I don't think that hosts (capable of using default gateway) with no
configured default gateway can arp for devices on a different network. Proxy
arp is for hosts with no concept of default gateway or subnet mask. These
hosts will arp for any IP address, and the local router (with proxy arp
enabled) will respond if the target IP address is on a different network,
and the router has a route to the target network.
I also think that hosts with a default gateway pointing to themselves will
arp for all addresses.
CM
> -----Original Message-----
> From: Ted Dronen [mailto:[EMAIL PROTECTED]]
> Sent: 12 July 2001 23:26
> To: [EMAIL PROTECTED]
> Subject: RE: The Proxy ARP process [7:12198]
>
>
> What it is:
>
> Proxy ARP is a method by which routers make themselves
> available to hosts
> that do not have a configured default gateway. Proxy ARP is
> enabled on
> Cisco routers by default.
>
> no ip proxy arp is the command to disable Proxy Arp on a per
> interface basis.
>
> Consider the following:
>
> Host A (192.168.1.2/24) needs to send a packet to host B
> (192.168.2.2/24)
> located in another network. A router with two ethernet
> ports connects to
> the 192.168.1.0 network on its first Ethernet port, and
> connects to the
> 192.168.2.0 network on its second Ethernet port.
>
> 192.168.1.0 192.168.2.0
> Network Network
> Host A---------------Router------------------Host B
> .2 .1 .1 .2
>
> Host A does not have a configured default gateway, and
> therefore does not
> know how to reach a router to connect to hosts outside the 192.168.1.0
> network. Consequently, it may issue an APR request for
> 192.168.2.2. The
> router, receiving this request on Ethernet 1 (with Proxy ARP
> enabled), and
> knowing how to reach network 192.168.2.0, will issue an ARP
> Reply with its
> own MAC address in the hardware address field of the ARP
> Reply. In doing
> so, Host A believes that the router's Ethernet1 interface is
> the interface
> of Host B. Host A will make an entry in its ARP table using
> the MAC address
> of Ethernet1 on the router for Host B and unicast all
> subsequent packets for
> Host B to the router.
>
> See RFCs 925, and 1027.
>
> Are you having specific trouble with something?
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=12255&t=12198
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