Alert Standard Format (ASF) Specification

Alert Standard Format (ASF) Specification v2.0 DMTF Document DSP0136
DSP0136 23 April 2003 Page 25 of 94
3. The Next Header field indicates the type of message that is encapsulated between the RSP
header and trailer. For this specification, the value in the Next Header field is defined as the
value in the Version field of the RMCP Header of the RMCP message being processed (e.g.;
06h for ASF).
4. The Integrity Data field is used to hold the results of an integrity algorithm (e.g., a keyed hash
function) performed over the specific fields of the RSP header, RMCP message, and RSP
trailer defined earlier. The length of this field depends on the integrity algorithm negotiated
during session setup. For this specification, the mandatory-to-implement integrity algorithm is
HMAC-SHA1-96 defined in [RFC2404].
These fields are specified in the following table.
Contents Type Offset Value
Pad Variable
Bytes
Used to provide DWORD-alignment of the Integrity Data field within the
message. If present, each Pad byte is set to 00h.
Pad
Length
1 Byte 4n-2 Defines the number of Pad bytes present in the message, in the range 0 to
3.
Next
Header
1 Byte 4n-1 Indicates the type of message that is encapsulated between the RSP
header and trailer. For this specification, the value of this field equals the
value in the Version field of the RMCP Header of the message being
processed.
Integrity
Data
Variable
Bytes
4n Holds the results of an integrity algorithm negotiated during session setup.
RSP Trailer
3.2.3.2 Outbound Message Processing
The sections that follow and the figure below outline the processing steps used by an alert-
sending device or management console to add security extensions to an outbound RMCP
message.
3.2.3.2.1 Device Security Policy and Session State Lookup
When an RMCP request initiator creates a message, its RMCP protocol engine accesses the
Device Security Policy to determine whether RMCP security extensions functionality is enabled.
If the functionality is enabled, RMCP determines if an appropriate RSP session exists for the
message.
If an appropriate session does not exist, RMCP uses the RSP Session Protocol (RSSP) to create
a session (see 3.2.3.4). If a session exists but the session is not in the Message Transfer phase
(the phase that allows RMCP messages to be exchanged), RMCP must wait until the session
reaches that phase before the RMCP message can be sent.
Data IP Hdr
Data UDP Hdr
Data RSP Tlr RSP Hdr
RMCP Message
Enet Hdr Data