A platform system
resource monitor process is created when any of the CAC features listed in the
following table are configured on the Cisco ASR 1000 Aggregated Services Router
platform using the corresponding command:
Table 1. CAC Features and
their Platform System Resource Monitor Commands
CAC Feature
|
Command
|
CPU
|
platform subscriber cac
cpu
|
MEM
|
platform subscriber cac
mem
|
BQS
|
platform subscriber cac bqs
|
The platform
resource monitor process is disabled when all of the above CAC features are
disabled on the platform.
The platform
resource monitor process periodically monitors system resources such as CPU,
memory, and Buffer, Queue, and Scheduler (BQS). You can set the periodic
monitoring interval using the following command:
platform subscriber cac timer interval
The timer value specifies the frequency at which the CAC process
is polled to check platform resources. The valid interval value is in the range
of 1 to 10 seconds with a granularity of 1 second. The default value is 5
seconds.
Note |
Committed Memory
is used for monitoring subscriber CAC memory resource utilization. It provides
an estimate of the percentage of RAM that is needed to ensure a 99.99 percent
guarantee that there is never an Out Of Memory (OOM) condition during
worst-case conditions. Normally, the kernel will over commit memory by sharing
the memory between several processes. A problem with the actual memory
availability can be seen only when the memory is being used. While the
Committed Memory is a good indicator of the memory status, the value is less
dynamic. That is, if you use the
platform subscriber cac
mem command as part of CAC, a session may stay rejected for a
long period of time if it reaches the memory limit. While this may be a good
indicator of the decreasing memory resources, it may not be useful in
production environments. We recommend that if you are using the
platform subscriber cac
mem command, ensure that the values are at least at the 95
percent threshold to enable additional troubleshooting.
|
Example:
Configuring CAC to monitor platform specific resources, such as forwarding
processor (FP) CPU, FP memory, and Quantum Flow Processor (QFP) memory.
platform subscriber cac timer 5 #configures the frequency at which the CAC process polls or monitors the PD resources
platform subscriber cac bqs active-queues 95
platform subscriber cac mem rp 95
platform subscriber cac mem fp 95
platform subscriber cac mem cc 95
platform subscriber cac mem qfp 95
platform subscriber cac cpu rp 95
Example:
Configuring CAC to monitor IOS CPU load, maximum number of sessions, and
session charges (or calls per second).
call admission new-model
call admission limit 1580
call admission cpu-limit 90
call admission session-limit 128000
call admission ip 10 1
CAC is applicable to
any initiator for IP sessions such as unclassified MAC or DHCP-initiated
sessions. To enable CAC, the
call admission
new-model command must always be configured.
The
call admission
limit command specifies the total session charge the system will
accept before it starts rejecting incoming calls. In the above example, the
cpu-limit of 90 means incoming calls will be dropped when the measured 5-second
CPU utilization is 90% or higher.
Depending on which
condition occurs first, cpu-limit or call admission limit (charge limit), the
IP sessions will be rejected. The
call admission
ip command specifies the charge for a single IP session. In the
example given above, the charge for a single session is 10 is and lifetime of
the fixed charge (2s) is 1.
In the example
above, CAC will accept 79 CPS based on the following calculation:
Approximate CPS = (Call admission limit)/(Single session charge * Charge lifetime)
= 1580/(10 * (1*2))
= 79 CPS