CISCO-ERM-MIB
Cisco Embedded Resource Manager (ERM) MIB. The Embedded Resource Manager (ERM) is a framework which helps in effectively managing resources such as cpu, memory, buffers, etc. There are two important scenarios where the ERM framework would be useful: 1. Resource Depletion - how to gracefully handle a situation where the system runs out of a finite resource. 2. Resource Separation - how to share resources fairly between different entities in the system such that activity of one entity does not adversely affect others. The ERM framework has the following entities: 1. Resource Owner Resource Owner (RO) provides resources to one or more resource users. Example: cpu, memory and buffer. The resource owner doesn't mean the physical resource. For example, 'memory' resource owner would actually mean the memory manager rather than the physical memory. 2. Resource User Type Resource User Type (RUT) is a template which defines a set of resource owners from where resources can be obtained by any of the resource users instantiated from the resource user type. 3. Resource User Resource User (RU) is a logical entity or application that consumes one or more resources. Resource users are instantiated from the Resource User Type. Resource user can also be called as 'instance of a resource user type'. A resource user registers with a resource user type and thus it is indirectly registered with all resource owners defined by the resource user type. 4. Resource User Group Resource User Group (RG) is a logical entity which contains group of resource users. It would hence forth be referred as Resource Group. In some cases (for example, multiple users with same name), user may want to set threshold value for sum of resource utilized by a group of resource users. In such case, those resource users can be grouped/added under a resource group. Then, user can apply a resource policy to the resource group. 5. Resource Usage Monitor This is also called as Resource Monitor (RM). The resource monitor is a logical entity or application that monitors resource owner, resource user, resource policy and resource owner <-> resource user relationship. When any applied resource policy is violated, all resource monitors monitoring the resource policy will be notified and the resource monitor can take appropriate action based on the resource owner and resource user attributes. The ERM framework allows three types of thresholding: 1) System Global Thresholding When total utilization of a resource exceeds the applied global rising threshold value, all resource users which consume resources from the concerned resource owner are notified to take appropriate action. The notification order is determined by priority of the resource users. Resource users with a lower priority are notified first, so as to enable lower priority resource users to reduce its resource consumption prior to any higher priority resource users. This order prevents higher priority resource users to start freeing up their resource, thereby not affecting their performance. 2) User Local Thresholding When utilization of a resource by a specific resource user exceeds the applied user local rising threshold value, a notification is sent *only* to the concerned resource user. The user local thresholding method can be used to prevent a resource user from monopolizing any available resources. 3) Per User Global Thresholding When total utilization of a resource exceeds the applied per user global rising threshold value, a notification is sent *only* to the concerned resource user. Each resource user can have its own per user global threshold value (per resource owner). Per User Global Thresholding is similar to System Global Thresholding, except that notification for Per User Global Threshold violation is sent only to the corresponding resource user. The main purpose of the Per User Global Thresholding is that a resource user can take preventive actions based on the global resource utilization of a resource. The Embedded Resource Manager (ERM) framework allows applying and monitoring threshold limit for usage of resources such as cpu, memory, buffer, etc. Exceeding any applied rising threshold value will trigger an 'up' notification to relevant resource user(s) and resource monitor(s) based on the type of violated resource policy. After the 'up' notification, if the utilization goes below the falling threshold value, a 'down' notification will be sent to the resource user(s) and resource monitor(s). The 'up' and 'down' notifications do not mean the SNMP notifications/traps. Rising threshold value and falling threshold value should be different to avoid flapping. The ERM framework enables configuration of resource policy in which rising/falling threshold values for a set of resource owners can be specified. There are two types of resource policies which can be configured. 1) Global Resource Policy There can be only one global resource policy applied in the system at any point of time, though multiple global resource policies can be configured. On violation of a applied global resource policy, all resource users (which consume resources from the concerned resource owner) and resource monitors (which watch the concerned resource owner) will be notified to take appropriate action. 2) Local Resource Policy The local resource policy is configured for a specific resource user type. This policy can be applied for a resource user (or group) of the same resource user type. A local resource policy can be applied for more than one resource users (or groups). Both user local thresholding and per user global thresholding can be configured under a local resource policy. On violation of any local resource policy, only those resource users on which the violated resource policy was applied, will be notified in order to take appropriate action. Whenever a resource is consumed, current utilization of the resource will be compared against the applied rising threshold value. The ERM framework provides a mechanism to send notifications to resource user(s) and resource monitor(s) whenever resource utilization exceeds any applied rising threshold value or falls below any applied falling threshold value. In such situations, the resource user(s) can take appropriate corrective action (for example, limiting or avoiding resource consumption). Thus, the ERM framework helps in preventing catastrophic system failures caused by high levels of resource depletion. The ERM framework can be extended to all kinds of resources (for example, incoming control plane packets) that need to be managed. The ERM MIB module facilitates the following operations: 1. Getting information about all the above mentioned ERM entities available in a managed system. 2. Creating/modifying/removing a resource policy. 3. Creating/modifying/removing a threshold configuration for a particular resource policy. 4. Creating/removing a resource group. 5. Adding/removing a resource user to/from a particular resource group. 6. Applying global resource policy. 7. Applying local resource policy for a resource user or resource group.