How far can an arp request go?
If a computer is on the other side of the world and you have its mac
address can you send an arp request through routers and multiple hops?
I know the mac address of the router and I am trying to get its DHCP
assigned IP address.

TIA.
B.

In article <1162998575.661949.109120@f16g2000cwb.googlegroups .com>,
SpreadTooThin <bjobrien62@gmail.com> wrote:
>How far can an arp request go?

Only as far as your local IP router.

>If a computer is on the other side of the world and you have its mac
>address can you send an arp request through routers and multiple hops?

Nope. ARP is a local (broadcast domain) protocol only.

>I know the mac address of the router and I am trying to get its DHCP
>assigned IP address.

In what environment? Are we talking local or are you trying to get the
IP address of a router "around the world"?? You're gonna need more than
a MAC address to figure that out.

Why don't you describe what problem you're trying to solve so we all have
a better picture of what you need to do??

========= For LAN/WAN Protocol Analysis, check out PacketView Pro! =========
Patrick Klos Email: patrick@klos.com
Klos Technologies, Inc. Web: http://www.klos.com/
================================================== ==========================

"SpreadTooThin" <bjobrien62@gmail.com> wrote:\

> How far can an arp request go?
> If a computer is on the other side of the world and you have its mac
> address can you send an arp request through routers and multiple hops?
> I know the mac address of the router and I am trying to get its DHCP
> assigned IP address.

Normal ARP requests are broadcast to an all 1s MAC address. Which means,
they will go as far as your L2 network goes. But normal ARP, i.e. RFC
826, has no IP encapsulation, hence no IP packet with destination
address, so standard ARP won't go beyond the first router.

But there are other forms, like Directed ARP (RFC 1433), where routers
participate in the address resolution effort by forwarding ARP requests
(in standard ARP frames) on to the next hop router, until they reach the
intended host one the remote IP subnet.

Bert

Patrick Klos wrote:

>
> Why don't you describe what problem you're trying to solve so we all have
> a better picture of what you need to do??
>

I suspect the problem he is trying to solve is "homework" or perhaps
"take-home exam".

Justa Lurker wrote:
> Patrick Klos wrote:
>
> >
> > Why don't you describe what problem you're trying to solve so we all have
> > a better picture of what you need to do??
> >
>
> I suspect the problem he is trying to solve is "homework" or perhaps
> "take-home exam".

I suspect you are paraniod.

Albert Manfredi wrote:
> "SpreadTooThin" <bjobrien62@gmail.com> wrote:\
>
> > How far can an arp request go?
> > If a computer is on the other side of the world and you have its mac
> > address can you send an arp request through routers and multiple hops?
> > I know the mac address of the router and I am trying to get its DHCP
> > assigned IP address.
>
> Normal ARP requests are broadcast to an all 1s MAC address. Which means,
> they will go as far as your L2 network goes. But normal ARP, i.e. RFC
> 826, has no IP encapsulation, hence no IP packet with destination
> address, so standard ARP won't go beyond the first router.
>
> But there are other forms, like Directed ARP (RFC 1433), where routers
> participate in the address resolution effort by forwarding ARP requests
> (in standard ARP frames) on to the next hop router, until they reach the
> intended host one the remote IP subnet.
>
> Bert

Thanks.

"Albert Manfredi" <albert.e.manfredi@nospam.com> writes:
> But there are other forms, like Directed ARP (RFC 1433), where routers
> participate in the address resolution effort by forwarding ARP
> requests (in standard ARP frames) on to the next hop router, until
> they reach the intended host one the remote IP subnet.

1433 is an experiment (not standards-track) document from 1993. Given
that it hasn't progressed since then, I think it's somewhat unlikely
that anyone would encounter this bizarre behavior in the real world.

--
James Carlson, KISS Network <james.d.carlson@sun.com>
Sun Microsystems / 1 Network Drive 71.232W Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677