Document ID: 15182 | PDF Downloads
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- How is routing update overhead calculated in the Performance Service Manager?
- How is average delay calculated in the Performance Service Manager?
- When calculating delay caused by an access list, does Netsys Service Manager (NSM) look at the order of the statements in the access list?
- How do I take into consideration the effect of traffic that is not in the baseline model on links/routers that are in the model?
- Why does changing burst rate not have any effect on performance statistics? In this case, I want to change CIR on a Frame Relay circuit and see the effect.
- Does NSM take into account the impact of stack compression when configured on a router?
Related Information
- Q: How is routing update overhead calculated in the
Performance Service Manager?
- A: Routing update overhead considers update packet size and update interval for distance vectored protocols and hello interval for link state protocols. It is calculated during data collection.
- Q: How is average delay calculated in the Performance
Service Manager?
- A: Average delay is averaged over all possible paths from end system
to end system.
The following factors are used to calculate average delay:
- delay caused by FIFO-buffer-type queuing
- user-configured delay on a given interface
- switching-based delay
The Average Delay report reflects a one-way delay from the source to the destination, and will only report on the 100 worst (highest) values.
- delay caused by FIFO-buffer-type queuing
- Q: When calculating delay caused by an access list,
does Netsys Service Manager (NSM) look at the order of the statements in the
access list?
- A: The length of the access list on an interface is taken into account when formulating the delay factor. An on-average delay factor is taken into account, independently of where the rule occurs in the list.
- Q: How do I take into consideration the effect of
traffic that is not included in the baseline model on links and routers that
are in the model?
- A: Traffic that has a source or destination end system (or both)
that is not in the baseline model is displayed in the Remote Networks Report.
To consider the effects of such traffic on the existing model, edit that traffic
so it references two known end systems which would most closely follow the
path of the original unmapped traffic.
To accomplish this:
- Display the Communicating Pairs Report and filter for the Remote Network.
This gives you a list of traffic that originates or ends from an unknown
end system.
- Sort the resulting report by source address.
- Select as many entries as possible that can be mapped into any one
known subnet.
- Click on the "Edit" button.
- The "Task Manger" window appears with the Edit Traffic task highlighted.
- Follow the task steps to change the IP address of the selected report
entries.
- Repeat steps 3 through 6 for all unmapped traffic that you want considered.
- Display the Communicating Pairs Report and filter for the Remote Network.
This gives you a list of traffic that originates or ends from an unknown
end system.
- Q: Why does changing burst rate not have any effect
on performance statistics? In this case, I want to change the committed information
rate (CIR) on a Rrame Relay circuit and see the effect.
- A: The Performance Service Manager computes utilization and delay
at steady state. The resulting packet rate on a Frame Relay circuit will be
some (constant) number, and utilization will be relative to bandwidth. In
this situation, changing CIR is equivalent to changing bandwidth, and utilization
will vary inversely with bandwidth.
Because NSM does not model for transient analysis, you have to model both the "average" as well as the "worst" case in different scenarios to see whether CIR is exceeded.
NSM will provide information with regards to an average, whether you are within your subscription, and how much is available for bursts. It is recommended that this value be used as a measure of how much freedom you have for bursting rather than to change the traffic inputs and recompute the "averages."
- Q: Does NSM take into account the impact of stack
compression when configured on a router?
- A: NSM does not currently model the effect of stack compression when
configured on a router.
Related Information
| Updated: Oct 01, 2009 | Document ID: 15182 |