Introduction to IPv6
Path MTU (PMTU) Discovery
Path MTU (PMTU) DiscoveryIPv6 PMTU operation is managed automatically by the IPv6 nodes between the source and destination of a transmission. For Ethernet frames, the default MTU is 1500 bytes. If a router on the path cannot forward the default MTU size, it sends an ICMPv6 message (PKT_TOO_BIG) with the recommended MTU to the sender of the frame. If the sender of the frame is an IPv6 node that supports PMTU discovery, it will then use the MTU specified by the router and cache it for future reference.
For related information, refer to:
■RFC 1981: “Path MTU Discovery for IP version 6”