Switch WS-C3850 Vlan troublshooting

[Valentyn Lytvynov]

Firewall was replaced and after that users started complaining deny internet access only in one vlan 40 but for another is ok! Switch connected to firewall directly due to IP/29 and ping ca't path only through GW of vlan 40. Also if specify gw as firewal too users have access. 

The Main thing without changing of switch config after firewall replacement access to internet has been lost - how I can check from switch, if don't have any ACL restrict.

All another vlan have access to internet

[Valentyn Lytvynov · Accepted solution]

[Valentyn Lytvynov · Accepted solution]

Resolved: Due to connection to same subnet on two interfaces, collision were on the switch and it was blocked traffic
after disabling one - all work properly
Very interesting case but so trivial task

[Richard Burts]

Thanks for sharing your experience with us. Glad that you were able to find the solution to your own problem.

[Joseph W. Doherty]

That's a bit surprising as usually Cisco L3 devices throw an error for multiple interfaces on the same subject.