Is the Internet heading for melt-down?

The routing table is growing out of control

At the recent FutureNet conference, one of the three major topics was the future of the Internet. Nemertes Research, the host of FutureNet, brought a very impressive group of Internet experts to the conference to discuss the issue.

Johna Till Johnson, president of Nemertes and moderator of a spirited round table discussion about the Internet at FutureNet, wrote about the Internet's forecast earlier this week, predicting "snow days." A couple other stories were also written this week about issue, one using another weather metaphor and another using a Chicken Little-like sky-is-falling description.

I thought I'd give a simpler description of the issue, with a router-jockey view.

Two big issues:

  • 1 - We are running out of IPv4 space (we knew that).
  • 2 - The global Internet routing table is too big now and getting bigger fast.

First, we've heard for years about the lack of IPv4 space. This was the main driver for IPv6's development in the 1990s. However, this problem has been mitigated, for a while, by NAT. Pure network engineers don't like NAT, but let's be honest - it works! However, even with NAT, there is still a growing need for public IPv4 space for companies and organisations. And, while there are 4,294,967,296 IPv4 addresses, poor address allocations over the last 30 years have led to a much smaller pool.

Enter IPv6 with its 340,282,366,920,938,000,000,000,000,000,000,000,000 addresses. Problem solved, right? Well....

But, for now, let's discuss problem #2, which is caused by problem #1. Since there is a smaller and smaller pool of IPv4 addresses, companies are getting smaller and smaller public IPv4 assignments. For example, let's say your company gets its own /20. But, that's for your whole company, and you have 16 global sites that need to use that public IPv4 space. So you break-up your /20 into /24s and give each site, in different parts of the world connected to different ISPs, a /24.

Oh, and don't forget, you're a good network engineer so each of those sites is multi-homed to two carriers, so that /24 is advertised twice - once to each carrier. Your company, which had a nice, single /20 public IP range, has just created 32 more routes in the global Internet routing table. Ouch. Now, imagine thousands of companies and organisations around the world doing that. Double Ouch.

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