Re: cidr & inet types

--On Sunday, July 20, 2003 15:33:14 +0800 Lincoln Yeoh
<lyeoh@pop.jaring.my> wrote:

> At 08:25 PM 7/15/2003 -0400, Tim Conrad wrote:
>
>
>> And, the values are actually all there:
>> nettest=> select * from cidr;
>>      net
>> -------------
>>  10.1.0.0/22
>>  10.1.4.0/22
>>  10.1.0.0/20
>> (3 rows)
>>
>> While it seems intelligent enough to know that 10.1.1.0/22 would
>> overlap, it doesn't know that 10.1.0.0/20 would envelop other networks
>> that already exist in it's dataset. Am I doing something incorrectly
>> here?
>
> And what if 10.1.0.0/20 covers the range of other networks? Even if Big
> Org network totally covers the Dept A and Dept B networks, why shouldn't
> you be able to insert all 3? The Unique constraint should prevent people
> from successfully inserting Big Org Network more than once, but that's
> about it.
>
> You're assuming a much narrower range of usage/application for cidr stuff.
>
>
>> While it's possible it's just my viewpoint, it seems that this is kind
>> of  weird
>> behavior. If the datatype has any notion of networks and that data being
>> 'unique' shouldn't it also know about netmasks? I guess it's a different
>> kind of unique than people are used to seeing. But, you can't have two
>> networks, one 10.1.0.0/22 and 10.1.0.0/20 on the same wire, or connected
>> to a  router, or whatever.
>
> You can have two networks 10.1.0.0/22 and 10.1.0.0/20 on the same router
> and on the same wire too.
>
> A router could have two different routes: packets to 10.1.0.0/22 will be
> sent via 10.1.1.1 and the rest matching 10.1.0.0/20 via 10.1.1.2.
>
> The more specific route takes precedence. But that does not exclude the
> existence of a more general network.
>
> You might be able to create a functional index that does what you want. I
> don't know how but I think it could be possible.
>
> Regards,
> Link.
I work for an ISP, and wrote our IP Management database using the CIDR
type, and USE
the ability to have the overlapping networks.

If I couldn't have 10.0.0.0/8, 10.1.0.0/16, etc in my database WITH A
UNIQUE constraint,
my application would BREAK.

My application automatically splits netblocks to make smaller ones,  and a
status field
says it is "subdivided".

Just another point of view.

LER

--
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 972-414-9812                 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749