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Thanks in advance for reading this post. I have five HP V1910 switches, three for office LAN, one for the server rack and the last was purchased for redundancy in the server rack. The first of the three for the office LAN has links to each of the other switches (hub and spoke topology from what someone else told me), and it is connected to the router that provides internet connectivity. This should mean that any device should only have one hop to get out to the internet and there should be no STP involved.

The redundant switch is now setup in the rack and it has a link to the main switch which connects everything together. The problem occurs when I try to link the two server rack switches together. This additional link between the two is specifically set for the storage VLAN which is a different VLAN than the office VLAN but as soon as it is connected, I lose connectivity to this switch (eg a continuous ping to this switch starts timing out).

Based on what I'm reading on this forum, it appears to be related to STP since that is now introduced with me linking these switches together. In the switch GUI, it has a section called MSTP and lists the following global settings:

Enable STP Globally: Enabled
BPDU Protection: Disabled
Mode: RSTP
Max Hops: 20
Path Cost Standard: Legacy

Is it the mode of STP that is being used that is causing this issue? I thought that since it was a different VLAN that it wouldn't have a problem with me adding a link between the switches. Or perhaps I shouldn't be even linking the two switches together? The thought was that since each physical host and storage has two links, we could separate the two links between the two switches and if one switch dies, then the environment still keeps running.

I appreciate any feedback. Thanks!

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    RSTP can have only one topology. Even though your new inter-switch link is on a different VLAN, it is still an inter-switch link. You would need a proprietary STP (such as Cisco's PVST+) or MST with your VLANs in different domains to achieve the effect you are looking to get. However it would appear you need a much better understanding of spanning tree before trying to implement MST. – YLearn Apr 23 '14 at 18:59
  • How are you connecting your servers to the two switches? Are you using separate IP addresses for each NIC? Are you "nic-teaming", or are you planning to run LACP (probably not in this configuration)? – Ron Trunk Apr 23 '14 at 21:03
  • Setting up a trunk port between the two switches will allow one cable to carry both VLANs traffic. Then you don't need the second link unless you want physical redundancy (but you will need STP in that case). – Jim G. Apr 23 '14 at 22:24
  • Thanks all for providing feedback. It appears the issue is with the setup using RSTP and that is causing it to drop packets on the link with the primary VLAN. Since it's not a huge concern, the link between the switches will be removed for now until I learn more about MSTP. – network_beginner Apr 28 '14 at 22:35
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 10 '17 at 3:49
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It appears the issue is with the setup using RSTP and that is causing it to drop packets on the link with the primary VLAN. Since it's not a huge concern, the link between the switches will be removed for now until I learn more about MSTP.

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