I can ping from a PC to another PC on different subnet but the reverse is not

0

I had set up my LAN like this. enter image description here

I can ping from the laptop to PC, but I can't ping from PC to laptop. The result:

PING 192.168.11.25 (192.168.11.25) 56(84) bytes of data.
From 192.168.2.123 icmp_seq=1 Destination Host Unreachable

I have the Routing Table on Router 1:

2   192.168.2.0 255.255.255.0   0.0.0.0 LAN & WLAN

and Routing Table on Router 2:

2   192.168.2.0     255.255.255.0   0.0.0.0 Intranet WAN
2   192.168.11.0    255.255.255.0   0.0.0.0 LAN

I had tried to add the route 192.168.11.0 255.255.255.0 0.0.0.0 LAN to router 1 but it didn't work.

UPDATE I used the Ping Tool in Router 1 then ping to 192.168.2.100 - Router 2 and it shows Request time out

Davuz

Posted 2016-10-14T05:27:29.310

Reputation: 727

Does the laptop have a firewall that blocks ICMP echoes by chance? – Seth – 2016-10-14T05:31:09.877

I'm not sure but others laptop on router 2 can ping it. – Davuz – 2016-10-14T05:33:10.563

What models of routers are those? What OS are they running? – Seth – 2016-10-14T05:54:25.783

1This is how SoHo NAT works. Downstream devices can initiate contact with upstream devices but upstream devices cannot initiate contact with downstream ones. You can talk to Google's web server. But Google can't start a conversation with your computer. From the laptop's point of view, the desktop is a WAN device that it can reach out to but that cannot reach in to it. – David Schwartz – 2016-10-14T06:00:58.137

You just have to tell your first router where to find devices from your second one. Looking at your post that should look something like that: 192.168.11.0 255.255.255.0 192.168.2.100 – Yamakaja – 2016-10-14T06:17:24.073

Answers

1

Make sure you have Router 2 set up as a plain old IP forwarding router, and not a NAT gateway.

On Router 1 add a route:

192.168.11.0 255.255.2550 192.168.2.100 LAN

That is, the 192.168.11/24 subnet should be routed to the router whose IP address on the local subnet is 192.168.2.100.

Edit: As David pointed out, the above instructions won't allow the devices behind Router 2 to reach the Internet unless you configure the NAT gateway in Router 1 to support both NAT private subnets simultaneously. I suspect what you really need is the stuff I had written below:

Or better yet, if you're not doing this to learn about IP subnetting and routing, just turn router 2 into a simple bridge so you can use a single subnet for the whole LAN.

Spiff

Posted 2016-10-14T05:27:29.310

Reputation: 84 656

1If you do that, then devices connected to router 2 won't be able to reach the Internet. – David Schwartz – 2016-10-14T06:01:47.123

@DavidSchwartz Oh yeah, good point. Fixed. – Spiff – 2016-10-14T06:09:12.700

thank you. I found an option in Router 2's Operation Mode is "Bridge with AP". I'll try that. – Davuz – 2016-10-14T06:26:20.833