topic It looks like the broadcast in Switching

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

Sean Devo — Fri, 08 Mar 2019 04:42:33 GMT

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.

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.

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.

Hey Sean,What is the default

Rajeev Sharma — Wed, 10 Sep 2014 18:31:36 GMT

Hey Sean,

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

Regards,
RS.

I am not able to reach the

Sean Devo — Wed, 10 Sep 2014 18:43:02 GMT

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

Rajeev Sharma — Wed, 10 Sep 2014 19:23:16 GMT

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 any an

Sean Devo — Wed, 10 Sep 2014 20:07:41 GMT

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

Rajeev Sharma — Wed, 10 Sep 2014 20:12:00 GMT

Paste the router configuration.

Ahhhh, as I was pasting the

Sean Devo — Wed, 10 Sep 2014 20:23:22 GMT

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 :)

Rajeev Sharma — Wed, 10 Sep 2014 22:43:47 GMT

happy to help 🙂