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New Member

About misconfigured default gateway.....

Hi all,

I have a question. I mistyped default gateway on client PC by chance.

But Commuication was success and good, I could connect anywhere.

I thought It's not noraml. So When I looked in the arp table on client PC,

the Default Gateway Address was of course wrong, but Mac Address was HSRP's virtual MAC Address. Anytime the result is same.

My Boss wants ... " If the Gateway is wrong , the communication should not success."

Any answer welcome...

Thanks in advance

Diagram

Cat 3550 12G----Cat 3550 12G(ios,emi)

..........l............................l

......Trunk..................Trunk

...............l...................l

...................Cat 3548

..........................l

.....................Client PC

3 REPLIES
Cisco Employee

Re: About misconfigured default gateway.....

If you send packets to some other device, and that other device has its default gateway set correctly, then that device will forward the packets on and then send an ICMP redirect back to your PC to tell it to send packets for that destination straight to the correct default gateway from now on. If the HSRP address is the correct default gateway, then when your PC receives the redirect it'll add that MAC address in as it's default gateway.

Remember that if these are all on teh same subnet/LAN, then it'll use the MAC address to send the packets to, not the IP address, so as long as the MAC address is correct for the default gateway that's all that matters, and it's probably correct simply because of an ICMP redirect.

Bronze

Re: About misconfigured default gateway.....

This might be proxy-arp at work. Try a "no ip proxy-arp" in interface configuration mode on the router in question.

New Member

Re: About misconfigured default gateway.....

Thanks all . I think it will work ~~^^

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