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?
Jim
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
I do it. Reasons are to control inbound traffic better, some routes are
annnounced to all upstreams, some are to some specific ones, some have
different communities tagged to them, etc. I have one block which is /19
which I do not announce and only announce multiple /23, /24 out of. It
works just fine - I'v not seen one place which does not route there...
{Historical lessons of atomic aggregates and the dangers of passing them
along should be background}
[snip]
companies requiring the longer prefixes. Are there companies that
actually announce their smaller routes despite controlling the shorter
prefix?
Yes.
What would be the benefit of doing so?
They mistakenly believe that all providers will proagate their
more-specifics and want to attranct traffic in a certain way for
a certain longest-match. If they
- anticipate this link-juggling to ONLY occur along contracted
paths
- appropriately tag NO-EXPORT
- also announce the greater aggregate
...then they'll get what they want out of the parties with whom
they contract. It is trivial and stunning that service providers
don't actively promote it to their customers. Some would rather
collect money for customers grazing on the commons rather than
for providing *service*.