An application can receive status indications through asynchronous notification or polling. A status indication is sent to all applications when the corresponding network status changes. The following table describes the status indications:
Status indication |
Description |
StatPaused |
Delivery to the specified destination point code is not currently possible. It can mean that there is no route configured for the destination point code or that all routes to that point code are currently unavailable. |
StatResumed |
Occurs after a StatPaused indication if one or more routes to a particular destination point code become available. |
StatCongested |
Delivery to the destination SP failed due to network congestion at some point along the route. The user part or application must reduce traffic to that destination. |
StatCongestionEnds |
Occurs after a StatCongested indication when network congestion has abated. |
StatUsrUnavail |
Message was delivered to the remote MTP 3 layer, but no application was registered to receive data with the service information octet (SIO) contained in the message. For example, data was sent with an SIO indicating an ISUP message, but there was no ISUP application running at the destination. The remote MTP 3 layer discards the message. |
StatRestart |
Local MTP 3 layer is going through a restart. The restart is followed by a StatRestartEnds. The application must not send any data messages after receiving this indication. Messages will be discarded during the restart procedure. |
StatRestartEnds |
Local MTP 3 layer completed its restart. The application can resume sending data messages. |
StatPrimary |
Local MTP 3 is the primary in a redundant configuration. |
StatBackup |
Local MTP 3 is the backup in a redundant configuration. |
StatStandAlone |
MTP 3 is not in a redundant configuration. |
An extended status indication is sent to all applications registered to receive extended status indications (using MTP3RegXStaReq) when certain components of the MTP layer change state. MTP 2 links are the only components that support this feature. The following table describes the extended status indications:
Extended status indication |
Description |
XStatLinkUp |
Link finished aligning and is now available to the MTP 3 layer. Traffic can be carried over the available link. |
XStatLinkDown |
Link is out of service. The MTP 3 layer now uses other links, if available, to carry traffic. |
XStatLinkInh |
Link is inhibited. Links become inhibited by management requests. The network (MTP layer) never inhibits a link by itself, although it can uninhibit the link. An inhibited link is no longer used by the MTP 3 layer to carry traffic. |
XStatLinkInhDen |
MTP 3 management entity attempted to inhibit a link, but the inhibition was denied because inhibiting the link causes a destination to become inaccessible. |
XStatLinkUninh |
Link became uninhibited and is now available to the MTP 3 layer for carrying traffic. Links can be uninhibited by MTP 3 management entities or automatically by the MTP 3 layer. |
XStatLinkUninhDen |
Uninhibition of a link was denied. This indication occurs when the local MTP 3 layer is not able to negotiate the uninhibition of the link with the remote MTP layer. The link is still unavailable to the MTP 3 layer to carry traffic. |
XStatLinkRemBlock |
Link is remotely blocked as a result of a processor outage on the remote side of the link. The link is no longer available to carry traffic. |
XStatLinkRemUnblock |
Link is no longer remotely blocked. The link is now available to carry traffic unless inhibited or locally blocked. |
XStatLinkLocBlock |
Link is locally blocked as a result of a local processor outage. The link is no longer available to carry traffic. |
XStatLinkLocUnblock |
Link is no longer locally blocked. The link is now available to carry traffic unless inhibited or remotely blocked. |