Patent Application
20060020853
This invention relates generally to redundancy-based systems and more particularly to operational switchover from one service unit to another.
Many modern systems, such as communications networks, are comprised of a plurality of networked but discrete platforms. One approach to facilitating full-time or near full-time system availability and operability provides for one or more such discrete platforms that serve in a stand-by mode. So configured, when a given system node fails, that failure will typically be noted by another system element (for example, by the absence of an expected so-called heartbeat signal from the failed node). This system element can then instigate substitution of the stand-by platform for the failed node.
Such a strategy provides adequate service under at least some operating conditions. In other settings, however, such an approach can prove inadequate. As one example, a system (such as many communication systems) handling time critical or time sensitive operations can experience considerably degraded service when employing such teachings. Problems can arise, for example, due to a minimum amount of time that may be required to first detect the failure and to then effect the operational substitute of the stand-by unit. In some instances, considerable time can be required to bring a given stand-by unit sufficiently up to speed to ensure that it will likely adequately meet the present needs of the system. For example, it may be necessary to populate the stand-by platform with present and unique operational settings and parameters as pertain to the present tasks and/or operations of the failed node.
The above needs are at least partially met through provision of the switchover facilitation apparatus and method described in the following detailed description, particularly when studied in conjunction with the drawings, wherein:
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will also be understood that the terms and expressions used herein have the ordinary meaning as is usually accorded to such terms and expressions by those skilled in the corresponding respective areas of inquiry and study except where other specific meanings have otherwise been set forth herein.
Generally speaking, pursuant to these various embodiments, one detects a level of degraded operational status as corresponds to an active service unit. In a preferred embodiment this degraded operational status corresponds to a level of degradation that is less degraded than a failed operational status. One then simultaneously and automatically both continues to operate the active service unit notwithstanding the degraded operational status while also actively preparing a stand-by service unit to operationally replace the active service unit. Finally, one then essentially simultaneously and automatically ceases operation of the active service unit and initiates operation of the stand-by service unit as a hot-switchover to replace the active service unit. In a preferred embodiment this further comprises resetting the active service unit.
So configured, a redundant back-up is instigated prior to failure of the replaced platform. In many instances this permits the switchover itself to occur with little or no effective latency or interruption to service. In particular, the replaced service unit, though operating in a degraded mode of operation, is still nevertheless providing some level of service until the switchover occurs. In addition, the stand-by platform has the opportunity to become properly pre-configured prior to accepting the switchover responsibility and in parallel with continued operation of the unit to be replaced. This will often result in little or no interim preparation time being necessary once the switchover is actually authorized.
These and other benefits will become more evident upon making a thorough review and study of the following detailed description.
Referring now to the drawings, and in particular to
Pursuant to a preferred approach, the active service unit 11 has stored therein (or otherwise has access to) at least one partially degraded operational state criterion. The active service unit 11 further preferably has, in addition to its normal mode(s) of operation, a switchover mode of operation that is responsive, at least in part, to the partially degraded operational state criterion and a reset mode of operation. So configured, and with momentary reference to
Pursuant to a preferred approach, the partially degraded operational state criterion corresponds to a level of operability that represents a higher level of operability than a failed operational state. That is, although the active service unit may be operating at a less than optimum state, or may be operating momentarily at an ordinary level of performance but in parallel with one or more circumstances that likely indicate that such performance will likely degrade in the relatively near future, the active service unit is nevertheless providing service within the system 10 as versus having failed in this regard. Various such criterion can be used, including but not limited to (and alone or in combination with one another):
Referring again to
Those skilled in the art will appreciate that such a system, or such other enabling platform(s) as may be substituted therefor, can be readily programmed and configured to facilitate an overall process 30 as appears in
Upon detecting an unacceptable level of operability that is still nevertheless less degraded than a failed operational state, this process 30, simultaneously and automatically, continues 35 to operate the active service unit while also actively preparing the stand-by service unit to operationally replace the active service unit. As will be shown below, such preparation can comprise, pursuant to one approach, communicating a switchover message to the stand-by service unit. Such preparation can also include, for example, providing data to the stand-by service unit as corresponds to current activities of the active service unit to thereby better facilitate the ability of the stand-by service unit to effectively substitute for the active service unit.
This process 30 then, essentially simultaneously and automatically, ceases 36 operation of the active service unit and initiates operation of the stand-by service unit as a hot-switchover to replace the active service unit. In a preferred optional embodiment these events occur regardless of any subsequently developed or received information regarding the operational status of the active service unit; that is, the switchover occurs regardless of how healthy the active service unit presently appears and/or how transitory the triggering condition of concern may now appear to be. In a preferred approach and as presented below in more detail, initiation of the switchover can comprise detection of the present non-operational status of the active service unit (by a third unit such as, but not limited to, the above-described controller) and a corresponding initiation by that third unit of operation of the stand-by service unit as a replacement for the active service unit.
In a preferred approach, cessation of operations by the active service unit further comprises effecting a reset (and preferably an automatic reset) of the active service unit. In some cases this action may be expected to clear whatever condition had occasioned the detected partially degraded operational state. This, in turn, makes more reasonable an optional step of using 37 the now inactive active service unit as a stand-by service unit for another active service unit when and if such substitution becomes appropriate.
So configured, it will be appreciated that a stand-by service unit can be effectively prepared for its operational assignment prior to actually literally needing a switchover. This, in turn, can permit the stand-by service unit to potentially be more completely configured and apprised of relevant operating conditions, needs, and requirements and therefore more likely to produce a switchover that is both transparent to the user and effective in purpose.
Such processes can be facilitated in various ways. As but one exemplary illustration, and referring now to
Those skilled in the art will recognize that such a message can comprise a single signal or message packet or can, if desired, comprise a plurality of discrete signals/messages. Those skilled in the art will also recognize that such a message can be communicated using any appropriate communication medium or link as may be available for use by the active and stand-by service units in a given setting.
Upon then receiving 43 a switchover message from the stand-by service unit, the active service unit can then cease 44 its own current operations. Again, this switchover message can comprise any signal(s), message(s), or combination thereof as can be established to serve in this fashion. As will be shown below, in a preferred embodiment, the stand-by service unit sources this switchover message to signal its own present readiness to now assume the operational activities of the active service unit. Also in a preferred embodiment, the active service unit will effect this cessation of operations regardless of other operational status information as may have been determined by the active service unit subsequent to communicating the switchover message to the stand-by service unit.
In addition to ceasing its present operations, in an optional embodiment the active service unit can also be reset. That is, and in accordance with well understood prior art technique, the active service unit can have some, most, or all of its operational parameters, settings, and states reinitialized to some basic initial operational state. In at least some cases this resetting may clear the condition or conditions that gave rise to the detected degraded operating condition. It is also worth noting that, in at least some instances, resetting the active service unit while exhibiting a somewhat degraded operational state but prior to become more completely degraded may more likely lead to a successful resolution of the problem or problems besetting the active service unit, thus, in the broader view of things, leaving the system with a higher overall level of capability and continuing operability than some prior art techniques.
Similarly, and referring now to
The stand-by service unit can then communicate 53 a switchover message to the active service unit to indicate operational readiness to replace the active service unit. In a preferred embodiment this message will not be sourced until the stand-by service unit in fact has completed its prepatory steps, though there may be instances or situations where such a message can be appropriately sent notwithstanding that complete preparations have not been completed (for example, when the communication link between the stand-by service unit and the active service unit exhibits a considerable degree of known or at least expected latency).
Upon then receiving 54, from a third unit (such as a system controller, shelf controller, or the like), an instruction to replace the active service unit, the stand-by service unit can then assume support 55 of the activities of the active service unit.
The stand-by service unit conducts its replacement preparation activities 64 and, when ready, transmits a reply switchover message 65 to the active service unit to indicate its own readiness. Pursuant to this approach, then, the active service unit can unilaterally and automatically cease its own current operations 66 (and, optionally, reset itself as well). In accordance with prior art practice, this cessation of operations can be detected by the controller that responds, again in accord with prior art practice, by sending a replacement instruction message 67 to the stand-by service unit. The latter can then effect the switchover and assume the activities of the previously active service unit. This example again will be understood to comprise only one example of many and those skilled in the art will appreciate that the teachings set forth herein can be applied in myriad ways.
So configured, a hot switchover can be facilitated that poses reduced risk of undesired transition events (dropped calls, incompleted calls, undesirable communication artifacts, and so forth). In addition, in at least some instances, overall system resources are likely preserved and maintained at a higher level of effective readiness than may be expected with at least some prior art approaches. These processes can be effected with little or no hardware alterations and hence, in many instances, can be facilitated at reasonable cost.
Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept. For example, rather than having the active service unit monitor itself for somewhat degraded operating performance or conditions, an external component or components can be tasked with this activity. Upon detecting such a condition, the external element(s) could then transmit a corresponding message to the monitored active service unit to then trigger the remaining actions and events described above.
