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How to stop Cisco 1721 from automatically routing between Vlans

Posted on 2008-09-30
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Last Modified: 2012-05-05
I have a Cisco 1721 with a 10bt WIC in it.

I have trunking configured on the fa0 interface and PAT configured on the e0 interface.  I have 2 vlans trunked with dot1q to the fa0 interface

Vlan1: 192.168.20.0/24
Vlan2: 192.168.100.0/24

PAT/DHCP are enabled to serve both vlans.

My question is, how do i prevent Vlan1 from pinging/accessing Vlan2 and vice versa?

Seeing as how both vlans are in my connected routes in show ip route, the router just assumes it should route to them, but I want them segmented, yet still able to access the internet through e0

Thanks.
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Question by:Probity
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JFrederick29 earned 500 total points
ID: 22607420
Use an access-list instead:

ip access-list extended 150
deny ip 192.168.20.0 0.0.0.255 192.168.100.0 0.0.0.255
deny ip 192.168.100.0 0.0.0.255 192.168.20.0 0.0.0.255
permit ip any any

int vlan1
ip access-group 150 in

int vlan2
ip access-group 150 in
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LVL 23

Expert Comment

by:that1guy15
ID: 22607428
Apply an ACL to both sub interfaces that block traffic from the other vlan.
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