Reference Guide

NOTE: Dell Networking OS provides the flexibility to add prefixes on Router Advertisements (RA) to
advertise responses to Router Solicitations (RS). By default, RA response messages are sent when an
RS message is received. Enable the RA response messages with the ipv6 nd prefix default
command in INTERFACE mode.
Dell Networking OS manipulation of IPv6 stateless autoconfiguration supports the router side only.
Neighbor discovery (ND) messages are advertised so the neighbor can use this information to auto-
configure its address. However, received ND messages are not used to create an IPv6 address.
The router redirect functionality in the neighbor discovery protocol (NDP) is similar to IPv4 router redirect
messages. NDP uses ICMPv6 redirect messages (Type 137) to inform nodes that a better router exists on
the link.
IPv6 Headers
The IPv6 header has a fixed length of 40 bytes. This fixed length provides 16 bytes each for source and
destination information and eight bytes for general header information.
The IPv6 header includes the following fields:
• Version (4 bits)
• Traffic Class (8 bits)
• Payload Length (16 bits)
• Next Header (8 bits)
• Hop Limit (8 bits)
• Source Address (128 bits)
• Destination Address (128 bits)
IPv6 provides for extension headers. Extension headers are used only if necessary. There can be no
extension headers, one extension header or more than one extension header in an IPv6 packet. Extension
headers are defined in the Next Header field of the preceding IPv6 header.
IPv6 Header Fields
The 40 bytes of the IPv6 header are ordered, as shown in the following illustration.
Figure 58. IPv6 Header Fields
IPv6 Routing
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