One of the most basic lessons from The Art of War is not to fight a war on two fronts simultaneously, but that is exactly what many network operators are doing as they pursue tactics to avoid full IPv6 migrations.
On one hand, companies don’t want the headache of fully migrating to IPv6, and are pushing the American Registry for Internet Numbers (ARIN) to de-aggregate the routing table and squeeze as much IPv4 out of the remaining allocations as possible. However, this battle to de-aggregate IPv4 is accelerating the growth of the BGP routing table, and in part contributing to older routers hitting the default 512k routing limit we’ve heard so much about in the last two weeks.
If a company is humming along with a BGP routing table of 500,000 routes from its Internet provider, then all of a sudden a Tier1 provider adds 15,000 routes to the table, they are now pushed over the 512,000 route limit and everything goes sideways. Today we are at about 500,000 routes in the global table, which grows by about 1,000 a week on average. As the global routing table continues to grow, there will likely be an increase in routing instability over the next few months, and many network operators will learn some very painful lessons if they don’t take the appropriate steps to prepare.