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You might not have the best network yet, however you have done a lot of work to keep things going. So far, the business network is up and running. But then you realize that network performance is not as it was used to be. Therefore you wonder, what happen? What cause the network to seem to go "slow"? And perhaps more important question is how you should improve the network performance.
Following discussion might remind yourself of your network with its current problem.
»Advice on Networking.
As solving any issue, you have to collect all necessary info to fully understand what happen on your network. In terms of network performance, you could have the following metrics in general.
* Line quality
* Network Device environment
* Network Design
* Bandwidth utilization
* CPU and memory utilization
* Software/Application performance
A first step of improving network performance is to set a baseline of how the network should perform based on metrics like the above. With that in mind, there should be a QA (Quality Assurance) or staging phase before anything is implemented into a production network. To accommodate potential "real" network slowness incidents such as delays and jitters, such should be introduced into the staging phase in order to have better understanding of how software or application's behavior is during network issues.
Once a baseline is set, you can assess to find out if there are illegitimate traffic or unexpected behavior in place or if you need to upgrade hardware, software, or services to meet your network requirement.
The term "line" here applies to all of the following
* Wiring and cabling between network devices (LAN)
* Circuit wiring (WAN)
LAN Wiring and Cabling
Let's say you have two network devices such as two servers. These servers are connected to each other using some kind of cable. In LAN technology, typically cables used are some Category 3 (RJ-11 analog telephone or POTS), Category 5/5E (RJ-45 10/100 Ethernet cable), or Category 6 (RJ 10/100/1000 Ethernet cable or LC/SC fiber cable). For best performance of connection between the two servers, the cable used should be Category 6 or fiber since Category 6 or fiber supports wider bandwidth.
When connection between these two servers go through wall or go between building, then typically there are patch panel and inside wiring (wiring within the wall) that are involved. You need to make sure that these patch panels and inside wiring support the same specification as the cable you use to connect the server and the patch panel. As example; if you use Category 6 cable to connect the server and the patch panel, then cables between patch panels and inside wiring also must match or exceed Category 6 specification. To make sure that end-to-end cable specification matches the Category 6 requirement, it is highly recommended to use special network gear such as Fluke meter to test the physical cable specifications.
»[Other] Cisco 6509 Possible Distance Issue
Beside using cable and wire to provide connections between the two servers, it is possible to use wireless technology. When such wireless technology is in place, you also need to make sure that the wireless connection support Category 6 specification. Since wireless connection is in general more prone to disruption than wired connection, there are more things involved. Check out the following FAQ for more info.
»Wireless Networking Forum FAQ
When connection between the two servers go over dispersed geographic location, then typically there are some WAN circuits involved such as DSL, Cable, T1/E1, ISDN, and the likes. Similarly, you have to make sure that these WAN circuits are up to their specification without degradations. Depending on how your network is setup, typically there are some kind of modem or router that provide WAN circuit connection. You might want to check the circuit quality by looking the modem or router reports on the line health. Check out the following FAQ for illustration.
»Cisco Forum FAQ »Technical Aspects in xDSL/Cable Internet connection
»Cisco Forum FAQ »Circuit Commission and Troubleshooting
Network Device Environment
As any machines, network devices generate heat. Therefore air flow is one of the key to keep network devices in healthy condition. One factor to keep good air flow is to make sure intake air is cool and exhaust air is hot. You also need to know how exactly your network device air flow works to make sure cool air is in and hot air is out.
Network devices also need to operate within certain temperature. Typically room temperature is preferable, however the device manual or official technical support is your best source. Certain room coolant like AC system is recommended to provide steady temperature.
Just like any electronic devices, network devices require power source. In addition, most network devices require power source with steady voltage and current. Such steady voltage and current coming from power source is called clean power source. Therefore network devices should never receive dirty power where the voltage and current are fluctuating. Typically you need some kind of UPS (Uninterrupted Power Supply) to ensure your network devices receive clean power source at all times.
Regularly maintain physical room where your network devices are is critical. The devices should never have dust bunnies, unknown gooey stuff, dirt, water, or anything that should not be there; since these kind of things are blocking the devices to have good air flow, to work within certain temperature, and to receive clean power source. Therefore typically the room where the network devices are should be well-insulated, dust free, and well-maintained.
Check out the following FAQ for more info
»Cisco Forum FAQ »Network Design Tips
»Cisco Forum FAQ »Tips in connecting hosts to switches
»Catalyst 3500 Series Dropping Like Flies?
Here is a list of common issues related to poorly design which can severely degrade network performance.
* Low reliability of network gears
* Poor cabling and physical interconnectivity
* Improper routing and switching design/implementation
* Poor concept and implementation of security zones
* Running untested/unbenchmarked software
* Incorrect software or operating system setup
Hire senior engineers to professionally review network design and setup is a good start to make decision moving forward. The review mechanism may involve vendors and telco providers in addition to lengthy and grueling process.
Bandwidth Utilization and Latency
There is a myth that in order to speed things up over network, simply upgrade the bandwidth as resolution. This statement is inaccurate since network bandwidth is only part of potential problem. The network latency instead is most likely be more of a concern rather than the bandwidth size.
As illustration, let's say your application is most likely using 2 Mbps bandwidth every time. If you currently have 10 Mbps bandwidth, upgrading the bandwidth from 10 Mbps to 100 Mbps with the intention to solve slowness issue may not be the best solution since 2 Mbps is still 20 percent bandwidth utilization of 10 Mbps pipe, which is well below used.
Your operating system, software, and all applications run over your network devices require certain bandwidth and/or latency threshold to work as expected. Consult vendor of the operating system, software, and all applications to find out how much bandwidth or latency threshold these systems require to normally operate, since the vendor should be the best source. Keep in mind that this step is essential to obtain baseline of how the systems should operate.
In addition, there should be a regular monitoring of how the bandwidth there is in your network is consumed. If the bandwidth utilization is high, find out if this utilization is caused by legitimate traffic and not caused by some virus or errors on the operating system, software, or any applications run over your network devices. When there is a baseline of how the systems should operate, your job of finding legitimate traffic will be easier.
When the bandwidth utilization is high and is caused by legitimate traffic, then upgrade the bandwidth is highly recommended to ensure the smooth operation of the system.
CPU and Memory Utilization
Your network devices are pretty much computers. Just like any computers, there are CPU (computer's brain power) and memory to process all traffic pass through the devices. Typically by running more and more software and applications, there will be a need for more brain power (CPU power) and larger memory.
Regular check of these CPU and memory utilization will suggest the current and possible future utilization. Similar to the bandwidth utilization, upgrading CPU and memory is highly recommended to ensure the smooth operation of the system when CPU and memory utilization is high and is caused by legitimate processes.
As mentioned briefly, there should be a baseline of all software and application run over the network. This baseline include the inner working of the software to find out what network to expect to ensure smooth operation of the software. Typical inner working within the baseline is how client-server relationship should occur within certain time period. In addition there should be a baseline how much bandwidth, CPU, and memory the software need to ensure the smooth operation.
Note that the software vendor might not be able to provide a precise baseline since networks are different from one organization to another. Therefore you might need some kind of software performance monitoring like OPNET and Cascade to find out exactly what happen during the client-server relationship and if those events happen as expected or not. The use of such software performance monitoring will also help you to establish baseline of your own network, which should be more precise than general baseline provided by the software vendor.
More info on performance monitoring
Check out following FAQ for more info on bandwidth, CPU, memory utilization monitoring and software/application performance monitoring.
»Cisco Forum FAQ »Automatic Network Health Monitoring and Reporting System: An Introduction
»Cisco switch into non-cisco switch, unknown initial lag