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IPv4 Routing Table Expansion

The IPv4 global routing table expanded to just over 500.000 routes on the 24th of April. Between the 24th of April and the 13th of May the number of routes in the global routing table oscillated around the 500.000 mark. Since the 13th of May, the global routing table has been recording more than 500.000 routes on a daily basis.

The growth of the global routing table is a major concern observed by our customers and most of the attendees at the RIR meetings. The 500.000 mark has not passed unnoticed. Cisco released a notice signaling that many of their routers and switches will be affected once more than 512k routes will be seen in the global routing table.

Cisco also provides a few tips/workarounds on how to stay connected to the internet if you use one of the older or lower cost switches/routers that may run out of TCAM memory at 512k routes.

Nevertheless, we expect to see/hear of some bugs once the internet reaches 512k routes. If the growth of the routing table will continue as in the past months, we expect to see 512k routes in the global routing table not earlier than August and not later than October.

While the website shows that we could have less than 300k routes in the global routing table today, de-aggregation currently practiced by many has almost doubled the routing table.

IPv4 transfers will continue to be a reason to routing table growth. As long as holders of allocations will split some of them and transfer parts of their allocation, the global routing table will continue growing faster and faster.

On the other hand, the IPv6 routing table has experienced an unexplainable drop (of ~1k routes) at the beginning of May 2014 and instead of continuing the growth trend it has had since 2011, May 2014 has seen a flattening of the line below 17600 routes.

All the data used in this article was collected from the (Geoff Huston’s personal) website.

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