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Router can ping internet, but switch connected to router cannot ping internet

Sean Devo
Level 1
Level 1

I am trying to set up a second private network within our production network for lab purposes.  Public IP address --> Production:172.16.0.0/24 --> Lab:192.168.0.0/24

The topology I have set up looks like this:

WAN ----------------------------------> R1 --------------- >S1----------------------------------->R2----------------->S2

Public IP                                 172.16.0.1        172.16.0.2                               192.168.0.1       192.168.0.2

                                                     (Production Network)                                           (Lab Network)

 

Production network is up and functional. R1 is configured as a DHCP server for our production network.

 

R2

After configuring R2 with the proper routing protocols, I am able to successfully ping 8.8.8.8 through both interfaces of R2.  fa0/0 is the internet coming in from S1 while fa0/1 is for the "Lab Network". DHCP pool is enabled on this router to provide ip addresses.

When I plug my computer straight into R2 int fa0/1, I am able to browse and access the internet.

 

S2

Since this is a lab environment I am setting up, I introduced a second switch to R2. I CAN ping R2, but I cannot ping 8.8.8.8 nor my production network. Here is my config (which is no difference from S1, just different vlan 1 ip address):

 

*Mar  1 19:25:10.883: %SYS-5-CONFIG_I: Configured from console by consolerun
Building configuration...

Current configuration : 3007 bytes
!
version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Switch
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
switch 1 provision ws-c3750-24p
system mtu routing 1500
ip subnet-zero
!

spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
!
!
interface FastEthernet1/0/1
!
interface FastEthernet1/0/2
!
interface FastEthernet1/0/3
!
interface Vlan1
 ip address 192.168.0.2 255.255.255.0
!
ip classless
ip http server
ip http secure-server
!
!
!
control-plane
!
!
line con 0
line vty 5 15
!
end

 

---------

Additionally, I am able to ping from R2 to R1, but cannot pring from R1 to R2. Hope my explanation was clear. Thanks

 

I thought since this is a very simple network, there should be no problem creating a second flat private network using an IP address given from my first production private network.

1 Accepted Solution

Accepted Solutions

It looks like the broadcast domain is somehow broken. Since its a lab network so I believe you can configure debugs.

Configure debug ip dhcp server packet on R2 and check if it receives any DHCP discover from client.

HTH.

Regards,

RS.
 

View solution in original post

7 Replies 7

Rajeev Sharma
Cisco Employee
Cisco Employee

Hey Sean,

What is the default gateway of PC when connected to Sw2?

Regards,
RS.

I am not able to reach the DHCP server of R2, so my PC receives a self-assigned IP of 167.x.x.x

 

It looks like the broadcast domain is somehow broken. Since its a lab network so I believe you can configure debugs.

Configure debug ip dhcp server packet on R2 and check if it receives any DHCP discover from client.

HTH.

Regards,

RS.
 

So I waited patiently and an IP address was given. My default-gateway/router is set to the ip address of R2, 192.168.0.1, which is what is set up under my dhcp pool parameters I configured on R2.  I am able to ping the gateway, but no interent access.  Would you like to see my router configurations?

Paste the router configuration.

Ahhhh, as I was pasting the router configurations, I noticed my ACL's and NAT overload configs were not there anymore! I must have not saved the configs from the day before! Thanks for troubleshooting this with me.

happy to help :)

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