Dell S3048-ON, Configuration Manual

Page: 384 / 1036

• 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.
The recommended MTU for IPv6 is 1280. Greater MTU settings increase processing efficiency because each packet carries more data
while protocol overheads (for example, headers) or underlying per-packet delays remain fixed.
Figure 46. Path MTU Discovery Process
IPv6 Neighbor Discovery
The IPv6 neighbor discovery protocol (NDP) is a top-level protocol for neighbor discovery on an IPv6 network.
In place of address resolution protocol (ARP), NDP uses “Neighbor Solicitation” and “Neighbor Advertisement” ICMPv6 messages for
determining relationships between neighboring nodes. Using these messages, an IPv6 device learns the link-layer addresses for neighbors
known to reside on attached links, quickly purging cached values that become invalid.
NOTE: If a neighboring node does not have an IPv6 address assigned, it must be manually pinged to allow the IPv6 device to
determine the relationship of the neighboring node.
NOTE: To avoid problems with network discovery, Dell Networking recommends configuring the static route last or assigning an
IPv6 address to the interface and assigning an address to the peer (the forwarding router’s address) less than 10 seconds apart.
384 IPv6 Routing