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New Member

LAN Traffic Disrupted When WAN Shutdown

I have a Cisco 2801 ISR with IOS 12.4. It has a basic configuration with F0/0 connected to the public internet and F0/1 connected to my private LAN. My problem is when I administratively shutdown of F0/0, for testing purposes, my connectivity to the LAN interface, is lost. Interestingly however, when I connect to the router via console cable; F0/1 shows as being up and line protocol up and it can be pinged locally however from the router I cannot ping into the rest of the LAN. Executing the clear interface F0/1 command fixes the problem however I don't believe this behaviour is normal. When F0/0 is brought back online, all connectivity is restored. Please let me know if you require any further details or configuration commands, any help would be greatly appreciated.

Thanks in advance,

Chris

Everyone's tags (1)
5 REPLIES
Cisco Employee

Re: LAN Traffic Disrupted When WAN Shutdown

Chris,

     This discussion forum is focused on the Cisco Small Business router series.  Your question/issue around the 28XX ISR series would be better served on the Netpro forum under "LAN Routing & Switching" located here.

Best Regards,

New Member

Re: LAN Traffic Disrupted When WAN Shutdown

Thank you Glenn

New Member

Re: LAN Traffic Disrupted When WAN Shutdown

Hi all,

just nudging this one. Any ideas would be greatly appreciated.

Thanks in advance.

Cisco Employee

Re: LAN Traffic Disrupted When WAN Shutdown

Hello,

Can you please post the running configuration and the output of "show arp"

from the router?

Regards,

NT

New Member

Re: LAN Traffic Disrupted When WAN Shutdown

Attached is the running config as well as the capture of a test that I did from the console port.

Let me know if you have any questions.

Cheers

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