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trouble after using cisco switches

Hi, after we replaced out old switches with Cisco SG300 there is some strange problems. We have 2 x SG300 10 port and 4 x SG300 28 port. There isnt any Vlan or anything, its static IP on them. 20-30 times a day the network loose the connection to the router/firewall, the router/firewall is a Sonicwall NSA 240 and i have tried to replace that with a new one, didnt help. When the connection to the Sonicwall is gone everything else works as normal, i have tried to move sonicwall to a new port on the Cisco switch, i have also tried to connect a dlink switch between the sonicwall and cisco, that dont help. If i dont do anything the connection is back in 1-10 min. If i restart the sonicwall its back, but i dont know if its the restart that do that. On the sonicwall i have DMZ and the computers in DMZ works okey, but they loose the connection to the LAN.
Its seems like the problem is growing with more Cisco switches in the network. I updatet to the newest firmware today and it looks like it got a litle better, but it still loose connection all the time.
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per-w
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per-w
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2 Solutions
 
giltjrCommented:
For any port that is connected to a host I would configure the port as spanning-tree portfast.

Leave any port that is connected to a switch with it turned off so spanning tree can do its job.
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per-wAuthor Commented:
ok, i will try that. But should i see the Sonicwall as a host or switch?
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per-wAuthor Commented:
After upgrade of all firmware so all cisco switches has same firmware seems to have fix the problem.
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giltjrCommented:
Glad to here the firmware upgrade fixed the problem.

The Sonicwall would be a host.

What I was thinking was causing the problem was that when a PC re-booted the switch would see the port go down, then back up.  When spanning tree is enabled, the switch will go through a 30 second process to figure out if the device on that port is another switch or a "regular host".

Spanning tree prevents loops in the network and that should only happen when you have switches connected or a device that can bridge traffic and is connect to two different switches that have a common layer 2 network path someplace.

Sometimes when a switch goes through spanning tree learning process it interrupts traffic for a little while.
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per-wAuthor Commented:
firmware solved the problem
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