When configuring IPv6 basics, go to these
sections for information you are interested in:
l
IPv6 Overview
l
IPv6 Basics Configuration Task List
l
Configuring Basic IPv6 Functions
l
Configuring IPv6 NDP
l
Configuring PMTU
Discovery
l
Configuring IPv6 TCP
Properties
l
Configuring ICMPv6
Packet Sending
l
Configuring IPv6 DNS
l
Displaying and
Maintaining IPv6 Basics Configuration
l
IPv6 Configuration Example
l
Troubleshooting IPv6
Basics Configuration
The term
“router” or the router icon in this document refers to a router in
a generic sense or a Layer 3 Ethernet switch running a routing protocol.
Internet Protocol Version 6 (IPv6), also
called IP next generation (IPng), was designed by the Internet Engineering Task
Force (IETF) as the successor to Internet Protocol Version 4 (IPv4). The
significant difference between IPv6 and IPv4 is that IPv6 increases the IP
address size from 32 bits to 128 bits.This section covers the following:
l
IPv6 Features
l
Introduction to IPv6 Address
l
Introduction to IPv6 Neighbor Discovery Protocol
l
IPv6 PMTU Discovery
l
Introduction to IPv6 DNS
l
Protocols and Standards
1.1.1 IPv6 Features
I. Header format simplification
IPv6 cuts down some IPv4 header fields or
move them to the IPv6 extension headers to reduce the length of the basic IPv6
header. IPv6 uses the basic header with a fixed length, thus making IPv6 packet
handling simple and improving the forwarding efficiency. Although the IPv6
address size is four times that of IPv4 addresses, the size of basic IPv6
headers is 40 bytes and is only twice that of IPv4 headers (excluding the
Options field).
Figure
1-1 Comparison between IPv4 packet header format
and basic IPv6 packet header format
II. Adequate address space
The source and destination IPv6 addresses
are both 128 bits (16 bytes) long. IPv6 can provide 3.4 x 1038
addresses to completely meet the requirements of hierarchical address division
as well as allocation of public and private addresses.
III. Hierarchical address
structure
IPv6 adopts the hierarchical address structure
to quicken route search and reduce the system source occupied by the IPv6
routing table by means of route aggregation.
IV. Automatic address
configuration
To simplify the host configuration, IPv6
supports stateful and stateless address configuration.
l
Stateful address configuration means that a host
acquires an IPv6 address and related information from a server (for example,
DHCP server).
l
Stateless address configuration means that a
host automatically configures an IPv6 address and related information on basis
of its own link-layer address and the prefix information advertised by a
router.
In addition, a host can generate a
link-local address on basis of its own link-layer address and the default
prefix (FE80::/64) to communicate with other hosts on the link.
V. Built-in security
IPv6 uses IPSec as its standard extension
header to provide end-to-end security. This feature provides a standard for
network security solutions and improves the interoperability between different
IPv6 applications.
VI. QoS support
The Flow Label field in the IPv6 header
allows the device to label packets in a flow and provide special handling for
these packets.
VII. Enhanced neighbor discovery
mechanism
The IPv6 neighbor discovery protocol is
implemented through a group of Internet Control Message Protocol Version 6
(ICMPv6) messages that manages the information exchange between neighbor nodes
on the same link. The group of ICMPv6 messages takes the place of Address
Resolution Protocol (ARP) message, Internet Control Message Protocol version 4
(ICMPv4) router discovery message, and ICMPv4 redirection message to provide a
series of other functions.
VIII. Flexible extension headers
IPv6 cancels the Options field in IPv4
packets but introduces multiple extension headers. In this way, IPv6 enhances
the flexibility greatly to provide scalability for IP while improving the
handling efficiency. The Options field in IPv4 packets contains 40 bytes at
most, while the size of IPv6 extension headers is restricted by that of IPv6
packets.
1.1.2 Introduction to IPv6 Address
I. IPv6 address format
An IPv6 address is represented as a series
of 16-bit hexadecimals, separated by colons. An IPv6 address is divided into
eight groups, and the 16 bits of each group are represented by four hexadecimal
numbers which are separated by colons, for example,
2001:0000:130F:0000:0000:09C0:876A:130B.
To simplify the representation of IPv6
addresses, zeros in IPv6 addresses can be handled as follows:
l
Leading zeros in each group can be removed. For
example, the above-mentioned address can be represented in shorter format as
2001:0:130F:0:0:9C0:876A:130B.
l
If an IPv6 address contains two or more
consecutive groups of zeros, they can be replaced by the double-colon ::
option. For example, the above-mentioned address can be represented in the
shortest format as 2001:0:130F::9C0:876A:130B.
Caution:
The double-colon ::
option can be used only once in an IPv6 address. Otherwise, the device is
unable to determine how many zeros double-colons represent when converting them
to zeros to restore a 128-bit IPv6 address.
An IPv6 address consists of two parts:
address prefix and interface ID. The address prefix and the interface ID are
respectively equivalent to the network ID and the host ID in an IPv4 address.
An IPv6 address prefix is written in
IPv6-address/prefix-length notation, where IPv6-address is an IPv6 address in
any of the notations and prefix-length is a decimal number indicating how many
bits from the utmost left of an IPv6 address are the address prefix.
II. IPv6 address classification
IPv6 addresses fall
into three types: unicast address, multicast address, and anycast address.
l
Unicast address: An identifier for a single
interface, similar to an IPv4 unicast address. A packet sent to a unicast
address is delivered to the interface identified by that address.
l
Multicast address: An identifier for a set of
interfaces (typically belonging to different nodes), similar to an IPv4
multicast address. A packet sent to a multicast address is delivered to all
interfaces identified by that address.
l
Anycast address: An identifier for a set of
interfaces (typically belonging to different nodes). A packet sent to an
anycast address is delivered to one of the interfaces identified by that
address (the nearest one, according to the routing protocols’ measure of
distance).
There are no broadcast addresses in IPv6. Their function is
superseded by multicast addresses.
The type of an IPv6 address is designated
by the first several bits called format prefix. Table 1-1 lists the mappings between
address types and format prefixes.
Table 1-1 Mapping between address types
and format prefixes
|
Type
|
Format prefix (binary)
|
IPv6 prefix ID
|
|
Unicast address
|
Unassigned address
|
00...0 (128 bits)
|
::/128
|
|
Loopback address
|
00...1 (128 bits)
|
::1/128
|
|
Link-local address
|
1111111010
|
FE80::/10
|
|
Site-local address
|
1111111011
|
FEC0::/10
|
|
Global unicast address
|
other forms
|
—
|
|
Multicast address
|
11111111
|
FF00::/8
|
|
Anycast address
|
Anycast addresses are taken from unicast
address space and are not syntactically distinguishable from unicast
addresses.
|
III. Unicast address
There are several forms of unicast address
assignment in IPv6, including aggregatable global unicast address, link-local
address, and site-local address.
l
The aggregatable global unicast address,
equivalent to an IPv4 public address, is provided for network service
providers. The type of address allows efficient route prefix aggregation to
restrict the number of global routing entries.
l
The link-local address is used for communication
between link-local nodes in neighbor discovery and stateless autoconfiguration.
Routers must not forward any packets with link-local source or destination
addresses to other links.
l
IPv6 unicast site-local addresses are similar to
private IPv4 addresses. Routers must not forward any packets with site-local
source or destination addresses outside of the site (equivalent to a private
network).
l
Loopback address: The unicast address
0:0:0:0:0:0:0:1 (represented in the shortest format as ::1) is called the
loopback address and may never be assigned to any physical interface. Like the
loopback address in IPv4, it may be used by a node to send an IPv6 packet to
itself.
l
Unassigned address: The unicast address
"::” is called the unassigned address and may not be assigned to any
node. Before acquiring a valid IPv6 address, a node may fill this address in
the source address field of an IPv6 packet, but may not use it as a destination
IPv6 address.
IV. Multicast address
IPv6 multicast addresses listed in Table 1-2
are reserved for special purpose.
Table 1-2 Reserved
IPv6 multicast addresses
|
Address
|
Application
|
|
FF01::1
|
Node-local scope all-nodes multicast
address
|
|
FF02::1
|
Link-local scope all-nodes multicast
address
|
|
FF01::2
|
Node-local scope all-routers multicast
address
|
|
FF02::2
|
Link-local scope all-routers multicast
address
|
|
FF05::2
|
Site-local scope all-routers multicast
address
|
Besides, there is another type of multicast
address: solicited-node address. A solicited-node multicast address is used to
acquire the link-layer addresses of neighbor nodes on the same link and is also
used for duplicate address detection (DAD). Each IPv6 unicast or anycast
address has one corresponding solicited-node address. The format of a
solicited-node multicast address is as follows:
FF02:0:0:0:0:1:FFXX:XXXX
Where, FF02:0:0:0:0:1 FF is permanent and
consists of 104 bits, and XX:XXXX is the last 24 bits of an IPv6 unicast or
anycast address.
V. Interface identifier in IEEE
EUI-64 format
Interface identifiers in IPv6 unicast
addresses are used to identify interfaces on a link and they are required to be
unique on that link. Interface identifiers in IPv6 unicast addresses are
currently required to be 64 bits long. An interface identifier in IEEE EUI-64
format is derived from the link-layer address of that interface. Interface
identifiers in IPv6 addresses are 64 bits long, while MAC addresses are 48 bits
long. Therefore, the hexadecimal number FFFE needs to be inserted in the middle
of MAC addresses (behind the 24 high-order bits). To ensure the interface
identifier obtained from a MAC address is unique, it is necessary to set the
universal/local (U/L) bit (the seventh high-order bit) to “1”.
Thus, an interface identifier in IEEE EUI-64 format is obtained.
Figure
1-2 Convert a MAC address into an EUI-64 interface
identifier
1.1.3 Introduction to IPv6 Neighbor Discovery Protocol
IPv6 Neighbor Discovery Protocol (NDP) uses
five types of ICMPv6 messages to implement the following functions:
l
Address resolution
l
Neighbor
reachability detection
l
Duplicate
address detection
l
Router/prefix
discovery and address autoconfiguration
l
Redirection
Table 1-3 lists the types and functions
of ICMPv6 messages used by the NDP.
Table 1-3 Types and functions of ICMPv6
messages
|
ICMPv6 message
|
Number
|
Function
|
|
Neighbor solicitation (NS) message
|
135
|
Used to acquire the link-layer address of
a neighbor
|
|
Used to verify whether the neighbor is
reachable
|
|
Used to perform a duplicate address
detection
|
|
Neighbor advertisement (NA) message
|
136
|
Used to respond to an NS message
|
|
When the link layer changes, the local
node initiates an NA message to notify neighbor nodes of the node information
change.
|
|
Router solicitation (RS) message
|
133
|
After started, a node sends an RS message
to request the router for an address prefix and other configuration
information for the purpose of autoconfiguration.
|
|
Router
advertisement (RA) message
|
134
|
Used to
respond to an RS message
|
|
With the RA message suppression disabled,
the router regularly sends an RA message containing information such as
prefix information options and flag bits.
|
|
Redirect message
|
137
|
When a certain condition is satisfied,
the default gateway sends a redirect message to the source host so that the
host can reselect a correct next hop router to forward packets.
|
The NDP mainly provides the following
functions:
I. Address resolution
Similar to the ARP function in IPv4, a node
acquires the link-layer addresses of neighbor nodes on the same link through NS
and NA messages. Figure
1-3 shows how node A acquires the link-layer address of node B.
Figure
1-3 Address resolution
The address resolution procedure is as
follows:
1)
Node A multicasts an NS message. The source
address of the NS message is the IPv6 address of an interface of node A and the
destination address is the solicited-node multicast address of node B. The NS
message contains the link-layer address of node A.
2)
After receiving the NS message, node B judges
whether the destination address of the packet corresponds to the solicited-node
multicast address. If yes, node B can learn the link-layer address of node A,
and unicasts an NA message containing its link-layer address.
3)
Node A acquires the link-layer address of node B
from the NA message.
II. Neighbor reachability detection
After node A acquires the link-layer
address of its neighbor node B, node A can verify whether node B is reachable
according to NS and NA messages.
1)
Node A sends an NS message whose destination
address is the IPv6 address of node B.
2)
If node A receives an NA message from node B,
node A considers that node B is reachable. Otherwise, node B is unreachable.
After node A acquires an IPv6 address, it
will perform duplicate address detection (DAD) to determine whether the address
is being used by other nodes (similar to the gratuitous ARP function of IPv4).
DAD is accomplished through NS and NA messages. Figure 1-3 shows the DAD procedure.
Figure
1-4 Duplicate address detection
The DAD procedure is as follows:
1)
Node A sends an NS message whose source address
is the unassigned address :: and destination address is the corresponding
solicited-node multicast address of the IPv6 address to be detected. The NS
message contains the IPv6 address.
2)
If node B uses this IPv6 address, node B returns
an NA message. The NA message contains the IPv6 address of node B.
3)
Node A learns that the IPv6 address is being
used by node B after receiving the NA message from node B. Otherwise, node B is
not using the IPv6 address and node A can use it.
Router/prefix discovery means that a node
locates the neighboring routers, and learns the prefix of the network where the
host is located, and other configuration parameters from the received RA
message.
Stateless address autoconfiguration means
that a node automatically configures an IPv6 address according to the
information obtained through router/prefix discovery.
The router/prefix discovery is implemented
through RS and RA messages. The router/prefix discovery procedure is as
follows:
1)
After started, a node sends an RS message to
request the router for the address prefix and other configuration information
for the purpose of autoconfiguration.
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.
l
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.
l
An automatically generated address is applicable
within the valid lifetime and will be removed when the valid lifetime times
out.
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:
l
The receiving interface is the forwarding
interface.
l
The selected route itself is not created or
modified by an IPv6 ICMP redirect message.
l
The selected route is not the default route.
l
The forwarded IPv6 packet does not contain any
routing header.
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. Figure 1-5
shows the working procedure of the PMTU discovery.
Figure 1-5 Working procedure of the PMTU
discovery
The working procedure of the PMTU discovery
is as follows:
1)
The source host uses its MTU to fragment packets
and then sends them to the destination host.
2)
If the MTU supported by the forwarding interface
is less than the packet size, the forwarding device will discard the packet and
return an ICMPv6 error packet containing the interface MTU to the source host.
3)
After receiving the ICMPv6 error packet, the
source host uses the returned MTU to fragment the packet again and then sends
it.
4)
Step 2 to step 3 are repeated until the
destination host receives the packet. In this way, the minimum MTU of all links
in the path from the source host to the destination host is determined.
1.1.5 Introduction to IPv6 DNS
In the IPv6 network, a Domain Name System
(DNS) supporting IPv6 converts domain names into IPv6 addresses, instead of
IPv4 addresses.
However, just like an IPv4 DNS, an IPv6 DNS
also covers static domain name resolution and dynamic domain name resolution.
The function and implementation of these two types of domain name resolution
are the same as those of an IPv4 DNS. For details, refer to DNS
Configuration.
Usually, the DNS server connecting IPv4 and
IPv6 networks not only contain A records (IPv4 addresses), but also AAAA
records (IPv6 addresses). The DNS server can convert domain names into IPv4
addresses or IPv6 addresses. In this way, the DNS server implements the
functions of both IPv6 DNS and IPv4 DNS.
1.1.6 Protocols and Standards
Protocols and standards related to IPv6
include:
l
RFC 1881: IPv6 Address Allocation Management
l
RFC 1887: An Architecture for IPv6 Unicast
Address Allocation
l
RFC 1981: Path MTU Discovery for IP version 6
l
RFC 2375: IPv6 Multicast Address Assignments
l
RFC 2460: Internet Protocol, Version 6 (IPv6)
Specification.
l
RFC 2461: Neighbor Discovery for IP Version 6
(IPv6)
l
RFC 2462: IPv6 Stateless Address
Autoconfiguration
l
RFC 2463: Internet Control Message Protocol
(ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification
l
RFC 2464: Transmission of IPv6 Packets over
Ethernet Networks
l
RFC 2526: Reserved IPv6 Subnet Anycast Addresses
l
RFC 3307: Allocation Guidelines for IPv6
Multicast Addresses
l
RFC 3513: Internet Protocol Version 6 (IPv6)
Addressing Architecture
l
RFC 3596: DNS Extensions to Support IP Version 6
1.2 IPv6 Basics Configuration Task List
Complete the following tasks to perform
IPv6 basics configuration:
Before IPv6-related configurations, you
must enable the IPv6 packet forwarding function. Otherwise, an interface cannot
forward IPv6 packets even if an IPv6 address is configured, resulting in
communication failures in the IPv6 network.
Follow these steps to enable the IPv6
packet forwarding function:
|
To do...
|
Use the command...
|
Remarks
|
|
Enter
system view
|
system-view
|
—
|
|
Enable the
IPv6 packet forwarding function
|
ipv6
|
Required
Disabled
by default.
|
IPv6 site-local addresses and aggregatable
global unicast addresses can be configured in the following ways:
l
EUI-64 format: When the EUI-64 format is adopted
to form IPv6 addresses, the IPv6 address prefix of an interface is the
configured prefix and the interface identifier is derived from the link-layer
address of the interface.
l
Manual configuration: IPv6 site-local addresses
or aggregatable global unicast addresses are configured manually.
IPv6 link-local addresses can be configured
in either of the following ways:
l
Automatic generation: The device automatically
generates a link-local address for an interface according to the link-local
address prefix (FE80::/64) and the link-layer address of the interface.
l
Manual assignment: IPv6 link-local addresses can
be assigned manually.
Follow these steps to configure an IPv6
unicast address:
|
To
do...
|
Use the
command...
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Enter interface view
|
interface interface-type interface-number
|
—
|
|
Configure an IPv6 aggregatable global
unicast address or site-local address
|
Manually assign an IPv6 address
|
ipv6 address { ipv6-address prefix-length | ipv6-address/prefix-length
}
|
Required to use either command.
By default, no site-local address or
aggregatable global unicast address is configured for an interface.
|
|
Adopt the EUI-64 format to form an IPv6
address
|
ipv6 address ipv6-address/prefix-length eui-64
|
|
Configure
an IPv6 link-local address
|
Automatically
generate a link-local address
|
ipv6
address auto link-local
|
Optional
By
default, after an IPv6 site-local address or aggregatable global unicast
address is configured for an interface, a link-local address will be
generated automatically.
|
|
Manually assign a link-local address for
an interface
|
ipv6 address ipv6-address link-local
|
l
After an IPv6 site-local address or aggregatable
global unicast address is configured for an interface, a link-local address
will be generated automatically. The automatically generated link-local address
is the same as the one generated by using the ipv6 address auto link-local
command. If a link-local address is manually assigned to an interface, this
link-local address takes effect. If the manually assigned link-local address is
removed, the automatically generated link-local address takes effect.
l
The manual assignment takes precedence over the
automatic generation. That is, if you first adopt the automatic generation and
then the manual assignment, the manually assigned link-local address will
overwrite the automatically generated one. If you first adopt the manual
assignment and then the automatic generation, the automatically generated
link-local address will not take effect and the link-local address of an
interface is still the manually assigned one. If you delete the manually
assigned address, the automatically generated link-local address is validated.
l
You need to execute the ipv6 address auto
link-local command before the undo ipv6 address auto link-local command.
However, if an IPv6 site-local address or aggregatable global unicast address
is already configured for an interface, the interface still has a link-local
address because the system automatically generates one for the interface. If no
IPv6 site-local address or aggregatable global unicast address is configured,
the interface has no link-local address.
1.4 Configuring
IPv6 NDP
The IPv6 address of a neighbor node can be
resolved into a link-layer address dynamically through NS and NA messages or through
a manually configured neighbor entry.
The device uniquely identifies a static
neighbor entry according to the IPv6 address and the layer 3 interface ID.
Currently, there are two configuration methods:
l
Configure an IPv6 address and link-layer address
for a Layer 3 interface.
l
Configure an IPv6 address and link-layer address
for a port in a VLAN.
Follow these steps to configure a static
neighbor entry:
|
To do...
|
Use the command...
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Configure a static neighbor entry
|
ipv6 neighbor ipv6-address mac-address { vlan-id
port-type port-number | interface interface-type
interface-number }
|
Required
|
Caution:
You can adopt either
of the two methods above to configure a static neighbor entry for a VLAN
interface.
l
After a static neighbor entry is configured by
using the first method, the device needs to resolve the corresponding Layer 2
port information of the VLAN interface.
l
If you adopt the second method to configure a
static neighbor entry, you should ensure that the corresponding VLAN interface
exists and that the layer 2 port specified by port-type port-number
belongs to the VLAN specified by vlan-id. After a static neighbor entry
is configured, the device relates the VLAN interface to an IPv6 address to
uniquely identify a static neighbor entry.
The device can dynamically acquire the
link-layer address of a neighbor node and add it into the neighbor table
through NS and NA messages. Too large a neighbor table from which neighbor
entries can be dynamically acquired may lead to the forwarding performance
degradation of the device. Therefore, you can restrict the size of the neighbor
table by setting the maximum number of neighbors that an interface can
dynamically learn. When the number of dynamically learned neighbors reaches the
threshold, the interface will stop learning neighbor information.
Follow these steps to configure the maximum
number of neighbors dynamically learned:
|
To do…
|
Use the command…
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Enter interface view
|
interface interface-type interface-number
|
—
|
|
Configure the maximum number of neighbors
dynamically learned by an interface
|
ipv6 neighbors max-learning-num number
|
Optional
|
You can configure whether
the interface sends an RA message, 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 1-4
lists the configurable parameters in an RA message and their descriptions.
Table 1-4 Parameters in an RA message
and their descriptions
|
Parameters
|
Description
|
|
Cur hop limit
|
When sending an IPv6 packet, a host uses the
value of this parameter to fill the Cur Hop Limit field in IPv6 headers.
Meanwhile, the value of this parameter is equal to the value of the Cur Hop
Limit field in response messages of the device.
|
|
Prefix information options
|
After receiving the prefix information
advertised by the device, the hosts on the same link can perform stateless
autoconfiguration operations.
|
|
M flag
|
This field determines whether hosts use
the stateful autoconfiguration to acquire IPv6 addresses.
If the M flag is set to 1, hosts use the
stateful autoconfiguration to acquire IPv6 addresses. Otherwise, hosts use
the stateless autoconfiguration to acquire IPv6 addresses, that is, hosts
configure IPv6 addresses according to their own link-layer addresses and the
prefix information issued by the router.
|
|
O flag
|
This field determines whether hosts use
the stateful autoconfiguration to acquire information other than IPv6
addresses.
If the O flag is set to 1, hosts use the
stateful autoconfiguration (for example, DHCP server) to acquire information
other than IPv6 addresses. Otherwise, hosts use the stateless
autoconfiguration to acquire information other than IPv6 addresses.
|
|
Router lifetime
|
This field is used to set the lifetime of
the router that sends RA messages to serve as the default router of hosts.
According to the router lifetime in the received RA messages, hosts determine
whether the router sending RA messages can serve as the default router of
hosts.
|
|
Retrans timer
|
If the device fails to receive a response
message within the specified time after sending an NS message, the device
will retransmit it.
|
|
Reachable time
|
After the neighbor reachability detection
shows that a neighbor is reachable, the device considers the neighbor is
reachable within the reachable time. If the device needs to send a packet to
a neighbor after the reachable time expires, the device will again confirm
whether the neighbor is reachable.
|
The values of the
Retrans Timer field and the Reachable Time field configured for an interface
are sent to hosts via RA messages. Furthermore, this interface sends NS
messages at intervals of Retrans Timer and considers a neighbor reachable
within the time of Reachable Time.
Follow these steps to configure parameters
related to an RA message:
|
To do…
|
Use the command…
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Configure the current hop limit
|
ipv6 nd hop-limit value
|
Optional
64 by default.
|
|
Enter interface view
|
interface interface-type interface-number
|
—
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Disable the RA message suppression
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undo ipv6 nd ra halt
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Optional
By default, RA messages are suppressed.
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