Users Guide

ICMPv6
ICMP for IPv6 combines the roles of ICMP, IGMP and ARP in IPv4. Like IPv4, it provides functions for reporting
delivery and forwarding errors, and provides a simple echo service for troubleshooting. The Dell Networking
OS implementation of ICMPv6 is based on RFC 4443.
Generally, ICMPv6 uses two message types:
• Error reporting messages indicate when the forwarding or delivery of the packet failed at the destination
or intermediate node. These messages include Destination Unreachable, Packet Too Big, Time
Exceeded and Parameter Problem messages.
• Informational messages provide diagnostic functions and additional host functions, such as Neighbor
Discovery and Multicast Listener Discovery. These messages also include Echo Request and Echo Reply
messages.
The Dell Networking OS ping and traceroute commands extend to support IPv6 addresses. These
commands use ICMPv6 Type-2 messages.
Path MTU Discovery
Path MTU, 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.
IPv6 Routing 448