Hallo,This is because of a

ciscoengsa · ‎04-01-2014

Hi guy

Recently we broguht 4506-E with Supp-8E and when connect our Stack switch 3750 with 4506 port gi2/1 in trunk mode and configure vlan 1 with ip address, from clinet site i can ping the 4506 ping for sudden period and after than i cannot ping it.

Ruben Cocheno · ‎04-02-2014

Spanning-tree?

Tag me to follow up.
Please mark it as Helpful and/or Solution Accepted if that is the case. Thanks for making Engineering easy again.
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Thomas Stahl · ‎04-08-2014

Hallo,

This is because of a bug

CSCuj73571

If you don't use VLAN1 the issue won't happen.

Another Workaround is to turn on and off "ipv6 snooping"...

Upgrading stack switch 3750 to switch 4506-E with sup8E