Internet speed dropped down

[maharbiayuob]

Hello everyone 

We face a big problem in one of our schools

The internet speed dropped from 100 mb/s to less than 5 mb for a short of time then back up to 100 mb/s. this occur all day. All the switch the installed are catalyst 2960 with basic configuration.

Any advice to how to resolve or find the issues.

Sorry for my bad English.

[Joseph W. Doherty]

"Any advice to how to resolve or find the issues."

Hire or contract an experienced network engineer.

Probably not the answer you're looking for, but there can be so many causes.  Also, I'm guessing, possibly, you're not real knowledgeable about networks, so you might not understand technical questions and/or suggestions.  Also, "school" is a red flag.

If you wish to further pursue help here, can you provide detailed network topology, network device configurations, specific network device models with specific installed OSs, feature licenses, information about your ISP, etc.?

[Kasun Bandara]

@maharbiayuob hello, there can be may facts to this issue. you can start by checking with ISP and check the throughput of your devices such as firewalls, routers and switches when issue happens. try top-down troubleshooting method. also check if issue is common for only few users and try to isolate the reason.

[balaji.bandi]

I will be in line with other post and suggestions.

Is this speed issue - when does this started ? is the issue there from the day one ? what was the recent changes in the network ?

i would like to add some more test if you can able to do. do you have any NMS which can give you full picture how the utilization in the network, Do you have high level diagram of your network.

You trying from end device which is connected to access switch for the speed.

Did you connected the Test PC where the ISP link connected and tested ? is the same results ?

Off peak time can you remove Internet Link and connect directly to your PC (if can simulate that your ISP link is stable ? and get all time 100MB or 80% of the link speed all time ?)