A few weeks ago the global routing table reached its 300,000th route. Below is a graph showing the exponential growth over the last 15 years.
BGP Table (Yearly)
Let’s do a little math:
Assuming all 4.3 billion IPv4 addresses are used (which isn’t quite true), each route represents approximately 4,294,967,296 / 300,000 = 14317 addresses. This is almost equivalent to a /18 (16,384 addresses). However, there are only 2^18 = 262,144 subnets of this size.
Why are there so many routes in the table?
Because there are BGP Administrators who advertise junk like this. AT&T WorldNet Services is advertising over 1100 prefixes; most of them are /24s. Due to their lack of summarization, this one group of routers is responsible for almost .5% of the fluctuation in global routing tables during any given week. That’s really bad.
Poke around here for some more info on BGP and the global routing table.
That graph doesn’t look exponential. Looks linear to me. Any idea what the spike right before ‘98 is associated with?
I can’t narrow down on that timeframe or figure out which AS caused the spike in updates. The AS7007 incident occurred in April 1997 which may account for the smaller spikes at the beginning of the year, but I don’t know about the big one.
So what does this mean to the normal person?