11-26-2018 12:51 AM - edited 03-08-2019 04:40 PM
Hi,
I have just installed 2 Catalyst 3850 switches in the stack and trying to connect them to another 2 Cisco SG550XG-8F8T switches via 10Gb SFP+ interfaces but they don't really like each other. Both constantly complaining about flapping interfaces and ports getting blocked. If I am using only one link, both ends show interface up but no traffic flow between them except CDP. I've tried both trunk and access port, tried even disable spanning tree on 500 switch but still have the same issue.
Connection between those switches via regular 1Gb Ethernet works fine.
Do you guys know what could cause that?
Thank you
11-26-2018 01:02 AM
Hi,
Are you using the correct SFP+ (MM or SM) on both sides of the connection?
How about the fiber patch?
HTH
11-26-2018 01:18 AM
It should be correct. I’ve ordered them together with switch. Is there any compatibility matrix available?
Sorry, I don’t have a fiber.
11-26-2018 12:07 PM
adding to other post,
can you post the logs and configuration if possible. also show spanning-tree block from cisco 3850
do you have UDLD enable on 3850 ?
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