Routing using FastEthernet

[shoddy1988]

Hi,

I have a 2801 router and i am having trouble routing the 2 fast ethernet ports.

From the router i can ping the gateway 203.25.120.4 and the host machine 10.0.0.1 but i can't ping the gateway from the host machine.

The host machine is set with the ip 10.0.0.1 255.0.0.0 10.0.0.254

Can someone please tell me what i have done wrong?

Thanks in advance

below is the config of the router

Current configuration : 755 bytes

!

version 12.4

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname Router

!

boot-start-marker

boot-end-marker

!

!

no aaa new-model

!

resource policy

!

mmi polling-interval 60

no mmi auto-configure

no mmi pvc

mmi snmp-timeout 180

ip subnet-zero

ip cef

!

!

no ip dhcp use vrf connected

!

!

interface FastEthernet0/0

ip address 203.25.120.202 255.255.255.0

duplex auto

speed auto

!

interface FastEthernet0/1

ip address 10.0.0.254 255.0.0.0

duplex auto

speed auto

!

ip classless

ip route 0.0.0.0 0.0.0.0 203.25.120.4

!

!

no ip http server

no ip http secure-server

!

!

control-plane

!

!

line con 0

line aux 0

line vty 0 4

login

!

end

[Jan Hrnko]

Hi Brendon,

which gateway can't you ping from the host?

203.25.120.202 or the local gateway for the host which is 10.0.0.254?

Because host should be able to ping 10.0.0.254 with no problem at all. In that case, the router is configured correctly, I suggest that the problem is at the host machine.

Best regards,

Jan

[shoddy1988]

Hi Jan

I can ping 10.0.0.254 from the host and i can ping 203.25.120.202 from the host as well.

I just can't get to the other side which is the 203.25.120.4 which is my default gateway for the rest of the network.

From the router i can ping 203.25.120.4 so i know that it is active and works.

Thanks Brendon

[glen.grant]

  what is the device at 203.25.120.4  ? 

[Jan Hrnko · Accepted solution]

Hi Brendon,

aaah I see.

Well, does the router (gateway) with IP address 203.25.120.4 know how to get back to the 10.x.x.x network? Have you tried examine the routing table there with command show ip route ?

My best guess here is that when you do ping from the router with no source IP address specified, the source address is 203.25.120.202 and that's why the ping makes it back to the 2801 router - It knows how to get to the 203.25.120.x /24 network because it is indeed directly connected.

So my suggestion is this:

try to ping 203.25.120.204 source 10.0.0.254 from your 2801 router

If it fails - make sure that 10.x.x.x /8 network is in the routing table of your gateway (the one with IP address 203.25.120.4)

If it is there - make sure it points to your 2801 router

Best regards,

Jan

[shoddy1988]

Hi Jan

That was indeed my problem

Thank you very much for your help

Brendon

[Jan Hrnko]

Hi Brendon,

I'm happy to hear that, you're welcome!

Best regards,

Jan