Re: Network issue........
On Tue, Sep 13, 2016 at 01:20:30PM CEST, Darac Marjal <mailinglist@darac.org.uk> said:
> On Tue, Sep 13, 2016 at 07:07:51AM -0400, rhkramer@gmail.com wrote:
> >On Tuesday, September 13, 2016 04:54:08 AM Darac Marjal wrote:
> >>On Tue, Sep 13, 2016 at 04:26:55PM +1000, Charlie wrote:
> >>>Kernel IP routing table
> >>>Destination Gateway Genmask Flags MSS Window irtt Iface
> >>>0.0.0.0 10.80.2.85 0.0.0.0 UG 0 0 0 eth0
> >>>10.80.2.84 0.0.0.0 255.255.255.252 U 0 0 0 eth0
> >>
> >>This translates as "For 10.80.2.84 to 10.80.2.87, talk directly to the
> >>host, otherwise gateway through 10.80.2.85".
> >
> >I'm not the OP, but maybe I can learn something.
> >
> >I can sort of see where you got the 10.80.2.84--oh, and I was going to say
> >that I don't see where the 10.80.2.87 came from, but, without doing the math,
> >maybe that comes from the 255.255.255.252 netmask?
>
> Yes. I actually plugged the numbers into http://www.subnet-calculator.com/
> as I'm lazy, but 255.255.255.252 is also written as /2 and it defines a
> subnet where everything but the last 2 bits of the address are the same.
> We're lucky that, in this instance 10.80.2.84 is on the lower boundary of
> this range (Actually, the routing table might enforce that), so the next 4
> (inclusive) hosts make up the range .84 (which would usually be the
> 'network' address), .85 and .86 (which are both 'usable' hosts) and .87
> (which would be the 'broadcast' address).
That's /30 (30 fixed bits) not /2
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