starnge router problem

tnmmm · 09-07-2008, 02:26 AM

i have 1841 cisco router connecting between two lans.from the router i can ping both networks but from my pc i can ping only the two interfaces of the routers.from the other side which is 10.1.0.0 network i can connect to the other side from any pc but from my side i cannot. the configurtion for the router is simple just direct interfaces connected without any thing else. any body can help me please.

snedie · 11-16-2008, 01:38 PM

If you have simply plugged in the two lans into the fast ethernet interfaces, applied Ip addresses to those interface and nothing else, then you have an obvious flaw in your network, no routing.

To route information between two LANs you need a routing protocol (its easier than static routing). I would use RIP as its very easy and straight forward to setup.

config t
router rip
version 2
network 10.1.0.0
network <the ip address range of the other LAN>

That config will enable data to pass freely between the two LANs

bernmeister · 12-12-2008, 02:00 PM

You shouldn't have to run RIP, as the router will take both directly connected interfaces
and create "C" entries for the networks connected to them in the routing table. Only
if you have a more elaborate topology would I dive into RIP. And I would prefer static
routes first.

But your problem sounds more like an ARP issue, and not a routing. The hosts on the
network, when trying to send to the other network, need a dest MAC address, which
they'll obtain from an ARP request. If no reply from the ARP, they'll send the packets
to the default gateway obtained from DHCP. Depending on your setup, you could
solve this a couple different ways. Either make sure the default gateway is the
router's port, or enable proxy arp on the router port, to get the packet to the router.

In any case, look at the "show interface" packet counts in the router to verify if
it's an ARP issue or not.

09-07-2008, 02:26 AM	#1 (permalink)
tnmmm Registered User Join Date: Sep 2008 Posts: 1 OS: xp	starnge router problem i have 1841 cisco router connecting between two lans.from the router i can ping both networks but from my pc i can ping only the two interfaces of the routers.from the other side which is 10.1.0.0 network i can connect to the other side from any pc but from my side i cannot. the configurtion for the router is simple just direct interfaces connected without any thing else. any body can help me please.

11-16-2008, 01:38 PM	#2 (permalink)
snedie Registered User Join Date: Feb 2008 Location: UK Posts: 136 OS: Windows 7 Ultimate x64	Re: starnge router problem If you have simply plugged in the two lans into the fast ethernet interfaces, applied Ip addresses to those interface and nothing else, then you have an obvious flaw in your network, no routing. To route information between two LANs you need a routing protocol (its easier than static routing). I would use RIP as its very easy and straight forward to setup. config t router rip version 2 network 10.1.0.0 network <the ip address range of the other LAN> That config will enable data to pass freely between the two LANs

12-12-2008, 02:00 PM	#3 (permalink)
bernmeister Registered User Join Date: Dec 2008 Posts: 9 OS: winxp, SP3	Re: starnge router problem You shouldn't have to run RIP, as the router will take both directly connected interfaces and create "C" entries for the networks connected to them in the routing table. Only if you have a more elaborate topology would I dive into RIP. And I would prefer static routes first. But your problem sounds more like an ARP issue, and not a routing. The hosts on the network, when trying to send to the other network, need a dest MAC address, which they'll obtain from an ARP request. If no reply from the ARP, they'll send the packets to the default gateway obtained from DHCP. Depending on your setup, you could solve this a couple different ways. Either make sure the default gateway is the router's port, or enable proxy arp on the router port, to get the packet to the router. In any case, look at the "show interface" packet counts in the router to verify if it's an ARP issue or not.