Dell Force10 S4810P - Path MTU Discovery

IPv6 Routing | 547
Path MTU Discovery
IPv6 MTU Discovery is supported on platforms c e s z
Path MTU (Maximum Transmission Unit), in accordance with RFC 1981, defines the largest packet size
that can traverse a transmission path without suffering fragmentation. Path MTU for IPv6 uses ICMPv6
Type-2 messages to discover the largest MTU along the path from source to destination and avoid the need
to fragment the packet.
The recommended MTU for IPv6 is 1280. Greater MTU settings increase processing efficiency because
each packet carries more data while protocol overheads (headers, for example) or underlying per-packet
delays remain fixed.
Figure 25-2. MTU Discovery Path
Router B
Router A
MTU  1600 MTU  1400 MTU  1200
ICMPv6 (Type 2)
Use MTU  1400
Packet (MTU  1600)
Packet (MTU  1400)
ICMPv6 (Type 2
)
Use MTU  1200
Packet (MTU  1200)
Packet Received
Source
Destination