[Re: selective auto-aggregation]

my company does it (not by my choice) - my downstreams do it regularly
(mostly because they don't understand how/why to do something different)
i have been told that it is that way for 'backup' purposes (they
announce one or two /2[456]s to me with about 15 as prepends, and
announce their entire /20, plus all of their longer prefixes, to another
provider)
they also told me that it will not be changed...apparently, as routers
get more powerful and memory gets 'cheaper', they feel that it is not
their responsibility to help maintain global routing table sizes

McBurnett, Jim wrote:
> Only 1 question:
> What about the companies that have a /24 out of the /20 0r /21 that are

multi-homed?

> If the route rules are not carefully prepared the multi-homed customer

then might be single-homed and tied to the upstream they got the IP's from.

>
> Thoughts?
>

I was curious how much of the de-aggregation was due to multi-homed
companies requiring the longer prefixes. Are there companies that
actually announce their smaller routes despite controlling the shorter
prefix? What would be the benefit of doing so?

-Jack

"Walk with me through the Universe,
And along the way see how all of us are Connected.
Feast the eyes of your Soul,
On the Love that abounds.
In all places at once, seemingly endless,
Like your own existence."
     - Stephen Hawking -

Joshua Smith wrote:

i have been told that it is that way for 'backup' purposes (they announce one or two /2[456]s to me with about 15 as prepends, and announce their entire /20, plus all of their longer prefixes, to another
provider)
they also told me that it will not be changed...apparently, as routers
get more powerful and memory gets 'cheaper', they feel that it is not
their responsibility to help maintain global routing table sizes

That's just beyond me. Since local preference is chosen before AS hop count, providers that are setup right allow for easily crafting your routing. I run an AS prepend out Sprint with default LP, which allows any packet that makes it to their network to come strait to me, but anyone that is multi-homed or exterior will probably go out another way. I work with communities to make routing symetrical as possible (not perfect, but close). Then I shoot out my aggregates via Qwest untouched and it's smooth sailing with a backup.

Then again, when dealing with various providers over the years, I've gotten some funny looks when I start talking communities and the need for symetrical routing.

-Jack