Ipv6 Mtu Discovery - D-Link xStack DGS-3610 Series Configuration Manual

Chapter 32 IPv6 Configuration
Hop Limit:

The length is 8 bits. When one router forwards the packet for one time, this field will reduce 1.
If this field is 0, this packet will be discarded. It is similar to the life span field in the IPv4
packet header.
Source Address (Source Address):

The length is 128 bits. It indicates the sender address of an IPv6 packet.
Destination Address (Destination Address):

The length is 128 bits. It indicates the receiver address of an IPv6 packet.
At present, the following extended header is defined for the IPv6:
Hop-by-Hop Options:

This extended header must directly follow an IPv6 header. It contains the option data that
must be checked by each node on the passed paths.
Routing Header (Routing (Type 0)):

This extended header indicates the nodes that a packet will go through before reaching the
destination. It contains the address list of various nodes that the packet goes through. The
initial destination address of the IPv6 header is the first one of a series of addresses in the
route header, other than the final destination address of the packet. After receiving this
packet, the node of this address will process the IPv6 header and the routing header, and
send the packet to the second address of the routing header list. In this way, continue it until
the packet reaches the final destination.
Fragment Header (Fragment):

This extended header is used to frag packets longer than source node and destination node
path MTU by the source node.
Destination Option Header (Destination Options):

This extended header replaces the IPv4 option field. At present, the only defined destination
option is to fill the option with an integer multiple of 64 bits (8 bytes) when necessary. This
extended header can be used to carry the information checked by the destination node.
Upper-layer Extended Header (Upper-layer header):

It indicates the protocols for upper-layer transfer data, such as TCP(6) and UDP(17).
Furthermore, the extended header of the Authentication and the Encapsulating Security
Payload will be described in the IPSec section. At present, the IPv6 implemented by use
cannot support the IPSec.
32.1.4

IPv6 MTU Discovery

It is similar with the path MTU discovery of the IPv4, the path MTU discovery of the IPv6
allows one host to discover and adjust the size of the MTU in the data transmission path.
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DGS-3610 Series Configuration Guide