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L3 Switch to internet connectivity

I have a Cisco Switch 3850X which is totally fibre interfaces. I have created 5 vlan and there is intervlan routing at L3 in the switch. Each vlan has dhcp pool. The switch is further connected to 8 access switches with gigaethernet access ports. At access layer, all the ports are getting dhcp of their respected vlan and can ping to other vlan and their default gateway. 


Our internet router has ip address which is normal modem, not Cisco router. To connect to internet, I have created separate vlan 80 and made L3 routing. interface vlan 80 has the ip address


interface Vlan30
ip address
interface Vlan40
ip address
interface Vlan50
ip address
interface Vlan60
ip address
interface Vlan70
ip address

interface Vlan80
ip address


This vlan is assigned to the port in other switch which is having the access vlan 80. And ethernet is connected to the router 

I created below ip route

ip route 

to point internet traffic to the internet router. 

From the main core switch 3850, I am able to ping the router and also innternet dns which means internet is working there. But when my computer is connected to any other vlan IP Address like, I am able to ping only. While I can't ping the connected router which is Thus I am not able to ping the internet also or from the PC.


Could anyone suggest the possible reason or solution? Will appreciate your help in this regard. 

Hall of Fame Guru

Re: L3 Switch to internet connectivity

Your router needs routes back to the subnets on your 3850 eg: on your router - 


"ip route" 


you would need a route per subnet added or you could just do a route for if you wanted. 


Note the above is Cisco syntax but it should give you the idea. If your modem does not support adding routes then you are out of luck I'm afraid as the 3850 does not support NAT.


You will also need to setup NAT on your modem for the other subnets, again some modems support this, some don't. 



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