John - is that a publicly accessible paper?
-e-
"John Neiberger" <[EMAIL PROTECTED]> wrote:
> I'm reading through Lou Rossi's token ring paper and read something that
> is ponderous. Over ethernet, an ARP request is broadcast but the reply
> is unicast. In this paper (p. 4) there is a scenario where two hosts
> are separated by two bridges and a ring. Host A wants to transmit to
> Host B so it ARPs for B's MAC address.
>
> Now, the paper mentions that after the ARP reply, A knows the MAC
> address of B but not the location. My question is this: is an ARP
> reply over token ring unicast or broadcast? If it's unicast then how
> did B send the response to A? Wouldn't it have to send an explorer
> packet first to find the path to A?
>
> It seems to me that this is the process:
>
> A wants to say hi to B
> A sends an ARP request (broadcast) to B
> B receives request and wants to send unicast response to A
> B sends a local explorer for A (no response)
> B sends an all-routes explorer for A (gets a response)
> B sends a unicast ARP reply to A
>
> Is that right? If that's the case, then here's what I gather happens
> next:
>
> A now has B's MAC address
> A sends a local explorer for B (no response)
> A sends an all-routes explorer for B (gets a response)
> A proceeds to transmit data to B
>
> Here's what doesn't make sense to me. If B had to know the path to A
> to send an ARP reply, why doesn't A just take the data in the RIF from
> that reply to figure out the reverse path back to B? Why waste time
> with explorer packets when it was just given the path in the ARP
> reply??
>
> Or, do ARP requests/replies even have RIFs? If not, are they all
> broadcast in token ring?
>
> Can you tell I'm just starting out studying token ring and SRB? <g>
>
> Thanks as usual!
>
> John
>
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