# Basic IPv6 Settings

## 1. Function Overview

This product is compatible with the following IPv6 network environment settings, mainly for the purpose of maintenance (configuring the switch settings).

1. IPv6 address settings

2. Route information settings

3. Neighbor cache table settings

4. MTU settings

5. IPv6 RA settings

6. DHCPv6-PD client settings

## 2. Definition of Terms Used

RA (Router Advertisement)

This is a system that automatically sets address information and network settings on the IPv6 network for devices of the network that is associated with a router.

IPv6 address

The IPv6 address is 128 bits expressed as hexadecimal. As shown below, it is divided into eight 16-bit fields separated by ":".

- 2001:02f8:0000:0000:1111:2222:0000:4444

The expression can be abbreviated according to the following rules.

- If the beginning of a field is a zero, the zero can be omitted.

- A field that consists of four zeros can be abbreviated as a single zero.

- Multiple fields consisting of only "0" can be omitted with "::" in only one place overall.

Applying these rules to the above address, we get the following.

- 2001:2f8::1111:2222:0:4444

IPv6 link-local address

This is an address that is only valid within the same segment, and is in the following range.

- [Start] FE80:0000:0000:0000:0000:0000:0000:0000

- [End] FE80:0000:0000:0000:FFFF:FFFF:FFFF:FFFF

SLAAC (StateLess Address AutoConfiguration)

A mechanism where hosts automatically generate IPv6 addresses using the Prefix Information option of RA.

## 3. Function Details

### 3.1. IPv6 address settings

This product lets you specify the IPv6 address and prefix length for a VLAN interface.
The setting method supports either fixed settings, setting addresses automatically via RAs (router advertisement), or setting addresses automatically by DHCPv6.

- In order to specify an IPv6 address, IPv6 functionality must be enabled for the corresponding VLAN interface.

  - To enable IPv6 functionality, use the ipv6 enable command.

  - When IPv6 functionality is enabled, an IPv6 link local address is automatically assigned.

- To set a fixed/automatic IPv6 address, use the ipv6 address command.

- The following actions occur if addresses are specified automatically by DHCPv6.

  - Executing the ipv6 address dhcp command enables the DHCPv6 stateful actions (IA_NA).

  - If the no ipv6 address dhcp command is executed with addresses specified automatically, a message is sent to the DHCPv6 server indicating that the IPv6 addresses acquired were released.

  - The information obtained from the DHCPv6 server is checked using the show ipv6 dhcp interface command.

- Specifying stateless as the parameter for the ipv6 address autoconfig command used to specify addresses automatically by RA (router advertisements) enables DHCPv6 stateless actions.

- For IPv6 addresses, up to 5 global addresses (including automatically specified addresses and IPv6 addresses specified by a DHCPv6 client or using DHCPv6-PD) and 1 link local address can be specified per VLAN interface.
  Up to 256 IPv6 addresses can be specified across the entire system.
  The IPv6 address that is allocated to a VLAN interface can be checked using the show ipv6 interface command.

### 3.2. Route information settings

This product refers to a routing table when sending syslog messages and when sending out voluntary IPv6 packets as an IPv6 host for NTP-based time adjustments and so on.
This product uses the following functions to perform the routing table operations.

- Set VLAN interface route information

- Set default gateway

- Set static route information

- Show route information

#### 3.2.1. Route information for VLAN interfaces

When setting an IPv6 address on this product for a VLAN interface, the correspondence between the network address and VLAN ID is automatically set as route information.
When releasing IPv6 addresses set for the VLAN interface, the above settings will be deleted.

#### 3.2.2. Set default gateway

The destination for IPv6 packets sent to network addresses that are not set in the routing table can be set as the default gateway on this product.

- To set the default gateway, use the ipv6 route command.

- To show the default gateway, use the show ipv6 route command.

- When ipv6 address dhcp, ipv6 dhcp client pd, or ipv6 address autoconfig commands are specified, device addresses to which RAs were sent are automatically added to the default gateway.

  - Automatic default gateway registration by RAs can be enabled/disabled using the ipv6 nd accept-ra-default-routes command.

#### 3.2.3. Set static route information

A static route to the destination network address (the gateway address to which packets will be sent) can be set on this product.

- Static route information is set using the ipv6 route command.

- Static route information is displayed using the show ipv6 route command.

#### 3.2.4. Routing table and route selection

You will use the following two types of table to specify routing information.

- RIB (Routing Information Base: IP routing table)

- FIB (Forwarding Information Base: IP forwarding table)

The roles of each are explained below.

- RIB
  RIB (Routing Information Base: IP routing table) is a database that stores various routing information.

  - A route is registered in the RIB in the following cases.

    - When an IPv6 address is assigned to a VLAN interface

    - When a static route or a default gateway are specified manually

  - To check the RIB, use the show ipv6 route database command.

- FIB
  FIB (Forwarding Information Base: IP forwarding table) is a database that is referenced when deciding how to forward IP packets.
  Of the routes that are registered in the RIB, the FIB registers only the route that is determined to be “optimal” and is actually used for forwarding packets.

  - The conditions by which a route is determined to be optimal are as follows.

    - The corresponding VLAN interface is in the link up state

    - If multiple routes to the same destination are registered in the RIB, only one is decided in the following order of priority

      1. A route whose gateway has a higher IP address value takes priority

  - To check the FIB, use the show ipv6 route command.

### 3.3. Neighbor cache table settings

When sending IPv6 packets, this product uses Neighbor Discovery Protocol to obtain the MAC addresses from the IPv6 addresses.
The correspondence between IPv6 address and MAC address is saved in the neighbor cache table with the following specifications.

- The neighbor cache entries saved in the neighbor cache table manage the following information.

  - IPv6 address

  - MAC address

  - VLAN interface

- Up to 16384 entries are stored in the neighbor cache table, including dynamic and static entries.

- Dynamic entries saved in the neighbor cache table can be cleared by using the clear ipv6 neighbors command.

- Settings for the static entries in the neighbor cache table are made using the ipv6 neighbor command. Up to 1023 items can be registered.

- Use the show ipv6 neighbor command to check the neighbor cache table.

### 3.4. MTU settings

This product enables MTU values to be specified for VLAN interfaces.

- Use the mtu command to set MTU values.

- The default MTU value is 1500 bytes, but setting values ranging from 68 bytes to 9216 bytes can be specified.
  However, the setting range for VLAN interfaces with “ipv6 enable” specified is from 1280 bytes to 9216 bytes.

- A maximum of seven MTU values, besides the default value, can be specified.

- To route received packets, use the following steps.

  - If the IPv4 header “Total Length” field value for IPv4 packets exceeds the MTU value, then packets are forwarded divided into parts (IP fragments).
    IPv4 packets appended with a DF (don’t fragment) bit are discarded without being divided into IP fragments and an ICMP error (fragmentation needed) is returned.

  - If the IPv6 header “Payload Length” field value for IPv6 packets exceeds the MTU value, then an ICMPv6 error (packet too big) is returned and the packet is discarded.

  - Packets larger than the maximum receivable frame size specified by the mru command are not routed. To forward extra large frames, use the mru command to adjust the maximum receivable frame size setting as necessary.

  - *If divided (IP fragmentation) for forwarding, then software is used for forwarding, which limits the forwarding speed and also dramatically increases the CPU usage rate. *
    It is recommended that the mtu command be used to set a frame size large enough to forward extra-large frames without dividing them (IP fragmentation).

- This product forwards packets according to the following steps.

  - If the IPv4/IPv6 packet size sent is larger than the MTU value for the VLAN interface where packets are being sent, then packets are divided (IP fragmentation) based on the MTU value.

### 3.5. IPv6 RA settings

This product can be configured to send RA from a specified IPv6 interface.
RA (Router Advertisement) is an ICMPv6 message sent from a router to an IPv6 host.
RAs are periodically sent by the router via multicast.
Sending an RA primarily enables the following:

- Hosts will be able to discover the router.

- Hosts will be able to be notified of prefix information.

  - Hosts will be able to automatically configure IPv6 addresses using the prefix in RA (SLAAC).

- Hosts will be able to be notified of whether DHCPv6 is available.

- Hosts will be able to set the default router (gateway).

The operating specifications for the IPv6 RA function are outlined below:

1. When configuring the transmission settings for the IPv6 RA function, do so for the VLAN interface.

   - Configure using the ipv6 nd send-ra command.

     - No setting is specified in default settings.

   - The ipv6 nd send-ra command is only available when the ipv6 command is enabled on the target interface.

2. You can configure the prefix information to be included in RA using the ipv6 nd prefix command.

   - If the ipv6 nd prefix command is not available, the prefixes of all IPv6 addresses set on the interface will be advertised.

   - No setting is specified in default settings.

   - The parameters of the ipv6 nd prefix command allows you to modify the Prefix Information option field in the RA packet to be sent. For details, refer to the Command Reference.

   - The ipv6 nd prefix command can be configured up to the following number on one VLAN interface.

     - The number of IPv6 global addresses that can be configured on one VLAN interface.

3. For periodic RA transmissions, a random value between the set minimum and maximum transmission times is used.

   - You can set the maximum time using the ipv6 nd ra-interval command.

     - The default value is 600 seconds

   - You can set the minimum time using the ipv6 nd minimum-ra-interval command.

     - The default value is 198 seconds

4. You can modify the fields in the RA packet to be sent using the following command. For details, refer to the Command Reference.

   - List of Applicable Commands

     Commands | Target Fields in RA Packets | Initial Value
     --- | --- | ---
     ipv6 nd current-hoplimit | Cur Hop Limit | 64
     ipv6 nd managed-config-flag | M Flag | No settings
     ipv6 nd other-config-flag | O Flag | No settings
     ipv6 nd ra-lifetime | Router Lifetime | 1800秒
     ipv6 nd reachable-time | Reachable Time | 0 milliseconds
     ipv6 nd retransmission-time | Retrans Timer | 0 milliseconds

### 3.6. DHCPv6-PD client settings

This product enables DHCPv6-PD clients to be specified for VLAN interfaces.
Prefixes can be obtained from a DHCPv6-PD server for specifying addresses or reassigning the user’s own DHCPv6 server.

- Executing the ipv6 dhcp client pd and prefixname commands will enable DHCPv6-PD stateful actions (IA_PD).

- Prefixes obtained with the prefixname command can be used for the following.

  - Using the ipv6 address pd command to specify IPv6 addresses using the prefixes obtained.

  - Using the range command in the DHCPv6 mode to specify the range of IPv6 addresses to be dynamically assigned in the DHCPv6 server using the prefixes obtained (only on models compatible with DHCPv6 server).

  - Using the prefix-delegation command in the DHCPv6 mode to reassign prefixes to the DHCPv6 server using the prefixes obtained (only on models compatible with DHCPv6 server).

- The information obtained from the DHCPv6 server is checked using the show ipv6 dhcp interface command.

## 4. Related Commands

Related commands are indicated below.
For details on the commands, refer to the Command Reference.

Function types | Operations | Operating commands
--- | --- | ---
IPv6 address settings | Enable/disable IPv6 addresses | ipv6 enable/disable
IPv6 address settings | ipv6 address
Specifies IPv6 addresses using DHCPv6-PD. | ipv6 address pd
Show IPv6 address | show ipv6 interface
Set RA setting for IPv6 address | ipv6 address autoconfig
Specifies IPv6 addresses dynamically using a DHCPv6 client. | ipv6 address dhcp
DHCPv6-PD client settings | ipv6 dhcp client pd
Specifies automatic registration of default gateways using an RA. | ipv6 nd accept-ra-default-routes
Displays status of DHCPv6 client. | show ipv6 dhcp interface
Resets DHCPv6 client. | clear ipv6 dhcp client
Setting for ND prefix received when setting DHCPv6 client settings | ipv6 dhcp client nd-prefix
Route information settings | Set default gateway | ipv6 route
Show default gateway | show ipv6 route
Set static route information | ipv6 route
Show static route information | show ipv6 route
Show route information | show ipv6 route
Neighbor cache settings | Set static neighbor cache entry | ipv6 neighbors
Show neighbor cache table | show ipv6 neighbors
Clear neighbor cache table | clear ipv6 neighbors
MTU settings | MTU settings | mtu
IPv6 RA settings | IPv6 RA transmission settings | ipv6 nd send-ra
Setting prefix information to be notified by RA | ipv6 nd prefix
Set the maximum interval for periodic RA transmissions | ipv6 nd ra-interval
Set the minimum interval for periodic RA transmissions | ipv6 nd minimum-ra-interval
Setting the Cur Hop Limit field in RA | ipv6 nd current-hoplimit
Setting the M flag in RA | ipv6 nd managed-config-flag
Setting the O flag in RA | ipv6 nd other-config-fla
Router Lifetime setting in RA | ipv6 nd ra-lifetime
RA Reachable Time settings | ipv6 nd reachable-time
RA Retrans Timer settings | ipv6 nd retransmission-time
RA MTU option setting | ipv6 nd link-mtu
Show RA information | show ipv6 nd ra

## 5. Examples of Command Execution

### 5.1. Setting up an IPv6 network environment (fixed settings)

In this example, the IPv6 addresses are manually set on this product, and an environment is set up for accessing the unit from a remote terminal.

- Maintenance for this product is done using the default VLAN (VLAN #1).

- The IPv6 address is set manually for the default VLAN (VLAN #1).

- Web/TFTP access permission is given from a host connected to VLAN #1.

1. This sets 2001:db8:1::2/64 for the default VLAN (VLAN #1).

       Yamaha#configure terminal
       Enter configuration commands, one per line.  End with CNTL/Z.
       Yamaha(config)#interface vlan1
       Yamaha(config-if)#ipv6 enable (1)
       Yamaha(config-if)#ipv6 address 2001:db8:1::2/64 (2)

   1 | Enable IPv6
   2 | Specify an IPv6 address

2. Check the IPv6 address that was set.

       Yamaha(config-if)#end
       Yamaha#show ipv6 interface brief
       Interface        IP-Address                                  Status                Protocol
       vlan1            2001:db8:1::2/64                            up                    up
                        fe80::2a0:deff:fe:2/64

3. Set the default VLAN (VLAN #1) to permit access from HTTP servers and TFTP servers.
   Access using a remote host over the Web after settings are made.

       Yamaha(config)#http-server interface vlan1 (1)
       Yamaha(config)#tftp-server interface vlan1 (2)

   1 | HTTP server access permission
   2 | TFTP server access permission

### 5.2. Setting up an IPv6 network environment (automatic settings using RA)

In this example, the IPv6 addresses are automatically set on this product, and an environment is set up for accessing the unit from a remote terminal.

- Maintenance for this product is done using the default VLAN (VLAN #1).

- The IPv6 address is set automatically by RA for the default VLAN (VLAN #1).

- Web/TFTP access permission is given from a host connected to VLAN #1.

1. Specify RA for the default VLAN (VLAN #1).

       Yamaha#configure terminal
       Enter configuration commands, one per line.  End with CNTL/Z.
       Yamaha(config)#interface vlan1
       Yamaha(config-if)#ipv6 enable (1)
       Yamaha(config-if)#ipv6 address autoconfig (2)

   1 | Enable IPv6
   2 | Set up RA

2. Check the IPv6 address that was obtained from RA.

       Yamaha(config-if)#end
       Yamaha#show ipv6 interface brief
       Interface        IP-Address                                  Status                Protocol
       vlan1            2001:db8::2a0:deff:fe:2/64                  up                    up
                        fe80::2a0:deff:fe:2/64

3. Set the default VLAN (VLAN #1) to permit access from HTTP servers and TFTP servers.
   Access using a remote host over the Web after settings are made.

       Yamaha(config)#http-server interface vlan1 (1)
       Yamaha(config)#tftp-server interface vlan1 (2)

   1 | HTTP server access permission
   2 | TFTP server access permission

### 5.3. IPv6 RA transmission settings

Enable sending IPv6 RA on vlan1.
In the example below, RAs with prefix information "2001:db8:1::/64" will be sent periodically.

1. Enable the IPv6 function on vlan1 and set the IPv6 address.

       Yamaha(config)# interface vlan1
       Yamaha(config-if)# ipv6 enable
       Yamaha(config-if)# ipv6 address 2001:db8:1::1/64

2. Configure IPv6 RA transmission settings.

       Yamaha(config-if)# ipv6 nd send-ra

### 5.4. IPv6 network environment setting (DHCPv6)

In this example, the IPv6 addresses are set on this product, and an environment is set up for accessing the unit from a remote terminal.

- Maintenance for this product is done using the default VLAN (VLAN #1).

- The IPv6 address is set automatically by DHCPv6 for the default VLAN (VLAN #1).

- Web/TFTP access permission is given from a host connected to VLAN #1.

1. Specify DHCPv6 for the default VLAN (VLAN #1).

       Yamaha#configure terminal
       Enter configuration commands, one per line.  End with CNTL/Z.
       Yamaha(config)#interface vlan1
       Yamaha(config-if)#ipv6 enable (1)
       Yamaha(config-if)#ipv6 address dhcp (2)

   1 | Enable IPv6
   2 | Set DHCPv6

2. Check the IPv6 address information obtained by DHCPv6.

       Yamaha(config-if)#end
       Yamaha#show ipv6 interface brief
       Interface       IPv6-Address                                Admin-Status  Link-Status
       vlan1          *2001:db8:1:aa10::dd37/128
                       fe80::ae44:f2ff:fe84:efdd/64                up            up

3. Set the default VLAN (VLAN #1) to permit access from HTTP servers and TFTP servers.
   Access using a remote host over the Web after settings are made.

       Yamaha(config)#http-server interface vlan1 (1)
       Yamaha(config)#tftp-server interface vlan1 (2)

   1 | HTTP server access permission
   2 | TFTP server access permission

### 5.5. IPv6 network environment settings (DHCPv6-PD)

In this example, the IPv6 addresses are set on this product, and an environment is set up for accessing the unit from a remote terminal.

- Maintenance for this product is done using the default VLAN (VLAN #1).

- DHCPv6-PD is specified for VLAN #100 and prefixes are obtained.

- The IPv6 address is specified using a prefix obtained by DHCPv6-PD for the default VLAN (VLAN #1).

- Web/TFTP access permission is given from a host connected to VLAN #1.

1. Specify DHCPv6-PD for VLAN #100.

       Yamaha#configure terminal
       Enter configuration commands, one per line.  End with CNTL/Z.
       Yamaha(config)#interface vlan100
       Yamaha(config-if)#ipv6 enable
       Yamaha(config-if)#ipv6 dhcp client pd PD_VLAN100 (1)
       Yamaha(config-if)#end

   1 | Obtain prefix with the name PD_VLAN100

2. Check the prefix information obtained by DHCPv6-PD.

       Yamaha#show ipv6 dhcp interface
       Interface vlan100
         Client Type        : IA_PD
         Prefix name        : PD_VLAN100
         prefix             : 2001:db8:1:aaf0::/60 (1)
         IAID               : 0f28924a
         DUID               : 000100010000000000a0de000000
         preferred lifetime : 604800
         valid lifetime     : 2592000
         expires            : 2023/4/19 08:08:04

   1 | Obtain 2001:db8:1:aaf0::/60

3. Specify an IPv6 address for the default VLAN (VLAN #1).
   Use the prefix obtained by DHCPv6-PD to specify 2001:db8:1:aaf2::1/64.

       Yamaha#configure terminal
       Enter configuration commands, one per line.  End with CNTL/Z.
       Yamaha(config)#interface vlan1
       Yamaha(config-if)#ipv6 enable (1)
       Yamaha(config-if)#ipv6 address pd PD_VLAN100 ::2:0:0:0:1/64 (2)

   1 | Enable IPv6
   2 | Specify an IPv6 address

4. Check the IPv6 address that was set.

       Yamaha(config-if)#end
       Yamaha#show ipv6 interface brief
       Interface       IP-Address                                  Admin-Status  Link-Status
       vlan1          *2001:db8:1:aaf2::1/64
                       fe80::ae44:f2ff:fe84:efdd/64                up            up

5. Set the default VLAN (VLAN #1) to permit access from HTTP servers and TFTP servers.
   Access using a remote host over the Web after settings are made.

       Yamaha(config)#http-server interface vlan1 (1)
       Yamaha(config)#tftp-server interface vlan1 (2)

   1 | HTTP server access permission
   2 | TFTP server access permission

## 6. Points of Caution

- If opposing DHCPv6 server settings are changed while DHCPv6 client functionality is being used, the setting changes may not be applied properly in the DHCPv6 client. If that occurs, use the clear ipv6 dhcp client command to reset the DHCPv6 client.

- The DHCPv6 client for this product does not support the following operations.

  - Requesting an SOL_MAX_RT option for solicit messages sent by a DHCPv6 client.

  - Overwriting SOL_MAX_RT parameter settings inside a DHCPv6 client after a SOL_MAX_RT option is received.

    - Note that SOL_MAX_RT parameters inside a DHCPv6 client remain active for a fixed 120 seconds.

  - Requesting an INF_MAX_RT option for request messages sent by a DHCPv6 client.

  - Overwriting INF_MAX_RT parameter settings inside a DHCPv6 client after an INF_MAX_RT option is received.

    - Note that INF_MAX_RT parameters inside a DHCPv6 client remain active for a fixed 120 seconds.

## 7. Related Documentation

- Layer 2 Function: VLAN

- Maintenance and Operation Functions: Remote Access Control

- Yamaha RTpro: What is ARP?

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