Route table growth and hardware to the filter

John A. Kilpatrick john at
Fri Sep 21 17:55:10 UTC 2007

On 9/21/07 7:18 AM, "Pekka Savola" <pekkas at> wrote:

> The way I see it, a network which is considering "Juniper M7i or Cisco
> 7300 plus a couple of switches" as an option does not _need_ 220K IPv4
> routes in its routing table.  Whether it has 150K, 40K (Hi Simon!) or
> 5K shouldn't matter that much from the functionality perspective.

There are a couple of reasons:

1.  The "captain obvious" suggestion of a default means that now I'm paying
for multiple links but can only use one.  That's not cost effective and will
provide lower performance for some destinations.  I have done defaults in
the past where appropriate but it's not appropriate in this application.

2.  The idea of a complex filtering strategy is, from my perspective, an
even worse idea.  You get all of the downsides of a default with increased
operational complexity that may not scale across multiple sites depending on
the size of your ops team.  Oh, and don't forget, for testing and validation
you'd need to buy a router that can take these multiple feeds to test the
results of the filtering policy.

Both of those options are viable (#1 obviously over #2) if just basic
connectivity is required.  However I find myself not really wanting to have
to continually support solutions with such limitations when there are other

                                John A. Kilpatrick
john at                Email|
john-page at      Text pages|          ICQ: 19147504
                  remember:  no obstacles/only challenges

More information about the NANOG mailing list