troubleshooting Question

NAT problems from VLANs on CISCO router

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ralonso asked on
Routers
9 Comments2 Solutions3432 ViewsLast Modified:
I have a CISCO 1710 router and a Netgear FS526T Switch.

After a while I've been able to sort most of the configuration out but there´s something that does not quite work properly.

I use the switch to create port-based vlans All the ports but one are untagged. The last port in the switch uses 802.1q vlan tagging and belongs to all the vlans.

That port is connected to the fastethernet interface in the cisco.

Up to here, everything is fine. I can connect machines to different ports and they can all access the router, but when I try to access the internet there is a strange behaviour: The VLAN 1 works normally and at full speed. The other VLANs experience problems accessing some web sites.

I can trace a route, query a dns server, even download web pages from some sites (i.e. microsoft or cocacola), but not others (like google or altavista).

I'll paste a bit of configuration to see if anyone can find my mistake.
(I found a web page with the same problem but no solution:
http://www.groupstudy.com/archives/associate/200104/msg00325.html)

interface Ethernet0
 ip address XX.XX.XX.XX 255.255.255.248
 ip nat outside
 half-duplex
!
interface FastEthernet0
 no ip address
 ip nat inside
 speed 100
 full-duplex
!
interface FastEthernet0.1
 encapsulation dot1Q 1 native
 ip address 192.168.37.1 255.255.255.0
 ip nat inside
!
interface FastEthernet0.2
 encapsulation dot1Q 2
 ip address 172.16.22.1 255.255.255.0
 ip nat inside
!
interface FastEthernet0.3
 encapsulation dot1Q 3
 ip address 172.16.24.1 255.255.255.0
 ip nat inside
!
ip nat inside source list 110 interface Ethernet0 overload
ip classless
ip route 0.0.0.0 0.0.0.0 XX.XX.XX.XX
no ip http server
no ip http secure-server
!

access-list 110 permit ip 192.168.37.0 0.0.0.255 any
access-list 110 permit ip 192.168.47.0 0.0.0.255 any
access-list 110 permit ip 172.16.0.0 0.0.255.255 any
access-list 110 permit ip 172.17.0.0 0.0.255.255 any

Thanks
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