On 11/21/01 2:58 PM, "Gert Doering" <gert@greenie.muc.de> wrote:
> Hi,
>
> On Wed, Nov 21, 2001 at 06:51:41PM +0100, sthaug@nethelp.no wrote:
>>>> Bzzzt. Still wrong. There's nothing to stop anyone with an ARIN /20
>>>> announcing smaller blocks.
>>>
>>> No. But there is nothing either that is going to force *me* to ever
>>> increase my router's CPU and memory. If those people want to be reached,
>>> they can announce the /20. If they do not want, they can announce it
>>> as /32s (which would be ridiculous, but then, where is the border to
>>> "ridiculous"?).
>>
>> I think this is pretty ridiculous, actually:
>>
>> *>i24.154.32.0/24 213.239.22.241 200 0 8918 701 7046 ?
>> *>i24.154.33.0/24 213.239.22.241 200 0 8918 701 7046 ?
>> *>i24.154.34.0/24 213.239.22.241 200 0 8918 701 7046 ?
>> *>i24.154.35.0/24 213.239.22.241 200 0 8918 701 7046 ?
>
> [ Lots of ugly things snipped... ]
>
> Yes, these are like what I'm talking about. I cannot see a single reason
> why it is "necessary" that those prefixes are visible on *my* routers,
> and everybody elses in the whole world.
>
> Even if 7046 has multiple links to 701, it would be possible to send
> out a /20 *and* all the /24s, and tag the /24s as "do not export
> elsewhere".
>
What if 7046 has a connection to 1239 as well? If 701 announces the /20 as
such, while 1239 announces the /24, traffic is going to follow the longest
path every time.
>
> this means: 73,000 prefixes are there that are more specific than what the
> registries allocate, read: "that are likely to be aggregateable to a LOT
> less".
>
That's because lots of ISP's have multihomed customers using a
sub-allocation of their address space.
I am not arguing that there are misconfigured routers out there where people
couldn't figure out the "mask" statement, but there are also lots of small
providers trying to provide quality of service to their small markets by
having more than one upstream provider.
Mike
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