I have a star topology consisting of 12 switches. Recently, we began running low on available IP addresses (192.168.100.0/24) and I was asked to open up a new scope (192.168.50.0/24) on the DHCP server.
The scope has been created, I tied it to the same VLAN 50 on all switches, tagged and untagged the appropriate ports and everything seemed to be fine. The clients correctly grab their IP address from the newly designated scope, and they have full network access.
The problem we are seeing is that when a host tries to communicate with a host on the other VLAN, there is anywhere between 0-10% packet loss. If I run a constant ping across the VLANs and it isn't dropping any packets, I will get 3-4ms per attempt and then a 30-40ms packet every 15-20. Any host that communicates with its own VLAN is flawless.
The switches are mostly HP Procurve 1920-24G, with a couple of 1910-24G models that haven't been replaced yet.
I have checked on multiple occasions to make sure that there isn't a loop in the network, because the switch logs all seem to show ports intermittently changing their status to DOWN and back to UP right away over a period of a few seconds. Sometimes this will happen every 90 minutes or so, and the port is not always the same.
It just seems quite strange that there are only issues when the communication crosses over to the other VLAN.
I can upload any configs or output, if needed.
Best Answer
If the problem only happens between VLANs, you need to look at the router which is used to route between the VLANs. It may be overloaded on its CPU or buffers, but that is the common point between VLANs, and that is the place to start your investigation.