IP address woes
afraiett at bigpond.net.au
Thu May 20 08:37:48 UTC 2004
Chris Johns wrote:
> Angelo Fraietta wrote:
>> You are right in that it is not in the arp cache - I tested with arp
>> - a , and the RTEMS machine was definately not there on the list -
>> even though it responded back directly. Is there a way to set it to
>> load it to the cache when it receives a message?
> I assume the 'arp -a' command was run on MacOS. If so it would seem
> interesting to have this happen as the Steven's book is based on a BSD
> stack and so is MacOS X and RTEMS. I assume this is MacOS X.
yes it is
> There are ways to directly play with the ARP cache but I would not
> recommend this approach.
>> Also, when the RTEMS is unable to respond to the broadcast from the
>> mac, it is able to respond to a broadcast from the Windows machine.
> What do mean by cannot respond ?
Couldn't send out socket - host is down
>> Why is that the case? When this occurs, I unplug and replug my mac
>> back in, and RTEMS can now find it - but the mac still can't find the
> Not sure. Maybe the Mac's ARP cache is being flushed when disconnected.
It is - but the enry wass not there in the first place. Mayby it
remembers that it could not find it?
> I would check the ARP cache entries against the tcpdump data.
>> How does a ping work? The machine pinging does not yet have the
>> ethernet address before the ping?
> Ping is an ICMP echo command. ICMP sits next to IP and uses the same
> ARP cache in the same manner as IP.
> What are the IP network configurations of each machine involved ?
>> I don't think that this is the case.
> You can prove this with all machines connected and tcpdump. It may be
> a good to check this out.
> Also how are these machine connected, ie hub, switch etc ?
Tried on both a hub and a crossover cable
What would I do in RTEMS to do the tcpdump?
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