Ipv6 Headers; Ipv6 Header Fields - Dell Force10 Z9000 Configuration Manual

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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.

NOTE: Inconsistencies in router advertisement values between routers are logged per RFC 4861. The values checked for

consistency include:

Cur Hop limit

M and O flags

Reachable time

Retrans timer

Preferred and valid lifetime values for the same prefix

Only management ports support stateless auto-configuration as a host.

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 8

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.

The 40 bytes of the IPv6 header are ordered, as shown in the following illustration.

Figure 41. IPv6 Header Fields

IPv6 Routing