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,

[SOcchiogrosso · Accepted solution]

Are you NATing the affected subnet?

Sent from Cisco Technical Support Android App

[Allam Aly]

No. do I need to perform NATing for the second subnet? shouldn't it work as long as im routing it to the internet gateway?

Thanks for relping.

[paul driver]

Hello

You don't state where this 172.x network is residing
It could be172.x hasn't a return path to 10.1.x network
Also on your 3560 you don't need ip default-gateway when you have routing enabled

A simple topology of this network would help us to understand this better

Res
Paul

Sent from Cisco Technical Support iPad App

[Allam Aly]

Thanks for repling.

I didnt mention it as it out of my breach. It belongs to ISP, I've known about it when I did a trace route.

Tracing route to yahoo.com [98.139.183.24]

over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  X3000 [192.168.1.1]

  2     8 ms     7 ms     7 ms  172.31.1.122 <<<<<<<

  3     8 ms     7 ms     7 ms  172.21.28.178

  4    11 ms    10 ms    11 ms  ^C

[blau grana · Accepted solution]

Hello Allam,

As SOcchiogrosso said, it would be probably problem with NAT.

do I need to perform NATing for the second subnet? shouldn't it work as long as im routing it to the internet gateway?

Yes you have to perform NAT for both your private subnets (192.168.1.0/24 and 10.1.1.0/24).

I assume that you are NATing 192.168.1.0/24 on Linksys X300 to your public IP, so ISP can return traffic back. But if you do not NAT 10.1.1.0/24 subnet, ISP will drop these packets because they are destinated to private networks (which is not allowed in internet) and also for your ISP it is uknown traffic.

Best Regards

Please rate all helpful posts and close solved questions

[Allam Aly]

Finally I can live in peace

Thank you all I appreciate it!