Configure an IPv6 Interface
The information in this section can help you configure an IPv6 interface to make IPv6 active on the interface and fine-tune IPv6 neighbor discovery to control the frequency of protocol traffic.
By default, IPv6 forwarding is enabled on an interface.
Compared to IPv4/ARP, the IPv6 neighbor discovery mechanism maintains more protocol state, timers, and protocol traffic overhead.
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ipv6 interface reachable-time
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ipv6 interface retransmit-timer
Before you begin
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Before you can assign an IPv6 address to the interface, you must configure an IPv6 interface for a VLAN or brouter port.
You must configure a VLAN before you can give the VLAN an interface identifier or an IPv6 address.
The switch supports port-based and IPv6 protocol-based VLANs.
For information about how to configure VLANs, see the followings:
Procedure
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Enter Interface Configuration
mode:
enable
configure terminal
interface GigabitEthernet {slot/port[/sub-port][-slot/port[/sub-port]][,...][slot/all][all]} or interface vlan <1–4059>
Note
If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port.
Example
Note
In contrast to IPv6 interface creation and address assignment in EDM, you use the ipv6 interface CLI command to create an interface and specify a single global address in one step.
Create and administratively enable the interface:
Switch:1>enable Switch:1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch:1(config)#interface gigabitethernet 1/4 Switch:1(config-if)#ipv6 interface enable
Variable Definitions
Use the data in the following table to use the ipv6 interface command.
|
Variable |
Value |
|---|---|
|
hop-limit <1–255> |
Configures the maximum hops. The default is 64. |
|
link-local WORD<0–19> |
Specifies the 64-bit interface ID used to calculate the actual link-local address as a name up to 19 characters long. |
|
mac-offset <0-511> |
Specifies a number by which to offset the MAC address from the chassis MAC address. This ensures that each IP address has a different MAC address. If you omit this variable, a unique MAC offset is automatically generated. Note:
This parameter applies only to VLANs. You can specify a MAC offset when you configure IPv6 on a VLAN, or the system can assign a MAC address from within the available range. |
|
mtu <1280–9500> |
Configures the maximum transmission unit for the interface: 1280–1500, 1850, or 9500. This value must be the same for all addresses defined on this interface. The default is 1500. Different hardware platforms support different MTU values. To see what values your switch supports, use the CLI command completion help. |
|
name WORD<0–255> |
Assigns a descriptive name. The network management system also configures this string. |
|
reachable-time <0–3600000> |
Controls how long IPv6 neighbor entries learned on an interface remain in the REACHABLE state (as described in RFC 4861). The system randomizes the value you configure, per RFC specifications, to be 50%-150% of the configured value. By default the reachable-time base value is 30 seconds, with an actual 15-45 second range when you consider the randomization factor. The default is 3000 milliseconds |
|
retransmit-timer <0–4294967295> |
Controls the time, in milliseconds, between retransmission of Neighbor Solicitation messages when the system attempts to resolve or reconfirm the reachability of an IPv6 neighbor. By default, the system sends three Neighbor Solicitation messages with a one second interval between each message. If the system does not receive a corresponding Neighbor Advertisement within an interval equal to 3 X retransmit-timer milliseconds, the system declares the IPv6 neighbor unreachable. Tip:
You can increase the retransmit-timer to extend the interval that the switch waits until it declares the neighbor unreachable. For example: a retransmit-timer value of 5000 means the switch waits 3 X 5000 milliseconds which equals 15000 milliseconds or 15 seconds. The default is 1000 milliseconds |
|
vlan <1-4059> |
Specifies the VLAN ID in the range of 1 to 4059. By default, VLAN IDs 1 to 4059 are configurable and the system reserves VLAN IDs 4060 to 4094 for internal use. On switches that support the vrf-scaling and spbm-config-mode boot configuration flags, if you enable these flags, the system also reserves VLAN IDs 3500 to 3998. VLAN ID 1 is the default VLAN and you cannot create or delete VLAN ID 1. This value corresponds to the lower 12 bits of the IEEE 802.1Q VLAN tag. |
Use the data in the following table to use the ipv6 rvs-path-chk command.
|
Variable |
Value |
|---|---|
|
mode {strict|exist-only} |
Specifies the mode for Unicast Reverse Path Forwarding (uRPF). In strict mode, uRPF checks whether the source IP address of the incoming packet exists in the FIB. If the incoming interface is not the best reverse path, the packet check fails and uRPF drops the packet. In exist-only mode, uRPF checks whether the source IP address of the incoming packet exists in the FIB. The packet is dropped only if the source address is not reachable via any interface on that router. |
Use the data in the following table to use the interface command.
|
Variable |
Value |
|---|---|
|
<1-4059> |
Specifies the VLAN ID in the range of 1 to 4059. By default, VLAN IDs 1 to 4059 are configurable and the system reserves VLAN IDs 4060 to 4094 for internal use. On switches that support the vrf-scaling and spbm-config-mode boot configuration flags, if you enable these flags, the system also reserves VLAN IDs 3500 to 3998. VLAN ID 1 is the default VLAN and you cannot create or delete VLAN ID 1. |
|
{slot/port[/sub-port][-slot/port[/sub-port]][,...][slot/all][all]} |
Identifies the
slot and port in one of the following formats:
|