H3C Technologies H3C S12500-X Series Switches - Manual (Page 132)

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• If you use the undo ipv6 nd ra hop-limit unspecified command, the device sets the hop limit value
configured by this task in a sent RA message. A host receiving the RA message fills the value into
the Hop Limit field of sent IPv6 packets.
To set the hop limit:
Step Command Remarks
1. Enter system view. system-view N/A
2. Set the Hop Limit field in the IP header. ipv6 hop-limit value The default setting is 64.
Configuring parameters for RA messages
You can enable an interface to send RA messages, and configure the interval for sending RA messages
and parameters in RA messages. After receiving an RA message, a host can use these parameters to
perform corresponding operations. Table 8 describes the configurable parameters in an RA message.
Table 8 Parameters in an RA message and their descriptions
Parameter Description
Hop Limit
Maximum number of hops in RA messages. A host receiving the RA message fills the
value in the Hop Limit field of sent IPv6 packets.
Prefix information
After receiving the prefix information, the hosts on the same link can perform
stateless autoconfiguration.
MTU Guarantees that all nodes on the link use the same MTU.
M flag
Determines whether a host uses stateful autoconfiguration to obtain an IPv6
address.
If the M flag is set to 1, the host uses stateful autoconfiguration (for example, from a
DHCPv6 server) to obtain an IPv6 address. Otherwise, the host uses stateless
autoconfiguration to generate an IPv6 address according to its link-layer address
and the prefix information in the RA message.
O flag
Determines whether a host uses stateful autoconfiguration to obtain configuration
information other than IPv6 address.
If the O flag is set to 1, the host uses stateful autoconfiguration (for example, from a
DHCPv6 server) to obtain configuration information other than IPv6 address.
Otherwise, the host uses stateless autoconfiguration.
Router Lifetime
Tells the receiving hosts how long the advertising router can live. If the lifetime of a
router is 0, the router cannot be used as the default gateway.
Retrans Timer
If the device does not receive a response message within the specified time after
sending an NS message, it retransmits the NS message.
Reachable Time
If the neighbor reachability detection shows that a neighbor is reachable, the
device considers the neighbor reachable within the specified reachable time. If the
device needs to send a packet to the neighbor after the specified reachable time
expires, the device reconfirms whether the neighbor is reachable.
Router Preference
Specifies the router preference in a RA message. A host selects a router as the
default gateway according to the router preference. If router preferences are the
same, the host selects the router from which the first RA message is received.