Explains how IPv6 path MTU discovery dynamically identifies MTU differences along a path so the source can handle fragmentation, and describes its TCP-only support and key IPv6 MTU requirements.
Path MTU discovery for IPv6 is a host behavior that
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discovers MTU differences for each link along a data path
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lets the IPv6 packet source handle fragmentation when a link MTU is too small, and
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helps save router processing resources by keeping fragmentation at the source.
Path MTU discovery is supported only for applications that use TCP.
In IPv4, the minimum link MTU is 68 octets. In IPv6, the minimum link MTU is 1280 octets. Use an MTU value of 1500 octets for IPv6 links.
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Feature Name |
Release Information |
Feature Description |
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Path MTU discovery for IPv6 |
Release 25.4.1 |
Introduced in this release on: Fixed Systems (8700 [ASIC: K100])(select variants only*) *This feature is supported on:
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Path MTU discovery for IPv6 |
Release 25.1.1 |
Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*) *This feature is supported on Cisco 8011-4G24Y4H-I routers. |
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Path MTU discovery for IPv6 |
Release 24.4.1 |
Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100, K100])(select variants only*); Modular Systems (8800 [LC ASIC: P100])(select variants only*) The network stack now supports simultaneous IPv4 and IPv6 operations, enhancing protocol flexibility and network efficiency. This dual-stack approach ensures interoperability and smooth transition between IPv4 and IPv6, accommodating diverse application requirements. It allows for more efficient use of IP addresses and prepares networks for future growth, making it easier to handle various network scenarios without service disruption. *Previously this feature was supported on Q200 and Q100. *This feature is now supported on:
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