Users Guide
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, denes the largest packet size that can traverse a transmission path without suering
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 eciency because each packet carries more data
while protocol overheads (for example, headers) or underlying per-packet delays remain xed.
Figure 45. 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 conguring 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.
With ARP, each node broadcasts ARP requests on the entire link. This approach causes unnecessary processing by uninterested nodes.
With NDP, each node sends a request only to the intended destination via a multicast address with the unicast address used as the last 24
bits. Other hosts on the link do not participate in the process, greatly increasing network bandwidth eciency.
IPv6 Routing
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