[c-nsp] ARP entries from another subnet

Jared Mauch jared at puck.nether.net
Tue May 30 08:04:02 EDT 2006


	You may want to disable proxy-arp on
your interfaces.

	int fastethernet x/y
	no ip proxy-arp

	- jared

On Mon, May 29, 2006 at 05:00:31PM +0200, Vincent De Keyzer wrote:
> Hello,
> 
>  
> 
> I have the following weird situation:
> 
> * two LANs, A and B
> 
> * LAN A has IP 10.1.1.0/24
> 
> * LAN B has IP 10.2.2.0/24
> 
> * def. gateway for LAN A is router Ra = 10.1.1.1
> 
> * def. gateway for LAN B is router Rb = 10.2.2.1
> 
> * Ra and Rb are connected together via a network (cloud)
> 
> * host Ha = 10.1.1.10 is on LAN A
> 
> * host Hb = 10.2.2.10 is on LAN B
> 
>  
> 
> Now, something went wrong and LAN A and LAN B ended up connected together
> (say: a UTP cable between the two switches).
> 
>  
> 
> Within the ARP table of Ha, there was an entry for 10.2.2.10 ! So to reach
> Hb, it would go directly instead of using its default gateway (Ra).
> 
>  
> 
> How did this ARP entry arrive in there?
> 
>  
> 
> Vincent
> 
>  
> 
> PS: Ha is a Catalyst 2950.
> 
>  
> 
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-- 
Jared Mauch  | pgp key available via finger from jared at puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.


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