Networking issues - latency/packets loss/page loading/file transfer

[pdenableetoavit19698]

Hi there,

On some networks we are using -still basic topo cisco router 880>cisco switch catlyst 2960/3500>wlan aironet-ME and similars, we have been noticing issues with high latency, packets loss, web pages needing to reloaded 3/5 times before actually connecting and being loaded, devices on the lan needing to be found via ip address only and cant be found via the server/host name, files taking days to transfer instead than a few minutes, and having a bit of issue trying to troubleshoot and find where the issue is. 

Where would you start from? 

What tests would you run?

What parts of the setup/devices tend to be the culprit of such issues? firewall? DNS? vlans/intervlan setup? router? Switch?

Thank you for any tips, trying to start from a fresh clean sheet of paper with new inputs.

Thank you

[M02@rt37 · Accepted solution]

Hello @pdenableetoavit19698,

Here are some steps you could take to troubleshoot and identify the root cause of the problem:

--Check the network utilization of the router and switches. High utilization could cause latency and packet loss. You can use tools like Cisco's IOS command

show interfaces

to check the interface utilization, or use SNMP-based network monitoringto monitor the bandwidth usage over time.

--Network loops can cause broadcast storms, which could lead to high network utilization and packet loss. Check if there are any physical or logical loops in the network topology. You can use the STP to prevent loops in the network.

--If you are experiencing issues with name resolution, check the DNS settings on your devices. Ensure that your devices are using the correct DNS server IP addresses, and that the DNS servers are functioning properly. You can use tools like nslookup or dig to test DNS resolution.

--If you have a firewall in your network, ensure that it is configured correctly and not blocking any necessary traffic. Check the firewall logs for any alerts or errors.

--If you have VLANs configured, ensure that the VLANs are correctly set up, and that devices are in the correct VLAN. Misconfigured VLANs can cause connectivity issues between devices.

=> If the above steps do not provide a clear indication of the issue, you can perform a packet capture to analyze the network traffic. Tools like Wireshark can help you identify network performance issues, such as packet loss or high latency.