vijay gill wrote:
Andre Oppermann wrote:
I guess it's time to have a look at the actual scalability issues we
face in the Internet routing system. Maybe the area of action becomes
a bit more clear with such an assessment.
In the current Internet routing system we face two distinctive
scalability
issues:
1. The number of prefixes*paths in the routing table and interdomain
routing system (BGP)
This problem scales with the number of prefixes and available paths
to a particlar router/network in addition to constant churn in the
reachablility state. The required capacity for a routers control
plane is:
capacity = prefix * path * churnfactor / second
I think it is safe, even with projected AS and IP uptake, to assume
Moore's law can cope with this.
Moore's law for CPUs is kaput. Really, Moore's Law is more of an
observation, than a law. We need to stop fixating on Moore's law for the
love of god. It doesn't exist in a vacuum, Components don't get on the
curve for free. Each generation requires enormously more capital to
engineer the improved Si process, innovation, process, which only get
paid for by increasing demand. If the demand slows down then the
investment won't be recovered and the cycle will stop, possibly before
the physics limits, depending on the amount of demand, amount of
investment required for the next turn etc.
Predicting the future was a tricky business ten years ago and still is
today. What makes you think the wheel stops turning today? Customer
access speed will no increase? No more improvements in DSL, Cable and
Wireless technologies? Come on, you're kidding. Right?
Also, no network I know is on the upgrade path at a velocity that they
are swapping out components in a 18 month window. Ideally, for an
economically viable network, you want to be on an upgrade cycle that
lags Moore's observation. Getting routers off your books is not an 18
month cycle, it is closer to 48 months or even in some cases 60 months.
When you are buying a router today do you specify it to cope with 200k
routes or more? Planning ahead is essential.
Then we have the issue of an memory bandwidth to keep the ever changing
prefixes updated and synced.
Compared to link speed this is nothing. And nowhere near to memory bandwidth.
--
Andre
