Usage Guidelines

The clear ipv6 access-list command is similar to the clear ip access-list counters command, except that it is IPv6-specific.

The clear ipv6 access-list command used without the access-list-name argument resets the match counters for all IPv6 access lists configured on the router.

This command resets the IPv6 global ACL hardware counters.

Usage Guidelines

The clear ipv6 dhcp command deletes DHCP for IPv6 information.

Usage Guidelines

The clear ipv6 dhcp binding command is used as a server function.

A binding table entry on the DHCP for IPv6 server is automatically:

• Created whenever a prefix is delegated to a client from the configuration pool.

• Updated when the client renews, rebinds, or confirms the prefix delegation.

• Deleted when the client releases all the prefixes in the binding voluntarily, all prefixes’ valid lifetimes have expired, or an administrator runs the clear ipv6 dhcp binding command.

If the clear ipv6 dhcp binding command is used with the optional ipv6-address argument specified, only the binding for the specified client is deleted. If the clear ipv6 dhcp binding command is used without the ipv6-address argument, then all automatic client bindings are deleted from the DHCP for IPv6 binding table. If the optional vrf vrf-name keyword and argument combination is used, only the bindings for the specified VRF are cleared.

Usage Guidelines

The clear ipv6 dhcp client command restarts the DHCP for IPv6 client on specified interface after first releasing and unconfiguring previously acquired prefixes and other configuration options (for example, Domain Name System [DNS] servers).

Usage Guidelines

When you configure the DHCPv6 server to detect conflicts, it uses ping. The client uses neighbor discovery to detect clients and reports to the server through a DECLINE message. If an address conflict is detected, the address is removed from the pool, and the address is not assigned until the administrator removes the address from the conflict list.

If you use the asterisk (*) character as the address parameter, DHCP clears all conflicts.

If the vrf vrf-name keyword and argument are specified, only the address conflicts that belong to the specified VRF will be cleared.

Usage Guidelines

The clear ipv6 dhcp relay binding command deletes a specific IPv6 address or IPv6 prefix of a DHCP for IPv6 relay binding. If no relay client is specified, no binding is deleted.

Usage Guidelines

Use the clear ipv6 eigrp command without any arguments or keywords to clear all EIGRP for IPv6 routing table entries. Use the as-number argument to clear routing table entries on a specified process, and use the neighbor ipv6-address keyword and argument, or the interface-type interface-number argument, to remove a specific neighbor from the neighbor table.

Usage Guidelines

After you enable the clear ipv6 mfib counters command, you can determine if additional traffic is forwarded by using one of the following show commands that display traffic counters:

• show ipv6 mfib

• show ipv6 mfib active

• show ipv6 mfib count

• show ipv6 mfib interface

• show ipv6 mfib summary

Usage Guidelines

Use the clear ipv6 mld counters command to clear the MLD counters, which keep track of the number of joins and leaves received. If you omit the optional interface-type argument, the clear ipv6 mld counters command clears the counters on all interfaces.

Usage Guidelines

Using the clear ipv6 mld traffic command will reset all MLD traffic counters.

Usage Guidelines

If a router is flooded with ICMPv6 toobig messages, the router is forced to create an unlimited number of entries in the MTU cache until all available memory is consumed. Use the clear ipv6 mtu command to clear messages from the MTU cache.

Usage Guidelines

Using the clear ipv6 multicast aaa authorization command without the optional interface-type and interface-number arguments will clear all authorization parameters on a network.

Usage Guidelines

The clear ipv6 nd destination command clears IPv6 host-mode destination cache entries. If the vrf vrf-name keyword and argument pair is used, then only information about the specified VRF is cleared.

Usage Guidelines

Use the clear ipv6 nd on-link prefix command to clear locally reachable IPv6 addresses (e.g., on-link prefixes) learned through RAs. If the vrf vrf-name keyword and argument pair is used, then only information about the specified VRF is cleared.

Usage Guidelines

Use the clear ipv6 nd router command to clear ND device entries learned through RAs. If the vrf vrf-name keyword and argument pair is used, then only information about the specified VRF is cleared.

Usage Guidelines

The clear ipv6 neighbor command clears ND cache entries. If the command is issued without the vrf keyword, then the command clears ND cache entries on interfaces associated with the default routing table (e.g., those interfaces that do not have a vrf forwarding statement). If the command is issued with the vrf keyword, then it clears ND cache entries on interfaces associated with the specified VRF.

Usage Guidelines

When the process keyword is used with the clear ipv6 ospf command, the OSPF database is cleared and repopulated, and then the shortest path first (SPF) algorithm is performed. When the force-spf keyword is used with the clear ipv6 ospf command, the OSPF database is not cleared before the SPF algorithm is performed.

Use the process-id option to clear only one OSPF process. If the process-id option is not specified, all OSPF processes are cleared.

Usage Guidelines

Use the neighbor neighbor-interface option to clear counters for all neighbors on a specified interface. If the neighbor neighbor-interface option is not used, all OSPF counters are cleared.

Use the neighbor neighbor-id option to clear counters at a specified neighbor. If the neighbor neighbor-id option is not used, all OSPF counters are cleared.

Usage Guidelines

Use the optional process-id argument to clear the IPv6 event log content of a specified OSPF routing process. If the process-id argument is not used, all event log content is cleared.

Usage Guidelines

Using the clear ipv6 pim reset command breaks the PIM-MRIB connection, clears the topology table, and then reestablishes the PIM-MRIB connection. This procedure forces MRIB resynchronization.

Caution

Use the clear ipv6 pim reset command with caution, as it clears all PIM protocol information from the PIM topology table. Use of the clear ipv6 pim reset command should be reserved for situations where PIM and MRIB communication are malfunctioning.

Usage Guidelines

This command clears PIM protocol information from all group entries located in the PIM topology table. Information obtained from the MRIB table is retained. If a multicast group is specified, only those group entries are cleared.

Usage Guidelines

This command clears PIM traffic counters. If the vrf vrf-name keyword and argument are used, only those counters are cleared.

Usage Guidelines

The clear ipv6 prefix-list command is similar to the clear ip prefix-list command, except that it is IPv6-specific.

The hit count is a value indicating the number of matches to a specific prefix list entry.

Usage Guidelines

When the name argument is specified, only routes for the specified IPv6 RIP process are deleted from the IPv6 RIP routing table. If no name argument is specified, all IPv6 RIP routes are deleted.

Use the show ipv6 rip command to display IPv6 RIP routes.

Use the clear ipv6 rip name vrf vrf-name command to delete the specified VRF instances for the specified IPv6 RIP process.

Usage Guidelines

The clear ipv6 route command is similar to the clear ip route command, except that it is IPv6-specific.

When the ipv6-address or ipv6-prefix/ prefix- length argument is specified, only that route is deleted from the IPv6 routing table. When the * keyword is specified, all routes are deleted from the routing table (the per-destination maximum transmission unit [MTU] cache is also cleared).

Usage Guidelines

The clear ipv6 spd command removes the most recent SPD state transition and any trend historical data.

Usage Guidelines

When VRRPv3 is in use, VRRP version 2 (VRRPv2) is unavailable.

Usage Guidelines

The ip address dhcp command allows any interface to dynamically learn its IP address by using the DHCP protocol. It is especially useful on Ethernet interfaces that dynamically connect to an Internet service provider (ISP). Once assigned a dynamic address, the interface can be used with the Port Address Translation (PAT) of Cisco IOS Network Address Translation (NAT) to provide Internet access to a privately addressed network attached to the device.

The ip address dhcp command also works with ATM point-to-point interfaces and will accept any encapsulation type. However, for ATM multipoint interfaces you must specify Inverse ARP via the protocol ip inarp interface configuration command and use only the aa15snap encapsulation type.

Some ISPs require that the DHCPDISCOVER message have a specific hostname and client identifier that is the MAC address of the interface. The most typical usage of the ip address dhcp client-id interface-type number hostname hostname command is when interface-type is the Ethernet interface where the command is configured and interface-type number is the hostname provided by the ISP.

A client identifier (DHCP option 61) can be a hexadecimal or an ASCII value. By default, the client identifier is an ASCII value. The client-id interface-type number option overrides the default and forces the use of the hexadecimal MAC address of the named interface.

If a Cisco device is configured to obtain its IP address from a DHCP server, it sends a DHCPDISCOVER message to provide information about itself to the DHCP server on the network.

If you use the ip address dhcp command with or without any of the optional keywords, the DHCP option 12 field (hostname option) is included in the DISCOVER message. By default, the hostname specified in option 12 will be the globally configured hostname of the device. However, you can use the ip address dhcp hostname hostname command to place a different name in the DHCP option 12 field than the globally configured hostname of the device.

The no ip address dhcp command removes any IP address that was acquired, thus sending a DHCPRELEASE message.

You might need to experiment with different configurations to determine the one required by your DHCP server. The table below shows the possible configuration methods and the information placed in the DISCOVER message for each method.

Usage Guidelines

Use this command to automatically configure the IP address of a LAN interface when there are DHCP clients on the attached LAN that should be serviced by the DHCP pool on the device. The DHCP pool obtains its subnet dynamically through IPCP subnet negotiation.

Usage Guidelines

An interface can have one primary IP address and multiple secondary IP addresses. Packets generated by the Cisco IOS software always use the primary IP address. Therefore, all devices and access servers on a segment should share the same primary network number.

Hosts can determine subnet masks using the Internet Control Message Protocol (ICMP) mask request message. Devices respond to this request with an ICMP mask reply message.

You can disable IP processing on a particular interface by removing its IP address with the no ip address command. If the software detects another host using one of its IP addresses, it will print an error message on the console.

The optional secondary keyword allows you to specify an unlimited number of secondary addresses. Secondary addresses are treated like primary addresses, except the system never generates datagrams other than routing updates with secondary source addresses. IP broadcasts and Address Resolution Protocol (ARP) requests are handled properly, as are interface routes in the IP routing table.

Secondary IP addresses can be used in a variety of situations. The following are the most common applications:

• There may not be enough host addresses for a particular network segment. For example, your subnetting allows up to 254 hosts per logical subnet, but on one physical subnet you need 300 host addresses. Using secondary IP addresses on the devices or access servers allows you to have two logical subnets using one physical subnet.

• Many older networks were built using Level 2 bridges. The judicious use of secondary addresses can aid in the transition to a subnetted, device-based network. Devices on an older, bridged segment can be easily made aware that many subnets are on that segment.

• Two subnets of a single network might otherwise be separated by another network. This situation is not permitted when subnets are in use. In these instances, the first network is extended , or layered on top of the second network using secondary addresses.

Note

If any device on a network segment uses a secondary address, all other devices on that same segment must also use a secondary address from the same network or subnet. Inconsistent use of secondary addresses on a network segment can very quickly cause routing loops. When you are routing using the Open Shortest Path First (OSPF) algorithm, ensure that all secondary addresses of an interface fall into the same OSPF area as the primary addresses. If you configure a secondary IP address, you must disable sending ICMP redirect messages by entering the no ip redirects command, to avoid high CPU utilization.

Usage Guidelines

The ipv6 access-list command is similar to the ip access-list command, except that it is IPv6-specific.

The standard IPv6 ACL functionality supports --in addition to traffic filtering based on source and destination addresses--filtering of traffic based on IPv6 option headers and optional, upper-layer protocol type information for finer granularity of control (functionality similar to extended ACLs in IPv4). IPv6 ACLs are defined by using the ipv6 access-list command in global configuration mode and their permit and deny conditions are set by using the deny and permit commands in IPv6 access list configuration mode. Configuring the ipv6 access-list command places the device in IPv6 access list configuration mode--the device prompt changes to Device(config-ipv6-acl)#. From IPv6 access list configuration mode, permit and deny conditions can be set for the defined IPv6 ACL.

Note	IPv6 ACLs are defined by a unique name (IPv6 does not support numbered ACLs). An IPv4 ACL and an IPv6 ACL cannot share the same name.

For backward compatibility, the ipv6 access-list command with the deny and permit keywords in global configuration mode is still supported; however, an IPv6 ACL defined with deny and permit conditions in global configuration mode is translated to IPv6 access list configuration mode.

Refer to the deny (IPv6) and permit (IPv6) commands for more information on filtering IPv6 traffic based on IPv6 option headers and optional, upper-layer protocol type information. See the "Examples" section for an example of a translated IPv6 ACL configuration.

Note

Every IPv6 ACL has implicit permit icmp any any nd-na , permit icmp any any nd-ns , and deny ipv6 any any statements as its last match conditions. (The former two match conditions allow for ICMPv6 neighbor discovery.) An IPv6 ACL must contain at least one entry for the implicit deny ipv6 any any statement to take effect. The IPv6 neighbor discovery process makes use of the IPv6 network layer service; therefore, by default, IPv6 ACLs implicitly allow IPv6 neighbor discovery packets to be sent and received on an interface. In IPv4, the Address Resolution Protocol (ARP), which is equivalent to the IPv6 neighbor discovery process, makes use of a separate data link layer protocol; therefore, by default, IPv4 ACLs implicitly allow ARP packets to be sent and received on an interface.

Note	IPv6 prefix lists, not access lists, should be used for filtering routing protocol prefixes.

Use the ipv6 traffic-filter interface configuration command with the access-list-name argument to apply an IPv6 ACL to an IPv6 interface. Use the ipv6 access-class line configuration command with the access-list-name argument to apply an IPv6 ACL to incoming and outgoing IPv6 virtual terminal connections to and from the device.

Note	An IPv6 ACL applied to an interface with the ipv6 traffic-filter command filters traffic that is forwarded, not originated, by the device.

Note

When using this command to modify an ACL that is already associated with a bootstrap router (BSR) candidate rendezvous point (RP) (see the ipv6 pim bsr candidate rp command) or a static RP (see the ipv6 pim rp-address command), any added address ranges that overlap the PIM SSM group address range (FF3x::/96) are ignored. A warning message is generated and the overlapping address ranges are added to the ACL, but they have no effect on the operation of the configured BSR candidate RP or static RP commands.

Duplicate remark statements can no longer be configured from the IPv6 access control list. Because each remark statement is a separate entity, each one is required to be unique.

Usage Guidelines

The ipv6 address-validate command is used to validate whether the interface identifiers in an assigned IPv6 address are a part of the reserved IPv6 interface identifiers range, as specified in RFC5453. If the interface identifiers of the assigned IPv6 address are a part of the reserved range, a new IPv6 address is assigned.

Only auto-configured addresses or addresses configured by DHCPv6 are validated.

Note

The no ipv6-address validate command disables the IPv6 address validation and allows assigning of IPv6 addresses with interface identifiers that are a part of the reserved IPv6 interface identifiers range. We do not recommend the use of this command. You must enter a minimum of eight characters of the ipv6-address validate command if you’re using CLI help (?) for completing the syntax of this command. If you enter less than eight characters the command will conflict with the no ipv6 address command in interface configuration mode.

Usage Guidelines

The ipv6 cef command is similar to the ip cef command, except that it is IPv6-specific.

The ipv6 cef command is not available on the Cisco 12000 series Internet routers because this distributed platform operates only in distributed Cisco Express Forwarding for IPv6 mode.

Note	The ipv6 cef command is not supported in interface configuration mode.

Note	Some distributed architecture platforms support both Cisco Express Forwarding for IPv6 and distributed Cisco Express Forwarding for IPv6. When Cisco Express Forwarding for IPv6 is configured on distributed platforms, Cisco Express Forwarding switching is performed by the Route Processor (RP).

Note	You must enable Cisco Express Forwarding for IPv4 by using the ip cef global configuration command before enabling Cisco Express Forwarding for IPv6 by using the ipv6 cef global configuration command.

Cisco Express Forwarding for IPv6 is advanced Layer 3 IP switching technology that functions the same and offer the same benefits as Cisco Express Forwarding for IPv4. Cisco Express Forwarding for IPv6 optimizes network performance and scalability for networks with dynamic, topologically dispersed traffic patterns, such as those associated with web-based applications and interactive sessions.

Usage Guidelines

The ipv6 cef accounting command is similar to the ip cef accounting command, except that it is IPv6-specific.

Configuring Cisco Express Forwarding for IPv6 network accounting enables you to collect statistics on Cisco Express Forwarding for IPv6 traffic patterns in your network.

When you enable network accounting for Cisco Express Forwarding for IPv6 by using the ipv6 cef accounting command in global configuration mode, accounting information is collected at the Route Processor (RP) when Cisco Express Forwarding for IPv6 mode is enabled and at the line cards when distributed Cisco Express Forwarding for IPv6 mode is enabled. You can then display the collected accounting information using the show ipv6 cef EXEC command.

For prefixes with directly connected next hops, the non-recursive keyword enables express forwarding of the collection of packets and bytes through a prefix. This keyword is optional when this command is used in global configuration mode after you enter another keyword on the ipv6 cef accounting command.

This command in interface configuration mode must be used in conjunction with the global configuration command. The interface configuration command allows a user to specify two different bins (internal or external) for the accumulation of statistics. The internal bin is used by default. The statistics are displayed through the show ipv6 cef detail command.

Per-destination load balancing uses a series of 16 hash buckets into which the set of available paths are distributed. A hash function operating on certain properties of the packet is applied to select a bucket that contains a path to use. The source and destination IP addresses are the properties used to select the bucket for per-destination load balancing. Use the load-balance-hash keyword with the ipv6 cef accounting command to enable per-hash-bucket counters. Enter the show ipv6 cef prefix internal command to display the per-hash-bucket counters.

Usage Guidelines

The ipv6 cef distributed command is similar to the ip cef distributed command, except that it is IPv6-specific.

Enabling distributed Cisco Express Forwarding for IPv6 globally on the router by using the ipv6 cef distributed in global configuration mode distributes the Cisco Express Forwarding processing of IPv6 packets from the Route Processor (RP) to the line cards of distributed architecture platforms.

Note

To forward distributed Cisco Express Forwarding for IPv6 traffic on the router, configure the forwarding of IPv6 unicast datagrams globally on your router by using the ipv6 unicast-routing global configuration command, and configure an IPv6 address and IPv6 processing on an interface by using the ipv6 address interface configuration command.

Note	You must enable distributed Cisco Express Forwarding for IPv4 by using the ip cef distributed global configuration command before enabling distributed Cisco Express Forwarding for IPv6 by using the ipv6 cef distributed global configuration command.

Cisco Express Forwarding is advanced Layer 3 IP switching technology. Cisco Express Forwarding optimizes network performance and scalability for networks with dynamic, topologically dispersed traffic patterns, such as those associated with web-based applications and interactive sessions.

Usage Guidelines

The ipv6 cef load-sharing algorithm command is similar to the ip cef load-sharing algorithm command, except that it is IPv6-specific.

When the Cisco Express Forwarding for IPv6 load-balancing algorithm is set to universal mode, each device on the network can make a different load-sharing decision for each source-destination address pair.

Usage Guidelines

The ipv6 cef optimize neighbor resolution command is very similar to the ip cef optimize neighbor resolution command, except that it is IPv6-specific.

Use this command to trigger Layer 2 address resolution of neighbors directly from Cisco Express Forwarding for IPv6.

Usage Guidelines

This command enters destination-guard configuration mode. The destination guard policies can be used to filter IPv6 traffic based on the destination address to block data traffic from an unknown source.

Usage Guidelines

Use the ipv6 dhcp-relay bulk-lease command in global configuration mode to configure bulk lease query parameters, such as data transfer timeout and bulk-lease TCP connection retries.

The DHCPv6 bulk lease query feature is enabled automatically when the DHCPv6 relay agent is enabled. The DHCPv6 bulk lease query feature itself cannot be enabled using this command. To disable this feature, use the ipv6 dhcp-relay bulk-lease command with the disable keyword.

Usage Guidelines

The ipv6 dhcp-relay option vpn command allows the DHCPv6 relay VRF-aware feature to be enabled globally on the device. If the ipv6 dhcp relay option vpn command is enabled on a specified interface, it overrides the global ipv6 dhcp-relay option vpn command.

Usage Guidelines

If the configured interface is shut down, or if all of its IPv6 addresses are removed, the relay will revert to its standard behavior.

The interface configuration (using the ipv6 dhcp relay source-interface command in interface configuration mode) takes precedence over the global configuration if both have been configured.

Usage Guidelines

The ipv6 dhcp binding track ppp command configures DHCP for IPv6 to automatically release any bindings associated with a PPP connection when that connection is closed. The bindings are released automatically to accommodate subsequent new registrations by providing sufficient resource.

Note

In IPv6 broadband deployment using DHCPv6, you must enable release of prefix bindings associated with a PPP virtual interface using this command. This ensures that DHCPv6 bindings are tracked together with PPP sessions, and in the event of DHCP REBIND failure, the client initiates DHCPv6 negotiation again.

A binding table entry on the DHCP for IPv6 server is automatically:

• Created whenever a prefix is delegated to a client from the configuration pool.

• Updated when the client renews, rebinds, or confirms the prefix delegation.

• Deleted when the client releases all the prefixes in the binding voluntarily, all prefixes’ valid lifetimes have expired, or an administrator clears the binding.

Usage Guidelines

The ipv6 dhcp database command specifies DHCP for IPv6 binding database agent parameters. The user may configure multiple database agents.

A binding table entry is automatically created whenever a prefix is delegated to a client from the configuration pool, updated when the client renews, rebinds, or confirms the prefix delegation, and deleted when the client releases all the prefixes in the binding voluntarily, all prefixes’ valid lifetimes have expired, or administrators enable the clear ipv6 dhcp binding command. These bindings are maintained in RAM and can be saved to permanent storage using the agent argument so that the information about configuration such as prefixes assigned to clients is not lost after a system reload or power down. The bindings are stored as text records for easy maintenance.

Each permanent storage to which the binding database is saved is called the database agent. A database agent can be a remote host such as an FTP server or a local file system such as NVRAM.

The write-delay keyword specifies how often, in seconds, that DHCP sends database updates. By default, DHCP for IPv6 server waits 300 seconds before sending any database changes.

The timeout keyword specifies how long, in seconds, the router waits for a database transfer. Infinity is defined as 0 seconds, and transfers that exceed the timeout period are canceled. By default, the DHCP for IPv6 server waits 300 seconds before canceling a database transfer. When the system is going to reload, there is no transfer timeout so that the binding table can be stored completely.

Usage Guidelines

The ipv6 dhcp iana-route-add command is disabled by default and has to be enabled if route addition is required. Route addition for Internet Assigned Numbers Authority (IANA) is possible if the client is connected to the relay or server through unnumbered interfaces, and if route addition is enabled with the help of this command.

Usage Guidelines

The DHCPv6 relay and the DHCPv6 server add routes for delegated prefixes by default. The presence of this command on a device does not mean that routes will be added on that device. When you configure the command, routes for delegated prefixes will only be added on the first Layer 3 relay and server.

Usage Guidelines

You must configure the LDRA functionality globally using the ipv6 dhcp-ldra command before configuring it on a VLAN or an access node (such as a Digital Subscriber Link Access Multiplexer [DSLAM] or an Ethernet switch) interface.

Usage Guidelines

The DHCPv6 server pings a pool address before assigning the address to a requesting client. If the ping is unanswered, the server assumes, with a high probability, that the address is not in use and assigns the address to the requesting client.

Setting the number argument to 0 turns off the DHCPv6 server ping operation

Usage Guidelines

Use the ipv6 dhcp pool command to create a DHCP for IPv6 server configuration information pool. When the ipv6 dhcp pool command is enabled, the configuration mode changes to DHCP for IPv6 pool configuration mode. In this mode, the administrator can configure pool parameters, such as prefixes to be delegated and Domain Name System (DNS) servers, using the following commands:

• address prefix IPv6-prefix [lifetime {valid-lifetime preferred-lifetime | infinite }] sets an address prefix for address assignment. This address must be in hexadecimal, using 16-bit values between colons.

• link-address IPv6-prefix sets a link-address IPv6 prefix. When an address on the incoming interface or a link-address in the packet matches the specified IPv6-prefix, the server uses the configuration information pool. This address must be in hexadecimal, using 16-bit values between colons.

• vendor-specific vendor-id enables DHCPv6 vendor-specific configuration mode. Specify a vendor identification number. This number is the vendor IANA Private Enterprise Number. The range is 1 to 4294967295. The following configuration command is available:

  • suboption number sets vendor-specific suboption number. The range is 1 to 65535. You can enter an IPv6 address, ASCII text, or a hex string as defined by the suboption parameters.

Note	The hex value used under the suboption keyword allows users to enter only hex digits (0-f). Entering an invalid hex value does not delete the previous configuration.

Once the DHCP for IPv6 configuration information pool has been created, use the ipv6 dhcp server command to associate the pool with a server on an interface. If you do not configure an information pool, you need to use the ipv6 dhcp server interface configuration command to enable the DHCPv6 server function on an interface.

When you associate a DHCPv6 pool with an interface, only that pool services requests on the associated interface. The pool also services other interfaces. If you do not associate a DHCPv6 pool with an interface, it can service requests on any interface.

Not using any IPv6 address prefix means that the pool returns only configured options.

The link-address command allows matching a link-address without necessarily allocating an address. You can match the pool from multiple relays by using multiple link-address configuration commands inside a pool.

Since a longest match is performed on either the address pool information or the link information, you can configure one pool to allocate addresses and another pool on a subprefix that returns only configured options.

Usage Guidelines

The ipv6 dhcp server option vpn command allows the DHCPv6 server VRF-aware feature to be enabled globally on a device.

Usage Guidelines

You cannot attach a NetFlow monitor to a port channel interface. If both service module interfaces are part of an EtherChannel, you should attach the monitor to both physical interfaces.

Usage Guidelines

Use the ipv6 general-prefix command to define an IPv6 general prefix.

A general prefix holds a short prefix, based on which a number of longer, more specific, prefixes can be defined. When the general prefix is changed, all of the more specific prefixes based on it will change, too. This function greatly simplifies network renumbering and allows for automated prefix definition.

More specific prefixes, based on a general prefix, can be used when configuring IPv6 on an interface.

When defining a general prefix based on an interface used for 6to4 tunneling, the general prefix will be of the form 2002:a.b.c.d::/48, where "a.b.c.d" is the IPv4 address of the interface referenced.

Usage Guidelines

Packets originating from a router are not normally policy routed. However, you can use the ipv6 local policy route-map command to policy route such packets. You might enable local PBR if you want packets originated at the router to take a route other than the obvious shortest path.

The ipv6 local policy route-map command identifies a route map to be used for local PBR. The route-map commands each have a list of match and set commands associated with them. The match commands specify the match criteria, which are the conditions under which packets should be policy routed. The set commands specify set actions, which are particular policy routing actions to be performed if the criteria enforced by the match commands are met. The no ipv6 local policy route-map command deletes the reference to the route map and disables local policy routing.

Usage Guidelines

All pool names must be unique.

IPv6 prefix pools have a function similar to IPv4 address pools. Contrary to IPv4, a block of addresses (an address prefix) are assigned and not single addresses.

Prefix pools are not allowed to overlap.

Once a pool is configured, it cannot be changed. To change the configuration, the pool must be removed and recreated. All prefixes already allocated will also be freed.

Usage Guidelines

MLDv2 snooping is supported on the Supervisor Engine 720 with all versions of the Policy Feature Card 3 (PFC3).

To use MLDv2 snooping, configure a Layer 3 interface in the subnet for IPv6 multicast routing or enable the MLDv2 snooping querier in the subnet.