Ping / Default Gateway Issue

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Jul 7th, 2010
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I have a CISCO 2811 Router

I have two ports configured.

Fe 0/0 is 192.168.1.1

Fe 0/1 is 192.168.0.9

Fe 0/1 is jumpered into a 9 port switch card (0/1/0) HWIC in the router.

I have a DHCP server sitting off port 0/1/1 on sw card set to 192.168.0.1. (DHCP 192.168.0.10 -- .50)

When I am consoled into the router, I can ping 192.168.0.1 fine.

When I try to ping 192.168.0.1 from external (i.e. through Fe 0/0) I get a time out.

I can however ping 192.168.0.9 successfully from external.

My problem:
The packets cannot find the path from 192.168.0.9 to 192.168.0.1 even though it is on the same network. When I change the default gateway on a device hanging off the HWIC to 0.9, I can ping the device.

What am I missing?

Thanks.

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manish arora Wed, 07/07/2010 - 11:46
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Hi

can you post sh ip route , sh ip int brief out put ?

also , what are you using as the gateway for the server when you are seeing issues ?

Thanks

Manish

kenrandrews Wed, 07/07/2010 - 12:03
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Your problem is that you have a physical interface that I am assuming is and on the same network as the devices on your switch. By default all traffic in the 192.168.0.0/24 network will be directed out that interface. What is the Fe 0/1 interface connected to? I believe what you want to do is get rid of the Fe 0/1 interface and assign the 192.168.0.9 ip address to the vlan 1 interface of the switch module.


Let me know if I misunderstood anything or you need some clarification.


Ken

sricker99 Wed, 07/07/2010 - 12:51
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Ken - thanks for the post.


fe 0/1 is connected via a jumper into the first slot on sw (0/1/0). The idea is to exend the 0.x network into the switch card for simplicity. From there, I can hang off DHCP (i.e. laptops) to obtain thier IP from the DHCP server I have in 0/1/1. This DHCP server is a modem set with an IP of 0.254 and hands out .10 -- .50 addresses.


The vlan-switch does include all 0/1/x interfaces. The router has been wiped (erase startup-config) and is virgin.


My problem is that the modem (DHCP server) does not have a default gateway assignment option. Otherwise, I'd change it to 0.9 and be done with it. Prior to the wipe, things (as I've described) were identical and worked perfectly. I am missing a step somewhere.

S.

kenrandrews Wed, 07/07/2010 - 13:12
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Steve,

  I think the part you are missing is that you are thinking of the router and switch as 2 different units when in fact they are now connected. I have not done much with switch modules so I am not sure on the process, but I will try, From what I remember of the Voicemail modules in voice routers you have to session into the module using the service-module session command. For some reason I am thinking it is different with switch modules and after it is inserted the commands become active in the router, ie: interface vlan 1 (in configuration mode). Try both of these out and let me know if either works


Either way I am pretty sure that you want to unplug that jumper and get a Vlan interface setup using that .9 address instead of the physical interface. While technically they are the same thing the vlan interface cannot physically break or be unplugged so it is more reliable.


As for the packets not finding the path. My guess is that they are finding the path there, but have no way of getting back to tell you they made it there (ping is a 2 way thing). This is most likely due to the whole dhcp server issue. Which brings me to this question, what is the purpose of this modem besides being a DHCP server and why not just use the DHCP server in the router.


Unless the modem has some alternate use that I am not aware of then setting up these two things should fix your issue.


Ken

sricker99 Wed, 07/07/2010 - 13:32
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Ken -


I believe this HWIC card is a layer 2 device. As such, how could DHCP work from it?

I'm willing to give it a go.

kenrandrews Wed, 07/07/2010 - 13:54
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You could be right, but for some reason I believe that having it attached to a router makes it a layer3 switch. If it is then I can't see any other way to get it to work besides what you did and I can't imagine that is how it is intended to be. I will look some more for some documentation on this, what is the model of the switch module?

sricker99 Wed, 07/07/2010 - 14:33
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Ken - thanks for hanging with me on this one ..


HWIC 9esw


When I try, I cannot configure an address to the card - returns error 'unable to assign an address to this Layer2 ..'

Nagaraja Thanthry Wed, 07/07/2010 - 16:47
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You assign the IP to the VLAN SVI on the router and then assign individual ports on the router to that VLAN.


Under router:


interface vlan 1

ip address

exit


interface fa 1/0/1

switchport access vlan 1

exit


Hope this helps.


Regards,


NT


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