Definition of Managed Objects for Synthetic Sources for Performance Monitoring Algorithms
Extracted elements (28)
Source configuration is split into two tables: sspmSourceProfileTable (reusable templates defining packet characteristics) and sspmSourceControlTable (specific measurement instances referencing a profile). This separation allows a single profile to be shared across many measurement instances.
sspmSourceControlSamplingDist supports both deterministic (fixed inter-packet interval) and Poisson (exponentially distributed inter-packet interval) injection. Poisson sampling is aligned with IPPM methodology to avoid synchronization artifacts with periodic network events.
sspmSourceProfile8021Tagging uses -1 to indicate untagged packets and 0–65535 for tag values, rather than a separate boolean, to consolidate the tagged/untagged choice and the tag value into a single object and minimize the number of objects requiring coordination.
The SSPM-MIB was developed to fill an explicit gap in the RMON/IPPM framework: existing IETF work defined passive monitoring and performance metrics, but did not define a remotely configurable active traffic generation capability ('active probe'). This MIB addresses that void.
The DISMAN pingMIB and tracerouteMIB (RFC 2925) provide active probes oriented toward connectivity determination, not quality measurement. The SSPM-MIB fills a complementary role: measuring the quality of connectivity. Both should be monitored with the same probes to reduce network overhead.
The SSPM-MIB could serve as an alternative control plane to the OWDP (One-Way Delay Protocol) control protocol being developed by the IPPM WG; the SSPM-MIB approach is redundant with but independent of that protocol.
The SSPM-MIB is designed for use in conjunction with APM-MIB (RFC 3729) and TPM-MIB (RFC 4150). The AppLocalIndex from APM-MIB is the cross-reference key used in sspmSourceProfileType, sspmSinkType, and sspmCapabilitiesInstance to correlate measurement configuration with reporting structures.
If sspmSourceControlFrequency is set to a value lower than sspmGeneralMinFrequency, the set operation MUST fail with an error-status of 'inconsistentValue'.
Implementers SHOULD NOT deploy SNMP versions prior to SNMPv3. Instead, SNMPv3 with full cryptographic mechanisms (authentication and privacy) is RECOMMENDED for managing this MIB module.
Once sspmSourceControlStatus is set to active(1), only sspmSourceControlEnabled may be modified; all other read-write and read-create attributes in sspmSourceControlTable MUST NOT be changed.
Once sspmSourceProfileStatus is set to active(1), no objects in the sspmSourceProfileTable may be changed, and an entry may not exist in the active state unless all objects have appropriate values.
sspmSinkSourceAddress MUST be set only to a valid address administratively configured on the device; an attempt to set it to an address not belonging to the device must fail with 'inconsistentValue'.
The device SHOULD NOT allow the source address on test packets to be set to addresses other than those administratively configured on the device. Source address control is enforced by using the InterfaceIndexOrZero syntax for sspmSourceControlSrc.
When sspmSourceControlDestAddr contains a DNS name, the agent MUST resolve it to an address before each measurement and SHOULD NOT cache the resolved address between measurements.
When sspmSourceProfilePacketFillType is 'url', sspmSourceProfilePacketFillValue must contain a dereferenceable URL of type 'http:', 'https:', or 'ftp:' only. If the URL cannot be retrieved when sspmSourceStatus becomes active, the row status is set to 'notReady' and the set fails with 'inconsistentValue'.
sspmCapabilitiesTable enumerates the AppLocalIndex values for which the probe supports SSPM configuration. A row must exist in this table before a corresponding sspmSourceProfileEntry or sspmSinkEntry can be created.
sspmGeneralGroup provides read-only probe metadata: sspmGeneralClockResolution (measurement resolution in microseconds), sspmGeneralClockMaxSkew (maximum clock offset error over 86400 seconds), sspmGeneralClockSource (NTP stratum of the local clock), and sspmGeneralMinFrequency (minimum supported inter-packet injection interval).
sspmSinkTable configures the measurement sink. For round-trip tests the sink is on the same probe as the source; for one-way tests it is on a separate probe. Attributes include expected packet rate, expected first sequence number, last sequence number received, and a counter of out-of-sequence packets.
sspmSourceControlTable instantiates specific measurements by referencing a profile entry. Each control entry specifies destination address (type + address), source interface, enabled state, timeout, sampling distribution (deterministic or Poisson), frequency, and first/last sequence numbers.
sspmSourceProfileTable defines reusable measurement templates. Each entry (indexed by sspmSourceProfileInstance, Unsigned32 1..65535) specifies packet parameters including size, fill type, TOS/FlowLabel, TTL, fragmentation bit, 802.1Q tagging, loose source route, and optional application-level credentials.
The sspmMIB module is registered under the RMON OID tree at { rmon 28 }, assigning OID subtrees for objects (sspmMIB 1), notifications (sspmMIB 2), and conformance (sspmMIB 3).
Even GET access to sensitive objects (credentials, source/destination addresses, routing options) should be controlled and the values encrypted in transit. Not all SNMP versions provide this capability, reinforcing the recommendation to use SNMPv3 with authentication and privacy.
The MIB can configure arbitrary packet sizes, injection rates, source/destination addresses, and routing options. If access is compromised, it can be exploited to launch denial-of-service attacks. The sspmGeneralMinFrequency object bounds the maximum packet generation rate a device is willing to support.
The sspmSourceProfileUsername and sspmSourceProfilePassword objects store application-level credentials in the MIB. Unauthorized read access to these objects may enable unauthorized use of application resources; encryption of SNMP traffic is therefore important.
SspmClockSource is defined as Integer32 (0..255), encoding the NTP stratum of the probe clock per RFC 1305: 0 = unspecified, 1 = primary reference, 2–255 = secondary (via NTP). Used by sspmGeneralClockSource.
SspmMicroSeconds is a textual convention defined as Unsigned32, representing time with microsecond resolution. Used for sspmGeneralClockResolution, sspmGeneralMinFrequency, sspmSourceControlTimeOut, sspmSourceControlFrequency, and sspmSinkExpectedRate.
sspmSourceProfile8021Tagging is an Integer32 (-1..65535): -1 indicates untagged packets; 0–65535 is the 802.1Q tag value. The 12-bit VLAN-ID field within the tag must not encode all-ones (value 4095); attempts to set such a value must be rejected with 'inconsistentValue'.
sspmSourceProfileLooseSrcRteFill is an OCTET STRING of up to 240 bytes encoding loose source route IP addresses as 32-bit IPv4 or 128-bit IPv6 values. The companion sspmSourceProfileLooseSrcRteLen (Integer32 0..240) specifies how many bytes to copy into the IP header option.