900 ISR DHCP WAN gi5 port No Internet

[T0mTheCat]

Hi!

Current network has Asus router connect to ISP Modem, local network is working ok.

Cisco Router connected to the local network switch -> router WAN port gi5

I am trying to test if the gi5 WAN port on dhcp is working 

I could not ping from router to 8.8.8.8 

R1(config)#int gi5
R1(config-if)#do ping 8.8.8.8
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

interface GigabitEthernet3
switchport access vlan 20
switchport mode access
no ip address
!
interface GigabitEthernet4
ip address dhcp
duplex auto
speed auto
!
interface GigabitEthernet5
ip address dhcp
ip nat outside
ip virtual-reassembly in
duplex auto
speed auto
!
interface Vlan1
no ip address
!
interface Vlan20
ip address 192.168.2.1 255.255.255.0
ip nat inside
ip virtual-reassembly in
!
ip forward-protocol nd
ip http server
ip http authentication local
ip http secure-server
!
!
ip nat inside source list 1 interface GigabitEthernet5 overload
ip nat inside source list list1 interface GigabitEthernet5 overload
ip route 0.0.0.0 0.0.0.0 GigabitEthernet5 dhcp
!
ip access-list standard list1
permit any
!
!
!
access-list 1 permit 0.0.0.0 255.255.255.0

What did I miss?

Much appreciate your assistance! Thank you!

[paul driver · Accepted solution]

Hello

I think you need to check the physical connectivity between asus and rtr1 i see you have two switches interconnected 

Also why are you setting the wan interface of rtr1 to dhcp - is the asus supposed to be providing address allocation for rtr1 ?

lastly remove the static route from the rtr1 that static route relating to the svi 250 on the rtr1 so it isn’t required 

Confirm the physical connectivity please 

[Richard Burts · Accepted solution]

The output of show ip interface brief shows G5 using DHCP but with no IP address learned. That would also explain why default routes using G5 are not being installed in the IP routing table. We need to figure out the issue with DHCP on this interface.

[T0mTheCat · Accepted solution]

Hi @Richard Burts and @paul driver 

Thank you so much! After I plug Cisco router gi5 direct to the TPLink Switch, it works!

Now, I can ping and tracert 8.8.8.8 from the PC plug to the Cisco switchport gi3

I cant get to any website or internet, i believe DNS or NAT is causing the issue?

Here is my config

ip dhcp pool pool1
import all
network 192.168.250.0 255.255.255.0
dns-server 75.75.75.75 ---> 8.8.8.8 it works now!!!
default-router 192.168.250.1
!
!
!
ip cef
no ipv6 cef


interface GigabitEthernet0
no ip address
!
interface GigabitEthernet1
no ip address
!
interface GigabitEthernet2
no ip address
!
interface GigabitEthernet3
switchport access vlan 250
switchport mode access
no ip address
!
interface GigabitEthernet4
no ip address
shutdown
duplex auto
speed auto
!
interface GigabitEthernet5
ip address dhcp
ip nat outside
ip virtual-reassembly in
duplex auto
speed auto
!
interface Vlan1
no ip address
!
interface Vlan250
ip address 192.168.250.1 255.255.255.0
ip nat inside
ip virtual-reassembly in
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
ip nat inside source list 1 interface GigabitEthernet5 overload
ip route 0.0.0.0 0.0.0.0 dhcp
!
!
!
access-list 1 permit 192.168.250.0 0.0.0.255

Much appreciate everyone help! =D

And hope this can help someone using 900 ISR 

[Richard Burts]

I am glad that you are making progress and that plugging directly into TPLink does now allow you to ping and traceroute to 8.8.8.8. I am puzzled by some things in this update. You tell us that "Now, I can ping and tracert 8.8.8.8 from the PC plug to the Cisco switchport gi3". But then you tell us that "I cant get to any website or internet". Success with ping and tracert to 8.8.8.8 sounds like Internet access. Is it perhaps that access by ip address does work but that access by name does not?

Assuming that there may be some problem I looked at the configuration and have some questions about this:

interface GigabitEthernet3
switchport access vlan 250
switchport mode access
no ip address

In general it is not supported to configure IP address parameters on a layer 2 interface. G3 is configured with switchport and so looks like a L2 but has no ip address which sounds like L3. Perhaps the output of show interface status and of show vlan might shed some light on this?

[T0mTheCat]

Hi Richard,

Yes, I did some research and after I change my DNS from 75.75.75.75 to 8.8.8.8 . I manage to access by name.

I could not set any IP in L2 for my 900 ISR

R1(config)#int gi2
R1(config-if)#ip address 192.168.3.1 255.255.255.0

% IP addresses may not be configured on L2 links.

I get above message and IP is not set everytime. I did some research and I have to set VLAN instead of setting it in L2.

[Richard Burts]

Thanks for the update. Glad to know that changing the address configured for dns server fixed the problem with access by name. It is expected behavior that you can not configure an IP address on a L2 interface. The usual solution is to configure a vlan interface and configure an IP address of that. For some L2 interfaces it is also possible to use the configuration command no switchport and this will change the function of the interface from L2 to L3 and then you can configure an IP address on it.

[T0mTheCat]

Hi Richard,

I tried no switchport however still unable to set IP.

[Richard Burts · Accepted solution]

Thanks for the update. On some devices no switchport does work and some devices it does not. So it looks like your device does not support this and you will need to assign interfaces to a vlan, configure the vlan interface to provide L3 functionality, and assign IP address to the vlan interface.

[Richard Burts]

I am glad that our suggestions have helped you find solutions for the problems that you were experiencing. Thank you for marking this question as solved. This will help other participants in the community to identify discussions which have helpful information. This community is an excellent place to ask questions and to learn about networking. I hope to see you continue to be active in the community.