cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements

Cisco Community Designated VIP Class of 2020

773
Views
0
Helpful
1
Replies
Highlighted
Beginner

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 192.168.8.1 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 192.168.8.254.

 

interface Vlan30
ip address 192.168.3.1 255.255.255.0
!
interface Vlan40
ip address 192.168.4.1 255.255.255.0
!
interface Vlan50
ip address 192.168.5.1 255.255.255.0
!
interface Vlan60
ip address 192.168.6.1 255.255.255.0
!
interface Vlan70
ip address 192.168.7.1 255.255.255.0

!
interface Vlan80
ip address 192.168.8.254 255.255.255.0

 

This vlan is assigned to the port in other switch which is having the access vlan 80. And ethernet is connected to the router 192.168.8.1. 

I created below ip route

ip route 0.0.0.0 0.0.0.0 192.168.8.1 

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 8.8.8.8 which means internet is working there. But when my computer is connected to any other vlan IP Address like 192.168.3.0, I am able to ping 192.168.8.254 only. While I can't ping the connected router which is 192.168.8.1. Thus I am not able to ping the internet also or 8.8.8.8 from the PC.

 

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

1 REPLY 1
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 192.168.3.0 255.255.255.0 192.168.8.254" 

 

you would need a route per subnet added or you could just do a route for 192.168.0.0/16 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. 

 

Jon

CreatePlease to create content
Content for Community-Ad
FusionCharts will render here