Routing error

Unanswered Question
Feb 7th, 2009

Hello friends ,

I connect two LANs together with two Cisco 2600 with PARADYNE 7975 M/SDSL.

I can telnet each of them trough another router.

But computers that each side can't ping another side.

LAN1 IP address is : 172.20.0.0 255.255.0.0

LAN2 IP address is : 172.17.0.0 255.255.0.0

---------- Router1 -------------------

interface FastEthernet0/0

ip address 172.20.2.3 255.255.0.0

duplex auto

speed auto

interface Serial0/1

ip address 172.18.2.5 255.255.255.0

encapsulation ppp

ip classless

ip route 0.0.0.0 0.0.0.0 FastEthernet0/0

ip route 172.17.0.0 255.255.0.0 Serial0/1

ip route 172.18.0.0 255.255.255.0 Serial0/1

ip route 172.20.0.0 255.255.0.0 FastEthernet0/0

no ip pim bidir-enable

---------- Router2 -------------------

interface FastEthernet0/0

ip address 172.17.2.1 255.255.0.0

duplex auto

speed auto

interface Serial0/1

ip address 172.18.2.6 255.255.255.0

encapsulation ppp

ip classless

ip route 0.0.0.0 0.0.0.0 Serial0/1

ip route 172.17.0.0 255.255.0.0 FastEthernet0/0

ip route 172.18.0.0 255.255.255.0 Serial0/1

ip route 172.20.0.0 255.255.0.0 Serial0/1

Thanks for your helping.

I have this problem too.
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ohassairi Sun, 02/08/2009 - 01:47

remove these routes they are not necessary:

from router1

ip route 172.18.0.0 255.255.255.0 Serial0/1

ip route 172.20.0.0 255.255.0.0 FastEthernet0/0

from router2

ip route 172.17.0.0 255.255.0.0 FastEthernet0/0

ip route 172.18.0.0 255.255.255.0 Serial0/1

ip route 172.20.0.0 255.255.0.0 Serial0/1

make sure you don't have "no ip routing" in the config file.

can you display the output of : show ip interfaces brief

Reza Rezazadeh Sun, 02/08/2009 - 03:19

Hello ohass,

Thank for your help ,

"ip route 172.20.0.0 255.255.0.0 Serial0/1 ", from router2 is necessary. right ?

here is output of :show ip interfaces brief

Router1

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 172.20.2.3 YES NVRAM up up

Serial0/0 unassigned YES NVRAM administratively down down

Serial0/1 172.18.2.5 YES manual up up

Router2

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 172.17.2.1 YES manual up up

Serial0/0 unassigned YES NVRAM administratively down down

FastEthernet0/1 unassigned YES NVRAM administratively down down

Serial0/1 172.18.2.6 YES manual up up

Thanks for helping

Nicholas Matthews Sun, 02/08/2009 - 13:04

You really should avoid using interfaces as the destinations of routes, unless you are also including an IP address.

This causes the router to ARP for the next address every time it sends a packet out that interface.

Try replacing the routing statements with IP addresses instead of interfaces, and see if it helps your problem.

hth,

nick

ohassairi Mon, 02/09/2009 - 20:59

yes it is necessary but since you have a default route (0.0.0.0) this will replace the static route. any way: any one will be enough.

now:

1-from rtr1 (console) try to ping wan of rtr2.

2-plz disp;ay the output of show ip route

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