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 RFC1819 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
The ST2+ over ATM protocol modifies RFC1819 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
[1] Borden, M., Crawley, E., Davie, B., and S. Batsell, "Integration
of Real-time Services in an IP-ATM Network Architecture", RFC
1821, August 1995.
[2] Jackowski, S., "Native ATM Support for ST2+", RFC1946, May 1996.
[3] S. Damaskos and A. Gavras, "Connection Oriented Protocols over
ATM: A case study", Proc. SPIE, Vol. 2188, pp.226-278, February
1994.
[4] Delgrossi, L., and L. Berger, Ed., "Internet Stream Protocol
Version 2 (ST2) Protocol Specification - Version ST2+", RFC1819,
August 1995.
[5] Wroclawski, J., "Specification of the Controlled-Load Network
Element Service", RFC2211, September 1997.
[6] Shenker, S., Partridge, C., and R. Guerin, "Specification of
Guaranteed Quality of Service", RFC2212, September 1997.
[7] Wroclawski, J., "The Use of RSVP with IETF Integrated Services",
RFC2210, September 1997.
[8] Garrett, M., and M. Borden, "Interoperation of Controlled-Load
Service and Guaranteed Service with ATM", RFC2381, August 1998.
[9] Ghanwani, A., Pace, J., and V. Srinivasan, "A Framework for
Providing Integrated Services Over Shared and Switched LAN
Technologies", Work in Progress.
[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-Network
Interface (UNI) Layer 3 Specification for Basic Call/Connection
Control", ITU-T Recommendation Q.2931, September 1995.
[13] ITU-T, "Broadband Integrated Services Digital Network (B-ISDN)-
Digital Subscriber Signaling System No. 2 (DSS 2)-User-Network
Interface Layer 3 Specification for Point-to-Multipoint
Call/Connection Control", ITU-T Recommendation Q.2971, October
1995.
[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 1995.
[16] Heinanen, J., "Multiprotocol Encapsulation over ATM Adaptation
Layer 5", RFC1483, July 1993.
[17] Laubach, M., "Classical IP and ARP over ATM", RFC1577, January
1994.
[18] Perez, M., Liaw, F., Mankin, A., Hoffman, E., Grossman, D., and
A. Malis, "ATM Signaling Support for IP over ATM", RFC1755,
February 1995.
[19] Luciani, J., Katz, D., Piscitello, D., and B. Cole, "NBMA Next
Hop Resolution Protocol (NHRP)", RFC2332, April 1998.
Acknowledgments
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 and Naotaka Morita of the NTT
Network Strategy Planning Dept., Shin-ichi Kuribayashi, Jun Aramomi,
and Takumi Ohba of the NTT Network Service Systems Labs., and also
Hisao Uose and Yoshikazu Oda 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
Muneyoshi Suzuki
NTT Multimedia Networks Laboratories
3-9-11, Midori-cho
Musashino-shi, Tokyo 180-8585, Japan
Phone: +81-422-59-2119
Fax: +81-422-59-2829
EMail: suzuki@nal.ecl.net
Appendix A. RFC1819 ST2+ Errata
A.1 4.3 SCMP Reliability
The following sentence in the second paragraph:
< For some SCMP messages (CONNECT, CHANGE, JOIN, and STATUS) the
should be changed to
> For some SCMP messages (CONNECT, CHANGE, and JOIN) the
A.2 4.4.4 User Data
The following sentence:
< option can be included with ACCEPT, CHANGE, CONNECT, DISCONNECT, and
< REFUSE messages. The format of the UserData parameter is shown in
should be changed to
> option can be included with ACCEPT, CHANGE, CONNECT, DISCONNECT, NOTIFY,
> and REFUSE messages. The format of the UserData parameter is shown in
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:
< notifies the processing ST agent which should respond with ReasonCode
< (FlowSpecMismatch).
should be changed to
> notifies the processing ST agent which should respond with a REFUSE
> message with ReasonCode (FlowSpecMismatch).
A.5 6.2.1 Problems in Stream Recovery
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
< message assigns a Reference number to the message that is unique
< with respect to the stream.
should be changed to
>o Reference is a transaction number. Each sender of a request control
> message assigns a Reference number to the message that is unique
> with respect to the stream for messages generated by each agent.
A.8 10.3.4 Origin
The following:
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
< | PCode = 5 | PBytes | NextPcol |OriginSAPBytes |
< +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
should be changed to
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | PCode = 4 | PBytes | NextPcol |OriginSAPBytes |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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:
< 32 PCodeUnknown Control PDU has a parameter with an invalid
< PCode.
should be removed because a common SCMP element with an unknown PCode
is equivalent to the UserData (RFC1819, Section 10.3.8).
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