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This chapter contains the following sections:
Use the clear ipv6 neighbors command in privileged EXEC mode to delete all entries in the IPv6 neighbor discovery cache, except static entries.
clear ipv6 neighbors
Privileged EXEC mode
The following example deletes all entries, except static entries, in the neighbor discovery cache:
switchxxxxxx# clear ipv6 neighbors
Use the ipv6 address command in Interface Configuration mode to configure a global unicast IPv6 address based on an IPv6 general prefix and enable IPv6 processing on an interface. To remove the address from the interface, use the no form of this command.
ipv6 address ipv6-address/prefix-length
no ipv6 address [ipv6-address/prefix-length]
ipv6-address—Specifies the global unicast IPv6 address assigned to the interface. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
prefix-length—The length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
No IP address is defined for the interface.
Interface Configuration mode
The ipv6 address command cannot be applied to define an IPv6 address on an ISATAP interface.
Using the no IPv6 address command without arguments removes all manually-configured IPv6 addresses from an interface, including link local manually configured addresses.
The following example defines the IPv6 global address 2001:DB8:2222:7272::72 on vlan 100:
switchxxxxxx(config)# interface vlan 100
switchxxxxxx(config-if)# ipv6 address 2001:DB8:2222:7272::72/64
switchxxxxxx(config-if)# exit
Use the ipv6 address anycast command in Interface Configuration mode to configure a global unicast IPv6 Anycast address and enable IPv6 processing on an interface. To remove the address from the interface, use the no form of this command.
ipv6 address ipv6-prefix/prefix-length anycast
no ipv6 address [ipv6-prefix/prefix-length]
ipv6-address—Specifies the global unicast IPv6 address assigned to the interface. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
prefix-length—The length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
No IP address is defined for the interface.
Interface Configuration mode
An Anycast address is an address that is assigned to a set of interfaces that typically belong to different nodes. A packet sent to an Anycast address is delivered to the closest interface—as defined by the routing protocols in use—identified by the Anycast address. Anycast addresses are syntactically indistinguishable from Unicast addresses because Anycast addresses are allocated from the Unicast address space. Nodes to which the Anycast address is assigned must be explicitly configured to recognize that the address is an Anycast address.
Anycast addresses can be used only by a router, not a host, and Anycast addresses must not be used as the source address of an IPv6 packet.
The subnet router Anycast address has a prefix concatenated by a series of zeros (the interface ID). The subnet router Anycast address can be used to reach a router on the link that is identified by the prefix in the subnet router Anycast address.
The ipv6 address anycast command cannot be applied to define an IPv6 address on an ISATAP interface.
The following example enables IPv6 processing on the interface, assigns the prefix 2001:0DB8:1:1::/64 to the interface, and configures the IPv6 Anycast address 2001:0DB8:1:1:FFFF:FFFF:FFFF:FFFE:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 address 2001:0DB8:1:1:FFFF:FFFF:FFFF:FFFE/64 anycast
switchxxxxxx(config-if)# exit
Use the ipv6 address autoconfig command in Interface Configuration mode to enable automatic configuration of IPv6 addresses using stateless auto configuration on an interface and enable IPv6 processing on the interface. Addresses are configured depending on the prefixes received in Router Advertisement messages. To disable automatic configuration of IPv6 addresses and to remove the automatically configured address from the interface, use the no form of this command.
ipv6 address autoconfig
no ipv6 address autoconfig
Stateless Auto configuration is enabled.
Interface Configuration mode
This command enables IPv6 on an interface (if it was disabled) and causes the switch to perform IPv6 stateless address auto-configuration to discover prefixes on the link and then to add the eui-64 based addresses to the interface.
Stateless auto configuration is applied only when IPv6 Forwarding is disabled.
When IPv6 forwarding is changed from disabled to enabled, and stateless auto configuration is enabled the switch stops stateless auto configuration and removes all stateless auto configured ipv6 addresses from all interfaces.
When IPv6 forwarding is changed from enabled to disabled and stateless auto configuration is enabled the switch resumes stateless auto configuration.
Additionally the ipv6 address autoconfig command enables on the interface the DHCPv6 Stateless client to receive DHCP stateless information and this information is received from a DHCPv6 server regardless whether IPv6 Forwarding is enabled or not.
The following example assigns the IPv6 address automatically:
switchxxxxxx(config)# interface vlan 100
switchxxxxxx(config-if)# ipv6 address autoconfig
switchxxxxxx(config-if)# exit
Use the ipv6 address eui-64 command in Interface Configuration mode to configure a global unicast IPv6 address for an interface and enables IPv6 processing on the interface using an EUI-64 interface ID in the low order 64 bits of the address. To remove the address from the interface, use the no form of this command.
ipv6 address ipv6-prefix/prefix-length eui-64
no ipv6 address [ipv6-prefix/prefix-length eui-64]
ipv6-prefix—Specifies the global unicast IPv6 address assigned to the interface. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
prefix-length—The length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
No IP address is defined for the interface.
Interface Configuration mode
If the value specified for the prefix-length argument is greater than 64 bits, the prefix bits have precedence over the interface ID.
The IPv6 address is built from ipv6-prefix and the EUI-64 Interface ID by the following way:
The first prefix-length bits are taken from ipv6-prefix.
If prefix-length < 64 then
The following (64-prefix-length) bits are filled by 0s.
The last 64 bits are taken from the EUI-64 Interface ID.
If prefix-length equals to 64 then the following 64 bits are taken from the EUI-64 Interface ID.
If prefix-length > 64 then the following (128-prefix-length) bits are taken from the last (64-(prefix-length -64)) bits of the EUI-64 Interface ID.
If the switch detects another host using one of its IPv6 addresses, it adds the IPv6 address and displays an error message on the console.
The following example enables IPv6 processing on VLAN 1, configures IPv6 global address 2001:0DB8:0:1::/64 and specifies an EUI-64 interface ID in the low order 64 bits of the address:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 address 2001:0DB8:0:1::/64 eui-64
switchxxxxxx(config-if)# exit
Use the ipv6 address link-local command in Interface Configuration mode to configure an IPv6 link local address for an interface and enable IPv6 processing on the interface. To remove the manually configured link local address from the interface, use the no form of this command.
ipv6 address ipv6-prefix link-local
no ipv6 address [link-local]
ipv6-address—Specifies the IPv6 network assigned to the interface. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
The default Link-local address is defined.
Interface Configuration mode
The switch automatically generates a link local address for an interface when IPv6 processing is enabled on the interface, typically when an IPv6 address is configured on the interface. To manually specify a link local address to be used by an interface, use the ipv6 address link-local command.
The ipv6 address link-local command cannot be applied to define an IPv6 address on an ISATAP interface.
The following example enables IPv6 processing on VLAN 1 and configures FE80::260:3EFF:FE11:6770 as the link local address for VLAN 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 address FE80::260:3EFF:FE11:6770 link-local
switchxxxxxx(config-if)# exit
Use the ipv6 default-gateway Global Configuration mode command to define an IPv6 default gateway. To remove the IPv6 default gateway, use the no form of this command.
ipv6 default-gateway {ipv6-address [outgoing-interface-id]} | interface-id
no ipv6 default-gateway [{ipv6-address [outgoing-interface-id]} | interface-id]
ipv6-address—Specifies the IPv6 address of an IPv6 router that can be used to reach a network.
outgoing-interface-id—Outgoing Interface identifier.
interface-id—Specifies the Interface Identifier of the outgoing interface that can be used to reach a network. This argument can be applied only to point-to-point interfaces (manual IPv6 over IPv4 tunnels).
No default gateway is defined.
Global Configuration mode
Example 1. The following example defines a default gateway with a global IPv6 address:
switchxxxxxx(config)# ipv6 default-gateway 5::5
Example 2. The following example defines a default gateway with a link-local IPv6 address:
switchxxxxxx(config)# ipv6 default-gateway FE80::260:3EFF:FE11:6770%vlan1
Example 3. The following example defines a default gateway on manual tunnel 1:
switchxxxxxx(config)# ipv6 default-gateway tunnel1
Use the ipv6 enable command in Interface Configuration mode to enable IPv6 processing on an interface.
To disable IPv6 processing on an interface that has not been configured with an explicit IPv6 address, use the no form of this command.
ipv6 enable
no ipv6 enable
IPv6 interface is disabled.
Interface Configuration mode
This command automatically configures an IPv6 link-local Unicast address on the interface while also enabling the interface for IPv6 processing. The no ipv6 enable command does not disable IPv6 processing on an interface that is configured with an explicit IPv6 address.
The following example enables VLAN 1 for the IPv6 addressing mode.
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 enable
switchxxxxxx(config-if)# exit
Use the ipv6 hop-limit command in Global Configuration mode to configure the maximum number of hops used in all IPv6 packets that are originated by the router.
To return the hop limit to its default value, use the no form of this command.
ipv6 hop-limit value
no ipv6 hop-limit
value—Maximum number of hops. The acceptable range is from 1 to 255.
The default is 64 hops.
Global Configuration mode
The following example configures a maximum number of 15 hops for all IPv6 packets that are originated from the router:
switchxxxxxx(config)# ipv6 hop-limit 15
Use the ipv6 icmp error-interval command in Global Configuration mode to configure the interval and bucket size for IPv6 ICMP error messages. To return the interval to its default setting, use the no form of this command.
ipv6 icmp error-interval milliseconds [bucketsize]
no ipv6 icmp error-interval
milliseconds—Time interval between tokens being placed in the bucket. Each token represents a single ICMP error message. The acceptable range is from 0 to 2147483647. A value of 0 disables ICMP rate limiting.
bucketsize—Maximum number of tokens stored in the bucket. The acceptable range is from 1 to 200.
The default interval is 100ms and the default bucketsize is 10 i.e. 100 ICMP error messages per second.
Global Configuration mode
Use this command to limit the rate at which IPv6 ICMP error messages are sent. A token bucket algorithm is used with one token representing one IPv6 ICMP error message. Tokens are placed in the virtual bucket at a specified interval until the maximum number of tokens allowed in the bucket is reached.
The milliseconds argument specifies the time interval between tokens arriving in the bucket. The optional bucketsize argument is used to define the maximum number of tokens allowed in the bucket. Tokens are removed from the bucket when IPv6 ICMP error messages are sent, which means that if the bucketsize is set to 20, a rapid succession of 20 IPv6 ICMP error messages can be sent. When the bucket is empty of tokens, IPv6 ICMP error messages are not sent until a new token is placed in the bucket.
Average Packets Per Second = (1000/ milliseconds) * bucketsize.
To disable ICMP rate limiting, set the milliseconds argument to zero.
The following example shows an interval of 50 milliseconds and a bucket size of 20 tokens being configured for IPv6 ICMP error messages:
switchxxxxxx(config)# ipv6 icmp error-interval 50 20
Use the Ipv6 link-local default zone command to configure an interface to egress a link local packet without a specified interface or with the default zone 0.
Use the no form of this command to return the default link local interface to the default value.
Ipv6 link-local default zone interface-id
no Ipv6 link-local default zone
interface-id—Specifies the interface that is used as the egress interface for packets sent without a specified IPv6Z interface identifier or with the default 0 identifier.
By default, link local default zone is disabled.
Global Configuration mode
The following example defines VLAN 1 as a default zone:
switchxxxxxx(config)# ipv6 link-local default zone vlan1
Use the ipv6 nd advertisement-interval in Interface Configuration mode to configure the advertisement interval option in router advertisements (RAs).
To reset the interval to the default value, use the no form of this command.
ipv6 nd advertisement-interval
no ipv6 nd advertisement-interval
Advertisement interval option is not sent.
Interface Configuration mode
Use the ipv6 nd advertisement-interval command to indicate to a visiting mobile node the interval at which that node may expect to receive RAs. The node may use this information in its movement detection algorithm.
The following example enables the advertisement interval option to be sent in RAs:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd advertisement-interval
switchxxxxxx(config-if)# exit
Use the ipv6 nd dad attempts command in Interface Configuration mode to configure the number of consecutive neighbor solicitation messages that are sent on an interface while duplicate address detection is performed on the Unicast IPv6 addresses of the interface.
To return the number of messages to the default value, use the no form of this command.
ipv6 nd dad attempts value
no ipv6 nd dad attempts
value—The number of neighbor solicitation messages. The acceptable range is from 0 to 600. Configuring a value of 0 disables duplicate address detection processing on the specified interface; a value of 1 configures a single transmission without follow-up transmissions.
1
Interface Configuration mode
Duplicate address detection verifies the uniqueness of new Unicast IPv6 addresses before the addresses are assigned to interfaces (the new addresses remain in a tentative state while duplicate address detection is performed). Duplicate address detection uses neighbor solicitation messages to verify the uniqueness of Unicast IPv6 addresses.
The DupAddrDetectTransmits node configuration variable (as specified in RFC 4862, IPv6 Stateless Address Autoconfiguration) is used to automatically determine the number of consecutive neighbor solicitation messages that are sent on an interface, while duplicate address detection is performed on a tentative Unicast IPv6 address.
The interval between duplicate address detection, neighbor solicitation messages (the duplicate address detection timeout interval) is specified by the neighbor discovery-related variable RetransTimer (as specified in RFC 4861, Neighbor Discovery for IPv6), which is used to determine the time between retransmissions of neighbor solicitation messages to a neighbor when resolving the address or when probing the reachability of a neighbor. This is the same management variable used to specify the interval for neighbor solicitation messages during address resolution and neighbor unreachability detection.
Duplicate address detection is suspended on interfaces that are administratively down. While an interface is administratively down, the Unicast IPv6 addresses assigned to the interface are set to a pending state. Duplicate address detection is automatically restarted on an interface when the interface returns to being administratively up.
An interface returning to administratively up, restarts duplicate address detection for all of the Unicast IPv6 addresses on the interface. While duplicate address detection is performed on the link-local address of an interface, the state for the other IPv6 addresses is still set to TENTATIVE. When duplicate address detection is completed on the link-local address, duplicate address detection is performed on the remaining IPv6 addresses.
When duplicate address detection identifies a duplicate address, the state of the address is set to DUPLICATE and the address is not used. If the duplicate address is the link-local address of the interface, the processing of IPv6 packets is disabled on the interface and an error SYSLOG message is issued.
If the duplicate address is a global address of the interface, the address is not used and an error SYSLOG message is issued.
All configuration commands associated with the duplicate address remain as configured while the state of the address is set to DUPLICATE.
If the link-local address for an interface changes, duplicate address detection is performed on the new link-local address and all of the other IPv6 address associated with the interface are regenerated (duplicate address detection is performed only on the new link-local address).
Note. Since DAD is not supported on NBMA interfaces the command is allowed but does not impact on an IPv6 tunnel interface of the ISATAP type it does not impact. The configuration is saved and will impacted when the interface type is changed on another type on which DAD is supported (for example, to the IPv6 manual tunnel).
The following example configures five consecutive neighbor solicitation messages to be sent on VLAN 1 while duplicate address detection is being performed on the tentative Unicast IPv6 address of the interface. The example also disables duplicate address detection processing on VLAN 2.
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd dad attempts 5
switchxxxxxx(config-if)# exit
switchxxxxxx(config)# interface vlan 2
switchxxxxxx(config-if)# ipv6 nd dad attempts 0
switchxxxxxx(config-if)# exit
Use the ipv6 nd hop-limit command in Global Configuration mode to configure the maximum number of hops used in router advertisements.
To return the hop limit to its default value, use the no form of this command.
ipv6 nd hop-limit value
no ipv6 nd hop-limit
value—Maximum number of hops. The acceptable range is from 1 to 255.
The default value is defined by the ipv6 hop-limit command, or is set to 64 hops, if the command was not configured.
Interface Configuration mode
Use this command if you want to change the default value. The default value is defined by the ipv6 hop-limit command.
The following example configures a maximum number of 15 hops for router advertisements on VLAN 2:
switchxxxxxx(config)# interface vlan 2
switchxxxxxx(config-if)# ipv6 nd hop-limit 15
switchxxxxxx(config-if)# exit
Use the ipv6 nd managed-config-flag command in Interface Configuration mode to set the “managed address configuration flag” in IPv6 router advertisements.
To clear the flag from IPv6 router advertisements, use the no form of this command.
ipv6 nd managed-config-flag
no ipv6 nd managed-config-flag
The “managed address configuration flag” flag is not set in IPv6 router advertisements.
Interface Configuration mode
Setting the Managed Address Configuration flag in IPv6 router advertisements indicates to attached hosts whether they should use stateful autoconfiguration to obtain addresses. If this flag is set, the attached hosts should use stateful autoconfiguration to obtain addresses, and if it is not set, the attached hosts should not use stateful autoconfiguration to obtain addresses.
Hosts may use stateful and stateless address autoconfiguration simultaneously.
The following example configures the Managed Address Configuration flag in IPv6 router advertisements on VLAN 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd managed-config-flag
switchxxxxxx(config-if)# exit
Use the ipv6 nd prefix command in Interface Configuration mode to configure which IPv6 prefixes are included in IPv6 Neighbor Discovery (ND) router advertisements.
To remove the prefixes, use the no form of this command.
ipv6 nd prefix {ipv6-prefix/prefix-length | default} [no-advertise | {[valid-lifetime preferred-lifetime] [no-autoconfig] [off-link | no-onlink]}]
no ipv6 nd prefix [ipv6-prefix/prefix-length | default]
ipv6-prefix—IPv6 network number to include in router advertisements. This argument must be in the form documented in RFC4293, where the address is specified in hexadecimal using 16-bit values between colons.
prefix-length—Length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
default—Default values used for automatic advertised prefixes configured as addresses on the interface using the ipv6 address command.
no-advertise—Prefix is not advertised.
valid-lifetime—Remaining length of time, in seconds, that this prefix will continue to be valid, i.e., time until invalidation. A value of 4,294,967,295 represents infinity. The address generated from an invalidated prefix should not appear as the destination or source address of a packet.
preferred-lifetime—Remaining length of time, in seconds, that this prefix will continue to be preferred, i.e., time until deprecation. A value of 4,294,967,295 represents infinity. The address generated from a deprecated prefix should no longer be used as a source address in new communications, but packets received on such an interface are processed as expected. The preferred-lifetime must not be larger than the valid-lifetime.
no-autoconfig—Indicates to hosts on the local link that the specified prefix cannot be used for IPv6 autoconfiguration.The prefix will be advertised with the A-bit clear.
off-link—Configures the specified prefix as off-link. The prefix will be advertised with the L-bit clear. The prefix will not be inserted into the routing table as a connected prefix. If the prefix is already present in the routing table as a connected prefix (for example, because the prefix was also configured using the ipv6 address command), then it will be removed.
no-onlink—Configures the specified prefix as not on-link. The prefix will be advertised with the L-bit clear.
All prefixes configured on interfaces that originate IPv6 router advertisements are advertised with a valid lifetime of 2,592,000 seconds (30 days) and a preferred lifetime of 604,800 seconds (7 days).
Note that by default:
All prefixes are inserted in the routing table as connected prefixes.
All prefixes are advertised as on-link (for example, the L-bit is set in the advertisement)
All prefixes are advertised as an auto-configuration prefix (for example, the A-bit is set in the advertisement)
Interface Configuration mode
This command enables control over the individual parameters per prefix, including whether the prefix should be advertised.
Use the ipv6 nd prefix ipv6-prefix/prefix-length command to add the prefix to the Prefix table.
Use the no ipv6 nd prefix ipv6-prefix/prefix-length command to remove the prefix from the Prefix table.
Use the no ipv6 nd prefix command without the ipv6-prefix/prefix-length argument o remove all prefixes from the Prefix Table.
Note. The no ipv6 nd prefix command does not return the default values to the original default values.
The switch supports the following advertisement algorithm:
Advertise all prefixes that are configured as addresses on the interface using the parameters defined by the ipv6 nd prefix default command (or the default value if the command has not been configured) except refixes that are placed in the Prefix table (changed (configured) by the ipv6 nd prefix command).
Advertise all prefixes configured by the ipv6 nd prefix command without the no-advertise keyword.
Default Keyword
The default keyword can be used to set default values for automatic advertised prefixes configured as addresses on the interface using the ipv6 address command.
Note. These default values are not used as the default values in the ipv6 nd prefix command.
Use the no ipv6 nd prefix default command to return the default values to the original default values.
On-Link
When on-link is “on” (by default), the specified prefix is assigned to the link. Nodes sending traffic to such addresses that contain the specified prefix consider the destination to be locally reachable on the link. An on-link prefix is inserted into the routing table as a Connected prefix.
Auto-configuration
When auto-configuration is on (by default), it indicates to hosts on the local link that the specified prefix can be used for IPv6 auto-configuration.
The configuration options affect the L-bit and A-bit settings associated with the prefix in the IPv6 ND Router Advertisement, and presence of the prefix in the routing table, as follows:
Default L=1 A=1, In the Routing Table
no-onlink L=0 A=1, In the Routing Table
no-autoconfig L=1 A=0, In the Routing Table
no-onlink no-autoconfig L=0 A=0, In the Routing Table
off-link L=0 A=1, Not in the Routing Table
off-link no-autoconfig L=0 A=0, Not in the Routing Table
Example 1. The following example includes the IPv6 prefix 2001:0DB8::/35 in router advertisements sent out VLAN 1 with a valid lifetime of 1000 seconds and a preferred lifetime of 900 seconds. The prefix is inserted in the Routing table:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd prefix 2001:0DB8::/35 1000 900
switchxxxxxx(config-if)# exit
Example 2. The following example advertises the prefix with the L-bit clear:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 address 2001::1/64
switchxxxxxx(config-if)# ipv6 nd prefix 2001::/64 3600 3600 no-onlink
switchxxxxxx(config-if)# exit
Use the ipv6 nd ra interval command in Interface Configuration mode to configure the interval between IPv6 router advertisement (RA) transmissions on an interface.
To restore the default interval, use the no form of this command.
ipv6 nd ra interval maximum-secs [minimum-secs]
no ipv6 nd ra interval
maximum-secs—Maximum interval between IPv6 RA transmissions in seconds. The range is from 4 to 1800.
minimum-secs—Minimum interval between IPv6 RA transmissions in seconds. The range is from 3 to 1350.
maximum-secs is 600 seconds.
minimum-secs is 0.33*maximum-secs, if the value .=> 3 seconds and is 3 seconds, if the value .< 3 seconds.
Interface Configuration mode
The interval between transmissions should be less than or equal to the IPv6 router advertisement lifetime if you configure the route as a default router by using this command. To prevent synchronization with other IPv6 nodes, the actual interval used is randomly selected from a value between the minimum and maximum values.
The minimum RA interval may never be more than 75% of the maximum RA interval and never less than 3 seconds.
Example 1. The following example configures an IPv6 router advertisement interval of 201 seconds for VLAN 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd ra interval 201
switchxxxxxx(config-if)# exit
Example 2. The following examples shows a maximum RA interval of 200 seconds and a minimum RA interval of 50 seconds:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd ra interval 200 50
switchxxxxxx(config-if)# exit
Use the ipv6 nd ra lifetime command in Interface Configuration mode to configure the Router Lifetime value in IPv6 router advertisements on an interface.
To restore the default lifetime, use the no form of this command.
ipv6 nd ra lifetime seconds
no ipv6 nd ra lifetime
seconds—Remaining length of time, in seconds, that this router will continue to be useful as a default router (Router Lifetime value). A value of zero indicates that it is no longer useful as a default router. The acceptable range is 0 or from <Maximum RA Interval> to 9000 seconds.
The default lifetime value is 3*<Maximum RA Interval> seconds.
Interface Configuration mode
The Router Lifetime value is included in all IPv6 router advertisements sent out the interface. The value indicates the usefulness of the router as a default router on this interface. Setting the value to 0 indicates that the router should not be considered a default router on this interface. The Router Lifetime value can be set to a non-zero value to indicate that it should be considered a default router on this interface. The non-zero value for the Router Lifetime value should not be less than the router advertisement interval.
The following example configures an IPv6 router advertisement lifetime of 1801 seconds for VLAN 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd ra lifetime 1801
switchxxxxxx(config-if)# exit
Use the ipv6 nd ra suppress command in Interface Configuration mode to suppress IPv6 router advertisement transmissions on an interface. To re-enable the sending of IPv6 router advertisement transmissions on an interface, use the no form of this command.
ipv6 nd ra suppress
no ipv6 nd ra suppress
LAN interface - IPv6 router advertisements are automatically sent.
Point-to-Point interface - IPv6 router advertisements are suppressed.
NBMA interface - IPv6 router advertisements are suppressed.
Interface Configuration mode
Use the no ipv6 nd ra suppress command to enable the sending of IPv6 router advertisement transmissions on a Point-to-Point interface (for example, manual tunnel).
NBMA interface - IPv6 router advertisements are suppressed.
Use the no ipv6 nd ra suppress command to enable the sending of IPv6 router advertisement transmissions on a NBMA interface (for example, ISATAP tunnel).
Example 1. The following example suppresses IPv6 router advertisements on vlan 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd ra suppress
switchxxxxxx(config-if)# exit
Example 2. The following example enables the sending of IPv6 router advertisements on tunnel 1:
switchxxxxxx(config)# interface tunnel 1
switchxxxxxx(config-if)# no ipv6 nd ra suppress
switchxxxxxx(config-if)# exit
Use the ipv6 nd reachable-time command in Interface Configuration mode to configure the amount of time that a remote IPv6 node is considered reachable after some reachability confirmation event has occurred.
To restore the default time, use the no form of this command.
ipv6 nd reachable-time milliseconds
no ipv6 nd reachable-time
milliseconds—Amount of time that a remote IPv6 node is considered reachable (in milliseconds). The acceptable range is from 0 to 3600000 milliseconds.
0 milliseconds (unspecified) is advertised in router advertisements and the value 30000 (30 seconds) is used for the neighbor discovery activity of the router itself.
Interface Configuration mode
The configured time enables the router to detect unavailable neighbors. Shorter configured times enable the router to detect unavailable neighbors more quickly; however, shorter times consume more IPv6 network bandwidth and processing resources in all IPv6 network devices. Very short configured times are not recommended in normal IPv6 operation.
The configured time is included in all router advertisements sent out of an interface so that nodes on the same link use the same time value. A value of 0 means indicates that the configured time is unspecified by this router.
The following example configures an IPv6 reachable time of 1,700,000 milliseconds for VLAN 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd reachable-time 1700000
switchxxxxxx(config-if)# exit
Use the ipv6 nd router-preference command in Interface Configuration mode to configure a default router preference (DRP) for the router on a specific interface.
To return to the default DRP, use the no form of this command.
ipv6 nd router-preference {high | medium | low}
no ipv6 nd router-preference
high—Preference for the router specified on an interface is high.
medium—Preference for the router specified on an interface is medium.
low—Preference for the router specified on an interface is low.
Router advertisements (RAs) are sent with the medium preference.
Interface Configuration mode
RA messages are sent with the DRP configured by the this command. If no DRP is configured, RAs are sent with a medium preference.
A DRP is useful when, for example, two routers on a link may provide equivalent, but not equal-cost, routing, and policy may dictate that hosts should prefer one of the routers.
The following example configures a DRP of high for the router on VLAN 1:
switchxxxxxx(config)# interface vlan 1
switchxxxxxx(config-if)# ipv6 nd router-preference high
switchxxxxxx(config-if)# exit
Use the ipv6 redirects command in Interface Configuration mode to enable the sending of ICMP IPv6 redirect messages to re-send a packet through the same interface on which the packet was received.
To disable the sending of redirect messages, use the no form of this command.
ipv6 redirects
no ipv6 redirects
The sending of ICMP IPv6 redirect messages is enabled.
Interface Configuration mode
The following example disables the sending of ICMP IPv6 redirect messages on VLAN 100 and re-enables the messages on VLAN 2:
switchxxxxxx(config)# interface vlan 100
switchxxxxxx(config-if)# no ipv6 redirects
switchxxxxxx(config-if)# exit
switchxxxxxx(config)# interface vlan 2
switchxxxxxx(config-if)# ipv6 redirects
switchxxxxxx(config-if)# exit
Use the ipv6 route command in Global Configuration mode to establish static IPv6 routes.
To remove a previously configured static route, use the no form of this command.
ipv6 route ipv6-prefix/prefix-length {{next-ipv6-address [outgoing-interface-id]} | interface-id} [metric]
no ipv6 route ipv6-prefix/prefix-length [{next-ipv6-address [outgoing-interface-id]} | interface-id]
ipv6-prefix—IPv6 network that is the destination of the static route. Can also be a host name when static host routes are configured.
prefix-length—Length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
next-ipv6-address—IPv6 address of the next hop that can be used to reach the specified network. If the next-ipv6-address argument is a link local address it must be defined in the zone format: IPv6 Zone Format> ::= IPv6-Link-Local-Address%Interface-ID. The interface-id argument must be coded without spaces.
outgoing-interface-id—Outgoing Interface identifier.
interface-id—Outgoing Interface identifier. This argument can be applied only to point-to-point interfaces (manual IPv6 over IPv4 tunnels).
metric—Static route metric. Acceptable values are from 1 to 65535. The default value is 1.
Static entries are not configured in the IPv6 neighbor discovery cache.
Global Configuration mode
Use the ipv6 route ipv6-prefix/prefix-length interface-id [metric] command to define a static route, if the outgoing interface is a manual tunnel.
If the next-ipv6-address argument is a global IPv6 address that belongs to an on-link prefix you can omit the outgoing-interface-id argument and in this case the L2 interface on which this on-link prefix is defined will be used as the outgoing interface. If the outgoing-interface-id argument is configured it overrides this switch decision.
If the next-ipv6-address argument is a global IPv6 address that does not belong to any on-link prefix you must configure the outgoing-interface-id argument.
If the next-ipv6-address argument is a link-local IPv6 address and the outgoing-interface-id argument is omitted the zone of the next-ipv6-address argument will be used as the outgoing interface. If the outgoing-interface-id argument is configured it overrides this zone.
Example 1. The following example defines a static route with a global next hop:
switchxxxxxx(config)# ipv6 route 2001::/64 5::5 10
Example 2. The following example defines a static route with a link-local next hop:
switchxxxxxx(config)# ipv6 route 2001:DB8:2222::/48 FE80::260:3EFF:FE11:6770%vlan1 12
Example 3. The following example defines a static route on manual tunnel 1:
switchxxxxxx(config)# ipv6 route 2001:DB8:2222::/48 tunnel1
Example 4. The following example defines a static route on with the outgoing interface:
switchxxxxxx(config)# ipv6 route 2001::/64 5::5 vlan10 10
Use the ipv6 unicast-routing command in Global Configuration mode to enable the forwarding of IPv6 Unicast datagrams.
To disable the forwarding of IPv6 Unicast datagrams, use the no form of this command.
ipv6 unicast-routing
no ipv6 unicast-routing
IPv6 Unicast routing is disabled.
Global Configuration mode
The following example enables the forwarding of IPv6 Unicast datagrams:
switchxxxxxx(config)# ipv6 unicast-routing
Use the ipv6 unreachables command in Interface Configuration mode to enable the generation of Internet Control Message Protocol for IPv6 (ICMPv6) unreachable messages for any packets arriving on a specified interface.
To prevent the generation of unreachable messages, use the no form of this command.
ipv6 unreachables
no ipv6 unreachables
The sending of ICMP IPv6 unreachable messages is enabled.
Interface Configuration mode
If the switch receives a Unicast packet destined for itself that uses a protocol it does not recognize, it sends an ICMPv6 unreachable message to the source.
If the switch receives a datagram that it cannot deliver to its ultimate destination because it knows of no route to the destination address, it replies to the originator of that datagram with an ICMP host unreachable message.
The following example disables the generation of ICMPv6 unreachable messages, as appropriate, on an interface:
switchxxxxxx(config)# interface vlan 100
switchxxxxxx(config-if)# no ipv6 unreachables
switchxxxxxx(config-if)# exit
Use the show ipv6 interface command in user EXEC or privileged EXEC mode to display the usability status of interfaces configured for IPv6.
show ipv6 interface [brief] | [[interface-id] [prefix]]
brief—Displays a brief summary of IPv6 status and configuration for each interface where IPv6 is defined.
interface-id—Interface identifier about which to display information.
prefix—Prefix generated from a local IPv6 prefix pool.
Option brief - all IPv6 interfaces are displayed.
User EXEC mode
Privileged EXEC mode
Use this command to validate the IPv6 status of an interface and its configured addresses. This command also displays the parameters that IPv6 uses for operation on this interface and any configured features.
If the interface’s hardware is usable, the interface is marked up.
If you specify an optional interface identifier, the command displays information only about that specific interface. For a specific interface, you can enter the prefix keyword to see the IPv6 neighbor discovery (ND) prefixes that are configured on the interface.
The keyword is supported only if IPv6 unicast routing is enabled.
Example 1. The show ipv6 interface command displays information about the specified interface:
switchxxxxxx# show ipv6 interface vlan 1
VLAN 1 is up/up
IPv6 is enabled, link-local address is FE80::0DB8:12AB:FA01
IPv6 Forwarding is enabled
Global unicast address(es):
Ipv6 Global Address Type
2000:0DB8::2/64 (ANY) Manual
2000:0DB8::2/64 Manual
2000:1DB8::2011/64 Manual
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF11:6770
MTU is 1500 bytes
ICMP error messages limited interval is 100ms; Bucket size is 10 tokens
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 0 milliseconds
ND router maximum advertisement interval is 600 seconds
ND router minimum advertisement interval is 198 seconds (DEFAULT)
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Stateless autoconfiguration is enabled.
Stateless autoconfiguration is not available (IPv6 Forwarding is enabled).
MLD Version is 2
Field Descriptions:
vlan 1 is up/up—Indicates the interface status: administrative/operational.
IPv6 is enabled, stalled, disabled (stalled and disabled are not shown in sample output)—Indicates that IPv6 is enabled, stalled, or disabled on the interface. If IPv6 is enabled, the interface is marked Enabled. If duplicate address detection processing identified the link-local address of the interface as being a duplicate address, the processing of IPv6 packets is disabled on the interface and the interface is marked Stalled. If IPv6 is not enabled, the interface is marked Disabled.
link-local address—Displays the link-local address assigned to the interface.
Global unicast address(es):—Displays the global Unicast addresses assigned to the interface. The type is manual or autoconfig.
Joined group address(es):—Indicates the Multicast groups to which this interface belongs.
MTU is 1500 bytes—Maximum transmission unit of the interface.
ICMP error messages—Specifies the minimum interval (in milliseconds) between error messages sent on this interface.
ICMP redirects—State of ICMP IPv6 redirect messages on the interface (the sending of the messages is enabled or disabled).
ND DAD—The state of duplicate address detection on the interface (enabled or disabled).
number of DAD attempts:—Number of consecutive neighbor solicitation messages that are sent on the interface while duplicate address detection is performed.
ND reachable time—Displays the neighbor discovery reachable time (in milliseconds) assigned to this interface.
ND advertised reachable time—Displays the neighbor discovery reachable time (in milliseconds) advertised on this interface.
ND advertised retransmit interval—Displays the neighbor discovery retransmit interval (in milliseconds) advertised on this interface.
ND router advertisements—Specifies the interval (in seconds) for neighbor discovery router advertisements sent on this interface and the amount of time before the advertisements expire.
ND advertised default router preference is Medium—DRP for the router on a specific interface.
MLD Version—Version of MLD
Example 2. The show ipv6 interface command displays information about the specified manual Ipv6 tunnel:
switchxxxxxx# show ipv6 interface tunnel 2
Tunnel 2 is up/up
IPv6 is enabled, link-local address is FE80::0DB8:12AB:FA01
IPv6 Forwarding is enabled
Global unicast address(es):
Ipv6 Global Address Type
2000:0DB8::2/64 (ANY) Manual
2000:0DB8::2/64 Manual
2000:1DB8::2011/64 Manual
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF11:6770
MTU is 1500 bytes
ICMP error messages limited interval is 100ms; Bucket size is 10 tokens
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 0 milliseconds
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.
Stateless autoconfiguration is disabled.
MLD Version is 2
Tunnel mode is manual
Tunnel Local IPv4 address : 10.10.10.1(auto)
Tunnel Remote Ipv4 address : 10.1.1.1
Field Descriptions:
vlan 1 is up/up—Indicates the interface status: administrative/operational.
IPv6 is enabled, stalled, disabled (stalled and disabled are not shown in sample output)—Indicates that IPv6 is enabled, stalled, or disabled on the interface. If IPv6 is enabled, the interface is marked “enabled.” If duplicate address detection processing identified the link-local address of the interface as being a duplicate address, the processing of IPv6 packets is disabled on the interface and the interface is marked “stalled.” If IPv6 is not enabled, the interface is marked “disabled.”
link-local address—Displays the link-local address assigned to the interface.
Global Unicast address(es):—Displays the global Unicast addresses assigned to the interface. The type is manual or autoconfig.
Joined group address(es):—Indicates the Multicast groups to which this interface belongs.
—Maximum transmission unit of the interface.
ICMP error messages—Specifies the minimum interval (in milliseconds) between error messages sent on this interface.
ICMP redirects—The state of Internet Control Message Protocol (ICMP) IPv6 redirect messages on the interface (the sending of the messages is enabled or disabled).
ND DAD—The state of duplicate address detection on the interface (enabled or disabled).
number of DAD attempts:—Number of consecutive neighbor solicitation messages that are sent on the interface while duplicate address detection is performed.
ND reachable time—Displays the neighbor discovery reachable time (in milliseconds) assigned to this interface.
ND advertised reachable time—Displays the neighbor discovery reachable time (in milliseconds) advertised on this interface.
ND advertised retransmit interval—Displays the neighbor discovery retransmit interval (in milliseconds) advertised on this interface.
ND router advertisements—Specifies the interval (in seconds) for neighbor discovery router advertisements sent on this interface and the amount of time before the advertisements expire.
ND advertised default router preference is Medium—The DRP for the router on a specific interface.
MLD Version—The version of MLD
Tunnel mode—Specifies the tunnel mode: manual
Tunnel Local IPv4 address—Specifies the tunnel local IPv4 address and have one of the following formats:
ipv4-address
ipv4-address (auto)
ipv4-address (interface-id)
Tunnel Remote Ipv4 address—Specifies the tunnel remote IPv4 address
Example 3. The show ipv6 interface command displays information about the specified ISATAP tunnel:
switchxxxxxx# show ipv6 interface tunnel 1
Tunnel 1 is up/up
IPv6 is enabled, link-local address is FE80::0DB8:12AB:FA01
ICMP redirects are disabled
Global unicast address(es):
Ipv6 Global Address Type
2000:0DB8::2/64 (ANY) Manual
2000:0DB8::2/64 Manual
2000:1DB8::2011/64 Manual
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF11:6770
is 1500 bytes
ICMP error messages limited interval is 100ms; Bucket size is 10 tokens
ICMP redirects are enabled
ND DAD is disabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 0 milliseconds
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Stateless autoconfiguration is disabled.
MLD Version is 2
Tunnel mode is ISATAP
Tunnel Local IPv4 address : 10.10.10.1(VLAN 1)
ISATAP Router DNS name is isatap
Field Descriptions:
ND DAD—The state of duplicate address detection on the interface (enabled or disabled). Note. The state of duplicate address detection on an IPv6 tunnel interface of ISATAP type always is displayed as disabled regardless of a value of the number of DAD attempts parameter because DAD is not supported on NBMA interfaces. The switch will enable DAD automatically when the user change the type of the tunnel to manual if a the parameter value bigger than 0.
number of DAD attempts:—Number of consecutive neighbor solicitation messages that are sent on the interface while duplicate address detection is performed.
vlan 1 is up/up—Indicates the interface status: administrative/operational.
IPv6 is enabled, stalled, disabled (stalled and disabled are not shown in sample output)—Indicates that IPv6 is enabled, stalled, or disabled on the interface. If IPv6 is enabled, the interface is marked “enabled.” If duplicate address detection processing identified the link-local address of the interface as being a duplicate address, the processing of IPv6 packets is disabled on the interface and the interface is marked “stalled.” If IPv6 is not enabled, the interface is marked “disabled.”
link-local address—Displays the link-local address assigned to the interface.
Global Unicast address(es):—Displays the global Unicast addresses assigned to the interface. The type is manual or autoconfig.
Joined group address(es):—Indicates the Multicast groups to which this interface belongs.
—Maximum transmission unit of the interface.
ICMP error messages—Specifies the minimum interval (in milliseconds) between error messages sent on this interface.
ICMP redirects—The state of Internet Control Message Protocol (ICMP) IPv6 redirect messages on the interface (the sending of the messages is enabled or disabled).
number of DAD attempts:—Number of consecutive neighbor solicitation messages that are sent on the interface while duplicate address detection is performed.
ND reachable time—Displays the neighbor discovery reachable time (in milliseconds) assigned to this interface.
ND advertised reachable time—Displays the neighbor discovery reachable time (in milliseconds) advertised on this interface.
ND advertised retransmit interval—Displays the neighbor discovery retransmit interval (in milliseconds) advertised on this interface.
ND router advertisements—Specifies the interval (in seconds) for neighbor discovery router advertisements sent on this interface and the amount of time before the advertisements expire.
ND advertised default router preference is Medium—The DRP for the router on a specific interface.
MLD Version—The version of MLD
Tunnel mode—Specifies the tunnel mode: isatap
Tunnel Local IPv4 address—Specifies the tunnel local IPv4 address and have one of the following formats:
ipv4-address
ipv4-address (auto)
ipv4-address (interface-id)
Tunnel Remote Ipv4 address—Specifies the tunnel remote IPv4 address
ISATAP Router DNS name is—The DNS name of the ISATAP Router
Example 4. The following command with the brief keyword displays information about all interfaces that IPv6 is defined on:
switchxxxxxx# show ipv6 interface brief
Interface Interface IPv6 Link Local MLD Number of
State State IPv6 Address Version Global Addresses
--------- --------- ------- ----------------- ------- ----------------
vlan 1 up/up enabled FE80::0DB8:12AB:FA01 1 1
vlan 2 up/up stalled FE80::0DB8:12AB:FA01 1 1
vlan 3 up/down enabled FE80::0DB8:12AB:FA01 1 3
vlan 4 down/down enabled FE80::0DB8:12AB:FA01 2 2
vlan 5 up/up enabled FE80::0DB8:12AB:FA01 1 1
vlan 100 up/up enabled FE80::0DB8:12AB:FA01 1 1
vlan 1000 up/up stalled FE80::0DB8:12AB:FA01 1 1
Example 5. This sample output shows the characteristics of VLAN 1 that has generated a prefix from a local IPv6 prefix pool:
switchxxxxxx# configure terminal
switchxxxxxx(config)# interface vlan1
switchxxxxxx(config-if)# ipv6 address 2001:0DB8:1::1/64
switchxxxxxx(config-if)# ipv6 address 2001:0DB8:2::1/64
switchxxxxxx(config-if)# ipv6 address 2001:0DB8:3::1/64
switchxxxxxx(config-if)# ipv6 nd prefix 2001:0DB8:1::/64 no-advertise
switchxxxxxx(config-if)# ipv6 nd prefix 2001:0DB8:3::/64 2912000 564900 off-link
switchxxxxxx(config-if)# ipv6 nd prefix 2001:0DB8:4::/64
switchxxxxxx(config-if)# ipv6 nd prefix 2001:0DB8:5::/64 2912000 564900 off-link
switchxxxxxx(config-if)# exit
switchxxxxxx(config)# exit
switchxxxxxx# show ipv6 interface vlan 1 prefix
IPv6 Prefix Advertisements VLAN 1
Codes: A - Address, P - Prefix is advertised, R is in Routing Table
Code Prefix Flags Valid Lifetime Preferred Lifetime
---- ---------------- ---- --------------- -----------------------
default LA 2592000 604800
AR 2001:0DB8:1::/64 LA infinite infinite
APR 2001:0DB8:2::/64 LA infinite infinite
AP 2001:0DB8:3::/64 A infinite infinite
PR 2001:0DB8:4::/64 LA 2592000 604800
P 2001:0DB8:5::/64 A 2912000 564900
Use the show ipv6 link-local default zone command in user EXEC or privileged EXEC mode to display the IPv6 link local default zone.
show ipv6 link-local default zone
User EXEC mode
Privileged EXEC mode
Example 1. The following example displays the default zone when it is defined:
switchxxxxxx# show ipv6 link-local default zone
Link Local Default Zone is VLAN 1
Example 2. The following example displays the default zone when it is not defined:
switchxxxxxx# show ipv6 link-local default zone
Link Local Default Zone is not defined
Use the show ipv6 nd prefix command in user EXEC or privileged EXEC mode to display IPv6 prefixes included in IPv6 Neighbor Discovery (ND) router advertisements.
show ipv6 nd prefix [interface-id]
interface-id—Specified interface identifier on which prefixes are advertised.
No prefixes are displayed.
User EXEC mode
Privileged EXEC mode
Use the how ipv6 nd prefix command with the interface-id argument to display prefixes advertised on a single interface.
The following example displays IPv6 prefixes:
switchxxxxxx# show ipv6 nd prefix vlan 100
vlan 100
default
valid-lifetime 2,592,000 secs
preferred-lifetime 604,800 secs
on-link
auto-config
prefix 2001::1/64
valid-lifetime 3,600 secs
preferred-lifetime 2,700 secs
prefix 2001:2:12/64
no advertise
prefix 2002::1/64
valid-lifetime 3,600 secs
preferred-lifetime 2,700 secs
on-link
prefix 2011::1/64
valid-lifetime 3,600 secs
preferred-lifetime 2,700 secs
off-link
auto-config
Use the show ipv6 neighbors command in User EXEC or Privileged EXEC mode to display IPv6 neighbor discovery (ND) cache information.
show ipv6 neighbors [interface-id | ipv6-address | ipv6-hostname]
interface-id—Specifies the identifier of the interface from which IPv6 neighbor information is to be displayed.
ipv6-address—Specifies the IPv6 address of the neighbor. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
ipv6-hostname—Specifies the IPv6 host name of the remote networking device.
All IPv6 ND cache entries are listed.
User EXEC mode
Privileged EXEC mode
When the interface-id argument is not specified, cache information for all IPv6 neighbors is displayed. Specifying the interface-id argument displays only cache information about the specified interface.
Example 1. The following is sample output from the show ipv6 neighbors command when entered with an interface-id:
switchxxxxxx# show ipv6 neighbors vlan 1
IPv6 Address Age Link-layer Addr State Interface Router
2000:0:0:4::2 0 0003.a0d6.141e REACH VLAN1 Yes
3001:1::45a - 0002.7d1a.9472 REACH VLAN1 -
FE80::203:A0FF:FED6:141E 0 0003.a0d6.141e REACH VLAN1 No
Example 2. The following is sample output from the show ipv6 neighbors command when entered with an IPv6 address:
switchxxxxxx# show ipv6 neighbors 2000:0:0:4::2
IPv6 Address Age Link-layer Addr State Interface Router
2000:0:0:4::2 0 0003.a0d6.141e REACH VLAN1 Yes
Field Descriptions:
Total number of entries—Number of entries (peers) in the cache.
IPv6 Address—IPv6 address of neighbor or interface.
Age—Time (in minutes) since the address was confirmed to be reachable. A hyphen (-) indicates a static entry.
Link-layer Addr—MAC address. If the address is unknown, a hyphen (-) is displayed.
Interface—Interface which the neighbor is connected to.
Router—Specifies if the neighbor is a Router. A hyphen (-) is displayed for static entries.
Use the show ipv6 route command in user EXEC or privileged EXEC mode to display the current contents of the IPv6 routing table.
show ipv6 route [ipv6-address | ipv6-prefix/prefix-length | protocol | interface interface-id]
ipv6-address—Displays routing information for a specific IPv6 address. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
ipv6-prefix—Displays routing information for a specific IPv6 network. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
prefix-length—The length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
protocol—Displays routes for the specified routing protocol using any of these keywords: bgp, isis, ospf, or rip; or displays routes for the specified type of route using any of these keywords: connected, static, nd, or icmp.
interface interface-id—Identifier of an interface.
All IPv6 routing information for all active routing tables is displayed.
User EXEC mode
Privileged EXEC mode
This command provides output similar to the show ip route command, except that the information is IPv6-specific.
When the ipv6-address or ipv6-prefix/prefix-length argument is specified, a longest match lookup is performed from the routing table and only route information for that address or network is displayed. When the icmp, nd, connected, local, or static keywords are specified, only that type of route is displayed. When the interface-id argument are specified, only the specified interface-specific routes are displayed.
Example 1. The following is sample output from the show ipv6 route command when IPv6 Routing is not enabled and the command is entered without an IPv6 address or prefix specified:
switchxxxxxx# show ipv6 route
Codes: > - Best
S - Static, C - Connected(from ipv6 address), I - ICMP Redirect, ND - Router Advertisment
[d/m]: d - route’s distance, m - route’s metric
IPv6 Forwarding is disabled
IPv6 Routing Table - 4 entries
S> ::/0 [1/1]
via:: fe80::77 VLAN 1
ND> ::/0 [3/2]
via:: fe80::200:cff:fe4a:dfa8 VLAN 1 Lifetime 1784 sec
C> 3002:1:1:1:1/64 [0/0]
via:: VLAN 1
ND> 3004:1:1:1:1/64 [0/0]
via:: VLAN 100 Lifetime 1784 sec
Use the show ipv6 route summary command in User EXEC or Privileged EXEC mode to display the current contents of the IPv6 routing table in summary format.
show ipv6 route summary
User EXEC mode
Privileged EXEC mode
The following is sample output from the show ipv6 route summary command:
switchxxxxxx# show ipv6 route summary
IPv6 Routing Table Summary - 97 entries
37 local, 35 connected, 25 static
Number of prefixes:
/16: 1, /28: 10, /32: 5, /35: 25, /40: 1, /64: 9
/96: 5, /112: 1, /127: 4, /128: 36
Use the show ipv6 static command in user EXEC or privileged EXEC mode to display the current static routes of the IPv6 routing table.
show ipv6 static [ipv6-address | ipv6-prefix/prefix-length] [interface interface-id][detail]
ipv6-address—Provides routing information for a specific IPv6 address. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
ipv6-prefix—Provides routing information for a specific IPv6 network. This argument must be in the form documented in RFC4293 where the address is specified in hexadecimal using 16-bit values between colons.
prefix-length—Length of the IPv6 prefix. A decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.
interface interface-id—Identifier of an interface.
detail—Specifies for invalid routes, the reason why the route is not valid.
All IPv6 static routing information for all active routing tables is displayed.
User EXEC mode
Privileged EXEC mode
When the ipv6-address or ipv6-prefix/prefix-length argument is specified, a longest match lookup is performed from the routing table and only route information for that address or network is displayed. Only the information matching the criteria specified in the command syntax is displayed. For example, when the interface-id argument is specified, only the specified interface-specific routes are displayed.
When the detail keyword is specified, the reason why the route is not valid is displayed for invalid direct or fully specified routes.
Example 1. The following is sample output from the show ipv6 static command without specified options:
switchxxxxxx# show ipv6 static
IPv6 Static routes Code: * - installed in Forwarding Information Base (FIB)
IPv6 Static routes distance is 1
* 3000::/16, via outgoing interface tunnel1, metric 1
5000::/16, via outgoing interface tunnel2, metric 1
* 5555::/16, via outgoing interface VLAN100 nexthop 4000::1 metric 1
5555::/16, via outgoing interface VLAN10 nexthop 9999::1 vlan100 metric 1
* 5555::/16, via outgoing interface VLAN100 nexthop 4001:AF00::1, metric 1
* 6000::/16, via outgoing interface VLAN1 nexthop 2007::1 metric 1
Example 2. The following is sample output from the show ipv6 static command when entered with the IPv6 prefix 2001:200::/35:
switchxxxxxx# show ipv6 static 2001:200::/35
IPv6 Static routes Code: * - installed in Forwarding Information Base (FIB)
IPv6 Static routes distance is 1
* 2001:200::/35, via outgoing interface VLAN100 nexthop 4000::1, metric 1
2001:200::/35, via outgoing interface VLAN10 nexthop 9999::1, metric 1
Example 3. The following is sample output from the show ipv6 static command when entered with the interface VLAN 1:
switchxxxxxx# show ipv6 static interface vlan 1
IPv6 Static routes Code: * - installed in Forwarding Information Base (FIB)
IPv6 Static routes distance is 1
* 5000::/16, via outgoing interface VLAN1 nexthop 4000::1, metric 1
Example 4. The following is sample output from the show ipv6 static command with the detail keyword:
switchxxxxxx# show ipv6 static detail
IPv6 Static routes Code: * - installed in Forwarding Information Base (FIB)
IPv6 Static routes distance is 1
* 3000::/16, via outgoing interface tunnel1, metric 1
5000::/16, via outgoing interface tunnel2, metric 1
5000::/16, via outgoing interface VLAN2 nexthop 2003::1, metric 1
Interface is down
* 5555::/16, via outgoing interface VLAN100 nexthop 4000::1, metric 1
5555::/16, via outgoing interface VLAN10 nexthop 9999::1, metric 1
Route does not fully resolve
* 5555::/16, via outgoing interface VLAN12 nexthop 4001:AF00::1, metric 1
* 6000::/16, via outgoing interface VLAN102 nexthop 2007::1, metric 1
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