Appendix A.1 if reading the .txt version)
Figure 5
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7.2 State ST_WR
(see the .pdf version for missing diagram or
refer to Appendix A.2 if reading the .txt version)
Figure 6
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(see the .pdf version for missing diagram or
refer to Appendix A.2 if reading the .txt version)
Figure 7
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(see the .pdf version for missing diagram or
refer to Appendix A.2 if reading the .txt version)
Figure 8
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7.3 State ST_INST
(see the .pdf version for missing diagram or
refer to Appendix A.3 if reading the .txt version)
Figure 9
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(see the .pdf version for missing diagram or
refer to Appendix A.3 if reading the .txt version)
Figure 10
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(see the .pdf version for missing diagram or
refer to Appendix A.3 if reading the .txt version)
Figure 11
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(see the .pdf version for missing diagram or
refer to Appendix A.3 if reading the .txt version)
Figure 12
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8. Actions and Transitions
This chapter describes the operation of the FSM.
8.1 State ST_IDLE
8.1.1 idle__rx_query
This function is executed when a QUERY message has arrived over the
network from GIST and the FSM is in State ST_IDLE. If a receiver
initiated reservation has been requested and the node position is
QNI, Direction is set to upstream and the message is passed to the
RMF. Transition is made to ST_WR. In all other cases a resource
query has been received, the message is passed to the RMF and
transition is done to ST_WR.
8.1.2 idle__rx_notify
A NOTIFY message has been received. If the node position is not the
final destination for this message, it is passed further along the
path.
8.1.3 idle__rx_reserve
A RESERVE from the network in ST_IDLE has arrived. If the T-Flag is
set, then the message is passed to the RMF to tear down the
reservation. Transition is made to ST_IDLE.
In the other case where a reservation request has arrived, Direction
is set to UPSTREAM at QNR's. On statefull nodes the state timer is
started. In any case the message is passed to the RMF and transition
is made to ST_WR.
8.1.4 idle__rx_response
In ST_IDLE the node is not expecting a RESPONSE message. It is
forwarded further to the final destination. The state ST_IDLE is
kept.
8.1.5 idle__rx_rmf_msg
If the RMF is triggering a RESPONSE message and the containing
INFO_SPEC object indicates either a reservation failure or that the
teardown was successful the message is passed further and transition
is done to ST_IDLE.
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If a QUERY message has been triggered, it is checked whether the R-
Flag is set or an RII object is present. In this case the response
timer is started and transition is made to ST_WR. If a normal QUERY
containing no R-Flag and no RII object has been triggered, no
response timer is started and transition is made to ST_IDLE.
In case the RMF has triggered a RESERVE message at statefull
intermediate nodes the state timer is started. If it contains no RII
object, then no response is triggered and the refresh timer is
started immediately to frequently refresh the session. If an RII
object is included in the message the response timer is started
instead of the refresh timer. The message is sent further along the
path.
At the QNI no state timer is started as this is the node which takes
care of the refreshes. It does not receive any refreshes which would
restart the state timer. The message is sent further along the path.
The QNR is starting only the state timer. As this is the end node it
does not propagate the message any further. No responses are expected
and no refresh messages will be sent.
Transition is made to ST_INST.
8.2 State ST_WR
8.2.1 wr__rx_query
A QUERY message has arrived over the network from GIST and the FSM is
in State ST_WR. The message is entirely passed to the RMF using
sendrmf(). Transition is made to ST_WR.
8.2.2 wr__rx_notify
If the node is not the final destination of the NOTIFY message it is
sent further along the path and transition is made to ST_WR.
8.2.3 wr__rx_reserve
If a reserve message with set T-Flag has been received, the message
is passed to the RMF to tear down the reservation and to construct a
new tearing reserve message. If no confirmation of state removal has
been requested, i.e. no RII object is present, transition is done to
ST_IDLE. QNR's and stateless nodes also go directly to ST_IDLE.
If the RII object in the tearing reserve is present, statefull nodes
except QNR's start the state timer for one refresh period and pass
the message to the RMF to remove reservation state. Transition is
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done to ST_WR .
If the received message is requesting a reservation the state timer
is started. The message is passed to the RMF to install reservation
state and transition is made to ST_WR. If the node position is QNR
then this is the requested RESERVE message for the Receiver Initiated
Reservation. The Response Timer is stopped. The state ST_WR is kept.
8.2.4 wr__rx_response
In ST_WR a RESPONSE message has arrived. If the node is configured as
QNE_Egress the message is forwarded with the BYPASS_STATELESS_ID as
nslp_id that stateless nodes do not intercept this message. If an
Ingress node receives a response with the BYPASS_STATELESS_ID, the
nslp_id is translated to the QOS_NSLP_ID and the message is forwarded
up to the requesting node. Normal QNE's just forward the response
message. At this point no state transition is done. The relevant
checkings follow in the next paragraph.
If the received RII is from the local node the response timer is
stopped. If there are no more outstanding RII's, either from the
local node or from foreign nodes transition is done to ST_IDLE
otherwise ST_WR. If the received RII was from a foreign node the same
transitions are done depending on the outstanding RII's. For a stored
foreign RII no response timer was started and therefore no response
timer has to be stopped.
8.2.5 wr__rx_rmf_msg
See the section 8.1.5 where a RESERVE message has been triggered.
Transition is made to ST_INST.
8.2.6 wr__timeout_response
A Response Timer has timed out while in ST_WR. If the maximum number
of retries has been reached, transition is done to ST_IDLE, if no
more response timers are pending, otherwise transition is done to
ST_WR. If the maximum number of retransmissions has not been reached,
then the query message is resent. The response timer is restarted and
transition is made to ST_WR.
8.2.7 wr__timeout_statelifetime
If the state timer in ST_WR times out the confirmation message for
state removal has not been sent. In this case no retransmissions of
the message is done and transition is done to ST_IDLE after stopping
all timers.
Fu, et al. [Page 25]
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8.2.8 wr__rx_rmf_msg
In ST_WR any triggered message from the RMF is forwarded and the same
state is kept.
8.3 State ST_INST
8.3.1 inst__rx_query
See wr__rx_query. Transition is made to ST_INST.
8.3.2 inst__rx_notify
Reduced Refreshes are the default for refreshing RESERVEs. Notify
messages are checked whether the next peer accepts reduced refreshes
or not. The state ST_INST is kept.
8.3.3 inst__rx_reserve
All incoming RESERVEs are checked for their RSN value. if it is
smaller than the stored peer RSN the message is rejected. If the
value is the same to the stored one the reservation is refreshed.
Larger RSN value modify the reservation state.
A tearing reserve is passed to the RMF to remove the existing
reservation state. If no confirmation is requested, i.e. no RII
object is present, transition is done to ST_IDLE. If a confirmation
is requested, the state timer is started for one refresh interval and
transition is done to ST_WR.
If no T_Flag is set the message is passed to the RMF to install or
modify the reservation if the RSN value is larger than the stored
peer RSN. The state timer is restarted for equal and larger RSN
values. The state ST_INST is kept.
8.3.4 inst__rx_response
In ST_INST a RESPONSE message has arrived. If the node position is
QNE and no Scoping Flag is set, then the RESPONSE message is
forwarded. If the RII value matches, then the Response Timer is
stopped. If the received Error Code of the INFO object is SUCCESS,
then the Response Timer is started. Transition is done to ST_INST.
If the Error Code is FAILURE, then the reservation state is deleted
and pending timers are stopped. Transition is made to ST_IDLE.
8.3.5 inst__timeout_response
Fu, et al. [Page 26]
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A Response Timer has timed out while in ST_INST. If the maximum
number of retries has been reached, then all pending timer are
stopped and the RMF is informed to remove existing reservation state.
Transition is made to ST_IDLE. If maximum numbers of retransmissions
has not been reached, then previously sent message is resent. The
Response Timer is restarted and the state ST_INST is kept.
8.3.6 inst__timeout_refresh
A refreshing RESERVE message is created. If Reduced Refreshes are
accepted, no QSPEC object is added. The refresh timer is being
restarted. Transition is made to ST_INST.
8.3.7 inst__timeout_statelifetime
The Statelife Timer timed out in ST_INST. All active timer are
stopped and existing reservations are removed. The RMF is informed to
teardown reservation state and to trigger a teardown message.
Transition is done to ST_IDLE.
8.3.8 inst__sii_changed
A different SII-Handle indicates that a route change has occurred. A
full reserve including QSPEC is sent on the new path. The reservation
on the old path is torn down using the old SII-Handle. The state
ST_INST is kept.
8.3.9 inst__network_notification
A network notification from GIST is indicating that a route change
has occurred. A full RESERVE including QSPEC is sent on the new path.
The state ST_INST is kept.
8.3.10 inst__rx_rmf_msg
See idle__rx_rmf_msg for details.
9. Security Considerations
This document does not raise new security considerations. Any
security concerns with QoS NSLP are likely reflected in security
related NSIS work already (such as [1] or [6]).
For the time being, the state machine described in this document does
not consider the security aspect of QoS NSLP protocol itself.
Fu, et al. [Page 27]
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10. Open Issues
This document tries to describe possible states and transitions for
QoS NSLP according to its current specification [1], Section 5. We
found some issues during the development of the state machines.
1. Bi-directional reservation is difficult to support as the state
machine becomes quite complex (note at one particular point in
time the protocol state engine can be only in one state).
2. How to signal unsuccessful reservation for Receiver initiated
reservation (No RII included; a resulting Response(RSN) cannot be
forwarded further than the next peer). We use NOTIFY message.
3. The case of unsuccessful reservation at a QNE node and no RII
specified by upstream nodes. According to the spec RESPONSE(RSN)
should not be forwarded further than the next peer. Currently we
use NOTIFY(RSN) that is sent further to the upstream nodes.
4. We assume that handling of QoS state lifetime expiration event is
based on the local policy of the node. NOTIFY/Reserve(Ton)
messages might be sent to other peers.
5. The draft states that RESERVE message MUST be sent only towards
the QNR. This is not the case when re-routing procedure is done
and RESERVE(Ton) message should be sent from merging QNE node for
deleting the old branch. We believe this is towards the QNI.
6. Re-routing functionality described in this document is not
complete and need further consideration.
11. Change History
11.1 Changes in Version -01
1. Notation of the nodes changed to QNI, QNE and QNR.
2. Description of soft state refresh functionality.
3. Support of ACK flag in the common header.
4. Include of QoS NSLP objects, flags from the common header and
entries stored with the installed QoS state in a node: ACK,
Replace, RSN, Error_SPEC, QSPEC, FlowID, SII.
5. Initial description of Re-routing functionality.
6. For support of all listed changes, some notations are changed.
11.2 Changes in Version -02
1. Switch to .pdf format of the draft and include graphic diagrams.
2. Update notation from "Summary refresh" to "Reduced refresh"
3. Description of QoS reservation update/upgrade
11.3 Changes in Version -03
Fu, et al. [Page 28]
Internet-Draft QoS NSLP State Machine October 2007
1. Deep review of the state machine architecture
11.4 Changes in Version -04
1. Reduced the three state machines of QNI, QNE and QNR to one for
all nodes.
2. Introduced new flags to have a finer control of the direction of
the message to be sent.
11.5 Changes in Version -05
1. Combined ST_WR2 and ST_INST into ST_INST
2. Support for Q-Flag in common header
3. Explanations on the execution of the State Machine added
11.6 Changes in Version -06
1. Interaction with RMF added
2. Trigger from local application removed
12. Acknowledgments
The authors would like to thank Sven Van den Bosch and Christian
Dickmann for their feedback.
Fu, et al. [Page 29]
Internet-Draft QoS NSLP State Machine October 2007
13. References
13.1. Normative References
[1] Manner, J., Karagiannis, G. and McDonald, A., "NSLP for
Quality-of-Service Signaling", Internet draft, draft-
ietf-nsis-qos-nslp-15 (work in progress), July 2007.
[2] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
13.2. Informative References
[3] Vollbrecht, J., Eronen, P., Petroni, N., and Y. Ohba,
"State Machines for Extensible Authentication Protocol
(EAP) Peer and Authenticator", RFC 4137, August 2005.
[4] Institute of Electrical and Electronics Engineers, "DRAFT
Standard for Local and Metropolitan Area Networks: Port-
Based
Network Access Control (Revision)", IEEE 802-1X-REV/D11,
July 2004.
[5] Ohba, Y., "State Machines for Protocol for Carrying
Authentication for Network Access (PANA)",
draft-ohba-pana-statemachine-01 (work in progress),
February 2005.
[6] Tschofenig, H. and D. Kroeselberg, "Security Threats for
NSIS", RFC 4081, June 2005.
Fu, et al. [Page 30]
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Appendix A. ASCII versions of state diagrams
This appendix contains the state diagrams in ASCII format. Please use
the PDF version whenever possible: it is much easier to understand.
The notation is as follows: for each state there is a separate table
that lists in each row:
- an event that triggers a transition,
- actions taken as a result of the incoming event,
- and the new state at which the transitions ends.
A.1. State ST_IDLE
ST_IDLE::EV_RX_QUERY
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(!(R-Flag && QNI)) { | ST_WR |
| sendrmf(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(R-Flag && QNI) { | ST_WR |
| Direction=UPSTREAM; | |
| sendrmf(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 13
ST_IDLE::EV_RX_NOTIFY
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(!QNI) tx_notify(Toggle=false); | ST_IDLE |
| | |
+---------------------------------------------------------+-----------+
Figure 14
Fu, et al. [Page 31]
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ST_IDLE::EV_RX_RESERVE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(T-Flag) sendrmf(); | ST_IDLE |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(!T-Flag) { | ST_WR |
| if(QNR) { | |
| Direction=UPSTREAM; | |
| startStateTimer(); | |
| sendrmf(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 15
ST_IDLE::EV_RX_RESPONSE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(!QNI) tx_response(Toggle=false); | ST_IDLE |
| | |
+---------------------------------------------------------+-----------+
Figure 16
ST_IDLE::EV_RX_RMF_MSG
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(rx_response && !QNI) tx_response(Toggle=false); | ST_IDLE |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(rx_query && (R-Flag || RII)) { | ST_WR |
| startResponseTimer(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
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| if(rx_reserve && !T-Flag) | ST_INST |
| if(QNE || QNE_Ingress || QNE_Egress) { | |
| startStateTimer(); | |
| if(RII) startResponseTimer(); | |
| else startRefreshTimer(); | |
| tx_reserve(); | |
| } else if(QNI) { | |
| if(RII) startResponseTimer(); | |
| else startRefreshTimer(); | |
| tx_reserve(); | |
| } else if(QNR) { | |
| startStateTimer(); | |
| } | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 17
A.2. State ST_WR
ST_WR::EV_RX_QUERY
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| sendrmf(); | ST_WR |
| | |
+---------------------------------------------------------+-----------+
Figure 18
ST_WR::EV_RX_NOTIFY
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(!QNI) tx_notify(Toggle=false); | ST_WR |
| | |
+---------------------------------------------------------+-----------+
Figure 19
Fu, et al. [Page 33]
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ST_WR::EV_RX_RESERVE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(T-Flag && (!RII || QNR || STATELESS)) { | ST_IDLE |
| send_rmf(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(T-Flag && RII && (STATEFULL && !QNR)) { | ST_WR |
| startStateTimer(REFRESH_PERIOD); | |
| send_rmf(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(!T-Flag && QNR) { | ST_WR |
| if(QNR) stopResponseTimer(); | |
| startStateTimer(); | |
| sendrmf(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 20
ST_WR::EV_RX_RESPONSE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(QNE_Egress) { | |
| tx_response(Toggle=false, BYPASS_STATELESS_ID); | |
| } else if(QNE || | |
| (QNE_Ingress && nslp_id==BYPASS_STATELESS_ID)) { | |
| tx_response(Toggle=false, QOS_NSLP_ID); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(is_local(RII)==true && !outstanding_foreign_rii) { | ST_IDLE |
| stopResponseTimer(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Fu, et al. [Page 34]
Internet-Draft QoS NSLP State Machine October 2007
| | |
| if(is_local(RII)==true && outstanding_foreign_rii) { | ST_WR |
| stopResponseTimer(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(is_foreign(RII)==true && !outstanding_local_rii) | ST_IDLE |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(is_foreign(RII)==true && outstanding_local_rii) | ST_WR |
| | |
+---------------------------------------------------------+-----------+
Figure 21
ST_WR::EV_TIMEOUT_RESPONSE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(MAX_RETRY && !TIMER_PENDING) | ST_IDLE |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(MAX_RETRY && TIMER_PENDING) | ST_WR |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(!MAX_RETRY) { | ST_WR |
| tx_query(Direction); | |
| restartResponseTimer(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 22
ST_WR::EV_TIMEOUT_STATELIFETIME
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| stopTimers(); | ST_IDLE |
Fu, et al. [Page 35]
Internet-Draft QoS NSLP State Machine October 2007
| | |
+---------------------------------------------------------+-----------+
Figure 23
ST_WR::EV_RX_RMF_MSG
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(rx_reserve && !T-Flag) | ST_INST |
| if(QNE || QNE_Ingress || QNE_Egress) { | |
| startStateTimer(); | |
| if(RII) startResponseTimer(); | |
| else startRefreshTimer(); | |
| tx_reserve(); | |
| } else if(QNI) { | |
| if(RII) startResponseTimer(); | |
| else startRefreshTimer(); | |
| tx_reserve(); | |
| } else if(QNR) { | |
| startStateTimer(); | |
| } | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 24
A.3. State ST_INST
ST_INST::EV_RX_QUERY
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| sendrmf(); | ST_INST |
| | |
+---------------------------------------------------------+-----------+
Figure 25
ST_INST::EV_RX_NOTIFY
+---------------------------------------------------------+-----------+
Fu, et al. [Page 36]
Internet-Draft QoS NSLP State Machine October 2007
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(ErrorClass==ERRORCLASS_INFO) { | ST_INST |
| if(ErrorCode==RR_NOT_SUPPORTED) { | |
| ReducedRefreshes = false; | |
| } else if(ErrorCode==RR_SUPPORTED) { | |
| ReducedRefreshes = true; | |
| } | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 26
ST_INST::EV_RX_RESERVE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(T-Flag && !RII) { | ST_IDLE |
| if(rsn>peer_rsn) { | |
| update_rsn(); | |
| sendrmf(); | |
| } | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(T-Flag && RII) { | ST_WR |
| if(rsn>peer_rsn) { | |
| update_rsn(); | |
| sendrmf(); | |
| start_statetimer(REFRESH_RELOAD); | |
| } | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(!T-Flag) { | ST_INST |
| if(rsn>=peer_rsn) { | |
| if(rsn>peer_rsn) { | |
| update_rsn(); | |
| sendrmf(); | |
| } | |
| restart_statetimer(); | |
| } | |
Fu, et al. [Page 37]
Internet-Draft QoS NSLP State Machine October 2007
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 27
ST_INST::EV_RX_RESPONSE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(QNE_Egress) { | |
| tx_response(toggle=false, BYPASS_STATELESS_ID); | |
| } else if(QNE || | |
| (QNE_Ingress && nslp_id==BYPASS_STATELESS_ID)) { | |
| tx_response(toggle=false, QOS_NSLP_ID); | |
| } | |
| if(is_local_rii) stopResponseTimer(); | |
| startRefreshTimer(); | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(INFO==SUCCESS) | ST_INST |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(INFO==FAILURE) { | ST_IDLE |
| sendrmf(); | |
| stop_timers(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 28
ST_INST::EV_RX_RMF_MSG
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(rx_response && (fail || tear_successful)) { | ST_IDLE |
| tx_response(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Fu, et al. [Page 38]
Internet-Draft QoS NSLP State Machine October 2007
| | |
| if(rx_response && success) { | ST_INST |
| tx_response(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(rx_reserve && !T-Flag) | ST_INST |
| if(QNE || QNE_Ingress || QNE_Egress) { | |
| startStateTimer(); | |
| if(RII) startResponseTimer(); | |
| else startRefreshTimer(); | |
| tx_reserve(); | |
| } else if(QNI) { | |
| if(RII) startResponseTimer(); | |
| else startRefreshTimer(); | |
| tx_reserve(); | |
| } else if(QNR) { | |
| startStateTimer(); | |
| } | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 29
ST_INST::EV_TIMEOUT_RESPONSE
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(MAX_RETRY) { | ST_IDLE |
| sendrmf(); | |
| stopTimers(); | |
| } | |
| | |
+---------------------------------------------------------+-----------+
| | |
| if(!MAX_RETRY) { | ST_INST |
| tx_reserve(Direction); | |
| restartResponseTimer() | |
| } | |
| | |
+---------------------------------------------------------+-----------+
Figure 30
Fu, et al. [Page 39]
Internet-Draft QoS NSLP State Machine October 2007
ST_INST::EV_TIMEOUT_REFRESH
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| if(ReducedRefreshes) { | ST_INST |
| tx_reserve(RSN, Direction); | |
| } else { | |
| tx_reserve(RSN, QSPEC, Direction); | |
| } | |
| restartRefreshTimer(); | |
| | |
+---------------------------------------------------------+-----------+
Figure 31
ST_INST::EV_TIMEOUT_STATELIFETIME
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| stopTimers(); | ST_IDLE |
| sendrmf(); | |
| | |
+---------------------------------------------------------+-----------+
Figure 32
ST_INST::EV_SII_CHANGED
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| tx_reserve(RII, RSN, QSPEC, SII); | ST_INST |
| | |
+---------------------------------------------------------+-----------+
Figure 33
ST_INST::EV_NETWORK_NOTIFICATION
+---------------------------------------------------------+-----------+
| Action | new State |
+---------------------------------------------------------+-----------+
| | |
| tx_reserve(RII, RSN, QSPEC); | ST_INST |
Fu, et al. [Page 40]
Internet-Draft QoS NSLP State Machine October 2007
| | |
+---------------------------------------------------------+-----------+
Figure 34
A.4 Commonly used functions:
A.4.1 update_rsn()
1 void update_rsn() {
2 if((STATEFULL && !QNE_Egress) ||
3 (QNE_Egress && nslp_id==BYPASS_STATELESS_ID)) {
4 peer_rsn=rsn;
5 }
6 }
7
Figure 35
This function is used to update the rsn value only on statefull peers. At
the egress node the rsn is updated when a message arrives with the nslp_id
BYPASS_STATELESS_ID.
A.4.2 send_rmf()
1 void sendrmf() {
2
3 switch(message_type) {
4
5 case QOS_MESSAGETYPE_RESERVE:
6
7 switch(nodepos) {
8
9 case QNI:
10
11 if(T-Flag) {
12 free_qos();
13 recv_rmf(reserve, DO_NOT_TOGGLE);
14
15 } else {
16 qos_available = reserve_qos();
17 if(qos_available) recv_rmf(reserve, DO_NOT_TOGGLE);
18 else recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
Fu, et al. [Page 41]
Internet-Draft QoS NSLP State Machine October 2007
19 }
20 break;
21
22 case QNE:
23
24 if(T-Flag) {
25 free_qos();
26 if(!S-Flag) recv_rmf(reserve, new_rsn, DO_NOT_TOGGLE);
27 else if(rii) recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
28
29 } else {
30 qos_available = reserve_qos();
31 if(!qos_available) recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
32 else if(!S-Flag) recv_rmf(reserve, DO_NOT_TOGGLE);
33 else recv_rmf(response, INFOSPEC=SUCCESS, DO_TOGGLE);
34 if(rr_supported) recv_rmf(notify, DO_TOGGLE);
35 }
36 break;
37
38 case QNE_Ingress:
39
40 if(T-Flag) {
41 free_qos();
42 recv_rmf(reserve, BYPASS_STATELESS_ID, DO_NOT_TOGGLE);
43 recv_rmf(reserve, new_rsn, new_rii, DO_NOT_TOGGLE);
44 } else {
45 qos_available = reserve_qos();
46 if(!qos_available) recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
47 else {
48 recv_rmf(reserve, BYPASS_STATELESS_ID, DO_NOT_TOGGLE);
49 recv_rmf(reserve, DO_NOT_TOGGLE);
50 }
51 if(rr_supported) recv_rmf, notify(DO_TOGGLE);
52 }
53 break;
54
55 case QNE_Interior:
56
57 if(T-Flag) {
58 free_qos();
59 recv_rmf(reserve(new_rsn, DO_NOT_TOGGLE));
60
61 } else {
62 qos_available = reserve_qos();
63 if(!qos_available) recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
64 else recv_rmf(reserve, DO_NOT_TOGGLE);
65 }
66 break;
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67
68 case QNE_Egress:
69
70 if(T-Flag) {
71 free_qos();
72 if(nslp_id==QOS_NSLP_ID && rii)
73 recv_rmf(response(new_rsn, new_rii, DO_NOT_TOGGLE));
74 } else {
75 qos_available = reserve_qos();
76 if(!qos_available) recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
77 if (nslp_id==QOS_NSLP_ID) {
78 if(rii) recv_rmf(response, INFOSPEC=SUCCESS, QOS_NSLP_ID);
79 if(rr_supported) recv_rmf(notify, QOS_NSLP_ID);
80 } else if (nslp_id==BYPASS_STATELESS_NODE && rr_supported)
81 recv_rmf(notify, BYPASS_STATELESS_NODE);
82 }
83 break;
84
85 case QNR:
86
87 if(T-Flag) {
88 free_qos();
89 if(rii) recv_rmf(response(DO_TOGGLE));
90 } else {
91 qos_available = reserve_qos();
92 if(!qos_available) recv_rmf(response, INFOSPEC=FAIL, DO_TOGGLE);
93 if(rii) recv_rmf(response, INFOSPEC=SUCCESS, DO_TOGGLE);
94 if(rr_supported) recv_rmf(notify, INFOSPEC=RR_SUPPORTED, DO_TOGGLE);
95 }
96 break;
97
98 }
99 break;
100
101 case QOS_MESSAGETYPE_QUERY:
102
103 if (QNI && R-Flag) {
104 reserve_qos();
105 send_rmf(reserve, new_rii, new_rsn, new_qspec);
106
107 } else if (QNR && R-Flag) {
108
109 query_rmf();
110 send_rmf(query, R-Flag, PC, QSPEC, Direction=DOWNSTREAM);
111
112 } else {
113
114 query_rmf();
Fu, et al. [Page 43]
Internet-Draft QoS NSLP State Machine October 2007
115 if(QNR) send_rmf(response);
116 else send_rmf(query);
117
118 }
119 break;
120
121 case QOS_MESSAGETYPE_RESPONSE:
122
123 break;
124
125 case QOS_MESSAGETYPE_NOTIFY:
126
127 break;
128
129 }
130
131 }
132
Figure 36
Message Type Reserve
At the QNI if the message has set the T-Flag the reservation is torn
down and a new reserve message is triggered using the API-call
recv_rmf(). If no T-Flag was set in the reserve message, reservation
state is installed. If successful a new reserve message is triggered
to be sent further along the path.
At QNE's the (tearing) reserve is sent further if the scoping flag is
not set. Otherwise this node triggers a response if an RII object is
present. If a reservation request fails a response is triggered to
inform the initiator about the failure. If reduced refreshes are
supported a notify message is sent back to the previous peer.
Ingress nodes trigger two new (tearing) reserve message, one with the
old nslp_id and one with the BYPASS_STATELESS_ID to bypass stateless
nodes. No special treatment of the messages is done at interior
nodes.
The egress node triggers a response message, if a response was
requested by including an RII object and if the nslp_id of the
received message is QOS_NSLP_ID. If a requested reservation fails, a
response is sent back in any case. Notify message for reduced
refreshes are sent with the corresponding nslp_id.
Fu, et al. [Page 44]
Internet-Draft QoS NSLP State Machine October 2007
The QNR as the destination of the message echoes a response if the
reservation fails or if a response was requested by including an RII
object. Also here a notify message is sent back to the previous node,
if reduced refreshes are accepted.
Fu, et al. [Page 45]
Internet-Draft QoS NSLP State Machine October 2007
Message Type QUERY
If a QUERY message with set R-Flag arrives at the QNI, the RMF
triggers a new RESERVE message to be sent towards the QNR. Resource
query messages are sent further after updating the QSPEC. The QNR
triggers a response message containing the QSPEC.
Fu, et al. [Page 46]
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Authors' Addresses
Xiaoming Fu
University of Goettingen
Telematics Group
Lotzestrasse 16-18
Goettingen 37083
Germany
Email: fu@cs.uni-goettingen.de
Hannes Tschofenig
Nokia Siemens Networks
Otto-Hahn-Ring 6
Munich, Bayern 81739
Germany
Email: Hannes.Tschofenig@nsn.com
URI: http://www.tschofenig.com
Tseno Tsenov
Nokia Siemens Networks
Otto-Hahn-Ring 6
Munich, Bayern 81739
Germany
Email: tseno.tsenov@mytum.de
Bernd Schloer
University of Goettingen
Telematics Group
Lotzestrasse 16-18
Goettingen 37083
Germany
Email: bschloer@cs.uni-goettingen.de
Fu, et al. [Page 47]
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