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Community Member

Cisco 3850 connect to Cisco 1900 Internet router


I am having a strange problem that I have not yet been able to resolve, I have done a fair bit of testing before posting this as it may get me a faster solution.

Currently I have a 3750 Switch with a number of Vlans, one of the Vlan's has a Cisco 1900 ISP feed router attached and all working fine, Routing via this switch is all working as expected.

Here's the problem.

I am replacing the 3750 with a 3850 stack and copy most of the configuration across, I say most as a few commands are no longer supported on the 3850.

I connect the Cisco 1900 ISP feed router as I had previously however now the Internet does no longer work, everything else is fine, from my client Vlan I can still ping the Vlan Interface the Cisco 1900 is connected to but I cannot ping the router from a client Vlan.

I can ping the Cisco 1900 router from the Cisco 3850 switch and I can ping the Internet from the 3850 Switch through the Cisco 1900.

If I connect a laptop to the same Vlan as the Cisco 1900 router and give it for example the IP address of the router I can ping the Laptop from the client Vlan suggesting to me there is no routing problem, however when I re-connect the Cisco 1900 I cannot ping it even though it's the same IP.

The router is pingable as I can ping it from the 3850 switch.

If I connect a laptop to the same Vlan as the Cisco 1900 and give it an IP in the same range and specify the router as my default gateway I can connect to the Internet.

From my client Vlan I can ping the Laptop but not the Cisco 1900 router.

What's going on, am I loosing it or is there a subtle command that I need to type on the Cisco 3850 to make this work.

Any suggestion however small as I'm currently going round in circles.


Thanks in advance.









VIP Super Bronze

Did you turn on "ip routing"

Did you turn on "ip routing" on the 3850?


Community Member

Thanks for your comment.I

Thanks for your comment.

I have indeed, when I replace the Cisco router with a laptop and give it the same IP I CAN ping it.

Community Member

Have you configured a default

Have you configured a default route, as this will be needed?

As to the issue I assume you have added or changed addresses, as it seems the 1900 does not have a route to the 'client' VLAN, hence why the laptop works.

As a tip, ping using a source address.


Community Member

Thanks all for your

Thanks all for your suggestions.


I managed to have a look at the Internet feed router configuration and noticed it had some EIGRP settings.

My L3 switch did not have the EIGRP protocol enabled until I licensed IPservices.

Added the required EIGRP configuration details and hey presto.


thanks again for your suggestions.




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