GbE2c cross link ports 17 and 18

[Robert Marek]

Hello,

I have c7000 enclosure with 6 blades and 8 switches. I created VLAN to separate 3 Lefthand nodes and 4 blades with ESXi hosts. They reside on the same VLAN. I'm using ports 17 and 18 to connect switches in pairs and also up linking switches vertically using trunking groups. So far all seems to be communicating fine but when I tried to change cabling and ports configurations my cross links didn't work.
I wonder if switches must be reset to default settings before I can create new configuration.

I just don't understand why port 17 and 18 wouldn't work since it's internal and connects left and right switch...as soon I changed my cabling (which has nothing to do with port 17 and 18) cross links works again....

Thanks in advance for any help.

[Pieter 't Hart]

please specify "cross links works again...."

changeing cabling may initiate a spanning-tree reconfiguration that results in this behaviour.
spanning tree may have blocked port17/18 ?

[Robert Marek]

Spanning tree may have cause this? Interesting. I'm very new to this and I'm trying to learn...
By "not working" I meant not being able to communicate between pair of switches A<-->B.

Is it possible to create redundant setup with 8 switches in one enclosure so if one or two goes offline rest of them will keep my network up? I guess they would need to be uplinked to my main switch - 5406zl and VlAN's would need to be created right there. Any suggestions for good setup?