1 Internet Connection - 2 cascaded routers

[Allam Aly]

Hi All,

I have a problem reaching the internet from my second cascaded network 10.1.1.0 on Cisco 3550.

I can reach the internet while I'm using the network 192.168.1.0, but when ever I try from 10.1.1.0 I always get request timed out.

Here is the topology:

Here is the configuration:

Linksys X300:

Not much on it 2 static routes.

ip route 10.1.1.0 255.255.255.0 192.168.1.3

ip route 41.68.42.89(public) 255.255.255.255 172.31.1.122(first hop)

Linksys E900: >> IP address only

Cisco 3550:

Enabled ip routing

default route >> ip route 0.0.0.0 0.0.0.0 192.168.1.1

Ip default-gateway 192.168.1.1

ip name-server 192.168.1.1

SVI interface vlan 10

ip add 10.1.1.3 255.255.255.0

int fa 0/24

no switchport

ip add 192.168.1.3 255.255.255.0

Tests

• I can ping from 10.1.1.0 to 192.168.1.0 and vise versa
• I can reach the internet from 192.168.1.0
• When I ping yahoo.com from 10.1.1.0 (computer) the dns work!! I mean it translates yahoo.com to 206.190.36.45 but it gives me request timed out.
  

Lastly I tried to ping from the cisco 3550 to 172.31.1.122 with source ip 10.1.1.3 and it also gave me the same request timed out.

Can you please help me guys I know I'm missing something and I dont know it and it is driving me nuts.

Thanks,

[Reza Sharifi]

Hi,

On the 3550, you need 2 SVIs, one for valn 10 and one for 192.168.1.0 subnet

I see you only posted the config for vlan 10 SVI.

If the 3550 supports only one SVI then you need just the layer-2 vlans on the 3550 and then a trunk to E300 through E900 if the Linksys E900 supports more then one vlan.

HTH

[Allam Aly]

Thanks for replying.

the second SVI is on the fa 0/24, I did a no switchport and gave the port the IP add.

However, I created the second SVI vlan 192 and gave it the ip add and im still facing the same issue.

[bdmckamey · Accepted solution]

My recommendations. If port Fa0/24 on the 3550 was turned into a layer 3 interface and is not a switchport, there should not be a vlan or SVI created for the IP address subnet assigned to that layer 3 interface. The ip address should still be configured directly on the interface as you posted originally and no SVI with the same IP address on it. IP routing should still be enabled and an ip route '0.0.0.0 0.0.0.0 192.168.1.1'. On the 3550, the command 'ip default-gateway' is not needed as you enable ip routing and configured a default route.

Where are you translating your private IP addresses to a public address/es (via NAT or PAT) to reach the internet? I don't see any configs posted on that. Can you please provide your network translation configs.

NOTE: you can route out of the network with a private but the return packet will be dropped due to the private address (since the private is the destination and no one owns a private address or is it routable publically).

[Allam Aly]

WOW finally it make sense!!

The NATing is only done for the subnet 192.168.1.0 while the no NATing is done for the 10.1.1.0

All the time i was depending on the static route and didnt cross my mind that i'm missing the NAT.

Thanks for you help I appreciate it.