Hello Frank,
On 03-Mar-00, you wrote:
FM> hi there,
FM>
FM> I took my Amiga into the school where I work today in order to test
FM> something we have been working on (it was far easier to test my
FM> Amiga than one of the servers)
FM>
FM> Anyway, when we were testing things we noticed that I couldn't ping
FM> the machine next to me, nor could it ping me even though we could
FM> both ping all the servers.
FM>
FM> It turns out that myself and all the servers were in the 192.168.3.
FM> range and the other PC was on the 192.168.1. range.
FM>
FM> I've tested this a bit further from home, and it seems that my Amiga
FM> doesn't want to communicate with anything other than 192.168.3.x
FM>
FM> I thought that this was a netmask thing (which is set to
FM> 255.255.255.0). The PC was set to 255.255.252.0, but I can't change
FM> my netmask to anything else. I've tried 255.255.0.0 but when I
FM> connect to the interface, Genesis says that it's invalid and reverts
FM> to it default.
FM>
FM> Can anybody help?
FM>
FM> Regards,
FM>
FM> Frank.
This sounds a bit like another problem posted here just one or two days
ago. Excuse me, everyone who already understands subnet masks, but they
work like this:-
An IP address is 32 bits long and is normally divided into four octets
of 8 bits (doesn't have to be though - you can use all 32 bits however
you like, pretty much). A subnet mask is also 32 bits long and must be
organised to match the IP address (see previous '()') and acts as a
filter to what other IP addresses you can see. If we look at your
current subnet mask (255.255.255.0) and three (possible) IP addresses
in the two subnets specified above e.g. 192.168.1.0, 192.168.3.0 &
192.168.3.1, in binary we get
11111111.11111111.11111111.00000000 (255.255.255.0)
11000000.10101000.00000001.00000000 (192.168.1.0)
11000000.10101000.00000011.00000000 (192.168.3.0)
11000000.10101000.00000011.00000001 (192.168.3.1)
Where there is a binary 1 in the subnet mask, the corresponding bits in
the IP address must match for the IP address to be 'visible'. Where
there is a 0 in the subnet mask, the corresponding bits in the IP
address don't have to match.
The first two octets of your subnet mask (255.255) require that the
first two octets of the IP addresses match exactly - and they do. The
last octet of your subnet mask doesn't require any matches, so we can
forget about it. The third octet also requires a perfect match (all
bits=1) and here they don't, because of the second bit in the IP
addresses. The subnet mask required to see all three IP addresses will
need the second bit of the third octet set to 0, which =253. A value
of 252 for the third octet would allow you to see x.x.1.x, x.x.2.x &
x.x.3.x:-
11111100 (252)
00000001 (1)
00000010 (2)
00000011 (3)
...so the subnet mask rejected by Genesis as 'invalid', isn't. At
least, it's not invalid as far as normal IP rules are concerned. In
the light of the other recent posting where a non 255.255.255.0 subnet
mask was rejected as invalid by Genesis, I'd say look for a later
version of Genesis to use - this sounds like a bug in your version that
rejects non 255.255.255.0 subnet masks.
Bye,
LeeE
--
http://www.spatial.freeserve.co.uk
...or something.
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