RE: Confusion reigns supreme (TCP/IP) -- MIDRANGE-L

With the last 4 bit at zero, it means that all the bits must match but the
last 4 do not have to.  So with your starting number of 112 you can have an
additional 15 address or 112 - 127.  Anything out side of that range your
ISP will not send to you through their router.  That is why you can ping
other machines on your intrAnet but not the internet.  Actually your ping
most likely reached its destination, but the response was not routed back to
you by your ISP.  It is still a little confusing to me too.  I went to our
network admin who ran a program.  He put in the starting range, x.x.x.112
and the subnet.  It then gave him the valid IP range.  

Your confusion has help me to learn.  I love this list.

Christopher K. Bipes
Mailto:chrisb@cross-check.com   


-----Original Message-----
From: Jim Langston [mailto:jlangston@conexfreight.com]
Sent: Thursday, October 07, 1999 4:13 PM
To: MIDRANGE-L@midrange.com
Subject: Re: Confusion reigns supreme (TCP/IP)


Hmm... I verified the default route and it was correct, and it still
wouldn't work.
I was assigning my AS/400 a high IP address, x.x.x.139 and it wouldn't work
We just got a new internet line and I had tried the same thing on my old
line, with
a high internet address, and it didn't work.

So, I just removed the x.x.x.139 address, and added x.x.x.115, added the
default
route and... it worked?!?

I am told that my ip range is x.x.x.112 Block Size: /28

So, I have 112-140.  My net mask is 255.255.255.240

This is what confuses me, and maybe it has something to do with it?
240 in binary is 11110000
255 in binary is 11111111

wouldn't a mask of 255.255.255.240 mask off all bits but the last 4?
so wouldn't my range be from 0 to 15 with 0 and 15 being unusable?
Or is there something I don't understand about net masks?  (I wouldn't
doubt that).

Anyway, thanks for the help, but there is something funny going on, I think,
with the AS/400 (or V3R7M0 in particular), IP address, netmasks and the
internet.

Regards,

A still confused Jim Langston



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