[ILUG] Re: new ethernet network

[David Ryan]

Based on the tcpdump output I would say that something like the
following is happening -
22:10:23.866358 arp who-has 192.168.0.200 tell 192.168.0.100
22:10:24.859897 arp who-has 192.168.0.200 tell 192.168.0.100
<> .100 goes out looking for a MAC address for .200 and gets no
response.  This is a bad thing.

22:11:14.534281 arp who-has 192.168.0.100 tell 192.168.0.200
22:11:14.534379 arp reply 192.168.0.100 is-at 0:60:8c:f4:d4:8d
<> .200 goes out looking for .100.  .100 generates a response giving
its MAC address as expected.

22:11:15.909922 arp who-has 192.168.0.100 tell 192.168.0.200
22:11:15.909974 arp reply 192.168.0.100 is-at 0:60:8c:f4:d4:8d
<> .200 goes out again looking for .100.  This indicates that .200
didn't receive the packet with the MAC address and is still looking
for it.

Make sure that the cards are configured to be on the same subnet -
255.255.255.0.  This *may* be part of your problem.  The fact that
you are using 192.168.0.x isn't a problem in this case, but it could
be if you used a different subnet.  You can change the subnet in 95
under Network properties.

You can normally see the arp table being built up as follows -
1) switch on machines and do "arp -a" on both - you should see empty
tables.
2) ping from .100 and you should see the arp table populated with the
MAC address of .200
3) you should also be able to see the MAC address of .100 in the
table on .200 since in order for it to be able to reply to the ping
it needs to find out the MAC address of .100

Hope some of this helps.

David

= Vincent Murphy <theDon at cs.ucc.ie> [19991003 2015]:
[snip..]
> ..  for now i'd like to verify that the
> ethernet works, and if it does try something else.

 i think i've managed to verify that the ethernet is working.  i
installed
tcpdump on the debian box, and did the following:

time   action
----   ------
22:10  on 192.168.0.100 (linux box):   `ping -c4 192.168.0.200'
22:11  on 192.168.0.200 (windows box): `ping 192.168.0.100'

 here's the tcpdump output (from the linux box):

22:10:23.866358 arp who-has 192.168.0.200 tell 192.168.0.100
22:10:24.859897 arp who-has 192.168.0.200 tell 192.168.0.100
22:10:25.859892 arp who-has 192.168.0.200 tell 192.168.0.100
22:10:26.860284 arp who-has 192.168.0.200 tell 192.168.0.100
22:10:27.859883 arp who-has 192.168.0.200 tell 192.168.0.100
22:10:28.859882 arp who-has 192.168.0.200 tell 192.168.0.100
22:11:14.534281 arp who-has 192.168.0.100 tell 192.168.0.200
22:11:14.534379 arp reply 192.168.0.100 is-at 0:60:8c:f4:d4:8d
22:11:15.909922 arp who-has 192.168.0.100 tell 192.168.0.200
22:11:15.909974 arp reply 192.168.0.100 is-at 0:60:8c:f4:d4:8d
22:11:17.409346 arp who-has 192.168.0.100 tell 192.168.0.200
22:11:17.409400 arp reply 192.168.0.100 is-at 0:60:8c:f4:d4:8d
22:11:18.909081 arp who-has 192.168.0.100 tell 192.168.0.200
22:11:18.909133 arp reply 192.168.0.100 is-at 0:60:8c:f4:d4:8d

>  should i try a crossover cable between the two NICs?

 i no longer intend on doing this, given what tcpdump told me.

 as yet, i still can't get these machines to ping each other, so i'm
still
looking for help, except now my problem is narrowed down a bit i hope.
perhaps there's a problem with arp, but i haven't a clue how that
works,
i just know that it's used for resolving ip addresses to ethernet
addresses.

-vinny <hunting for arp docs>