< draft-suzuki-st2-over-atm-01.txt   draft-suzuki-st2-over-atm-02.txt >
Network Working Group Muneyoshi Suzuki Network Working Group Muneyoshi Suzuki
INTERNET DRAFT NTT INTERNET DRAFT NTT
Expires September 25, 1997 March 25, 1997 Expires April 14, 1998 October 14, 1997
ST2+ over ATM ST2+ over ATM
Protocol Specification - UNI 3.1 Version Protocol Specification - UNI 3.1 Version
<draft-suzuki-st2-over-atm-01.txt> <draft-suzuki-st2-over-atm-02.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
skipping to change at page 3, line 12 skipping to change at page 3, line 12
Note: The UNI 3.1 version of the ST2+ over ATM protocol does not Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
support the above feature. It will be supported by the UNI 3.1/4.0 support the above feature. It will be supported by the UNI 3.1/4.0
version. version.
1.3 Goals and Non-goals of ST2+ over ATM Protocol 1.3 Goals and Non-goals of ST2+ over ATM Protocol
The ST2+ over ATM protocol is designed to achieve the following The ST2+ over ATM protocol is designed to achieve the following
goals. goals.
o Specify protocol interaction between ST2+ [4] and ATM on the ATM o Specify protocol interaction between ST2+ [4] and ATM on the ATM
Forum Private UNI 3.1/4.0 (Sb point) [5]. Forum Private UNI 3.1/4.0 (Sb point) [10, 11].
Note: The UNI 3.1 version of the ST2+ over ATM protocol does not Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
support UNI 4.0. It will be supported by the UNI 3.1/4.0 version. support UNI 4.0. It will be supported by the UNI 3.1/4.0 version.
o Support ST2+ stream across ATM and non-ATM networks. o Support ST2+ stream across ATM and non-ATM networks.
o Define one VC on the UNI corresponding to one ST2+ hop; this VC is o Define one VC on the UNI corresponding to one ST2+ hop; this VC is
not shared with other ST2+ hops, and also this ST2+ hop is not not shared with other ST2+ hops, and also this ST2+ hop is not
divided into multiple VCs. divided into multiple VCs.
o Support both SVC and PVC. o Support both SVC and PVC.
o Not require any ATM specification changes. o Not require any ATM specification changes.
o Coexist with RFC 1483 [14] IPv4 encapsulation. o Coexist with RFC 1483 [16] IPv4 encapsulation.
o Coexist with RFC 1577 [15] ATMarp.
o Coexist with RFC 1755 [16] ATM signaling for IPv4. o Coexist with RFC 1577 [17] ATMarp.
o Coexist with NHRP [17]. o Coexist with RFC 1755 [18] ATM signaling for IPv4.
o Incorporate the I.371 [13] ITU-T new traffic control recommendation o Coexist with NHRP [19].
for ATM WAN connectivity.
Because ST2+ is independent of both routing and IP address resolution Because ST2+ is independent of both routing and IP address resolution
protocols, the ST2+ over ATM protocol does not specify the following protocols, the ST2+ over ATM protocol does not specify the following
protocols. protocols.
o IP-ATM address resolution protocol o IP-ATM address resolution protocol
o Routing protocol o Routing protocol
Because the ST2+ over ATM protocol is specified for the UNI, it is Because the ST2+ over ATM protocol is specified for the UNI, it is
skipping to change at page 4, line 4 skipping to change at page 3, line 47
protocols. protocols.
o IP-ATM address resolution protocol o IP-ATM address resolution protocol
o Routing protocol o Routing protocol
Because the ST2+ over ATM protocol is specified for the UNI, it is Because the ST2+ over ATM protocol is specified for the UNI, it is
independent of: independent of:
o NNI protocol o NNI protocol
o Router/switch architecture o Router/switch architecture
2. Protocol Architecture 2. Protocol Architecture
The ST2+ over ATM protocol specifies the interaction between ST2+ and The ST2+ over ATM protocol specifies the interaction between ST2+ and
ATM on the user, management, and control planes, which correspond to ATM on the user, management, and control planes, which correspond to
the three planes in ITU-T Recommendation I.321 B-ISDN Protocol the three planes in ITU-T Recommendation I.321 B-ISDN Protocol
Reference Model [10]. Reference Model [14].
2.1 User Plane Architecture 2.1 User Plane Architecture
The user plane specifies the rules for encapsulating the ST2+ Data The user plane specifies the rules for encapsulating the ST2+ Data
PDU into the AAL5 [12] or AAL1 [11] PDU. An user plane protocol stack PDU into the AAL5 [15] PDU. An user plane protocol stack is shown in
is shown in Fig. 2.1. Fig. 2.1.
+---------------------------------+ +---------------------------------+
| RFC 1819 ST2+ | | RFC 1819 ST2+ |
| (ST2+ Data) | | (ST2+ Data) |
+---------------------------------+ Point of ST2+ over ATM +---------------------------------+ Point of ST2+ over ATM
|/////////////////////////////////| <--- protocol specification of |/////////////////////////////////| <--- protocol specification of
+----------------+----------------+ user plane +---------------------------------+ user plane
| | | | |
| | | | |
| I.363.1 | I.363.5 | | I.363.5 |
| | | | |
| AAL1 | AAL5 | | AAL5 |
| | | | |
| | | | |
+----------------+----------------+ +---------------------------------+
| I.361 ATM | | I.361 ATM |
+---------------------------------+ +---------------------------------+
| PHY | | PHY |
+----------------+----------------+ +----------------+----------------+
| UNI | UNI
+--------||------- +--------||-------
Fig. 2.1: User plane protocol stack. Fig. 2.1: User plane protocol stack.
If AAL1 is used for encapsulating the ST2+ Data PDU, the 12 bytes ST
header is not mapped to the AAL1 PDU, and the value of the Pri field
in the ST2+ Data PDU header is lost.
An example of interworking from an ATM network to an IEEE 802.X LAN An example of interworking from an ATM network to an IEEE 802.X LAN
is shown in Fig. 2.2. is shown in Fig. 2.2.
ST2+ ST2+ ST2+ ST2+ ST2+ ST2+
Origin ATM Cloud Intermediate Agent Target Origin ATM Cloud Intermediate Agent Target
+---------+ +---------+ +---------+ +---------+
| AP |--------------------------------------------->| AP | | AP |--------------------------------------------->| AP |
+---------+ +-------------------+ +---------+ +---------+ +-------------------+ +---------+
|ST2+ Data|------------------>| RFC 1819 ST2+ Data|----->|ST2+ Data| |ST2+ Data|------------------>| RFC 1819 ST2+ Data|----->|ST2+ Data|
+---------+ +---------+---------+ +---------+ +---------+ +---------+---------+ +---------+
|I.363 AAL|------------------>|I.363 AAL| SNAP |----->| SNAP | |I.363 AAL|------------------>|I.363 AAL| SNAP |----->| SNAP |
+---------+ +---------+ +---------+---------+ +---------+ +---------+ +---------+ +---------+---------+ +---------+
|I.361 ATM|--->|I.361 ATM|--->|I.361 ATM| LLC |----->| LLC | |I.361 ATM|--->|I.361 ATM|--->|I.361 ATM| LLC |----->| LLC |
+---------+ +---------+ +---------+---------+ +---------+ +---------+ +---------+ +---------+---------+ +---------+
| PHY |--->| PHY |--->| PHY |IEEE802.X|----->|IEEE802.X| | | | | | |IEEE802.X| |IEEE802.X|
| PHY |--->| PHY |--->| PHY | & 802.1p|----->| & 802.1p|
+---------+ +---------+ +---------+---------+ +---------+ +---------+ +---------+ +---------+---------+ +---------+
Fig. 2.2: Example of interworking from Fig. 2.2: Example of interworking from
an ATM network to an IEEE 802.X LAN. an ATM network to an IEEE 802.X LAN.
The ATM cell supports priority indication using the CLP field; The ATM cell supports priority indication using the CLP field;
indication is also supported by the ST2+ Data PDU by using the Pri indication is also supported by the ST2+ Data PDU by using the Pri
field. It may be feasible to map these fields to each other. The field. It may be feasible to map these fields to each other. The
ST2+ over ATM protocol specifies an optional function that maps the ST2+ over ATM protocol specifies an optional function that maps the
Pri field in the ST header to the CLP field in the ATM cell. Pri field in the ST header to the CLP field in the ATM cell.
However, implementors should note that current ATM standardization However, implementors should note that current ATM standardization
tends not to support tagging, and also that this optional function tends not to support tagging.
assumes the value of the Pri field can be obtained in the ATM
network.
2.2 Management Plane Architecture 2.2 Management Plane Architecture
The management plane specifies, or refers to a document that The management plane specifies the Null FlowSpec, the Controlled-Load
specifies, the Controlled-Load Service [6] FlowSpec and the Service [5] FlowSpec, and the Guaranteed Service [6] FlowSpec mapping
Guaranteed Service [7] FlowSpec mapping rules for UNI 3.1 traffic rules [8] for UNI 3.1 traffic management. A management plane
management. A management plane protocol stack is shown in Fig. 2.3. protocol stack is shown in Fig. 2.3.
+---------------------------------+ +---------------------------------+
| Null FlowSpec |
|Controlled-Load Service FlowSpec | |Controlled-Load Service FlowSpec |
| Guaranteed Service FlowSpec | | Guaranteed Service FlowSpec |
+---------------------------------+ Point of ST2+ over ATM +---------------------------------+ Point of ST2+ over ATM
|/////////////////////////////////| <--- protocol specification of |/////////////////////////////////| <--- protocol specification of
+---------------------------------+ management plane +---------------------------------+ management plane
| | | |
| UNI 3.1/4.0 | | UNI 3.1 |
| | | |
| | | |
| Traffic Management | | Traffic Management |
| | | |
| | | |
| CBR/VBR/UBR | | VBR/UBR |
| | | |
+---------------------------------+ +---------------------------------+
Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
support UNI 4.0. It will be supported by the UNI 3.1/4.0 version. Fig. 2.3: Management plane protocol stack.
Note: The UNI 3.1 version of the ST2+ over ATM protocol does not Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
support Guaranteed Services. It will be supported by the UNI 3.1/4.0 support Guaranteed Services. It will be supported by the UNI 3.1/4.0
version. version.
Fig. 2.3: Management plane protocol stack.
The ST2+ over ATM protocol specifies the ST FlowSpec format for the The ST2+ over ATM protocol specifies the ST FlowSpec format for the
Integrated Services. Basically, FlowSpec parameter negotiation, Integrated Services. Basically, FlowSpec parameter negotiation,
except for the MTU, is not supported. This is because, in the ST2+ except for the MTU, is not supported. This is because, in the ST2+
environment, negotiated FlowSpec parameters are not always unique to environment, negotiated FlowSpec parameters are not always unique to
each target. The current ATM standard does not support heterogeneous each target. The current ATM standard does not support heterogeneous
QoS to receivers. QoS to receivers.
The ST2+ over ATM protocol supports FlowSpec changes by using the The ST2+ over ATM protocol supports FlowSpec changes by using the
CHANGE message (RFC 1819, Section 4.6.5) if the I-bit in the CHANGE CHANGE message (RFC 1819, Section 4.6.5) if the I-bit in the CHANGE
message is set to one and if the CHANGE message affects all targets message is set to one and if the CHANGE message affects all targets
in the stream. This is because the current ATM standard does not in the stream. This is because the UNI 3.1 does not support QoS
support QoS changes. The ST2+ over ATM protocol supports FlowSpec changes. The ST2+ over ATM protocol supports FlowSpec changes by
changes by releasing old ATM connections and establishing new ones. releasing old ATM connections and establishing new ones.
The ST2+ over ATM protocol does not support stream preemption (RFC The ST2+ over ATM protocol does not support stream preemption (RFC
1819, Section 6.3). This is because the Integrated Services FlowSpec 1819, Section 6.3). This is because the Integrated Services FlowSpec
does not support the concept of precedence. does not support the concept of precedence.
It does not support the ST2+ FlowSpec (RFC 1819, Section 9.2). ST2+ It does not support the ST2+ FlowSpec (RFC 1819, Section 9.2). ST2+
FlowSpec specifies useful services, but requires a data link layer to FlowSpec specifies useful services, but requires a datalink layer to
support heterogeneous QoS to receivers. The current ATM standard support heterogeneous QoS to receivers. The current ATM standard
does not support heterogeneous QoS to receivers. does not support heterogeneous QoS to receivers.
2.3 Control Plane Architecture 2.3 Control Plane Architecture
The control plane specifies the relationship between ST2+ SCMP and The control plane specifies the relationship between ST2+ SCMP and
PVC management for ST2+ data and the protocol interaction between PVC management for ST2+ data and the protocol interaction between
ST2+ SCMP and Q.2931 UNI signaling [5, 9]. A control plane protocol ST2+ SCMP and UNI 3.1 signaling [10]. A control plane protocol stack
stack is shown in Fig. 2.4. is shown in Fig. 2.4.
+---------------------------------+ +---------------------------------+
| RFC 1819 ST2+ | | RFC 1819 ST2+ |
| (ST2+ SCMP) | | (ST2+ SCMP) |
+---------------------------------+ Point of ST2+ over ATM +---------------------------------+ Point of ST2+ over ATM
|/////////////////////////////////| <--- protocol specification of |/////////////////////////////////| <--- protocol specification of
+----------------+----------------+ control plane +----------------+----------------+ control plane
| IEEE 802 |Q.2931 Signaling| | IEEE 802 |UNI3.1 Signaling|
| SNAP +----------------+ | SNAP +----------------+
+----------------+ Q.2130 SSCF | +----------------+ Q.2130 SSCF |
| ISO 8802-2 +----------------+ | ISO 8802-2 +----------------+
| LLC Type1 | Q.2110 SSCOP | | LLC Type1 | Q.2110 SSCOP |
+----------------+----------------+ +----------------+----------------+
| I.363.5 AAL5 | | I.363.5 AAL5 |
+---------------------------------+ +---------------------------------+
| I.361 ATM | | I.361 ATM |
+---------------------------------+ +---------------------------------+
| PHY | | PHY |
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VCs for ST2+ SCMP transfer. Selection of these VCs depends on the VCs for ST2+ SCMP transfer. Selection of these VCs depends on the
implementation. implementation.
Implementors should note that when ST2+ data and SCMP belong to a Implementors should note that when ST2+ data and SCMP belong to a
stream, the routing directions on the ST2+ layer must be the same. stream, the routing directions on the ST2+ layer must be the same.
Implementors should also note that ST2+ and IPv4 directions for Implementors should also note that ST2+ and IPv4 directions for
routing to the same IP destination address are not always the same. routing to the same IP destination address are not always the same.
The ST2+ over ATM protocol supports both SVC and PVC for ST2+ Data The ST2+ over ATM protocol supports both SVC and PVC for ST2+ Data
PDU transfer. If SVC is used, the ST2+ and ATM layers establish a PDU transfer. If SVC is used, the ST2+ and ATM layers establish a
connection sequentially by using respectively ST2+ SCMP and Q.2931. connection sequentially by using respectively ST2+ SCMP and UNI 3.1
An example of ST2+ SCMP and Q.2931 message flows for establishing and signaling. An example of ST2+ SCMP and UNI 3.1 signaling message
releasing of ST2+ data connections is shown in Fig. 2.5, where (S) flows for establishing and releasing of ST2+ data connections is
means an ST2+ entity and (Q) means a Q.2931 entity. shown in Fig. 2.5, where (S) means an ST2+ entity and (Q) means a UNI
3.1 signaling entity.
ATM SW ATM SW ATM SW ATM SW
+------------+ UNI +----+ NNI +----+ UNI +------------+ +------------+ UNI +----+ NNI +----+ UNI +------------+
____|Intermediate|--||--| \/ |______| \/ |--||--|Intermediate|____ ____|Intermediate|--||--| \/ |______| \/ |--||--|Intermediate|____
| (Upstream) | | /\ | | /\ | |(Downstream)| | (Upstream) | | /\ | | /\ | |(Downstream)|
+------------+ +----+ +----+ +------------+ +------------+ +----+ +----+ +------------+
SCMP SCMP
------->(S)<------------------------------------------>(S)<------- ------->(S)<------------------------------------------>(S)<-------
\ Q.2931 Q.2931 / \ UNI Sig. UNI Sig. /
CONNECT | (Q)<--------->(Q)<-------->(Q)<--------->(Q) | CONNECT | (Q)<--------->(Q)<-------->(Q)<--------->(Q) |
-------->| | -------->| |
ACK <----|--------------------CONNECT------------------>| CONNECT ACK <----|--------------------CONNECT------------------>| CONNECT
|<---------------------ACK---------------------|--------> |<---------------------ACK---------------------|-------->
| |<--- ACK | |<--- ACK
| | ACCEPT | | ACCEPT
| |<-------- | |<--------
|<-------------------ACCEPT--------------------|---> ACK |<-------------------ACCEPT--------------------|---> ACK
|----------------------ACK-------------------->| |----------------------ACK-------------------->|
| | | |
skipping to change at page 8, line 44 skipping to change at page 8, line 45
DISCONN | | DISCONN | |
-------->| | -------->| |
ACK <----|-------------------DISCONNECT---------------->| ACK <----|-------------------DISCONNECT---------------->|
|<---------------------ACK---------------------| |<---------------------ACK---------------------|
| | | |
|->|---RELEASE-->| | | | |->|---RELEASE-->| | | |
|<-|<--REL COMP--|----------->|---RELEASE-->|->| DISCONN |<-|<--REL COMP--|----------->|---RELEASE-->|->| DISCONN
| | | |<--REL COMP--|<-|--------> | | | |<--REL COMP--|<-|-------->
| |<--- ACK | |<--- ACK
Fig. 2.5: Example of ST2+ SCMP and Q.2931 message flows. Fig. 2.5: Example of ST2+ SCMP and UNI 3.1 signaling message flows.
UNI 3.1/4.0 specifies PVC, point-to-point SVC, and point-to- UNI 3.1/4.0 specifies PVC, point-to-point SVC, and point-to-
multipoint SVC as VC styles. However, in actual ATM network multipoint SVC as VC styles. However, in actual ATM network
environments, especially public ATM WANs, only PVC and bi-directional environments, especially public ATM WANs, only PVC and bi-directional
point-to-point SVC may be supported. To support the diverse VC point-to-point SVC may be supported. To support the diverse VC
styles, the ST2+ over ATM protocol supports the following VC styles styles, the ST2+ over ATM protocol supports the following VC styles
for ST2+ Data PDU transfer. for ST2+ Data PDU transfer.
o PVC o PVC
skipping to change at page 10, line 22 skipping to change at page 10, line 22
| +-+-+ V | +-+-+ V
| | X | ATM SW | | X | ATM SW
| +-+-+ A | +-+-+ A
SCMP | | | NNI Signaling SCMP | | | NNI Signaling
| +-+-+ V | +-+-+ V
| | X | ATM SW | | X | ATM SW
| +-+-+ A | +-+-+ A
| | | | | |
| = | UNI Signaling | = | UNI Signaling
V | V V | V
+-----+------+ Non-ATM Link +-----+------+ IEEE 802.X & 802.1p
|Intermediate|--------------------+ | |<---------------------+
| Agent |<-----------------+ | |Intermediate|--------------------+ |
+------------+ SCMP | | | |<-----------------+ | |
A | A | | +------------+ L2 Signaling| | |
| = | UNI Signaling | | A | A | | |
| | | | | | = | UNI Signaling | | | SCMP
| +-+-+ V V_|__ | | | | | |
| | X | ATM SW / \ | +-+-+ V | | |
| +-+-+ A (Target ) | | X | ATM SW V | |
SCMP | | | NNI Signaling \ / | +-+-+ A +---+-|-+
| +-+-+ V ~~~~~ SCMP | | | NNI Signaling | \ /| |
| | X | ATM SW | +-+-+ V | X | |LAN SW
| +-+-+ A | | X | ATM SW | / \| |
| | | | +-+-+ A +---+-|-+
| = | UNI Signaling | | | A | |
V __|__ V | = | UNI Signaling | | |
/ \ V __|__ V V_|_V
(Target ) / \ / \
\ / (Target ) (Target )
~~~~~ \ / \ /
~~~~~ ~~~~~
Fig. 2.6: Example of ST2+ SCMP interworking. Fig. 2.6: Example of ST2+ SCMP interworking.
3. Revision of RFC 1819 ST2+ 3. Revision of RFC 1819 ST2+
To specify the ST2+ over ATM protocol, the functions in RFC 1819 ST2+ To specify the ST2+ over ATM protocol, the functions in RFC 1819 ST2+
must be extended to support ATM. However, it is difficult for the must be extended to support ATM. However, it is difficult for the
current ATM standard to support part of the specifications in RFC current ATM standard to support part of the specifications in RFC
1819 ST2+. This section specifies the extended, restricted, and 1819 ST2+. This section specifies the extended, restricted,
unsupported functions in RFC 1819 ST2+. Errata for RFC 1819 appears unsupported, and modified functions in RFC 1819 ST2+. Errata for RFC
in Appendix A. 1819 appears in Appendix A.
3.1 Extended Functions of RFC 1819 ST2+ 3.1 Extended Functions of RFC 1819 ST2+
3.1.1 ST FlowSpec for Controlled-Load Service 3.1.1 ST FlowSpec for Controlled-Load Service
The ST2+ over ATM protocol specifies the ST FlowSpec format for the The ST2+ over ATM protocol specifies the ST FlowSpec format for the
Integrated Services. Basically, FlowSpec parameter negotiation, Integrated Services. Basically, FlowSpec parameter negotiation,
except for the MTU, is not supported. The ST2+ intermediate agent except for the MTU, is not supported. The ST2+ intermediate agent
and the target decide whether to accept or refuse the FlowSpec and the target decide whether to accept or refuse the FlowSpec
parameters, except for the MTU. Therefore, each of the FlowSpec parameters, except for the MTU. Therefore, each of the FlowSpec
skipping to change at page 12, line 23 skipping to change at page 12, line 23
The Ver (Message Format Version) field identifies the Integrated The Ver (Message Format Version) field identifies the Integrated
Services FlowSpec message format version. The current version is Services FlowSpec message format version. The current version is
zero. zero.
The Overall Length field for the Controlled-Load Service is 7 The Overall Length field for the Controlled-Load Service is 7
words. words.
The SVC Number (Service ID Number) field identifies the Integrated The SVC Number (Service ID Number) field identifies the Integrated
Services. If the Integrated Services FlowSpec appears in the Services. If the Integrated Services FlowSpec appears in the
CONNECT or the CHANGE message, the value of the SVC Number field is CONNECT or CHANGE message, the value of the SVC Number field is 1.
1. If it appears in the ACCEPT, the NOTIFY, or the STATUS-RESPONSE If it appears in the ACCEPT, NOTIFY, or STATUS-RESPONSE message,
message, the value of the SVC Number field is 5. the value of the SVC Number field is 5.
The SVC Length (Service-specific Data Length) field for the The SVC Length (Service-specific Data Length) field for the
Controlled-Load Service is 6 words. Controlled-Load Service is 6 words.
The Param Num (Parameter Number) field is 127. The Param Num (Parameter Number) field is 127.
The Flags (Per-parameter Flags) field is zero. The Flags (Per-parameter Flags) field is zero.
The Param Length (Length of Per-parameter Data) field is 5 words. The Param Length (Length of Per-parameter Data) field is 5 words.
Definitions of the Token Bucket Rate [r], the Token Bucket Size Definitions of the Token Bucket Rate [r], the Token Bucket Size
[b], the Peak Data Rate [p], the Minimum Policed Unit [m], and the [b], the Peak Data Rate [p], the Minimum Policed Unit [m], and the
Maximum Packet Size [M] fields are given in [6]. See section 5 of Maximum Packet Size [M] fields are given in [5]. See section 5 of
[6] for details. [5] for details.
The ST2+ agent, that creates the FlowSpec element in the SCMP The ST2+ agent, that creates the FlowSpec element in the SCMP
message, must assign valid values to all fields. The other agents message, must assign valid values to all fields. The other agents
must not modify any values in the element. must not modify any values in the element.
The MaxMsgSize field in the CONNECT message is assigned by the origin The MaxMsgSize field in the CONNECT message is assigned by the origin
or the intermediate agent acting as origin, and updated by each agent or the intermediate agent acting as origin, and updated by each agent
based on the MTU value of the datalink layer. based on the MTU value of the datalink layer.
The negotiated value of MaxMsgSize is set back to the origin or the The negotiated value of MaxMsgSize is set back to the origin or the
skipping to change at page 13, line 34 skipping to change at page 13, line 34
3.1.2 ST FlowSpec for Guaranteed Service 3.1.2 ST FlowSpec for Guaranteed Service
Note: The UNI 3.1 version of the ST2+ over ATM protocol does not Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
support Guaranteed Services. It will be supported by the UNI 3.1/4.0 support Guaranteed Services. It will be supported by the UNI 3.1/4.0
version. version.
3.1.3 VC-type common SCMP element 3.1.3 VC-type common SCMP element
The ST2+ over ATM protocol specifies an additional common SCMP The ST2+ over ATM protocol specifies an additional common SCMP
element that designates the VC type used to support the diverse VC element that designates the VC type used to support the diverse VC
styles. The CONNECT and CHANGE messages that pass across UNIs must styles. The CONNECT and CHANGE messages that establish a hop with a
contain a VC-type common SCMP element. This element is valid between VC must contain a VC-type common SCMP element. This element is valid
neighboring ST2+ agents, but must not propagate beyond the previous- between neighboring ST2+ agents, but must not propagate beyond the
hop or next-hop ST2+ agent. previous-hop or next-hop ST2+ agent.
The format of the VC-type common SCMP element is shown in Fig. 3.2. The format of the VC-type common SCMP element is shown in Fig. 3.2.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCode = 8 | PBytes = 20 | VCType | | PCode = 8 | PBytes = 20 | VCType |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PVCIdentifer | | PVCIdentifer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 15, line 23 skipping to change at page 15, line 23
3.1.4 Reason Code 3.1.4 Reason Code
The extension of the Reason Code (RFC 1819, Section 10.5.3) to the The extension of the Reason Code (RFC 1819, Section 10.5.3) to the
ST2+ over ATM protocol is shown below. ST2+ over ATM protocol is shown below.
57 CantChange Partial changes not supported. 57 CantChange Partial changes not supported.
58 NoRecover Stream recovery not supported. 58 NoRecover Stream recovery not supported.
3.2 Restricted Functions of RFC 1819 ST2+ 3.2 Restricted Functions of RFC 1819 ST2+
3.2.1 Pri field in ST2+ Data PDU 3.2.1 FlowSpec changes
If AAL1 is used for encapsulating the ST2+ Data PDU, the value of the
Pri field in the ST2+ Data PDU header is lost.
3.2.2 FlowSpec changes
In the following cases, the ST2+ over ATM protocol supports stream In the following case, the ST2+ over ATM protocol supports stream
FlowSpec changes by using the CHANGE message. FlowSpec changes by using the CHANGE message.
o The I-bit is set to 1 and the G-bit is set to 1. o The I-bit is set to 1 and the G-bit is set to 1.
o The I-bit is set to 1, the G-bit is set to zero, and the TargetList In the following case, the CHANGE fails and a REFUSE message, with
matches all downstream targets.
In the following cases, the CHANGE fails and a REFUSE message, with
the E and N-bits set to 1 and the ReasonCode set to CantChange, is the E and N-bits set to 1 and the ReasonCode set to CantChange, is
propagated upstream. propagated upstream.
o The I-bit is set to zero. o The I and/or G-bits are set to zero.
o The I-bit is set to 1, the G-bit is set to zero, and the TargetList
does not match all downstream targets.
3.3 Unsupported Functions of RFC 1819 ST2+ 3.3 Unsupported Functions of RFC 1819 ST2+
3.3.1 ST2+ FlowSpec 3.3.1 ST2+ FlowSpec
The ST2+ over ATM protocol does not support the ST2+ FlowSpec (RFC The ST2+ over ATM protocol does not support the ST2+ FlowSpec (RFC
1819, Section 9.2). The ST2+ FlowSpec specifies useful services, but 1819, Section 9.2). The ST2+ FlowSpec specifies useful services, but
requires the data link layer to support heterogeneous QoS to requires the datalink layer to support heterogeneous QoS to
receivers. The current ATM standard does not support heterogeneous receivers. The current ATM standard does not support heterogeneous
QoS to receivers. QoS to receivers.
3.3.2 Stream preemption 3.3.2 Stream preemption
The ST2+ over ATM protocol does not support stream preemption (RFC The ST2+ over ATM protocol does not support stream preemption (RFC
1819, Section 6.3). This is because the Integrated Services FlowSpec 1819, Section 6.3). This is because the Integrated Services FlowSpec
does not support the concept of precedence. does not support the concept of precedence.
3.3.3 HELLO message 3.3.3 HELLO message
skipping to change at page 16, line 45 skipping to change at page 16, line 29
5.3.2, 6.2, and 6.2.1) are unclear and incomplete. It is thus 5.3.2, 6.2, and 6.2.1) are unclear and incomplete. It is thus
possible that if a link failure occurs and several ST2+ agents detect possible that if a link failure occurs and several ST2+ agents detect
it simultaneously, the recovery process may encounter problems. it simultaneously, the recovery process may encounter problems.
The ST2+ over ATM protocol does not support stream recovery. If The ST2+ over ATM protocol does not support stream recovery. If
recovery is needed, the application should support it. A CONNECT recovery is needed, the application should support it. A CONNECT
message in which the NoRecover option is not selected will fail; a message in which the NoRecover option is not selected will fail; a
REFUSE message in which the N-bit is set to 1 and the ReaseonCode is REFUSE message in which the N-bit is set to 1 and the ReaseonCode is
set to NoRecover is then propagated upstream. set to NoRecover is then propagated upstream.
3.3.5 IP encapsulation of ST 3.3.5 Subnet Resources Sharing
The ST2+ over ATM protocol does not support subnet resources sharing
(RFC 1819, Section 7.1.4). This is because ATM does not support the
concept of the MAC layer.
3.3.6 IP encapsulation of ST
The ST2+ over ATM protocol does not support IP encapsulation of ST The ST2+ over ATM protocol does not support IP encapsulation of ST
(RFC 1819, Section 8.7), because there is no need to implement IP (RFC 1819, Section 8.7), because there is no need to implement IP
encapsulation in this protocol. encapsulation in this protocol.
3.3.6 IP Multicasting 3.3.7 IP Multicasting
The ST2+ over ATM protocol does not support IP multicasting (RFC The ST2+ over ATM protocol does not support IP multicasting (RFC
1819, Section 8.8), because this protocol does not support IP 1819, Section 8.8), because this protocol does not support IP
encapsulation of ST. encapsulation of ST.
3.4 Modified Functions of RFC 1819 ST2+
The ST2+ receiver-oriented stream creation procedure has some fatal
problems: the value of the LnkReferecnce field in the CONNECT message
that is a response to a JOIN message is not valid, ST2+ agent cannot
update the LnkReference field in the JOIN-REJECT message, and ST2+
agent cannot deliver the JOIN-REJECT message to the target because
the JOIN-REJECT message does not contain a TargetList field. To
solve these problems, the ST2+ over ATM protocol modifies the ST2+
protocol processing rules.
3.4.1 Modifications of Message Processing Rules
Modifications of the CONNECT, JOIN, and JOIN-REJECT message
processing rules in the ST2+ over ATM protocol are described in the
following.
o The target that creates a JOIN message assigns the same value as in
the Reference field to the LnkReference field.
o The agent that creates a CONNECT message as a response to a JOIN
message assigns the same value as in the LnkReference field in the
JOIN message to the LnkReference field. In other cases, the value
of the LnkReference field in a CONNECT message is zero.
o The agent that creates a JOIN-REJECT message assigns the same value
as in the LnkReference field in the JOIN message to the
LnkReference field.
o An intermediate agent must not modify the value of the LnkReference
field in the CONNECT, JOIN, or JOIN-REJECT message. Note that this
rule differs from the LnkReference field processing rule in the
ACCEPT and REFUSE messages.
3.4.2 Modified JOIN-REJECT Control Message
The modified JOIN-REJECT control message in the ST2+ over ATM
protocol is shown in Fig. 3.3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OpCode = 9 | 0 | TotalBytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reference | LnkReference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SenderIPAddress |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | ReasonCode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GeneratorIPAddress |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: TargetList :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fig. 3.3: JOIN-REJECT Control Message.
The TargetList is assigned the same TargetList in the JOIN message as
the one that corresponds to the JOIN-REJECT message.
4. Protocol Specification of the User Plane 4. Protocol Specification of the User Plane
This section specifies the AAL5 [12] and AAL1 [11] PDU This section specifies the AAL5 PDU encapusulation for the ST2+ Data
encapusulations for the ST2+ Data PDU. On the ST2+ over ATM user PDU.
plane, AAL5 support is mandatory and AAL1 support is optional.
4.1 Service Primitives Provided by User Plane 4.1 Service Primitives Provided by User Plane
4.1.1 Overview of interactions 4.1.1 Overview of interactions
The ST2+ data layer entity on the user plane of the ST2+ over ATM The ST2+ data layer entity on the user plane of the ST2+ over ATM
protocol provides the following services to the upper layer. protocol provides the following services to the upper layer.
o st2p_unitdata.req o st2p_unitdata.req
skipping to change at page 20, line 39 skipping to change at page 23, line 5
ST2+ Data PDU. That is, the payload in AAL5 CPCS_PDU is mapped to ST2+ Data PDU. That is, the payload in AAL5 CPCS_PDU is mapped to
the ST2+ Data PDU. the ST2+ Data PDU.
If the value of STATUS in AAL5_UNITDATA.ind is valid, it is assigned If the value of STATUS in AAL5_UNITDATA.ind is valid, it is assigned
to the status in st2p_unitdata.ind. to the status in st2p_unitdata.ind.
4.3.3 Value of MTU 4.3.3 Value of MTU
The value of MTU is Maximum CPCS_SDU size. The value of MTU is Maximum CPCS_SDU size.
4.4 Service Primitives Provided by AAL1 5. Protocol Specification of the Management Plane
4.4.1 Requirements for AAL1
The requirements for the AAL1 layer on the ST2+ over ATM user plane
are as follows:
o The CS must support the synchronous circuit transport function
described in ITU-T Recommendation I.231. The others CS functions
need not be supported.
o Structured data transfer and forward error correction need not be
supported.
o The CBR rate is N * 64 Kbit/s, where N is between 1 and 65,535.
Note: It is recommended to support 1, 2, 3, 4, 5, 6, 8, 9, 10, 12,
15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180, and 360 as
values of N.
4.4.2 Overview of interactions
The AAL1 layer entity on the ST2+ over ATM user plane provides the
following services to the ST2+ data layer.
o AAL1_UNITDATA.req
o AAL1_UNITDATA.ind
4.4.2.1 AAL1_UNITDATA.req
The AAL1_UNITDATA.req primitive sends a request for an AAL1 data
transfer from the ST2+ data layer entity to the AAL1 layer entity.
The semantics of the primitive are as follows:
AAL1_UNITDATA.req (
DATA,
CLP
)
The DATA parameter specifies the AAL1 data to be transferred. The
CLP parameter specifies the value of the CLP field in the ATM cell.
4.4.2.2 AAL1_UNITDATA.ind
The AAL1_UNITDATA.ind indicates an AAL1 Data delivery from the AAL1
layer entity to the ST2+ data layer entity. The semantics of the
primitive are as follows:
AAL1_UNITDATA.ind (
DATA,
CLP,
STATUS [optional]
)
The DATA parameter indicates the delivered AAL1 data. The CLP
parameter indicates the value of the CLP field in the ATM cell. The
STATUS parameter is an optional parameter that indicates whether the
delivered AAL1 data is corrupt or not.
4.5 AAL1 Encapsulation for ST2+ Data PDU
4.5.1 Mapping from st2_unitdata.req to AAL1_UNITDATA.req
The data in st2_unitdata.req is regarded as a sequential-byte stream;
every 47 bytes of the data are assigned to the DATA parameter in
AAL1_UNITDATA.req. That is, as shown in Fig. 4.2, every 47 bytes of
the ST2+ data in the ST2+ Data PDU are continuously mapped to the
payload of AAL1 SAR_PDU.
Therefore, one st2_unitdata.req corresponds to one or more than one The management plane specifies the Null FlowSpec, the Controlled-Load
AAL1_UNITDATA.req, and one AAL1_UNITDATA.req may correspond to more Service FlowSpec, and the Guaranteed Service FlowSpec mapping rules
than one st2p_unitdata.req. for UNI 3.1 traffic management.
-------+ +-------+---------------------------+ 5.1 Mapping of the Null FlowSpec
| | ST | ST2+ data | ST2+
|..| header| | ...... Data PDU
-------+ +-------+---------------------------+
///\\\\\\ /////////\\\\\\\\\\\\\\\\\\\\\
// \\\\\\ ///////// \\\\\\\\\\\\\ \\\\\\\\
/ \\\\\\ ///////// \\\\\\\\\\\\\ \\\\\\\\
\\\\\\ ///////// \\\\\\\\\\\\\
\\\\\\///////// \\\\\\\\\\\\\
+-------+-----------+ +-------+-----------+
|SAR_PDU| SAR_PDU | |SAR_PDU| SAR_PDU | AAL1
|header | payload |..|header | payload |...... SAR_PDU
+-------+-----------+ +-------+-----------+
Fig. 4.2: Mapping of ST2+ data to AAL1 SAR_PDU payload. The Null FlowSpec is mapped to the UBR (VBR with the Best Effort
Indicator).
The value of the CLP in AAL1_UNITDATA.req depends on the The value of the PCR (CLP=0+1) is shown in section 6.7.2.
implementation: 1 (low priority) or zero (high priority) may be
assigned permanently, or they may be assigned depending on the value
of pri in st2_unitdata.req.
4.5.2 Mapping from AAL1_UNITDATA.ind to st2p_unitdata.ind 5.2 Mapping of the Controlled-Load Service FlowSpec
The DATA parameter in AAL1_UNITDATA.ind is regarded as a sequential- The Controlled-Load FlowSpec is mapped to the VBR whose PCR
byte stream. A certain number of bytes, where the number is equal to (CLP=0+1), SCR (CLP=0+1), and MBS (CLP=0+1) are specified.
or less than the negotiated downstream MTU value, are assigned to the
data in st2p_unitdata.ind. That is, as shown in Fig. 4.2, some bytes
of the payload in AAL1 SAR_PDU are mapped to the ST2+ data in the
ST2+ Data PDU.
Therefore, one st2_unitdata.ind corresponds to one or more than one The value of the PCR (CLP=0+1) is shown in section 6.7.2.
AAL1_UNITDATA.ind, and one AAL1_UNITDATA.ind may correspond to more
than one st2p_unitdata.ind.
An implementation-dependent value is assigned to pri in Let scr be the calculated value of the SCR (CLP=0+1). Based on the
st2p_unitdata.ind. value of the [r] field in the Controlled-Load FlowSpec, it is given
by:
scr = ([r] / 48) * S,
If the value of STATUS in AAL1_UNITDATA.ind is valid, it is assigned where S is the coefficient of segmentation, and in an implementation,
to the status in st2p_unitdata.ind. it must be configurable to any value between 1.0 and 56.0. The
recommended default value is 1.2. The value of the SCR (CLP=0+1) is
a minimum integer equal to or more than the calculated value of the
scr.
4.5.3 Value of MTU Let mbs be the calculated value of the MBS (CLP=0+1). Based on the
value of the [b] field in the Controlled-Load FlowSpec, it is given
by:
mbs = ([b] / 48) * S.
Because AAL1 is not designed to directly support packet The value of the MBS (CLP=0+1) is a minimum integer equal to or more
communications and thus has no MTU, the value of MTU is than the calculated value of the mbs.
implementation-dependent and equal to or less than 65,535 bytes. The
value of MTU may be determined by the rate of the VC, by the buffer
length, or by the packet-processing rule.
5. Protocol Specification of the Management Plane The values of the [p] and [m] fields in the Controlled-Load FlowSpec
are ignored.
TBD 5.3 Mapping of the Guaranteed Service FlowSpec
This section will be prepared based on the discussions of the ISSLL Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
working group. support Guaranteed Services. It will be supported by the UNI 3.1/4.0
version.
6. Protocol Specification of the Control Plane 6. Protocol Specification of the Control Plane
This section specifies the relationship between ST2+ SCMP and PVC This section specifies the relationship between ST2+ SCMP and PVC
management for ST2+ data, and the protocol interaction between ST2+ management for ST2+ data, and the protocol interaction between ST2+
SCMP and Q.2931 UNI signaling [5, 9]. SCMP and UNI 3.1 signaling.
6.1 AAL5 Encapsulation for ST2+ SCMP PDU 6.1 AAL5 Encapsulation for ST2+ SCMP PDU
This subsection describes AAL5 PDU encapsulation for the ST2+ SCMP This subsection describes AAL5 PDU encapsulation for the ST2+ SCMP
PDU. AAL5 encapsulation based on RFC 1483 and on the RFC 1483 PDU. AAL5 encapsulation based on RFC 1483 and on the RFC 1483
extension are specified. Selection of which one to use depends on extension are specified. Selection of which one to use depends on
the implementation. the implementation.
The ST2+ over ATM protocol does not cover a VC (SVC/PVC) that The ST2+ over ATM protocol does not cover a VC (SVC/PVC) that
transfers ST2+ SCMP. VCs for IPv4 transfer may be used for ST2+ SCMP transfers ST2+ SCMP. VCs for IPv4 transfer may be used for ST2+ SCMP
skipping to change at page 25, line 16 skipping to change at page 25, line 16
The RFC 1483 extension base encapsulation is the same as for RFC 1483 The RFC 1483 extension base encapsulation is the same as for RFC 1483
base encapsulation, except that the value of the OUI is 0x00-00-5E base encapsulation, except that the value of the OUI is 0x00-00-5E
(IANA) and the value of the PID is 0xXX-XX (TBD). (IANA) and the value of the PID is 0xXX-XX (TBD).
The RFC 1483 base encapsulation for the SCMP is ideal, but requires The RFC 1483 base encapsulation for the SCMP is ideal, but requires
modifying the IPv4 processing in the driver software of the WS or PC. modifying the IPv4 processing in the driver software of the WS or PC.
Therefore, the RFC 1483 base encapsulation may be difficult to Therefore, the RFC 1483 base encapsulation may be difficult to
implement. This encapsulation is designed to solve this problem. implement. This encapsulation is designed to solve this problem.
The following subsections will be added in the next draft.
6.2 Service Primitives Provided by Control Plane 6.2 Service Primitives Provided by Control Plane
6.3 Service Primitives Provided by ST2+ SCMP RFC 1819 ST2+ does not specify SCMP state machines. And the ST2+
over ATM protocol does not correspond to SCMP state machines.
Therefore, the control plane specification assumes the following.
6.4 Service Primitives Provided by Q.2931 o The ST2+ agent has ST2+ SCMP layer entities that correspond to the
next hops and the previous hop in the stream.
6.5 CONNECT Processing o The SCMP layer entity terminates ACK, ERROR, and timeout processing
and provides reliable SCMP delivery.
6.6 CHANGE Processing o The origin consists of an upper layer entity, ST2+ SCMP layer
entities for next hops, and a routing machine that delivers SCMP
messages between these entities.
6.7 DISCONNECT Processing o The intermediate agent consists of ST2+ SCMP layer entities for a
previous hop and for next hops and a routing machine that delivers
SCMP messages between these entities.
6.8 REFUSE Processing o The target consists of an upper layer entity, an ST2+ SCMP layer
entity for a previous hop, and a routing machine that delivers SCMP
messages between these entities.
6.9 Q.2931 Information Element Coding At least, the ST2+ SCMP layer entity for the next hop provides the
following services to the routing machine.
6.10 State Transit of ST2+ SCMP Entity o connect.req
This primitive sends a request for a CONNECT message transfer to
the ST2+ SCMP layer entity.
o change.req
This primitive sends a request for a CHANGE message transfer to the
ST2+ SCMP layer entity.
o accept.ind
This primitive indicates an ACCEPT message delivery from the ST2+
SCMP layer entity.
o disconnect.req
This primitive sends a request for a DISCONNECT message transfer to
the ST2+ SCMP layer entity.
o refuse.ind
This primitive indicates a REFUSE message delivery from the ST2+
SCMP layer entity, or indicates detection of an abnormal status
such as an illegal message or timeout in the ST2+ SCMP layer
entity.
At least, the ST2+ SCMP layer entity for the previous hop provides
the following services to the routing machine.
o connect.ind
This primitive indicates a CONNECT message delivery from the ST2+
SCMP layer entity.
o change.ind
This primitive indicates a CHANGE message delivery from the ST2+
SCMP layer entity.
o accept.req
This primitive sends a request for an ACCEPT message transfer to
the ST2+ SCMP layer entity.
o disconnect.ind
This primitive indicates a DISCONNECT message delivery from the
ST2+ SCMP layer entity, or indicates detection of an abnormal
status such as an illegal message or timeout in the ST2+ SCMP layer
entity.
o refuse.req
This primitive sends a request for a REFUSE message transfer to the
ST2+ SCMP layer entity.
6.3 Service Primitives Provided by UNI 3.1 Signaling
The UNI 3.1 signaling layer entity on the ST2+ over ATM control plane
provides the following services to the ST2+ SCMP layer entity. The
ST2+ over ATM protocol does not specify the UNI 3.1 signaling state
machines. These are defined in [10, 12, 13].
o setup.req
This primitive sends a request for a SETUP message transfer from
the ST2+ SCMP layer entity to the UNI 3.1 signaling layer entity.
The ST2+ SCMP layer entity that sent this primitive receives an
acknowledgment. If the setup succeeds the acknowledgment is a
setup.conf primitive and if the setup fails it is a release.ind or
release.conf primitive.
o setup.conf
This primitive indicates a CONNECT message delivery from the UNI
3.1 signaling layer entity to the ST2+ SCMP layer entity.
o setup.ind
This primitive indicates a SETUP message delivery from the UNI 3.1
signaling layer entity to the ST2+ SCMP layer entity. The ST2+
SCMP layer entity that received this primitive sends an
acknowledgment. If the setup is accepted the acknowledgment is a
setup.resp primitive and if the setup is rejected it is a
release.resp primitive if the state of the UNI 3.1 signaling layer
entity is U6; otherwise it is a release.req primitive.
o setup.resp
This primitive sends a request for a CONNECT message transfer from
the ST2+ SCMP layer entity to the UNI 3.1 signaling layer entity.
The ST2+ SCMP layer entity that sent this primitive receives an
acknowledgment. If the setup is completed the acknowledgment is a
setup-complete.ind primitive and if the setup fails it is a
release.ind or release.conf primitive.
o setup-complete.ind
This primitive indicates a CONNECT ACKNOWLEDGE message delivery
from the UNI 3.1 signaling layer entity to the ST2+ SCMP layer
entity.
o release.req
This primitive sends a request for a RELEASE message transfer from
the ST2+ SCMP layer entity to the UNI 3.1 signaling layer entity.
The ST2+ SCMP layer entity that sent this primitive receives an
acknowledgment that is a release.conf primitive.
o release.conf
This primitive indicates a RELEASE COMPLETE message delivery, or
indicates a RELEASE message delivery when the status of the UNI 3.1
signaling layer entity is U11, or indicates detection of an
abnormal status such as an illegal message or timeout in the UNI
3.1 signaling layer entity, from the UNI 3.1 signaling layer entity
to the ST2+ SCMP layer entity.
o release.ind
This primitive indicates a RELEASE message delivery from the UNI
3.1 signaling layer entity to the ST2+ SCMP layer entity when the
status of the UNI 3.1 signaling layer entity is other than U11.
The ST2+ SCMP layer entity that received this primitive sends an
acknowledgment that is a release.resp primitive. And this
primitive also indicates detection of an abnormal status such as an
illegal message or timeout in the UNI 3.1 signaling layer entity
and then a REFUSE message is transferred. In this case, the ST2+
SCMP layer entity that received this primitive receives a
release.conf primitive in succession.
o release.resp
This primitive sends a request for a RELEASE COMPLETE message
transfer from the ST2+ SCMP layer entity to the UNI 3.1 signaling
layer entity.
o add-party.req
This primitive sends a request for an ADD PARTY message transfer
from the ST2+ SCMP layer entity to the UNI 3.1 signaling layer
entity. The ST2+ SCMP layer entity that sent this primitive
receives an acknowledgment. If the setup is succeeds the
acknowledgment is an add-party.conf primitive and if the setup
fails it is a drop-party.conf primitive.
o add-party.conf
This primitive indicates an ADD PARTY ACKNOWLEDGE message delivery
from the UNI 3.1 signaling layer entity to the ST2+ SCMP layer
entity.
o drop-party.req
This primitive sends a request for a DROP PARTY message transfer
from the ST2+ SCMP layer entity to the UNI 3.1 signaling layer
entity. The ST2+ SCMP layer entity that sent this primitive
receives an acknowledgment that is a drop-party.conf primitive.
o drop-party.conf
This primitive indicates an ADD PARTY REJECT message delivery, or
indicates a DROP PARTY ACKNOWLEDGE message delivery, or indicates
detection of an abnormal status such as an illegal message or
timeout in the UNI 3.1 signaling layer entity, from the UNI 3.1
signaling layer entity to the ST2+ SCMP layer entity.
o drop-party.ind
This primitive indicates a DROP PARTY message delivery from the UNI
3.1 signaling layer entity to the ST2+ SCMP layer entity. The ST2+
SCMP layer entity that sent this primitive receives an
acknowledgment that is a drop-party.resp primitive.
o drop-party.resp
This primitive sends a request for a DROP PARTY ACKNOWLEDGE message
transfer from the ST2+ SCMP layer entity to the UNI 3.1 signaling
layer entity.
6.4 VC Style Selection Criteria
The ST2+ over ATM protocol supports PVC, the reverse channel of bi-
directional SVC, point-to-point SVC, and point-to-multipoint SVC for
ST2+ Data PDU transfer. And SVC supports both upstream and
downstream call initiation styles.
A 32-bit PVC identifier that is unique between neighboring ST2+
agents is assigned to each PVC. And the reverse channel of the bi-
directional point-to-point SVC used by the existing stream is
identified by the SID of the stream that occupies the forward
channel.
When the ST2+ agent sets up a stream or changes QoS, the ST2+ agent
must select one VC style from these SVC and PVC styles as a hop that
is part of the stream. In the ST2+ over ATM protocol, VC style
selection criteria depend on the implementation.
This subsection describes examples of VC style selection criteria for
the ST2+ over ATM protocol as a reference for implementors. Note
that the following descriptions in this subsection are not part of
the ST2+ over ATM protocol specification.
6.4.1 Examples of PVC selection criteria
At least, the ST2+ agent may have to manage the following information
for each PVC that can be used by ST2+ Data PDU transfer.
o PVC identifier
o ATM interface identifier in the ST2+ agent
o VPI/VCI
o State of VC: e.g. enabled or disabled, occupied or vacant
o QoS of VC
o Nexthop IP address
When a PVC is selected for a hop of a stream, at least confirmations,
that is the state of the PVC is vacant and the next hop IP address
and QoS are consistent with the requirements from the stream, may be
needed.
It is also feasible to introduce access lists to each PVC and to
consider the access lists in the selection process. Examples of an
access list are shown in the following.
o Permit or deny use by a stream whose the previous hop is specified.
o Permit or deny use by a stream whose the origin is specified.
o Permit or deny use by a stream whose the SID is specified.
o Permit or deny use by a stream whose the target is specified.
o Permit or deny use by a stream whose the target and SAP are
specified.
o Any combination of the above.
6.4.2 Examples of reverse channel of bi-directional SVC selection
criteria
At least, the ST2+ agent may have to manage the following information
for each reverse channel of bi-directional SVCs.
o SID of the stream that occupies the forward channel
o ATM interface identifier in the ST2+ agent
o VPI/VCI
o State of the reverse channel in the VC: e.g. enabled or disabled,
occupied or vacant
o QoS of VC
o Nexthop IP address
When a reverse channel of the bi-directional point-to-point SVC used
by the existing stream is selected for a hop of a stream, at least
confirmations, that is the state of the channel is vacant and the
next hop IP address and QoS are consistent with the requirements from
the stream, may be needed.
It is also feasible to introduce selection rules to the ST2+ agent.
Examples of selection rule are shown in the following.
o Permit reuse of the reverse channel by a stream whose the origin is
one of targets in the stream that occupies the forward channel.
o Permit reuse of the reverse channel by a stream whose one of
targets is the origin in the stream that occupies the forward
channel.
o Permit reuse of the reverse channel by a stream whose the previous
hop is one of the next hops in the stream that occupies the forward
channel.
o Any combination of the avobe.
6.4.3 Examples of SVC selection criteria
When an SVC is used for a hop of a stream, at first, the ST2+ agent
must select point-to-point or point-to-multipoint SVC. Examples of
this selection rule are shown in the following.
o If the network supports only point-to-point SVC, select it.
o If the network supports point-to-multipoint SVC, select it.
If point-to-point SVC is selected, the ST2+ agent must select
upstream or downstream call initiation style. Examples of this
selection rule are shown in the following.
o A VC for a stream whose previous hop is specified is initiated from
upstream or downstream.
o A VC for a stream whose next hop is specified is initiated from
upstream or downstream.
o A VC for a stream whose origin is specified is initiated from
upstream or downstream.
o A VC for a stream whose SID is specified is initiated from upstream
or downstream.
o A VC for a stream whose target is specified is initiated from
upstream or downstream.
o A VC for a stream whose target and SAP are specified is initiated
from upstream or downstream.
o Any combination of the above.
6.5 VC Management
This subsection specifies VC management in the ST2+ over ATM
protocol.
6.5.1 Outgoing call processing of SVC
When outgoing call processing of the first leaf of a point-to-
multipoint SVC or a point-to-point SVC is required inside the ST2+
SCMP layer entity, a setup.req primitive is sent to the UNI 3.1
signaling layer entity. If the UNI 3.1 signaling layer entity
responds with a setup.conf primitive, the call processing is assumed
to have succeeded. If the UNI 3.1 signaling layer entity responds
with anything other than this primitive, the processing rule is the
same as the SVC disconnect processing that is shown in section 6.5.4
and the outgoing call processing is assumed to have failed.
When outgoing call processing of a later leaf of a point-to-
multipoint SVC is required, an add-party.req primitive is sent to the
UNI 3.1 signaling layer entity. If the UNI 3.1 signaling layer
entity responds with an add-party.conf primitive, the call processing
is assumed to have succeeded. If the UNI 3.1 signaling layer entity
responds with anything other than this primitive, the processing rule
is the same as the SVC disconnect processing that is shown in section
6.5.4 and the outgoing call processing is assumed to have failed.
6.5.2 Incoming call processing of SVC
When an incoming call processing of SVC is required inside the ST2+
SCMP layer entity, it sets a watchdog timer. The time interval of
the timer depends on the implementation.
The ST2+ SCMP layer entity waits for a setup.ind primitive indication
from the UNI 3.1 signaling layer entity. When this primitive is
indicated and the parameters in it are acceptable, the ST2+ SCMP
layer entity responds with a setup.resp primitive. If the parameters
are not acceptable, the ST2+ SCMP layer entity stops the timer, and
if the state of the UNI 3.1 signaling layer entity is U6, the entity
responds with a release.resp primitive, and if the state is other
than this, the entity responds with a release.req primitive, and then
waits for a release.conf primitive response and the incoming call
processing is assumed to have failed.
If the ST2+ SCMP layer entity responds with a setup.resp primitive,
then the entity waits for the next primitive indication, and when the
next primitive is indicated, the ST2+ SCMP layer entity stops the
timer. If a setup-complete.ind primitive is indicated, the incoming
call processing is assumed to have succeeded. If the UNI 3.1
signaling layer entity responds with anything other than this
primitive or if the timer expires, the processing rule is the same as
the SVC disconnect processing that is shown in section 6.5.4 and the
incoming call processing is assumed to have failed.
6.5.3 VC release processing inside ST2+ SCMP layer
When a VC release is required inside an ST2+ SCMP layer entity, if
the previous hop or next hop is connected with a PVC, the PVC state
is set to vacant and the VC release processing is assumed to be
completed.
If the previous hop or next hop is connected with a point-to-point
SVC whose reverse channel is occupied, the state of the channel in
the VC is set to vacant, the SID information of the VC is updated,
and the VC release processing is assumed to be completed.
If the previous hop or next hop is connected with a point-to-point
SVC whose reverse channel is vacant, if the previous hop is connected
with a point-to-multipoint SVC, or if the next hop is connected with
a point-to-multipoint SVC and the number of leaves is 1, then the
ST2+ SCMP layer entity sends a release.req primitive to the UNI 3.1
signaling layer entity, then waits for a release.conf primitive
indication; when one is indicated, the VC release processing is
assumed to be completed.
If the next hop is connected with a point-to-multipoint SVC and the
number of leaves is other than 1, the ST2+ SCMP layer entity sends a
drop-party.req primitive to the UNI 3.1 signaling layer entity, then
waits for a drop-party.conf primitive indication; when one is
indicated, the VC release processing is assumed to be completed.
6.5.4 VC disconnect processing from UNI 3.1 signaling layer
If an ST2+ SCMP layer entity corresponds to a UNI 3.1 signaling layer
entity, and if the ST2+ SCMP layer entity is sent a release.ind
primitive from the UNI 3.1 signaling layer entity, whose cause is a
delivery of a RELEASE message, the ST2+ SCMP layer entity responds
with a release.resp primitive, and then the VC disconnect processing
is assumed to be completed. If the ST2+ SCMP layer entity is sent a
release.ind primitive, whose cause is other than the previous case,
the ST2+ SCMP layer entity waits for a release.conf primitive
response. When a release.conf primitive is indicated, the VC
disconnect processing is assumed to be completed.
Note that if next hops from ST2+ SCMP layer entities are connected
with a point-to-multipoint SVC, the ST2+ SCMP layer entities to next
hops correspond to a UNI 3.1 signaling layer entity. In this case,
if the ST2+ SCMP layer entities are sent release.ind primitives from
the UNI 3.1 signaling layer entity, whose cause is the delivery of a
RELEASE message, one of the ST2+ SCMP layer entities responds with a
release.resp primitive, and then the VC disconnect processing in the
entities that are sent release.ind primitives are assumed to be
completed. If the ST2+ SCMP layer entities are sent release.ind
primitives, whose cause is other than the previous case, the ST2+
SCMP layer entities wait for release.conf primitives responses. When
release.conf primitives are indicated, the VC disconnect processing
in the entities that are indicated release.ind primitives are assumed
to be completed.
If the ST2+ SCMP layer entity is sent a drop-party.ind primitive from
the UNI 3.1 signaling layer entity, the ST2+ SCMP layer entity
responds with a drop-party.resp primitive, and then the VC disconnect
processing is assumed to be completed. If the ST2+ SCMP layer entity
is sent a drop-party.conf primitive, the VC disconnect processing is
assumed to be completed.
6.6 Additional SCMP Processing Rules
This subsection specifies the additional SCMP processing rules that
are defined in RFC 1819 ST2+ protocol specification. The following
additional rules are applied when the previous hop or next hop is
connected with an ATM connection in the ST2+ SCMP layer entity.
6.6.1 Additional connect.req processing rules
When a connect.req primitive is sent to the ST2+ SCMP layer entity
for the next hop, the entity confirms whether or not the VC for the
next hop exists.
If it does, the entity forwards a CONNECT message that does not
include a VC-type common SCMP element to the next hop.
If it does not, the entity selects a VC style. If the result is a
PVC or a reverse channel of a bi-directional point-to-point SVC used
by an existing stream, the VC state is set to occupied. The entity
forwards a CONNECT message with a VC-type common SCMP element that
reflects the result of the selection to the next hop.
6.6.2 Additional connect.ind processing rules
The ST2+ SCMP layer entity for the previous hop confirms whether or
not the CONNECT message includes a VC-type common SCMP element.
If a VC-type common SCMP element is not included and the VC for the
next hop exists, a connect.ind primitive is sent to the routing
machine. If the VC for the next hop does not exist, a REFUSE message
is forwarded to the previous hop.
If a VC-type common SCMP element is included and a point-to-point
SVC, whose calling party is the upstream or downstream, or a point-
to-multipoint SVC is specified, a connect.ind primitive is sent to
the routing machine. If a PVC or a reverse channel of a bi-
directional point-to-point SVC used by an existing stream is
specified and the specified VC exists, the VC state is set to
occupied and a connect.ind primitive is sent to the routing machine.
Otherwise, a REFUSE message is forwarded to the previous hop.
6.6.3 Additional change.req processing rules
When a change.req primitive is sent to the ST2+ SCMP layer entity for
the next hop, the entity releases the VC whose process is shown in
section 6.5.3.
Then, the entity selects a VC style. If the result is a PVC or a
reverse channel of a bi-directional point-to-point SVC used by an
existing stream, the VC state is set to occupied. The entity
forwards a CHANGE message with a VC-type common SCMP element that
reflects the result of the selection to the next hop.
6.6.4 Additional change.ind processing rules
The ST2+ SCMP layer entity for the previous hop confirms whether the
CHANGE message includes a VC-type common SCMP element. If a VC-type
common SCMP element is not included, a REFUSE message is forwarded to
the previous hop.
If a VC-type common SCMP element is included, the entity releases the
VC whose process is shown in section 6.5.3. If the element specifies
a point-to-point SVC, whose calling party is the upstream or
downstream, or a point-to-multipoint SVC, a change.ind primitive is
sent to the routing machine. If a PVC or a reverse channel of a bi-
directional point-to-point SVC used by an existing stream is
specified and the specified VC exists, the VC state is set to
occupied and a change.ind primitive is sent to the routing machine.
Otherwise, a REFUSE message is forwarded to the previous hop.
6.6.5 Additional accept.req processing rules
When an accept.req primitive is sent to the ST2+ SCMP layer entity
for the previous hop, the entity confirms the state of the UNI 3.1
signaling layer entity. If the state of the entity is other than U0
or U10, the accept.req primitive is queued and is processed after the
state changes to U0 or U10.
If the state of the entity is U0 or U10, the ST2+ SCMP layer entity
confirms whether or not the VC for the previous hop exists. If it
does, an ACCEPT message is forwarded to the previous hop.
If it does not and the CONNECT or CHANGE message that corresponds to
the accept.req primitive specified a point-to-point SVC whose calling
party is the upstream or a point-to-multipoint SVC, then the entity
processes an incoming call that is shown in section 6.5.2. If the
incoming call processing succeeds, an ACCEPT message is forwarded to
the previous hop. If the CONNECT or CHANGE message that corresponds
to the accept.req primitive specified a point-to-point SVC whose
calling party is downstream, the entity converts from the IP address
of the previous hop to the ATM address, and then the entity processes
an outgoing call that is shown in section 6.5.1. If the outgoing
call processing succeeds, an ACCEPT message is forwarded to the
previous hop. For cases other than those described above or if the
incoming or outgoing call processing fails, a REFUSE message is
forwarded to the previous hop and a disconnect.ind primitive is sent
to the routing machine.
6.6.6 Additional accept.ind processing rules
When an ACCEPT message is processed in the ST2+ SCMP layer entity for
the next hop, the entity confirms the state of the UNI 3.1 signaling
layer entity. If the state of the entity is other than U0 or U10,
the ACCEPT message is queued and is processed after the state changes
to U0 or U10.
If the state of the entity is U0 or U10, the ST2+ SCMP layer entity
confirms whether or not the VC for the next hop exists. If it does,
an accept.ind primitive is sent to the routing machine.
If it does not and the CONNECT or CHANGE message that corresponds to
the ACCEPT message specified a point-to-point SVC whose calling party
is the upstream or a point-to-multipoint SVC, then the entity
converts from the IP address of the next hop to the ATM address, and
then the entity processes an outgoing call that is shown in section
6.5.1. If the outgoing call processing succeeds, an accept.ind
primitive is sent to the routing machine. If the CONNECT or CHANGE
message that corresponds to the ACCEPT message specified a point-to-
point SVC whose calling party is downstream, the entity processes an
incoming call that is shown in section 6.5.2. If the incoming call
processing succeeds, an accept.ind primitive is sent to the routing
machine. For cases other than those described above or if the
incoming or outgoing call processing fails, a refuse.ind primitive is
sent to the routing machine and a DISCONNECT message is forwarded to
the next hop.
6.6.7 Additional disconnect.req processing rules
At first, the ST2+ SCMP layer entity for the next hop forwards a
DISCONNECT message to the next hop.
And then, after the disconnect.req processing, if there are no more
targets that are connected downstream of the entity and the entity is
not waiting for an ACCEPT or REFUSE message response from targets,
the entity releases the VC whose process is shown in section 6.5.3.
6.6.8 Additional disconnect.ind processing rules
AT first, after the disconnect.ind processing, if there are no more
targets that are connected downstream of the ST2+ SCMP layer entity
for the previous hop and the entity is not waiting for an ACCEPT or
REFUSE message response from targets, the entity releases the VC
whose process is shown in section 6.5.3.
And then, the entity sends a disconnect.ind primitive to the routing
machine.
6.6.9 Additional refuse.req processing rules
At first, the ST2+ SCMP layer entity for the previous hop forwards a
REFUSE message to the previous hop.
And then, after the refuse.req processing, if there are no more
targets that are connected downstream of the entity and the entity is
not waiting for an ACCEPT or REFUSE message response from targets,
the entity releases the VC whose process is shown in section 6.5.3.
6.6.10 Additional refuse.ind processing rules
At first, after the refuse.ind processing, if there are no more
targets that are connected downstream of the ST2+ SCMP layer entity
for the next hop and the entity is not waiting for an ACCEPT or
REFUSE message response from targets, the entity releases the VC
whose process is shown in section 6.5.3.
And then, the entity sends a refuse.ind primitive to the routing
machine.
6.6.11 SVC disconnect processing
When the ST2+ SCMP layer entity for the previous hop is sent a SVC
disconnect processing from the UNI 3.1 signaling layer entity and
then the SVC disconnect processing is completed, the entity forwards
a REFUSE message to the previous hop and sends a disconnect.ind
primitive to the routing machine.
When the ST2+ SCMP layer entity for the next hop is sent a SVC
disconnect processing from the UNI 3.1 signaling layer entity and
then the SVC disconnect processing is completed, the entity sends a
refuse.ind primitive to the routing machine and forwards a DISCONNECT
message to the previous hop.
6.7 UNI 3.1 Signaling Information Element Coding Rules
The ST2+ over ATM protocol does not specify the coding rules needed
for the following information elements in UNI 3.1 signaling. The
usages of these information elements are specified in [10].
o Protocol discriminator
o Call reference
o Message type
o Message length
o Call state
o Called party number
o Called party subaddress
o Calling party number
o Calling party subaddress
o Cause
o Connection identifier
o Broadband repeat indicator
o Restart indicator
o Broadband sending complete
o Transit network selection
o Endpoint reference
o Endpoint state
6.7.1 ATM adaptation layer parameters coding
The SETUP and ADD PARTY messages in the ST2+ over ATM protocol must
include an ATM adaptation layer parameters information element. The
CONNECT message may or may not include this element. The coding
rules for the fields are as follows.
o The AAL Type is set to AAL5.
o The value of the Forward maximum CPCS size field is set to the same
as that of the MaxMsgSize field in the CONNECT SCMP message
corresponding to the SETUP or ADD PARTY message.
o If the VC is established as a point-to-point call, the value of the
Backward maximum CPCS size field is set the same as that of the
Forward maximum CPCS size field. If the VC is established as a
point-to-multipoint call, the value of the Backward maximum CPCS
size field is set to zero.
o The SSCS type is set to null.
6.7.2 ATM traffic descriptor coding
If the Null FlowSpec is specified in the ST2+ over ATM protocol, the
coding rules for the fields in the ATM traffic descriptor information
element in the SETUP message are as follows.
o The value of the Forward PCR (CLP=0+1) field depends on the
specification of the ATM network. The Forward PCR (CLP=0+1) field
in each ATM interface in an implementation must be configurable to
any value between zero and 16,777,215.
o If the VC is established as a point-to-point call, the value of the
Backward PCR (CLP=0+1) field is set the same as that of the Forward
PCR (CLP=0+1) field. If the VC is established as a point-to-
multipoint call, the value of the Backward PCR (CLP=0+1) field is
set to zero.
o The Best effort indication must be present.
If the Controlled-Load Service FlowSpec is specified, the coding
rules for the fields are as follows.
o The value of the Forward PCR (CLP=0+1) field depends on the
specification of the ATM network. The Forward PCR (CLP=0+1) field
in each ATM interface in an implementation must be configurable to
any value between zero and 16,777,215.
o If the VC is established as a point-to-point call, the value of the
Backward PCR (CLP=0+1) field is set the same as that of the Forward
PCR (CLP=0+1) field. If the VC is established as a point-to-
multipoint call, the value of the Backward PCR (CLP=0+1) field is
set to zero.
o The method for calculating the Forward SCR (CLP=0+1) field is shown
in section 5.
o If the VC is established as a point-to-point call, the value of the
Backward SCR (CLP=0+1) field is set the same as that of the Forward
SCR (CLP=0+1) field. If the VC is established as a point-to-
multipoint call, this field must not be present.
o The method for calculating the Forward MBS (CLP=0+1) field is shown
in section 5.
o If the VC is established as a point-to-point call, the value of the
Backward MBS (CLP=0+1) field is set the same as that of the Forward
MBS (CLP=0+1) field. If the VC is established as a point-to-
multipoint call, this field must not be present.
o The Best effort indication, Tagging backward, and Tagging forward
fields must not be present.
6.7.3 Broadband bearer capability coding
If the Null FlowSpec is specified in the ST2+ over ATM protocol, the
coding rules for the fields in the Broadband bearer capability
information element in the SETUP message are as follows.
o The Bearer class depends on the specification of the ATM network.
The Bearer class in each ATM interface in an implementation must be
configurable as either BCOB-X or BCOB-C. BCOB-X is recommended as
the default configuration.
o The Traffic type and Timing requirements fields must not be
present.
o The Susceptibility to clipping field is set to not susceptible to
clipping.
o If the VC is established as a point-to-point call, the User plane
connection configuration field is set to point-to-point, and if the
VC is established as a point-to-multipoint call, it is set to
point-to-multipoint.
If the Controlled-Load Service FlowSpec is specified, the coding
rules for the fields are as follows.
o The Bearer class depends on the specification of the ATM network.
The Bearer class in each ATM interface in an implementation must be
configurable as either BCOB-X or BCOB-C. BCOB-X is recommended as
the default configuration.
o If the Bearer class is BCOB-X, the Traffic type and Timing
requirements fields depend on the specification of the ATM network.
The Traffic type and Timing requirements fields in each ATM
interface in an implementation must be configurable as either no
indication or VBR and Not required, respectively. No indication is
recommended as the default configuration. If the Bearer class is
BCOB-C, the Traffic type and Timing requirements fields must not be
present.
o The Susceptibility to clipping field depends on the specification
of the ATM network. The Susceptibility to clipping field in each
ATM interface in an implementation must be configurable as either
not susceptible to clipping or susceptible to clipping. Not
susceptible to clipping is recommended as the default
configuration.
o If the VC is established as a point-to-point call, the User plane
connection configuration field is set to point-to-point, and if the
VC is established as a point-to-multipoint call, it is set to
point-to-multipoint.
6.7.4 Broadband high layer information coding
The SETUP and ADD PARTY messages in the ST2+ over ATM protocol must
include a Broadband high layer information information element. The
coding rules for the fields are as follows.
o The High layer information type is set to User specific.
o The first 6 bytes in the High layer information field are set to
the SID of the stream corresponding to the VC.
6.7.5 Broadband low layer information coding
The SETUP and ADD PARTY messages in the ST2+ over ATM protocol must
include a Broadband low layer information information element. The
CONNECT message may or may not include this element. The coding
rules for the fields are as follows.
o The User information layer 3 protocol field is set to ISO/IEC TR
9577.
o The IPI field is set to IEEE 802.1 SNAP (0x80).
o The OUI field is set to IANA (0x00-00-5E).
o The PID field is set to ST2+ (TBD).
6.7.6 QoS parameter coding
If the Null FlowSpec is specified in the ST2+ over ATM protocol, the
coding rules for the fields in the QoS parameter in the SETUP message
are as follows.
o The QoS class forward and QoS class backward fields are set to QoS
class 0.
If the Controlled-Load Service FlowSpec is specified, the coding
rules for the fields are as follows.
o The QoS class forward and QoS class backward fields depend on the
specification of the ATM network. The QoS class forward and QoS
class backward fields in each ATM interface in an implementation
must be configurable as either QoS class 0 or QoS class 3. QoS
class 0 is recommended as the default configuration.
7. Security Considerations 7. Security Considerations
Security considerations are not discussed in this document. The ST2+ over ATM protocol modifies RFC 1819 ST2+ protocol, but
basically these modifications are minimum extensions for ATM support
and bug fixes, so they do not weaken the security of the ST2+
protocol.
The ST2+ over ATM protocol specifies protocol interaction between
ST2+ and UNI 3.1, and this does not weaken the security of the UNI
3.1 protocol.
In an ST2+ agent that processes an incoming call of SVC, if the
incoming SETUP message contains the calling party number and if it is
verified and passed by the ATM network or it is provided by the
network, then it is feasible to use the calling party number for part
of the calling party authentication to strengthen security.
References References
[1] M. Borden, E. Crawley, B. Davie, and S. Batsell, "Integration [1] M. Borden, E. Crawley, B. Davie, and S. Batsell, "Integration
of Real-time Services in an IP-ATM Network Architecture," RFC of Real-time Services in an IP-ATM Network Architecture," RFC
1821, August 1995. 1821, August 1995.
[2] S. Jackowski, "Native ATM Support for ST2+," RFC 1946, May [2] S. Jackowski, "Native ATM Support for ST2+," RFC 1946, May
1996. 1996.
[3] S. Damaskos and A. Gavras, "Connection Oriented Protocols over [3] S. Damaskos and A. Gavras, "Connection Oriented Protocols over
ATM: A case study," Proc. SPIE, Vol. 2188, pp.226-278, February ATM: A case study," Proc. SPIE, Vol. 2188, pp.226-278, February
1994. 1994.
[4] L. Delgrossi and L. Berger, Ed., "Internet Stream Protocol [4] L. Delgrossi and L. Berger, Ed., "Internet Stream Protocol
Version 2 (ST2) Protocol Specification - Version ST2+," RFC 1819, Version 2 (ST2) Protocol Specification - Version ST2+," RFC 1819,
August 1995. August 1995.
[5] The ATM Forum, "ATM User-Network Interface Specification [5] J. Wroclawski, "Specification of the Controlled-Load Network
Version 3.1," September 1994. Element Service," RFC 2211, September 1997.
[6] J. Wroclawski, "Specification of the Controlled-Load Network [6] S. Shenker, C. Partridge, and R. Guerin, "Specification of
Element Service," Internet Draft, November 1996, <draft-ietf- Guaranteed Quality of Service," RFC 2212, September 1997.
intserv-ctrl-load-svc-04.txt>.
[7] S. Shenker, C. Partridge, and R. Guerin, "Specification of [7] J. Wroclawski, "The Use of RSVP with IETF Integrated
Guaranteed Quality of Service," Internet Draft, February 1997, Services," RFC 2210, September 1997.
<draft-ietf-intserv-guaranteed-svc-07.txt>.
[8] J. Wroclawski, "The Use of RSVP with IETF Integrated [8] M. Garrett and M. Borden, "Interoperation of Controlled-Load
Services," Internet Draft, October 1996, <draft-ietf-intserv- Service and Guaranteed Service with ATM," Internet Draft, July
rsvp-use-01.txt>. 1997, <draft-ietf-issll-atm-mapping-03.txt>.
[9] ITU-T, "Broadband Integrated Services Digital Network (B- [9] A. Ghanwani, J. W. Pace, and V. Srinivasan, "A Framework for
Providing Integrated Services Over Shared and Switched LAN
Technologies," Internet Draft, May 1997, <draft-ietf-issll-is802-
framework-02.txt>.
[10] The ATM Forum, "ATM User-Network Interface Specification
Version 3.1," September 1994.
[11] The ATM Forum, "ATM User-Network Interface (UNI) Signaling
Specification Version 4.0," af-sig-0061.000, July 1996.
[12] ITU-T, "Broadband Integrated Services Digital Network (B-
ISDN)-Digital Subscriber Signaling System No. 2 (DSS 2)-User- ISDN)-Digital Subscriber Signaling System No. 2 (DSS 2)-User-
Network Interface (UNI) Layer 3 Specification for Basic Network Interface (UNI) Layer 3 Specification for Basic
Call/Connection Control," ITU-T Recommendation Q.2931, September Call/Connection Control," ITU-T Recommendation Q.2931, September
1995. 1995.
[10] ITU-T, "B-ISDN Protocol Reference Model and its Application," [13] ITU-T, "Broadband Integrated Services Digital Network (B-
CCITT Recommendation I.321, April 1991. ISDN)-Digital Subscriber Signaling System No. 2 (DSS 2)-User-
Network Interface Layer 3 Specification for Point-to-Multipoint
[11] ITU-T, "B-ISDN ATM Adaptation Layer (AAL) specification, Call/Connection Control," ITU-T Recommendation Q.2971, October
types 1 and 2," Draft new ITU-T Recommendation I.363.1, September
1995. 1995.
[12] ITU-T, "B-ISDN ATM Adaptation Layer (AAL) type 5 [14] ITU-T, "B-ISDN Protocol Reference Model and its Application,"
CCITT Recommendation I.321, April 1991.
[15] ITU-T, "B-ISDN ATM Adaptation Layer (AAL) type 5
specification," Draft new ITU-T Recommendation I.363.5, September specification," Draft new ITU-T Recommendation I.363.5, September
1995. 1995.
[13] ITU-T, "Traffic Control and Congestion Control in B-ISDN," [16] J. Heinanen, "Multiprotocol Encapsulation over ATM
ITU-T Recommendation I.371, July 1995.
[14] J. Heinanen, "Multiprotocol Encapsulation over ATM
Adaptation Layer 5," RFC 1483, July 1993. Adaptation Layer 5," RFC 1483, July 1993.
[15] M. Laubach, "Classical IP and ARP over ATM," RFC 1577, [17] M. Laubach, "Classical IP and ARP over ATM," RFC 1577,
January 1994. January 1994.
[16] M. Perez, F. Liaw, A. Mankin, E. Hoffman, D. Grossman, and A. [18] M. Perez, F. Liaw, A. Mankin, E. Hoffman, D. Grossman, and A.
Malis, "ATM Signaling Support for IP over ATM," RFC 1755, February Malis, "ATM Signaling Support for IP over ATM," RFC 1755, February
1995. 1995.
[17] J. Luciani, D. Katz, D. Piscitello, and B. Cole, "NBMA Next [19] J. Luciani, D. Katz, D. Piscitello, and B. Cole, "NBMA Next
Hop Resolution Protocol (NHRP)," Internet Draft, March 1997, Hop Resolution Protocol (NHRP)," Internet Draft, March 1997,
<draft-ietf-rolc-nhrp-11.txt>. <draft-ietf-rolc-nhrp-11.txt>.
Acknowledgments Acknowledgments
TBD ATM is a huge technology and without the help of many colleagues
at NTT who are involved in ATM research and development, it would
have been impossible for me to complete this protocol
specification. I would like to thank Hideaki Arai of the NTT
Network Strategy Planning Dept., Shin-ichi Kuribayashi of the NTT
Business Communications Hqs., Naotaka Morita, Jun Aramomi, and
Takumi Ohba of the NTT Network Service Systems Labs., and also
Hisao Uose of the NTT Multimedia Networks Labs. for their valuable
comments and discussions.
And I would also like to especially thank Eric Crawley of
Gigapacket Networks, John Wroclawski of MIT, Steven Jackowski of
Net Manage, Louis Berger of FORE Systems, Steven Willis of Bay
Networks, Greg Burch of Qosnetics, and Denis Gallant, James Watt,
and Joel Halpern of Newbridge Networks for their valuable comments
and suggestions.
Also this specification is based on various discussions during NTT
Multimedia Joint Project with NACSIS. I would like to thank
Professor Shoichiro Asano of the National Center for Science
Information Systems for his invaluable advice in this area.
Author's Address Author's Address
Muneyoshi Suzuki Muneyoshi Suzuki
NTT Multimedia Networks Laboratories NTT Multimedia Networks Laboratories
3-9-11, Midori-cho 3-9-11, Midori-cho
Musashino-shi, Tokyo 180, Japan Musashino-shi, Tokyo 180, Japan
Phone: +81-422-59-2119 Phone: +81-422-59-2119
Fax: +81-422-59-3203 Fax: +81-422-59-3203
skipping to change at page 28, line 19 skipping to change at page 46, line 19
The following sentence in the second paragraph: The following sentence in the second paragraph:
< For some SCMP messages (CONNECT, CHANGE, JOIN, and STATUS) the < For some SCMP messages (CONNECT, CHANGE, JOIN, and STATUS) the
should be changed to should be changed to
> For some SCMP messages (CONNECT, CHANGE, and JOIN) the > For some SCMP messages (CONNECT, CHANGE, and JOIN) the
A.2 4.4.4 User Data A.2 4.4.4 User Data
The following: The following sentence:
< option can be included with ACCEPT, CHANGE, CONNECT, DISCONNECT, and < option can be included with ACCEPT, CHANGE, CONNECT, DISCONNECT, and
< REFUSE messages. The format of the UserData parameter is shown in < REFUSE messages. The format of the UserData parameter is shown in
should be changed to should be changed to
> option can be included with ACCEPT, CHANGE, CONNECT, DISCONNECT, NOTIFY, > option can be included with ACCEPT, CHANGE, CONNECT, DISCONNECT, NOTIFY,
> and REFUSE messages. The format of the UserData parameter is shown in > and REFUSE messages. The format of the UserData parameter is shown in
A.3 5.5.1 Mismatched FlowSpecs A.3 5.3.2 Other Cases
The following sentence:
< CONNECT with a REFUSE message with the affected targets specified in
< the TargetList and an appropriate ReasonCode (StreamExists).
should be changed to
> CONNECT with a REFUSE message with the affected targets specified in
> the TargetList and an appropriate ReasonCode (TargetExists).
A.4 5.5.1 Mismatched FlowSpecs
The following sentence: The following sentence:
< notifies the processing ST agent which should respond with ReasonCode < notifies the processing ST agent which should respond with ReasonCode
< (FlowSpecMismatch). < (FlowSpecMismatch).
should be changed to should be changed to
> notifies the processing ST agent which should respond with a REFUSE > notifies the processing ST agent which should respond with a REFUSE
> message with ReasonCode (FlowSpecMismatch). > message with ReasonCode (FlowSpecMismatch).
A.4 10.2 Control PDUs A.5 6.2.1 Problems in Stream Recovery
The following: The following sentence:
< some time after a failure. As a result, the ST agent attempting the
< recovery may receive ERROR messages for the new CONNECTs that are
< ...
< failure, and will interpret the new CONNECT as resulting from a
< routing failure. It will respond with an ERROR message with the
< appropriate ReasonCode (StreamExists). Since the timeout that the ST
< ...
< remnants of the broken stream will soon be torn down by a DISCONNECT
< message. Therefore, the ST agent that receives the ERROR message with
< ReasonCode (StreamExists) should retransmit the CONNECT message after
should be changed to
> some time after a failure. As a result, the ST agent attempting the
> recovery may receive REFUSE messages for the new CONNECTs that are
> ...
> failure, and will interpret the new CONNECT as resulting from a
> routing failure. It will respond with a REFUSE message with the
> appropriate ReasonCode (TargetExists). Since the timeout that the ST
> ...
> remnants of the broken stream will soon be torn down by a DISCONNECT
> message. Therefore, the ST agent that receives the REFUSE message with
> ReasonCode (TargetExists) should retransmit the CONNECT message after
A.6 6.3 Stream Preemption}
The following sentence:
< (least important) to 256 (most important). This value is
should be changed to
> (least important) to 255 (most important). This value is
A.7 10.2 Control PDUs
The following sentence:
<o Reference is a transaction number. Each sender of a request control <o Reference is a transaction number. Each sender of a request control
< message assigns a Reference number to the message that is unique < message assigns a Reference number to the message that is unique
< with respect to the stream. < with respect to the stream.
should be changed to should be changed to
>o Reference is a transaction number. Each sender of a request control >o Reference is a transaction number. Each sender of a request control
> message assigns a Reference number to the message that is unique > message assigns a Reference number to the message that is unique
> with respect to the stream for messages generated by each agent. > with respect to the stream for messages generated by each agent.
A.5 10.3.4 Origin A.8 10.3.4 Origin
The following: The following:
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ < +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
< | PCode = 5 | PBytes | NextPcol |OriginSAPBytes | < | PCode = 5 | PBytes | NextPcol |OriginSAPBytes |
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ < +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
should be changed to should be changed to
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | PCode = 4 | PBytes | NextPcol |OriginSAPBytes | > | PCode = 4 | PBytes | NextPcol |OriginSAPBytes |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A.6 10.5.3 ReasonCode A.9 10.4.1 ACCEPT
The following sentence:
<o IPHops is the number of IP encapsulated hops traversed by the
< stream. This field is set to zero by the origin, and is incremented
< at each IP encapsulating agent.
should be changed to
>o IPHops is the number of IP encapsulated hops traversed by the
> stream.
A.10 10.4.2 ACK
The following:
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
< | OpCode = 2 | 0 | TotalBytes |
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
should be changed to
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | OpCode = 2 | 0 | TotalBytes = 16 |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A.11 10.4.3 CHANGE
The following sentence:
<o I (bit 7) is used to indicate that the LRM is permitted to interrupt
should be changed to
>o I (bit 9) is used to indicate that the LRM is permitted to interrupt
A.12 10.4.7 HELLO
The following:
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
< | OpCode = 7 |R| 0 | TotalBytes |
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
should be changed to
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | OpCode = 7 |R| 0 | TotalBytes = 20 |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A.13 10.4.9 JOIN-REJECT
The following sentence:
<o Reference contains a number assigned by the ST agent sending the
< REFUSE for use in the acknowledging ACK.
should be changed to
>o Reference contains a number assigned by the ST agent sending the
> JOIN-REJECT for use in the acknowledging ACK.
A.14 10.4.13 STATUS-RESPONSE
The following sentence:
< possibly Groups of the stream. It the full target list can not fit in
should be changed to
> possibly Groups of the stream. If the full target list can not fit in
A.15 10.5.3 ReasonCode
The following: The following:
< 32 PCodeUnknown Control PDU has a parameter with an invalid < 32 PCodeUnknown Control PDU has a parameter with an invalid
< PCode. < PCode.
should be removed because a common SCMP element with an unknown PCode should be removed because a common SCMP element with an unknown PCode
is equivalent to the UserData (RFC 1819, Section 10.3.8). is equivalent to the UserData (RFC 1819, Section 10.3.8).
 End of changes. 85 change blocks. 
265 lines changed or deleted 1200 lines changed or added

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