Analysis of IPv4 vs IPv6 in BGP Routing Tables

The blog post provides an analysis of the Border Gateway Protocol (BGP) routing tables’ growth and dynamics for both IPv4 and IPv6 during 2024.

Here’s a summary focusing on the comparison between IPv4 and IPv6 usage, including total counts and year-over-year growth percentages:

IPv4 BGP Routing Table:

Size and Growth: In 2024, the IPv4 BGP routing table contained between 950,000 and 1,000,000 entries. The net growth for the year was approximately 53,000 new entries, a significant increase compared to the modest growth of 3,000 entries observed in 2023. This represents a year-over-year growth of approximately 5.6%. Additionally, there was a net increase of 1,400 Autonomous System (AS) numbers in the IPv4 network during 2024, up from 1,100 in 2023.

IPv6 BGP Routing Table:

Size and Growth: The IPv6 BGP routing table experienced a growth rate of 17% in 2023, with the number of entries increasing from 172,400 in January 2023 to 201,200 in January 2024. The number of AS numbers in the IPv6 network grew by 7% during the same period, reaching 32,500 in January 2024.

Prefix Specificity: Routing advertisements of /48s are the most prevalent prefix size in the IPv6 routing table, comprising approximately 46% of all prefixes.

Comparative Insights:

Relative Growth: The IPv6 routing table is growing at a faster rate compared to IPv4. Despite this, the absolute size of the IPv6 table remains smaller than that of IPv4.

Stability and Instability: The IPv6 network exhibits higher relative instability. Although the IPv4 routing table has approximately five times more entries than IPv6, the volume of routing updates (indicating network instability) in the IPv6 network is comparable to, and sometimes greater than, that of IPv4. This suggests that, relative to its size, the IPv6 network experiences more frequent changes.

In summary, the IPv4 BGP routing table grew significantly more last year than years prior.  While IPv6 routing table is expanding, we are still only 50% globally adoped. The higher relative instability in the IPv6 network indicates ongoing adjustments and developments as IPv6 adoption progresses.

For a detailed breakdown, please refer to Geoff Huston’s (APNICs Chief Scientist) analysis of IPv4 vs IPv6 routing in BGP.