# Unintended Consequences of IPv6 SLAAC

DevFeed: [Unintended Consequences of IPv6 SLAAC](<https://devfeed.tech/articles/unintended-consequences-of-ipv6-slaac-10980.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2024/04/ipv6-slaac-unintended-consequences/>)

Published: 2024-04-16T06:45:00Z

Content type: opinion

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [Network](<https://devfeed.tech/topics/network.md>), [Network design](<https://devfeed.tech/topics/network-design.md>), [Caching](<https://devfeed.tech/topics/caching.md>), [Hardware](<https://devfeed.tech/topics/hardware.md>)

Tags: [cache](<https://devfeed.tech/tags/cache.md>), [cpu](<https://devfeed.tech/tags/cpu.md>), [hardware](<https://devfeed.tech/tags/hardware.md>), [ipv6](<https://devfeed.tech/tags/ipv6.md>), [load](<https://devfeed.tech/tags/load.md>), [network](<https://devfeed.tech/tags/network.md>), [network-design](<https://devfeed.tech/tags/network-design.md>), [performance](<https://devfeed.tech/tags/performance.md>), [tcp](<https://devfeed.tech/tags/tcp.md>)

## AI overview

The article explains how IPv6 SLAAC privacy address rotation, long-running TCP sessions, and device reconnections can increase neighbor-discovery cache usage. When hardware forwarding devices exhaust that cache, packets may be handled by the CPU or dropped, reducing performance. It outlines tradeoffs involving interface limits, RFC 7217 identifiers, and DHCPv6 address allocation.

## Source excerpt

One of my friends is running a large IPv6 network and has already experienced a shortage of IPv6 neighbor cache on some of his switches. Digging deeper into the root causes, he discovered: In my larger environments, I see significant neighbor table cache entries, especially on network segments with hosts that make many long-term connections. These hosts have 10 to 20 addresses that maintain state over days or weeks to accomplish their processes. What's going on? A perfect storm of numerous unrelated annoyances: Read more ...