The first one ip mtu 1400 will logically put the layer 3 mtu (not necessarily the physical MTU) at 1400. In my opinion this is the least effective of the 3 approaches. The crypto ipsec df-bit clear will clear the do not frament bit of TCP packets. This will prevent the problem of packet loss due to packets needing fragmentation but the do not
IPv6 nodes SHOULD implement Path MTU Discovery in order to discover and take advantage of paths with PMTU greater than the IPv6 minimum link MTU [IPv6-SPEC]. A minimal IPv6 implementation (e.g., in a boot ROM) may choose to omit implementation of Path MTU Discovery. IPv6 Datagram Size, Maximum Transmission Unit (MTU The most important differences between IPv4 and IPv6 with respect to datagram size, MTU, fragmentation and reassembly are: Increased Default MTU: In IPv4, the minimum MTU that routers and physical links were required to handle was 576 bytes. In IPv6, all links must handle a datagram size of at least 1280 bytes. IPv6 MTU Path Discovery - Cisco
[ipv6] Jumbo frames vs IPv6 - Networking | DSLReports Forums
For link layers that can support a configurable MTU size, RFC 2460 recommends that they be configured with an MTU size of at least 1500 bytes (the IPv6 MTU for Ethernet II encapsulation). An example of a configurable MTU is the Maximum Receive Unit (MRU) of a Point-to-Point Protocol (PPP) link.
Jan 28, 2013
Says ipv6 number must not be greater than vlan mtu A/ They are never supposed to be the same. The interface MTU will be normally (if not always) 18bytes bigger than the protocol MTU because while the protocol MTU talks about packets' sizes, the interface MTU talks about frames' sizes that include the 18 more bytes of the Ethernet header. Path MTU Discovery - PacketLife.net Aug 18, 2008 IPv6 (tutorial) - DD-WRT Wiki Internet Protocol version 6 (IPv6) is a network layer IP standard used by electronic devices to exchange data across a packet-switched network.It follows IPv4 as the second version of the Internet Protocol to be formally adopted for general use. There are too many devices in the world for 32-bit (2 32, or 4,294,967,296) IP addresses to be sufficient. IPv6, MTU, packet size Not sure what's going on. : ipv6