Ipv6 Pmtu Discovery - H3C S7500E Series Operation Manual

Operation Manual – IPv6 Configuration
H3C S7500E Series Ethernet Switches
2) The router returns an RA message containing information such as prefix
information option. (The router also regularly sends an RA message.)
3) The node automatically configures an IPv6 address and other information for its
interface according to the address prefix and other configuration parameters in the
RA message.
Note:
In addition to an address prefix, the prefix information option also contains the
preferred lifetime and valid lifetime of the address prefix. After receiving a periodic
RA message, the node updates the preferred lifetime and valid lifetime of the
address prefix accordingly.
An automatically generated address is applicable within the valid lifetime and will be
removed when the valid lifetime times out.
V. Redirection
When a host is started, its routing table may contain only the default route to the
gateway. When certain conditions are satisfied, the gateway sends an ICMPv6 redirect
message to the source host so that the host can select a better next hop to forward
packets (similar to the ICMP redirection function in IPv4).
The gateway will send an IPv6 ICMP redirect message when the following conditions
are satisfied:
The receiving interface is the forwarding interface.
The selected route itself is not created or modified by an IPv6 ICMP redirect
message.
The selected route is not the default route.
The forwarded IPv6 packet does not contain any routing header.

1.1.4 IPv6 PMTU Discovery

The links that a packet passes from the source to the destination may have different
MTUs. In IPv6, when the packet size exceeds the link MTU, the packet will be
fragmented at the source end so as to reduce the processing pressure of the
forwarding device and utilize network resources rationally.
The path MTU (PMTU) discovery mechanism is to find the minimum MTU of all links in
the path from the source to the destination.
the PMTU discovery.
Chapter 1 IPv6 Basics Configuration
Figure 1-5 shows the working procedure of
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