Bionic Buffalo Tech Note #108: DSM-CC Data Carousel and Module Identification
Variable
Identifies
Control
Messages?
Data
Msgs?
Remarks
privateData
(any)
yes
no
may be used for implementation-specific
purposes
moduleId
module
yes
yes
moduleVersion
module
yes
yes
used to detect module coherency problems
moduleInfo
module
yes
no
arbitary data for each module, which may
be examined by client to determine
applicability of the module, or may carry
ancillary data relating to the use of the
module
Discussion of Variables
serverId
The
serverId
is found only in optional
DownloadServerInitiate
messages.
These are used to redirect a client to a different connection, possibly depending on the
message's
compatibilityDescriptor
and
privateData
contents. The
serverId
value is an OSI NSAP address. When there are multiple
DownloadServerInitiate
messages with different
compatibilityDescriptor
s and
privateData
, then the client may select the
appropriate
serverId
to locate the applicable carousel.
transactionId
A server sends
DownloadInfoIndication
or
DownloadInfoResponse
messages to indicate the carousel's content. Each such message includes a
compatibilityDescriptor
,
privateData
, a
downloadId
, and information
about the modules. The
transactionId
is used as a versioning mechanism for these
messages: whenever any field in the messages changes (corresponding to an update of the
carousel), then the
transactionId
is incremented. A client need only look for
changed
transactionId
values; unchanged
transactionId
values represent
duplicates of messages which have already been received.
downloadId
A
downloadId
identifies a single instance of a scenario in progress. It should be unique
within the network, although the specification provides no guidance on how such
downloadId
values are assigned. (In a multi-vendor network, without some type of
coordinated assignment of values, it is conceivable that two different carousels might
improperly have the same
downloadId
value.)
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