Catalyst 3750-X and Catalyst 3560-X Switch Software Configuration Guide, Cisco IOS Release 15.0(2)SE and Later
Configuring IPv6 Unicast Routing
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Table of Contents

Configuring IPv6 Unicast Routing

Understanding IPv6

IPv6 Addresses

Supported IPv6 Unicast Routing Features

128-Bit Wide Unicast Addresses

DNS for IPv6

Path MTU Discovery for IPv6 Unicast

ICMPv6

Neighbor Discovery

First Hop Security In IPv6

Default Router Preference

IPv6 Stateless Autoconfiguration and Duplicate Address Detection

IPv6 Applications

Dual IPv4 and IPv6 Protocol Stacks

DHCP for IPv6 Address Assignment

Static Routes for IPv6

RIP for IPv6

OSPF for IPv6

OSPFv3 Graceful Restart

Fast Convergence: LSA and SPF Throttling

Authentication Support with IPsec

EIGRP IPv6

HSRP for IPv6

SNMP and Syslog Over IPv6

HTTP(S) Over IPv6

Unsupported IPv6 Unicast Routing Features

Limitations

IPv6 and Switch Stacks

Configuring IPv6

Default IPv6 Configuration

Configuring IPv6 Addressing and Enabling IPv6 Routing

Configuring First Hop Security in IPv6

Configuring an IPv6 Snooping Policy

Configuring IPv6 DHCP Guard

Configuring IPv6 Source Guard

Configuration Examples for Implementing First Hop Security in IPv6

Configuring Default Router Preference

Configuring IPv4 and IPv6 Protocol Stacks

Configuring DHCP for IPv6 Address Assignment

Default DHCPv6 Address Assignment Configuration

DHCPv6 Address Assignment Configuration Guidelines

Enabling DHCPv6 Server Function

Enabling DHCPv6 Client Function

Configuring IPv6 ICMP Rate Limiting

Configuring CEF and dCEF for IPv6

Configuring Static Routing for IPv6

Configuring RIP for IPv6

Configuring OSPF for IPv6

Tuning LSA and SPF Timers for OSPFv3 Fast Convergence

Configuring LSA and SPF Throttling for OSPFv3 Fast Convergence

Configuring IPSec on OSPFv3

Configuring EIGRP for IPv6

Configuring HSRP for IPv6

Enabling HSRP Version 2

Enabling an HSRP Group for IPv6

Displaying IPv6

Configuring IPv6 Unicast Routing

This chapter describes how to configure IPv6 unicast routing on the Catalyst 3750-X or 3560-X switch.

For information about configuring IPv4 unicast routing, see Chapter1, “Configuring IP Unicast Routing”For information about configuring IPv6 Multicast Listener Discovery (MLD) snooping, see Chapter1, “Configuring IPv6 MLD Snooping” For information on configuring IPv6 access control lists (ACLs) see Chapter1, “Configuring IPv6 ACLs”


Note To use all IPv6 features in this chapter, the switch or stack master must be running the IP services feature set. Switches running the IP base feature set support only IPv6 static routing and RIP for IPv6. Switches running the LAN base feature set support only IPv6 host functionality.


To enable IPv6 routing, you must you must configure the switch to use the a dual IPv4 and IPv6 switch database management (SDM) template. See the “Dual IPv4 and IPv6 Protocol Stacks” section.

Unless otherwise noted, the term switch refers to a Catalyst 3750-X or 3560-X standalone switch and to a Catalyst 3750-X switch stack.


Note For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS documentation referenced in the procedures


This chapter consists of these sections:

Understanding IPv6

IPv4 users can move to IPv6 and receive services such as end-to-end security, quality of service (QoS), and globally unique addresses. The IPv6 address space reduces the need for private addresses and Network Address Translation (NAT) processing by border routers at network edges.

For information about how Cisco Systems implements IPv6, go to:
http://www.cisco.com/en/US/products/ps6553/products_ios_technology_home.html

For information about IPv6 and other features in this chapter

  • See the Cisco IOS IPv6 Configuration Library .
  • Use the Search field on Cisco.com to locate the Cisco IOS software documentation. For example, if you want information about static routes, you can enter Implementing Static Routes for IPv6 in the search field to learn about static routes.

This section describes IPv6 implementation on the switch. These sections are included:

IPv6 Addresses

The switch supports only IPv6 unicast addresses. It does not support site-local unicast addresses, anycast addresses, or multicast addresses.

The IPv6 128-bit addresses are represented as a series of eight 16-bit hexadecimal fields separated by colons in the format: n:n:n:n:n:n:n:n. This is an example of an IPv6 address:

2031:0000:130F:0000:0000:09C0:080F:130B

For easier implementation, leading zeros in each field are optional. This is the same address without leading zeros:

2031:0:130F:0:0:9C0:80F:130B

You can also use two colons (::) to represent successive hexadecimal fields of zeros, but you can use this short version only once in each address:

2031:0:130F::09C0:080F:130B

For more information about IPv6 address formats, address types, and the IPv6 packet header, see the “Implementing IPv6 Addressing and Basic Connectivity” chapter of Cisco IOS IPv6 Configuration Library on Cisco.com.

In the “Information About Implementing Basic Connectivity for IPv6” chapter, these sections apply to the switch:

  • IPv6 Address Formats
  • IPv6 Address Type: Unicast
  • IPv6 Address Output Display
  • Simplified IPv6 Packet Header

Supported IPv6 Unicast Routing Features

These sections describe the IPv6 protocol features supported by the switch:

Support on the switch includes expanded address capability, header format simplification, improved support of extensions and options, and hardware parsing of the extension header. The switch supports hop-by-hop extension header packets, which are routed or bridged in software.

The switch provides IPv6 routing capability over native Ethernet Inter-Switch Link (ISL) or 802.1Q trunk ports for static routes, Routing Information Protocol (RIP) for IPv6, and Open Shortest Path First (OSPF) Version 3 Protocol. It supports up to 16 equal-cost routes and can simultaneously forward IPv4 and IPv6 frames at line rate.

128-Bit Wide Unicast Addresses

The switch supports aggregatable global unicast addresses and link-local unicast addresses. It does not support site-local unicast addresses.

  • Aggregatable global unicast addresses are IPv6 addresses from the aggregatable global unicast prefix. The address structure enables strict aggregation of routing prefixes and limits the number of routing table entries in the global routing table. These addresses are used on links that are aggregated through organizations and eventually to the Internet service provider.

These addresses are defined by a global routing prefix, a subnet ID, and an interface ID. Current global unicast address allocation uses the range of addresses that start with binary value 001 (2000::/3). Addresses with a prefix of 2000::/3(001) through E000::/3(111) must have 64-bit interface identifiers in the extended unique identifier (EUI)-64 format.

  • Link local unicast addresses can be automatically configured on any interface by using the link-local prefix FE80::/10(1111 1110 10) and the interface identifier in the modified EUI format. Link-local addresses are used in the neighbor discovery protocol (NDP) and the stateless autoconfiguration process. Nodes on a local link use link-local addresses and do not require globally unique addresses to communicate. IPv6 routers do not forward packets with link-local source or destination addresses to other links.

For more information, see the section about IPv6 unicast addresses in the “Implementing IPv6 Addressing and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

DNS for IPv6

IPv6 supports Domain Name System (DNS) record types in the DNS name-to-address and address-to-name lookup processes. The DNS AAAA resource record types support IPv6 addresses and are equivalent to an A address record in IPv4. The switch supports DNS resolution for IPv4 and IPv6.

Path MTU Discovery for IPv6 Unicast

The switch supports advertising the system maximum transmission unit (MTU) to IPv6 nodes and path MTU discovery. Path MTU discovery allows a host to dynamically discover and adjust to differences in the MTU size of every link along a given data path. In IPv6, if a link along the path is not large enough to accommodate the packet size, the source of the packet handles the fragmentation. The switch does not support path MTU discovery for multicast packets.

ICMPv6

The Internet Control Message Protocol (ICMP) in IPv6 generates error messages, such as ICMP destination unreachable messages, to report errors during processing and other diagnostic functions. In IPv6, ICMP packets are also used in the neighbor discovery protocol and path MTU discovery.

Neighbor Discovery

The switch supports NDP for IPv6, a protocol running on top of ICMPv6, and static neighbor entries for IPv6 stations that do not support NDP. The IPv6 neighbor discovery process uses ICMP messages and solicited-node multicast addresses to determine the link-layer address of a neighbor on the same network (local link), to verify the reachability of the neighbor, and to keep track of neighboring routers.

The switch supports ICMPv6 redirect for routes with mask lengths less than 64 bits. ICMP redirect is not supported for host routes or for summarized routes with mask lengths greater than 64 bits.

Neighbor discovery throttling ensures that the switch CPU is not unnecessarily burdened while it is in the process of obtaining the next hop forwarding information to route an IPv6 packet. The switch drops any additional IPv6 packets whose next hop is the same neighbor that the switch is actively trying to resolve. This drop avoids further load on the CPU.

First Hop Security In IPv6

This section provides information about configuring the functions that comprise the first hop security (FHS) feature in IPv6.

The functions available under FHS are also called as IPv6 policies. Policies can be applied at the interface or VLAN level. IPv6 policies provide policy database services to features with regard to storing and accessing those policies. Every time a policy is configured, the attributes of the policy are stored in the software policy database. The policy is then applied to an interface and the software policy database entry is updated to include this interface to which the policy is applied. You can use the following IPv6 policies:


Note Prerequisites for Implementing First Hop Security in IPv6:

  • You have configured the necessary IPv6 enabled SDM template.
  • You should be familiar with the IPv6 neighbor discovery feature. For information, see “ Implementing IPv6 Addressing and Basic Connectivity ” chapter of the Cisco IOS IPv6 Configuration Library on Cisco.com.


 


Note Restrictions for Implementing First Hop Security in IPv6:

Although visible in the command-line help strings, the IPv6 first hop security (FHS) is not supported on the Catalyst 3750-G and 3750v2 switches. The command-line help strings are visible on these switches to support the FHS feature in a mixed switch stack scenario where one of these switches could become a master.


 

IPv6 Snooping

IPv6 snooping acts as a container policy that enables most of the features available with FHS in IPv6. For more information, see the “Configuring an IPv6 Snooping Policy” section.

IPv6 First-Hop Security Binding Table

A database table of IPv6 neighbors connected to the switch is created from multiple sources of information, For example, Neighbor Discovery Protocol (NDP) snooping and Dynamic Host Configuration Protocol (DHCP) snooping. This database or binding table is used by various IPv6 guard features, such as, IPv6 Neighbor Discovery (ND) Inspection (to validate the link-layer address (LLA)), per-port address limit (to validate the IPv4 or IPv6 addresses), IPv6 device tracking (to prefix binding of the neighbors to prevent spoofing and redirect attacks).

These categories of traffic carry information that the binding table snoops for:

NDP Address Gleaning

The NDP address gleaning feature is enabled by default when you configure the ipv6 snooping policy global configuration command. To disable this function, enter the no protocol ndp global configuration command and attach the policy to the target port or VLAN.

IPv6 DHCP Address Gleaning

The IPv6 DHCP address gleaning feature provides the ability to extract addresses from DHCP messages and populate the binding table. The switch extracts address binding information from the following types of DHCPv6 exchanges (using User Datagram Protocol (UDP), ports 546 and 547):

  • DHCP-REQUEST
  • DHCP-CONFIRM
  • DHCP- RENEW
  • DHCP-REBIND
  • DHCP-REPLY
  • DHCP-RELEASE
  • DHCP-DECLINE

After a switch receives a DHCP-REQUEST message from a client, one of the following can happen:

  • The switch receives a DHCP-REPLY message from DHCP server and a binding table entry is created in the REACHABLE state and completed. The reply contains the IP address and the MAC address in the Layer 2 (L2) DMAC field.

Creating an entry in the binding table allows the switch to learn addresses assigned by DHCP. A binding table can have one of the following states:

INCOMPLETE—Address resolution is in progress and the link-layer address is not yet known.

REACHABLE—The table is known to be reachable within the last reachable time interval.

STALE—The table requires re-resolution.

SEARCH—The feature creating the entry does not have the L2 address and requests the binding table to search for the L2 address.

VERIFY—The L2 and Layer 3 (L3) addresses are known and a duplicate address detection (DAD) Neighbor solicitation (NS) unicast message is sent to the L2 and L3 destinations to verify the addresses.

DOWN—The interface from which the entry was learnt is down, preventing verification.

  • The DHCP server sends a DHCP-DECLINE or DHCP release message and the entry is deleted.
  • The client sends a DHCP-RENEW message to the server that allocated the address or a DHCP-REBIND message to any server and the lifespan of the entry is extended.
  • The server does not reply and the session is timed-out.

To enable this feature, configure a policy using the ipv6 snooping policy policy-name global configuration command. For more information, see the “Configuring an IPv6 Snooping Policy” section.

You can configure a policy and attach it to a DHCP guard to prevent the binding table from being filled with forged DHCP messages. For more information, see the “IPv6 DHCP Guard” section and “Configuring IPv6 DHCP Guard” section.

IPv6 Data Address Gleaning

The IPv6 data address gleaning feature provides the ability to extract addresses from redirected data traffic, to discover neighbors and to populate binding tables.

When a port receives a data packet where the binding is unknown, that is, the neighbor is in an INCOMPLETE state and the link-layer address is not yet known, the switch sends a DAD NS NDP unicast message to the port from which the data packet was received.

After the host replies with a DAD Neighbor Advertisement (NA) NDP message, the binding table is updated and a Private VLAN ACL (PVACL) is installed in the hardware for this binding.

If the host does not reply with a DAD NA, after the binding table timer expires, the hardware is notified and any resources associated with that binding are released.

To enable this feature, configure a policy with data-glean and attach the policy to a target port. To debug the policy, use the debug ipv6 snooping privileged EXEC command.

IPv6 ND Inspection

IPv6 ND inspection learns and secures bindings for stateless autoconfiguration addresses in L2 neighbor tables. IPv6 ND inspection analyzes neighbor discovery messages in order to build a trusted binding table database and IPv6 neighbor discovery messages that do not conform are dropped. An SA ND message is considered trustworthy if its IPv6-to-Media Access Control (MAC) mapping is verifiable.

This feature mitigates some of the inherent vulnerabilities of the ND mechanism, such as, attacks on DAD, address resolution, router discovery, and the neighbor cache.

IPv6 Device Tracking

The IPv6 device tracking feature provides IPv6 host liveness tracking so that a neighbor table can be updated when an IPv6 host disappears. The feature tracks the liveness of the neighbors connected through the L2 switch on regular basis in order to revoke network access privileges as they become inactive.

IPv6 Port-Based Access List Support

The IPv6 port-based access lists (PACL) feature provides the ability to provide access control (permit or deny) on L2 switch ports for IPv6 traffic. IPv6 PACLs are similar to IPv4 PACLs, which provide access control on L2 switch ports for IPv4 traffic.

With Catalyst 3750-E, 3750X, 3560E, 3560-X, 3750v2, and 3560 v2 switches, this feature is supported in hardware and only in ingress direction. In a mixed stack scenario where the stack has a switch that does not support IPv6 FHS, the VLAN target is disabled on the whole switch, for security. Port targets are allowed on the IPv6 FHS-capable ports of the switch. If a nonsupporting switch becomes the stack master then the IPv6 FHS functions are still supported on the IPv6 FHS-capable ports of the switch.

Access lists determine which traffic is blocked and which traffic is forwarded at switch interfaces and allow filtering based on source and destination addresses, inbound and outbound to a specific interface. Each access list has an implicit deny statement at the end. To configure an IPv6 PACL you have to create an IPv6 access list and then configure the PACL mode on the specified IPv6 L2 interface.

PACL can filter ingress traffic on L2 interfaces based on L3 and Layer 4 (L4) header information or non-IP L2 information.

IPv6 Router Advertisement Guard

The IPv6 Router Advertisement (RA) guard feature enables the network administrator to block or reject unwanted or rogue RA guard messages that arrive at the network switch platform. RAs are used by routers to announce themselves on the link. The RA Guard feature analyzes the RAs and filters out bogus RAs sent by unauthorized routers. In host mode, all router advertisement and router redirect messages are disallowed on the port. The RA guard feature compares configuration information on the L2 device with the information found in the received RA frame. Once the L2 device has validated the content of the RA frame and router redirect frame against the configuration, it forwards the RA to its unicast or multicast destination. If the RA frame content is not validated, the RA is dropped.

IPv6 DHCP Guard

You can use the DHCP guard to prevent forged messages from being entered in the binding table. The DHCP guard blocks DHCP server messages when they are received on ports that are not explicitly configured as facing a DHCP server or DHCP relay.

To use this feature, configure a policy and attach it to a DHCP guard. To debug DHCP guard packets, use the debug ipv6 snooping dhcp-guard privileged EXEC command.

IPv6 Source Guard

A source guard programs the hardware to allow or deny traffic based on source or destination addresses. It deals exclusively with data packet traffic.

The IPv6 source guard feature provides the ability to use the IPv6 binding table to install PACLs to prevent a host from sending packets with an invalid IPv6 source address.

To debug source-guard packets, use the debug ipv6 snooping source-guard privileged EXEC command.


Note The IPv6 PACL feature is supported only in the ingress direction; it is not supported in the egress direction.


The following restrictions apply:

  • When IPv6 source guard is enabled on a switchport, NDP or DHCP snooping must be enabled on the interface to which the switchport belongs. Otherwise all data traffic from this port will be blocked.
  • An IPv6 source guard policy cannot be attached to a VLAN.
  • IPv6 source guard is not supported on EtherChannels.

For information about configuring IPv6 access lists, see the " Implementing Traffic Filters and Firewalls for IPv6 Security " chapter of the Cisco IOS IPv6 Configuration Library on Cisco.com.

Default Router Preference

The switch supports IPv6 default router preference (DRP), an extension in router advertisement messages. DRP improves the ability of a host to select an appropriate router, especially when the host is multihomed and the routers are on different links. The switch does not support the Route Information Option in RFC 4191.

An IPv6 host maintains a default router list from which it selects a router for traffic to offlink destinations. The selected router for a destination is then cached in the destination cache. NDP for IPv6 specifies that routers that are reachable or probably reachable are preferred over routers whose reachability is unknown or suspect. For reachable or probably reachable routers, NDP can either select the same router every time or cycle through the router list. By using DRP, you can configure an IPv6 host to prefer one router over another, provided both are reachable or probably reachable.

For more information about DRP for IPv6, see the “Implementing IPv6 Addresses and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

IPv6 Stateless Autoconfiguration and Duplicate Address Detection

The switch uses stateless autoconfiguration to manage link, subnet, and site addressing changes, such as management of host and mobile IP addresses. A host autonomously configures its own link-local address, and booting nodes send router solicitations to request router advertisements for configuring interfaces.

For more information about autoconfiguration and duplicate address detection, see the “Implementing IPv6 Addressing and Basic Connectivity” chapter of Cisco IOS IPv6 Configuration Library on Cisco.com.

IPv6 Applications

The switch has IPv6 support for these applications:

  • Ping, traceroute, Telnet, and TFTP
  • Secure Shell (SSH) over an IPv6 transport
  • HTTP server access over IPv6 transport
  • DNS resolver for AAAA over IPv4 transport
  • Cisco Discovery Protocol (CDP) support for IPv6 addresses

For more information about managing these applications, see the “Managing Cisco IOS Applications over IPv6” chapter and the “Implementing IPv6 Addressing and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Dual IPv4 and IPv6 Protocol Stacks

You must use the dual IPv4 and IPv6 template to allocate hardware memory usage to both IPv4 and IPv6 protocols.

Dual IPv4 and IPv6 Support on an Interface shows a router forwarding both IPv4 and IPv6 traffic through the same interface, based on the IP packet and destination addresses.

Figure 1-1 Dual IPv4 and IPv6 Support on an Interface

 

Use the dual IPv4 and IPv6 switch database management (SDM) template to enable IPv6 routing dual stack environments (supporting both IPv4 and IPv6). For more information about the dual IPv4 and IPv6 SDM template, see Chapter1, “Configuring SDM Templates”

The dual IPv4 and IPv6 templates allow the switch to be used in dual stack environments.

  • If you try to configure IPv6 without first selecting a dual IPv4 and IPv6 template, a warning message appears.
  • In IPv4-only environments, the switch routes IPv4 packets and applies IPv4 QoS and ACLs in hardware. IPv6 packets are not supported.
  • In dual IPv4 and IPv6 environments, the switch routes both IPv4 and IPv6 packets and applies IPv4 QoS in hardware.
  • The switch supports QoS for both IPv4and IPv6 traffic.
  • If you do not plan to use IPv6, do not use the dual stack template because this template results in less hardware memory capacity for each resource.

For more information about IPv4 and IPv6 protocol stacks, see the “Implementing IPv6 Addressing and Basic Connectivity” chapter of Cisco IOS IPv6 Configuration Library on Cisco.com.

DHCP for IPv6 Address Assignment

DHCPv6 enables DHCP servers to pass configuration parameters, such as IPv6 network addresses, to IPv6 clients. The address assignment feature manages non-duplicate address assignment in the correct prefix based on the network where the host is connected. Assigned addresses can be from one or multiple prefix pools. Additional options, such as default domain and DNS name-server address, can be passed back to the client. Address pools can be assigned for use on a specific interface, on multiple interfaces, or the server can automatically find the appropriate pool.

Beginning with Cisco IOS Release 12.2(58)SE, the switch supports these features:

  • DHCPv6 Bulk-Lease Query

DHCPv6 bulk-lease query allows a client to request information about DHCPv6 bindings. This functionality adds new query types and allows the bulk transfer of DHCPv6 binding data through TCP. Bulk transfer of DHCPv6 binding data is useful when the relay server switch is rebooted and the relay server has lost all the binding information. After the reboot, the relay server automatically generates a bulk-lease query to get the binding information from the DHCP server.

  • DHCPv6 Relay Source Configuration

The DHCPv6 server replies to the source address of the DHCP relay agent. Typically, messages from a DHCPv6 relay agent show the source address of the interface from which they are sent. You can use the DHCPv6 relay source configuration feature to configure a more stable address (such as a loopback interface) as the source address for messages from the relay agent. You can configure the source address globally for the switch or for a specific interface. An address configured on an interface takes precedence over one configured globally.

For more information and to configure these features, see the Cisco IOS IPv6 Configuration Guide, Release 12.4 .

This document describes only the DHCPv6 address assignment. For more information about configuring the DHCPv6 client, server, or relay agent functions, see the “Implementing DHCP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Static Routes for IPv6

Static routes are manually configured and define an explicit route between two networking devices. Static routes are useful for smaller networks with only one path to an outside network or to provide security for certain types of traffic in a larger network.

For more information about static routes, see the “Implementing Static Routes for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

RIP for IPv6

Routing Information Protocol (RIP) for IPv6 is a distance-vector protocol that uses hop count as a routing metric. It includes support for IPv6 addresses and prefixes and the all-RIP-routers multicast group address FF02::9 as the destination address for RIP update messages.

For more information about RIP for IPv6, see the “Implementing RIP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

OSPF for IPv6

The switch running the IP-services feature set supports Open Shortest Path First (OSPF) for IPv6, a link-state protocol for IP. For more information, see the “Implementing OSFP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

OSPFv3 Graceful Restart

Beginning with Cisco IOS Release 12.2(58)SE, switches running the IP services feature set support the graceful restart feature in OSPFv3. This feature allows nonstop data forwarding along known routes while the OSPFv3 routing protocol information is restored. A switch uses graceful restart either in restart mode (for a graceful-restart-capable switch) or in helper mode (for a graceful-restart-aware switch).

To use the graceful restart function, a switch must be in high-availability stateful switchover (SSO) mode (dual route processor). A switch capable of graceful restart uses it when these failures occur:

  • A route processor failure that results in changeover to the standby route processor
  • A planned route processor changeover to the standby route processor

The graceful restart feature requires that neighboring switches be graceful-restart aware.

For more information, see the “Implementing OSFP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Fast Convergence: LSA and SPF Throttling

The OSPFv3 link-state advertisements (LSA) and shortest path first (SPF) throttling feature provides a dynamic method to slow down link-state advertisement updates in OSPFv3 during times of network instability. This feature also allows faster OSPFv3 convergence by providing LSA rate limiting in milliseconds.

OSPFv3 previously used static timers for rate-limiting SPF calculation and LSA generation. Although these timers are configurable, the values are specified in seconds, which poses a limitation on OSPFv3 convergence. LSA and SPF throttling achieves subsecond convergence by providing a more sophisticated SPF and LSA rate-limiting method can react quickly to changes and also provide stability and protection during prolonged periods of instability.

For more information, see the “ Implementing OSPFv3 ” chapter of the Cisco IOS IPv6 Configuration Library on Cisco.com.

Authentication Support with IPsec

To ensure that OSPF for IPv6 (OSPFv3) packets are not altered and resent to the switch, OSPFv3 packets must be authenticated. OSPFv3 uses the IPsec secure socket API to add authentication to OSPFv3 packets. This API has been extended to provide support for IPv6.

OSPFv3 requires the use of IPsec to enable authentication. Crypto images are required to use authentication, because only crypto images include the IPsec API needed for use with OSPFv3.

For more information, see the OSPFv3 Authentication Support with IPsec section of the Cisco IOS IPv6 Configuration Library on Cisco.com.

EIGRP IPv6

Switches running the IP services feature set support the Enhanced Interior Gateway Routing Protocol (EIGRP) for IPv6. It is configured on the interfaces on which it runs and does not require a global IPv6 address.


Note Switches running the IP base feature set do not support any IPv6 EIGRP features, including IPv6 EIGRP stub routing.


Before running, an instance of EIGRP IPv6 requires an implicit or explicit router ID. An implicit router ID is derived from a local IPv4 address, so any IPv4 node always has an available router ID. However, EIGRP IPv6 might be running in a network with only IPv6 nodes and therefore might not have an available IPv4 router ID.

For more information about EIGRP for IPv6, see the “Implementing EIGRP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com .

HSRP for IPv6

Switches running the IP-services feature set support the Hot Standby Router Protocol (HSRP) for IPv6. HSRP provides routing redundancy for routing IPv6 traffic not dependent on the availability of any single router. IPv6 hosts learn of available routers through IPv6 neighbor discovery router advertisement messages. These messages are multicast periodically or are solicited by hosts.

An HSRP IPv6 group has a virtual MAC address that is derived from the HSRP group number and a virtual IPv6 link-local address that is, by default, derived from the HSRP virtual MAC address. Periodic messages are sent for the HSRP virtual IPv6 link-local address when the HSRP group is active. These messages stop after a final one is sent when the group leaves the active state.

For more information about configuring HSRP for IPv6, see the “Configuring First Hop Redundancy Protocols in IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

SNMP and Syslog Over IPv6

To support both IPv4 and IPv6, IPv6 network management requires both IPv6 and IPv4 transports. Syslog over IPv6 supports address data types for these transports.

SNMP and syslog over IPv6 provide these features:

  • Support for both IPv4 and IPv6
  • IPv6 transport for SNMP and to modify the SNMP agent to support traps for an IPv6 host
  • SNMP- and syslog-related MIBs to support IPv6 addressing
  • Configuration of IPv6 hosts as trap receivers

For support over IPv6, SNMP modifies the existing IP transport mapping to simultaneously support IPv4 and IPv6. These SNMP actions support IPv6 transport management:

  • Opens User Datagram Protocol (UDP) SNMP socket with default settings
  • Provides a new transport mechanism called SR_IPV6_TRANSPORT
  • Sends SNMP notifications over IPv6 transport
  • Supports SNMP-named access lists for IPv6 transport
  • Supports SNMP proxy forwarding using IPv6 transport
  • Verifies SNMP Manager feature works with IPv6 transport

For information on SNMP over IPv6, including configuration procedures, see the “Managing Cisco IOS Applications over IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com .

For information about syslog over IPv6, including configuration procedures, see the “Implementing IPv6 Addressing and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

HTTP(S) Over IPv6

The HTTP client sends requests to both IPv4 and IPv6 HTTP servers, which respond to requests from both IPv4 and IPv6 HTTP clients. URLs with literal IPv6 addresses must be specified in hexadecimal using 16-bit values between colons.

The accept socket call chooses an IPv4 or IPv6 address family. The accept socket is either an IPv4 or IPv6 socket. The listening socket continues to listen for both IPv4 and IPv6 signals that indicate a connection. The IPv6 listening socket is bound to an IPv6 wildcard address.

The underlying TCP/IP stack supports a dual-stack environment. HTTP relies on the TCP/IP stack and the sockets for processing network-layer interactions.

Basic network connectivity (ping) must exist between the client and the server hosts before HTTP connections can be made.

For more information, see the “Managing Cisco IOS Applications over IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Unsupported IPv6 Unicast Routing Features

The switch does not support these IPv6 features:

  • IPv6 policy-based routing
  • IPv6 virtual private network (VPN) routing and forwarding (VRF) table support
  • Support for IPv6 routing protocols: multiprotocol Border Gateway Protocol (BGP) and Intermediate System-to-Intermediate System (IS-IS) routing
  • IPv6 packets destined to site-local addresses
  • Tunneling protocols, such as IPv4-to-IPv6 or IPv6-to-IPv4
  • The switch as a tunnel endpoint supporting IPv4-to-IPv6 or IPv6-to-IPv4 tunneling protocols
  • IPv6 unicast reverse-path forwarding
  • IPv6 general prefixes

Limitations

Because IPv6 is implemented in switch hardware, some limitations occur due to the IPv6 compressed addresses in the hardware memory. These hardware limitations result in some loss of functionality and limits some features.

These are feature limitations.

  • ICMPv6 redirect functionality is not supported for IPv6 host routes (routes used to reach a specific host) or for IPv6 routes with masks greater than 64 bits. The switch cannot redirect hosts to a better first-hop router for a specific destination that is reachable through a host route or through a route with masks greater than 64 bits.
  • Load balancing using equal cost and unequal cost routes is not supported for IPv6 host routes or for IPv6 routes with a mask greater than 64 bits.
  • The switch cannot forward SNAP-encapsulated IPv6 packets.

Note There is a similar limitation for IPv4 SNAP-encapsulated packets, but the packets are dropped at the switch and are not forwarded.


  • The switch routes IPv6-to-IPv4 and IPv4-to-IPv6 packets in hardware, but the switch cannot be an IPv6-to-IPv4 or IPv4-to-IPv6 tunnel endpoint.
  • Bridged IPv6 packets with hop-by-hop extension headers are forwarded in software. In IPv4, these packets are routed in software, but bridged in hardware.
  • Interface counters for IPv6 traffic include software-forwarded traffic only; hardware-switched traffic is excluded.
  • In addition to the normal SPAN and RSPAN limitations defined in the software configuration guide, these limitations are specific to IPv6 packets:

When you send RSPAN IPv6-routed packets, the source MAC address in the SPAN output packet can be incorrect.

When you send RSPAN IPv6-routed packets, the destination MAC address can be incorrect. Normal traffic is not affected.

  • The switch cannot apply QoS classification or policy-based routing on source-routed IPv6 packets in hardware.
  • The switch cannot generate ICMPv6 Packet Too Big messages for multicast packets.

IPv6 and Switch Stacks

The switch supports IPv6 forwarding across the stack and IPv6 host functionality on the stack master. The stack master runs the IPv6 unicast routing protocols and computes the routing tables. Using distributed CEF (dCEF), the stack master downloads the routing table to the stack member switches. They receive the tables and create hardware IPv6 routes for forwarding. The stack master also runs all IPv6 applications.


Note To route IPv6 packets in a stack, all switches in the stack should be running the IP services feature set.


If a new switch becomes the stack master, it recomputes the IPv6 routing tables and distributes them to the member switches. While the new stack master is being elected and is resetting, the switch stack does not forward IPv6 packets. The stack MAC address changes, which also changes the IPv6 address. When you specify the stack IPv6 address with an extended unique identifier (EUI) by using the ipv6 address ipv6-prefix/prefix length eui-64 interface configuration command, the address is based on the interface MAC address. See the “Configuring IPv6 Addressing and Enabling IPv6 Routing” section.

If you configure the persistent MAC address feature on the stack and the stack master changes, the stack MAC address does not change for approximately 4 minutes. For more information, see the “Enabling Persistent MAC Address” section in Chapter1, “Managing Switch Stacks”

These are the functions of IPv6 stack master and members:

  • Stack master:

runs IPv6 routing protocols

generates routing tables

distributes CEFv6 routing tables to stack members that use dCEFv6

runs IPv6 host functionality and IPv6 applications

  • Stack member (must be running the IP services feature set):

receives CEFv6 routing tables from the stack master

programs the routes into hardware


Note IPv6 packets are routed in hardware across the stack if the packet does not have exceptions (IPv6Options) and the switches in the stack have not run out of hardware resources.


flushes the CEFv6 tables on master re-election

Configuring IPv6

Default IPv6 Configuration

 

Table 1-1 Default IPv6 Configuration

Feature
Default Setting

SDM template

Default desktop.

IPv6 routing

Disabled globally and on all interfaces

CEFv6 or dCEFv6

Disabled (IPv4 CEF and dCEF are enabled by default)

Note When IPv6 routing is enabled, CEFv6 and dCEF6 are automatically enabled.

IPv6 addresses

None configured

Configuring IPv6 Addressing and Enabling IPv6 Routing

This section describes how to assign IPv6 addresses to individual Layer 3 interfaces and to globally forward IPv6 traffic on the switch.

Before configuring IPv6 on the switch, consider these guidelines:

  • Be sure to select a dual IPv4 and IPv6 SDM template.
  • Not all features discussed in this chapter are supported by the switch. See the “Unsupported IPv6 Unicast Routing Features” section.
  • In the ipv6 address interface configuration command, you must enter the ipv6-address and ipv6-prefix variables with the address specified in hexadecimal using 16-bit values between colons. The prefix-length variable (preceded by a slash [/]) is a decimal value that shows how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address).

To forward IPv6 traffic on an interface, you must configure a global IPv6 address on that interface. Configuring an IPv6 address on an interface automatically configures a link-local address and activates IPv6 for the interface. The configured interface automatically joins these required multicast groups for that link:

  • solicited-node multicast group FF02:0:0:0:0:1:ff00::/104 for each unicast address assigned to the interface (this address is used in the neighbor discovery process.)
  • all-nodes link-local multicast group FF02::1
  • all-routers link-local multicast group FF02::2

For more information about configuring IPv6 routing, see the “Implementing Addressing and Basic Connectivity for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com .

Beginning in privileged EXEC mode, follow these steps to assign an IPv6 address to a Layer 3 interface and enable IPv6 routing:

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

sdm prefer dual-ipv4-and-ipv6 { default | routing | vlan }

Select an SDM template that supports IPv4 and IPv6.

  • default —Set the switch to the default template to balance system resources.
  • routing —Set the switch to the routing template to support IPv4 and IPv6 routing, including IPv4 policy-based routing.
  • vlan —Maximize VLAN configuration on the switch with no routing supported in hardware.

Step 3

end

Return to privileged EXEC mode.

Step 4

reload

Reload the operating system.

Step 5

configure terminal

Enter global configuration mode after the switch reloads.

Step 6

interface interface-id

Enter interface configuration mode, and specify the Layer 3 interface to configure. The interface can be a physical interface, a switch virtual interface (SVI), or a Layer 3 EtherChannel.

Step 7

no switchport

Remove the interface from Layer 2 configuration mode (if it is a physical interface).

Step 8

ipv6 address ipv6-prefix/prefix length eui-64

or

ipv6 address ipv6-address/prefix length

or

ipv6 address ipv6-address link-local

or

ipv6 enable

Specify a global IPv6 address with an extended unique identifier (EUI) in the low-order 64 bits of the IPv6 address. Specify only the network prefix; the last 64 bits are automatically computed from the switch MAC address. This enables IPv6 processing on the interface.

Manually configure an IPv6 address on the interface.

Specify a link-local address on the interface to be used instead of the link-local address that is automatically configured when IPv6 is enabled on the interface. This command enables IPv6 processing on the interface.

Automatically configure an IPv6 link-local address on the interface, and enable the interface for IPv6 processing. The link-local address can only be used to communicate with nodes on the same link.

Step 9

exit

Return to global configuration mode.

Step 10

ip routing

Enable IP routing on the switch.

Step 11

ipv6 unicast-routing

Enable forwarding of IPv6 unicast data packets.

Step 12

end

Return to privileged EXEC mode.

Step 13

show ipv6 interface interface-id

Verify your entries.

Step 14

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To remove an IPv6 address from an interface, use the no ipv6 address ipv6-prefix/prefix length eui-64 or no ipv6 address ipv6-address link-local interface configuration command. To remove all manually configured IPv6 addresses from an interface, use the no ipv6 address interface configuration command without arguments. To disable IPv6 processing on an interface that has not been explicitly configured with an IPv6 address, use the no ipv6 enable interface configuration command. To globally disable IPv6 routing, use the no ipv6 unicast-routing global configuration command.

This example shows how to enable IPv6 with both a link-local address and a global address based on the IPv6 prefix 2001:0DB8:c18:1::/64. The EUI-64 interface ID is used in the low-order 64 bits of both addresses. Output from the show ipv6 interface EXEC command is included to show how the interface ID (20B:46FF:FE2F:D940) is appended to the link-local prefix FE80::/64 of the interface.

Switch(config)# sdm prefer dual-ipv4-and-ipv6 default
Switch(config)# ipv6 unicast-routing
Switch(config)# interface gigabitethernet1/0/11
Switch(config-if)# no switchport
Switch(config-if)# ipv6 address 2001:0DB8:c18:1::/64 eui 64
Switch(config-if)# end
Switch# show ipv6 interface gigabitethernet1/0/11
GigabitEthernet1/0/11 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::20B:46FF:FE2F:D940
Global unicast address(es):
2001:0DB8:c18:1:20B:46FF:FE2F:D940, subnet is 2001:0DB8:c18:1::/64 [EUI]
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF2F:D940
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
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
Hosts use stateless autoconfig for addresses.
 

Configuring an IPv6 Snooping Policy

 

Action or Command
Purpose

Step 1

enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Enters the global configuration mode.

Step 3

ipv6 snooping policy policy-name

Creates a snooping policy in global configuration mode.

Step 4

[ data-glean | default | device-role [ node | switch ] | limit { address-count value }| no | protocol [ all | dhcp | ndp ] | security-level [glean | guard | inspect] | tracking [ disable | enable ]| trusted-port }

Enables data address gleaning, validates messages against various criteria, specifies the security level for messages.

  • (Optional) data-glean —Enables data address gleaning. This option is disabled by default.
  • (Optional) default —Sets all default options.
  • (Optional) device-role [ node | switch ]—Qualifies the role of the device attached to the port.
  • (Optional) limit { address-count value }—Limits the number of addresses allowed per target.
  • (Optional) no —Negates a command or set its defaults.
  • (Optional) protocol [ all | dhcp | ndp ]—Specifies which protocol should be redirected to the snooping feature for analysis. The default, is all. To change the default, use the no protocol command.
  • (Optional) security-level [glean | guard | inspect] —Specifies the level of security enforced by the feature.

glean —Gleans addresses from messages and populates the binding table without any verification.

guard —Gleans addresses and inspects messages. In addition, it rejects RA and DHCP server messages. This is the default option.

inspect —Gleans addresses, validates messages for consistency and conformance, and enforces address ownership.

  • (Optional) tracking [ disable | enable ]—Overrides the default tracking behavior and specifies a tracking option.
  • (Optional) trusted-port —Sets up a trusted port. It disables the guard on applicable targets. Bindings learnt through a trusted port have preference over bindings learnt through any other port. A trusted port is also given preference in case of a collision while making an entry in the table.

Step 5

exit

Exits the snooping policy configuration mode.

Step 6

show ipv6 snooping policy policy-name

Displays the snooping policy configuration.

To attach a snooping policy to an interface or VLAN, complete the following steps:

 

Action or Command
Purpose

Step 1

enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Enters the global configuration mode.

Step 3

interface type number

Specifies an interface type and number, and enters the interface configuration mode.

Step 4

switchport

ipv6 snooping attach-policy policy-name

OR

vlan configuration vlan list

ipv6 snooping attach-policy policy-name

Attaches the snooping policy (where data gleaning is enabled) to an interface. Specifies the port and the policy that is attached to the port.


Note If you have enabled data-glean on a snooping policy, you must attach it to an interface and not a VLAN.


Step 5

show ipv6 snooping policy policy-name

Displays the snooping policy configuration.

Step 6

show ipv6 neighbors binding

Displays the binding table entries populated by the snooping policy.

Configuring IPv6 DHCP Guard

 

Action or Command
Purpose

Step 1

enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Enters the global configuration mode.

Step 3

ipv6 dhcp guard policy policy-name

Creates a policy in global configuration mode and enters the DHCP guard policy global configuration mode.

Step 4

[ default | device-role [ client | server ] | no | exit | trusted-port ]

Configures the parameters for the DHCP guard policy.

  • (Optional) default —Set a command to its defaults.
  • (Optional) device-role [ client | server ]—Qualifies the role of the device attached to the port.

client —Specifies that the attached device is a client. This is the default. Any server messages are dropped on this port.

server —Specifies that the attached device is a DHCP server. Server messages are allowed on this port.

  • (Optional) no —Removes the configured policy parameters.
  • (Optional) exit —Exits the DHCP guard policy global configuration mode.
  • (Optional) trusted-port —Sets the port to a trusted mode. No further policing takes place on the port.

Note If you configure a trusted port then the device-role option is not available.


Step 5

exit

Exits the DHCP guard policy global configuration mode.

Step 6

interface type number

Specifies an interface type and number and enters the interface configuration mode.

Step 7

ipv6 dhcp guard attach-policy policy-name

Or

vlan configuration vlan-id

Attaches the DHCP guard policy to an interface or VLAN.

Step 8

show ipv6 dhcp guard policy policy-name

Displays the DHCP guard policy configuration.

Configuring IPv6 Source Guard

 

Action or Command
Purpose

Step 1

enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Enters the global configuration mode.

Step 3

ipv6 source-guard policy policy-name

Specifies the source guard policy name and enters the source guard policy configuration mode.

Step 4

permit link-local

Allows all data traffic that is sourced by a link-local address.

Step 5

deny global-autoconf

Denies data traffic from auto-configured global addresses. This is useful when all global addresses on a link are DHCP-assigned and the administrator wants to block hosts with self-configured addresses to send traffic.

Step 6

ipv6 source-guard [ attach-policy policy-name]

Specifies the policy name.

(Optional) attach-policy policy-name—Filters based on the policy name

Step 7

exit

Exits the source guard policy configuration mode.

Step 8

show ipv6 source-guard policy policy name

Shows the policy configuration and all the interfaces where the policy is applied.

Configuration Examples for Implementing First Hop Security in IPv6

This example shows you how to attach a snooping policy to a VLAN and to configure an RA trusted router port and DHCP trusted server port:

Switch(config)# vlan configuration 100
Switch(config-vlan-config)# ipv6 snooping
Switch(config-vlan-config)# exit
 
Switch(config)# ipv6 nd raguard policy router
Switch(config-nd-raguard)# device-role router
Switch(config-nd-raguard)# exit
 
Switch(config)# ipv6 dhcp guard policy server
Switch(config-dhcp-guard)# device-role server
Switch(config-dhcp-guard)# exit
 

Here, 2/1/2 is a router-facing port:

Switch(config)# interface fastethernet 2/1/2
Switch(config-if)# switchport
Switch(config-if)# swithport access vlan 100
Switch(config-if)# ipv6 nd raguard attach-policy router
Switch(config-if)# exit
 

Here, 1/0/17 is a DHCP server-facing port:

Switch(config)# interface gigabitethernet 1/0/17
Switch(config-if)# switchport access vlan 100
Switch(config-if)# ipv6 dhcp guard attach-policy server
Switch(config-if)# exit
Switch(config)# exit
 
Switch# show ipv6 snooping policies
Target Type Policy Feature Target range
Gi1/0/17 PORT server DHCP Guard vlan all
Te2/1/2 PORT router RA guard vlan all
vlan 100 VLAN default Snooping vlan all
 

This example shows you how to create a snooping policy called Test and enable data address gleaning on it:

Switch(config)# ipv6 snooping policy Test
Switch(config-ipv6-snooping)# data-glean
Switch(config-ipv6-snooping)# device-role node
Switch(config-ipv6-snooping)# limit address-count 1
Switch(config-ipv6-snooping)# protocol dhcp
Switch(config-ipv6-snooping)# security-level glean
Switch(config-ipv6-snooping)# tracking enable
Switch(config-ipv6-snooping)# no trusted-port
Switch(config-ipv6-snooping)# exit
 

This example shows you how to configure snooping policy Test, enable data address gleaning on the policy, and enable source guard where link-local addresses are permitted and global autoconfiguration addresses are denied entry:

Switch(config)# ipv6 snooping policy Test
Switch(config-ipv6-snooping)# data-glean
Switch(config-ipv6-snooping)# exit
Switch(config)# ipv6 source-guard policy Test
Switch(config-sisf-sourceguard)# permit link-local
Switch(config-sisf-sourceguard)# deny global-autoconf
Switch(config-sisf-sourceguard)# exit
 

This example shows you how to attach a snooping policy with source guard, to an interface:

Switch(config)# interface gigabitethernet2/0/3
Switch(config-if)# ipv6 snooping attach-policy Test
Switch(config-if)# ipv6 source-guard attach-policy Test
 
Switch# show ipv6 source-guard policy Test
Policy Test configuration:
permit link-local
deny global-autoconf
Policy Test is applied on the following targets:
Target Type Policy Feature Target range
Gi2/0/3 PORT Test Source guard vlan all
 

This example shows you how to configure a DHCP guard policy Test and attach it to an interface:

Switch(config)# ipv6 dhcp-guard policy Test
Switch(config-dhcp-guard)# no trusted-port
Switch(config-dhcp-guard)# exit
 
Switch(config)# interface gigabitethernet2/0/3
Switch(config-if)# ipv6 dhcp guard attach-policy Test
Switch(config-if)# exit
OR
Switch(config)# vlan configuration 1-10
Switch(config-vlan-config)# ipv6 dhcp guard attach-policy Test
Switch(config-vlan-config)# exit
 
Switch# show ipv6 dhcp-guard policy Test
Dhcp guard policy: Test
Device Role: dhcp server
Target: Gi2/0/3 vlan 1 vlan 2 vlan 3 vlan 4 vlan 5 vlan 6 vlan 7 vlan 8 vlan 9 vlan 10
Max Preference: 255
Min Preference: 0
 

This example shows how you can enable the FHS feature on an interface or VLAN, without creating a snooping policy.


Note Creating a policy gives you the flexibility to configure as per your needs. If you enable the feature without creating a policy then the default policy configuration is applied:


Switch(config)# interface GigabitEthernet1/0/9
Switch(config-if)# ipv6 nd inspection
Switch(config-if)# ipv6 nd raguard
Switch(config-if)# ipv6 snooping
Switch(config-if)# ipv6 dhcp guard
Switch(config-if)# ipv6 source-guard
Switch(config-if)# end
 

OR

Switch(config)# vlan configuration 1
Switch(config-vlan-config)# ipv6 nd inspection
Switch(config-vlan-config)# ipv6 nd raguard
Switch(config-vlan-config)# ipv6 dhcp guard
Switch(config-vlan-config)# ipv6 snooping
 

Note You cannot apply a source-guard policy to the VLAN.


For more examples, see the Configuration Examples for Implementing First Hop Security in IPv6 section of the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring Default Router Preference

Router advertisement messages are sent with the default router preference (DRP) configured by the ipv6 nd router-preference interface configuration command. If no DRP is configured, RAs are sent with a medium preference.

A DRP is useful when two routers on a link might provide equivalent, but not equal-cost routing, and policy might dictate that hosts should prefer one of the routers.

Beginning in privileged EXEC mode, follow these steps to configure a DRP for a router on an interface.

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface interface-id

Enter interface configuration mode, and enter the Layer 3 interface on which you want to specify the DRP.

Step 3

ipv6 nd router-preference { high | medium | low }

Specify a DRP for the router on the switch interface.

Step 4

end

Return to privileged EXEC mode.

Step 5

show ipv6 interface

Verify the configuration.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no ipv6 nd router-preference interface configuration command to disable an IPv6 DRP.

This example shows how to configure a DRP of high for the router on an interface.

Switch# configure terminal
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# ipv6 nd router-preference high
Switch(config-if)# end
 

For more information about configuring DRP for IPv6, see the “Implementing IPv6 Addresses and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring IPv4 and IPv6 Protocol Stacks

Before configuring IPv6 routing, you must select an SDM template that supports IPv4 and IPv6. If not already configured, use the sdm prefer dual-ipv4-and-ipv6 { default | routing | vlan } [ desktop ] global configuration command to configure a template that supports IPv6. When you select a new template, you must reload the switch by using the reload privileged EXEC command so that the template takes effect.

Beginning in privileged EXEC mode, follow these steps to configure a Layer 3 interface to support both IPv4 and IPv6 and to enable IPv6 routing.

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

ip routing

Enable routing on the switch.

Step 3

ipv6 unicast-routing

Enable forwarding of IPv6 data packets on the switch.

Step 4

interface interface-id

Enter interface configuration mode, and specify the Layer 3 interface to configure.

Step 5

no switchport

Remove the interface from Layer 2 configuration mode (if it is a physical interface).

Step 6

ip address ip-address mask [ secondary ]

Specify a primary or secondary IPv4 address for the interface.

Step 7

ipv6 address ipv6-prefix/prefix length eui-64

or

ipv6 address ipv6-address link-local

or

ipv6 enable

Specify a global IPv6 address. Specify only the network prefix; the last 64 bits are automatically computed from the switch MAC address.

Specify a link-local address on the interface to be used instead of the automatically configured link-local address when IPv6 is enabled on the interface.

Automatically configure an IPv6 link-local address on the interface, and enable the interface for IPv6 processing. The link-local address can only be used to communicate with nodes on the same link.

Step 8

end

Return to privileged EXEC mode.

Step 9

show interface interface-id

show ip interface interface-id

show ipv6 interface interface-id

Verify your entries.

Step 10

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable IPv4 routing, use the no ip routing global configuration command. To disable IPv6 routing, use the no ipv6 unicast-routing global configuration command. To remove an IPv4 address from an interface, use the no ip address ip-address mask interface configuration command. To remove an IPv6 address from an interface, use the no ipv6 address ipv6-prefix/prefix length eui-64 or no ipv6 address ipv6-address link-local interface configuration command. To remove all manually configured IPv6 addresses from an interface, use the no ipv6 address interface configuration command without arguments. To disable IPv6 processing on an interface that has not been explicitly configured with an IPv6 address, use the no ipv6 enable interface configuration command.

This example shows how to enable IPv4 and IPv6 routing on an interface.

Switch(config)# sdm prefer dual-ipv4-and-ipv6 default
Switch(config)# ip routing
Switch(config)# ipv6 unicast-routing
Switch(config)# interface fastethernet1/0/11
Switch(config-if)# no switchport
Switch(config-if)# ip address 192.168.99.1 244.244.244.0
Switch(config-if)# ipv6 address 2001:0DB8:c18:1::/64 eui 64
Switch(config-if)# end

Default DHCPv6 Address Assignment Configuration

By default, no DHCPv6 features are configured on the switch.

DHCPv6 Address Assignment Configuration Guidelines

When configuring DHCPv6 address assignment, consider these guidelines:

  • In the procedures, the specified interface must be one of these Layer 3 interfaces:

DHCPv6 IPv6 routing must be enabled on a Layer 3 interface.

SVI: a VLAN interface created by using the interface vlan vlan_id command.

EtherChannel port channel in Layer 3 mode: a port-channel logical interface created by using the interface port-channel port-channel-number command.

  • Before configuring DHCPv6, you must select a Switch Database Management (SDM) template that supports IPv4 and IPv6.
  • The switch can act as a DHCPv6 client, server, or relay agent. The DHCPv6 client, server, and relay function are mutually exclusive on an interface.
  • The DHCPv6 client, server, or relay agent runs only on the master switch. When there is a stack master re-election, the new master switch retains the DHCPv6 configuration. However, the local RAM copy of the DHCP server database lease information is not retained.

Enabling DHCPv6 Server Function

Beginning in privileged EXEC mode, follow these steps to enable the DHCPv6 server function on an interface.

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

ipv6 dhcp pool poolname

Enter DHCP pool configuration mode, and define the name for the IPv6 DHCP pool. The pool name can be a symbolic string (such as Engineering) or an integer (such as 0).

Step 3

address prefix IPv6-prefix lifetime {t1 t1 | infinite }

(Optional) Specify an address prefix for address assignment.

This address must be in hexadecimal, using 16-bit values between colons.

lifetime t1 t1 —Specify a time interval (in seconds) that an IPv6 address prefix remains in the valid state. The range is 5 to 4294967295 seconds. Specify infinite for no time interval.

Step 4

link-address IPv6-prefix

(Optional) Specify 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.

Step 5

vendor-specific vendor-id

(Optional) Enter vendor-specific configuration mode and enter a vendor-specific identification number. This number is the vendor IANA Private Enterprise Number. The range is 1 to 4294967295.

Step 6

suboption number { address IPv6-address | ascii ASCII-string | hex hex-string}

(Optional) Enter a vendor-specific suboption number. The range is 1 to 65535. Enter an IPv6 address, ASCII text, or a hex string as defined by the suboption parameters.

Step 7

exit

Return to DHCP pool configuration mode.

Step 8

exit

Return to global configuration mode.

Step 9

interface interface-id

Enter interface configuration mode, and specify the interface to configure.

Step 10

ipv6 dhcp server [ poolname | automatic ] [ rapid-commit ] [ preference value] [ allow-hint ]

Enable DHCPv6 server function on an interface.

  • poolname —(Optional) User-defined name for the IPv6 DHCP pool. The pool name can be a symbolic string (such as Engineering) or an integer (such as 0).
  • automatic —(Optional) Enables the system to automatically determine which pool to use when allocating addresses for a client.
  • rapid-commit —(Optional) Allow two-message exchange method.
  • preference value —(Optional) The preference value carried in the preference option in the advertise message sent by the server. The range is from 0 to 255. The preference value default is 0.
  • allow-hint —(Optional) Specifies whether the server should consider client suggestions in the SOLICIT message. By default, the server ignores client hints.

Step 11

end

Return to privileged EXEC mode.

Step 12

show ipv6 dhcp pool

or

show ipv6 dhcp interface

Verify DHCPv6 pool configuration.

Verify that the DHCPv6 server function is enabled on an interface.

Step 13

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete a DHCPv6 pool, use the no ipv6 dhcp pool poolname global configuration command. Use the no form of the DHCP pool configuration mode commands to change the DHCPv6 pool characteristics. To disable the DHCPv6 server function on an interface, use the no ipv6 dhcp server interface configuration command.

This example shows how to configure a pool called engineering with an IPv6 address prefix :

Switch# configure terminal
Switch(config)# ipv6 dhcp pool engineering
Switch(config-dhcpv6)#address prefix 2001:1000::0/64
Switch(config-dhcpv6)# end
 

This example shows how to configure a pool called testgroup with three link-addresses and an IPv6 address prefix:

Switch# configure terminal
Switch(config)# ipv6 dhcp pool testgroup
Switch(config-dhcpv6)# link-address 2001:1001::0/64
Switch(config-dhcpv6)# link-address 2001:1002::0/64
Switch(config-dhcpv6)# link-address 2001:2000::0/48
Switch(config-dhcpv6)# address prefix 2001:1003::0/64
Switch(config-dhcpv6)# end
 

This example shows how to configure a pool called 350 with vendor-specific options:

Switch# configure terminal
Switch(config)# ipv6 dhcp pool 350
Switch(config-dhcpv6)# address prefix 2001:1005::0/48
Switch(config-dhcpv6)# vendor-specific 9
Switch(config-dhcpv6-vs)# suboption 1 address 1000:235D::1
Switch(config-dhcpv6-vs)# suboption 2 ascii "IP-Phone"
Switch(config-dhcpv6-vs)# end

Enabling DHCPv6 Client Function

Beginning in privileged EXEC mode, follow these steps to enable DHCPv6 client function on an interface.

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface interface-id

Enter interface configuration mode, and specify the interface to configure.

Step 3

ipv6 address dhcp [ rapid-commit ]

Enable the interface to acquire an IPv6 address from the DHCPv6 server.

rapid-commit—(Optional) Allow two-message exchange method for address assignment.

Step 4

ipv6 dhcp client request [ vendor-specific ]

(Optional) Enable the interface to request the vendor-specific option.

Step 5

end

Return to privileged EXEC mode.

Step 6

show ipv6 dhcp interface

Verify that the DHCPv6 client is enabled on an interface.

To disable the DHCPv6 client function, use the no ipv6 address dhcp interface configuration command. To remove the DHCPv6 client request, use the no ipv6 address dhcp client request interface configuration command.

This example shows how to acquire an IPv6 address and to enable the rapid-commit option:

Switch(config)# interface gigabitethernet2/0/1
Switch(config-if)# ipv6 address dhcp rapid-commit
 

This document describes only the DHCPv6 address assignment. For more information about configuring the DHCPv6 client, server, or relay agent functions, see the “Implementing DHCP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring IPv6 ICMP Rate Limiting

ICMP rate limiting is enabled by default with a default interval between error messages of 100 milliseconds and a bucket size (maximum number of tokens to be stored in a bucket) of 10.

Beginning in privileged EXEC mode, follow these steps to change the ICMP rate-limiting parameters:

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

ipv6 icmp error-interval interval [ bucketsize ]

Configure the interval and bucket size for IPv6 ICMP error messages:

  • interval— The interval (in milliseconds) between tokens being added to the bucket. The range is from 0 to 2147483647 milliseconds.
  • bucketsize —(Optional) The maximum number of tokens stored in the bucket. The range is from 1 to 200.

Step 3

end

Return to privileged EXEC mode.

Step 4

show ipv6 interface [ interface-id ]

Verify your entries.

Step 5

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To return to the default configuration, use the no ipv6 icmp error-interval global configuration command.

This example shows how to configure an IPv6 ICMP error message interval of 50 milliseconds and a bucket size of 20 tokens.

Switch(config)#ipv6 icmp error-interval 50 20

Configuring CEF and dCEF for IPv6

Cisco Express Forwarding (CEF) is a Layer 3 IP switching technology to improve network performance. CEF implements an advanced IP look-up and forwarding algorithm to deliver maximum Layer 3 switching performance. It is less CPU-intensive than fast-switching route-caching, allowing more CPU processing power to be dedicated to packet forwarding. In a Catalyst 3750-E switch stack, the hardware uses distributed CEF (dCEF) in the stack. IPv4 CEF and dCEF are enabled by default. IPv6 CEF and dCEF are disabled by default, but automatically enabled when you configure IPv6 routing.

To route IPv6 unicast packets, you must first globally configure forwarding of IPv6 unicast packets by using the ipv6 unicast-routing global configuration command, and you must configure an IPv6 address and IPv6 processing on an interface by using the ipv6 address interface configuration command.

To disable IPv6 CEF or distributed CEF, use the no ipv6 cef or no ipv6 cef distributed global configuration command. To reenable IPv6 CEF or dCEF if it has been disabled, use the ipv6 cef or ipv6 cef distributed global configuration command. You can verify the IPv6 state by entering the show ipv6 cef privileged EXEC command.

For more information about configuring CEF and dCEF, see the “Implementing IPv6 Addressing and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring Static Routing for IPv6

Before configuring a static IPv6 route, you must enable routing by using the ip routing global configuration command, enable the forwarding of IPv6 packets by using the ipv6 unicast-routing global configuration command, and enable IPv6 on at least one Layer 3 interface by configuring an IPv6 address on the interface.

Beginning in privileged EXEC mode, follow these steps to configure an IPv6 static route:

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

ipv6 route ipv6-prefix/prefix length { ipv6-address | interface-id [ ipv6-address ]} [ administrative distance ]

Configure a static IPv6 route.

  • ipv6-prefix— The IPv6 network that is the destination of the static route. It can also be a hostname when static host routes are configured.
  • /prefix length— The length of the IPv6 prefix. A decimal value that shows 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.
  • ipv6-address The IPv6 address of the next hop that can be used to reach the specified network. The IPv6 address of the next hop need not be directly connected; recursion is done to find the IPv6 address of the directly connected next hop. The address must be in the form documented in RFC 2373, specified in hexadecimal using 16-bit values between colons.
  • interface-id —Specify direct static routes from point-to-point and broadcast interfaces. With point-to-point interfaces, there is no need to specify the IPv6 address of the next hop. With broadcast interfaces, you should always specify the IPv6 address of the next hop, or ensure that the specified prefix is assigned to the link, specifying a link-local address as the next hop. You can optionally specify the IPv6 address of the next hop to which packets are sent.

Note You must specify an interface-id when using a link-local address as the next hop (the link-local next hop must also be an adjacent router).

  • administrative distance— (Optional) An administrative distance. The range is 1 to 254; the default value is 1, which gives static routes precedence over any other type of route except connected routes. To configure a floating static route, use an administrative distance greater than that of the dynamic routing protocol.

Step 3

end

Return to privileged EXEC mode.

Step 4

show ipv6 static [ ipv6-address | ipv6-prefix/prefix length ] [ interface interface-id ] [ recursive ] [ detail ]

or

show ipv6 route static [ updated ]

Verify your entries by displaying the contents of the IPv6 routing table.

  • interface interface-id— (Optional) Display only those static routes with the specified interface as an egress interface.
  • recursive—(Optional) Display only recursive static routes. The recursive keyword is mutually exclusive with the interface keyword, but it can be used with or without the IPv6 prefix included in the command syntax.
  • detail—(Optional) Display this additional information:

For valid recursive routes, the output path set, and maximum resolution depth.

For invalid routes, the reason why the route is not valid.

Step 5

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To remove a configured static route, use the no ipv6 route ipv6-prefix/prefix length { ipv6-address | interface-id [ ipv6-address ]} [ administrative distance ] global configuration command.

This example shows how to configure a floating static route to an interface with an administrative distance of 130:

Switch(config)# ipv6 route 2001:0DB8::/32 gigabitethernet0/1 130
 

For more information about configuring static IPv6 routing, see the “Implementing Static Routes for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring RIP for IPv6

Before configuring the switch to run IPv6 RIP, you must enable routing by using the ip routing global configuration command, enable the forwarding of IPv6 packets by using the ipv6 unicast-routing global configuration command, and enable IPv6 on any Layer 3 interfaces on which IPv6 RIP is to be enabled.

Beginning in privileged EXEC mode, follow these required and optional steps to configure IPv6 RIP:

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

ipv6 router rip name

Configure an IPv6 RIP routing process, and enter router configuration mode for the process.

Step 3

maximum-paths number-paths

(Optional) Define the maximum number of equal-cost routes that IPv6 RIP can support. The range is from 1 to 64, and the default is four routes.

Step 4

exit

Return to global configuration mode.

Step 5

interface interface-id

Enter interface configuration mode, and specify the Layer 3 interface to configure.

Step 6

ipv6 rip name enable

Enable the specified IPv6 RIP routing process on the interface.

Step 7

ipv6 rip name default-information { only | originate }

(Optional) Originate the IPv6 default route (::/0) into the RIP routing process updates sent from the specified interface.

Note To avoid routing loops after the IPv6 default route (::/0) is originated from any interface, the routing process ignores all default routes received on any interface.

  • only —Select to originate the default route, but suppress all other routes in the updates sent on this interface.
  • originate —Select to originate the default route in addition to all other routes in the updates sent on this interface.

Step 8

end

Return to privileged EXEC mode.

Step 9

show ipv6 rip [ name ] [ interface interface-id ] [ database ] [ next-hops ]

or

show ipv6 route rip [ updated ]

Display information about current IPv6 RIP processes.


Display the current contents of the IPv6 routing table.

Step 10

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable a RIP routing process, use the no ipv6 router rip name global configuration command. To disable the RIP routing process for an interface, use the no ipv6 rip name interface configuration command.

This example shows how to enable the RIP routing process cisco with a maximum of eight equal-cost routes and to enable it on an interface:

Switch(config)# ipv6 router rip cisco
Switch(config-router)# maximum-paths 8
Switch(config)# exit
Switch(config)# interface gigabitethernet2/0/11
Switch(config-if)# ipv6 rip cisco enable
 

For more information about configuring RIP routing for IPv6, see the “Implementing RIP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com

Configuring OSPF for IPv6

You can customize OSPF for IPv6 for your network. However, the defaults for OSPF in IPv6 are set to meet the requirements of most customers and features.

Follow these guidelines:

  • Be careful when changing the defaults for IPv6 commands. Changing the defaults might adversely affect OSPF for the IPv6 network.
  • Before you enable IPv6 OSPF on an interface, you must enable routing by using the ip routing global configuration command, enable the forwarding of IPv6 packets by using the ipv6 unicast-routing global configuration command, and enable IPv6 on Layer 3 interfaces on which you are enabling IPv6 OSPF.

Beginning in privileged EXEC mode, follow these required and optional steps to configure IPv6 OSPF:

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

ipv6 router ospf process-id

Enable OSPF router configuration mode for the process. The process ID is the number assigned administratively when enabling the OSPF for IPv6 routing process. It is locally assigned and can be a positive integer from 1 to 65535.

Step 3

area area-id range { ipv6-prefix/prefix length } [ advertise | not-advertise ] [ cost cost ]

(Optional) Consolidate and summarize routes at an area boundary.

  • area-id— Identifier of the area about which routes are to be summarized. It can be specified as either a decimal value or as an IPv6 prefix.
  • ipv6-prefix/prefix length The destination IPv6 network and a decimal value that shows 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.
  • advertise —(Optional) Set the address range status to advertise and generate a Type 3 summary link-state advertisement (LSA).
  • not-advertise —(Optional) Set the address range status to DoNotAdvertise. The Type 3 summary LSA is suppressed, and component networks remain hidden from other networks.
  • cost cost —(Optional) Metric or cost for this summary route, which is used during OSPF SPF calculation to determine the shortest paths to the destination. The value can be 0 to 16777215.

Step 4

maximum paths number-paths

(Optional) Define the maximum number of equal-cost routes to the same destination that IPv6 OSPF should enter in the routing table. The range is from 1 to 64, and the default is 16 paths.

Step 5

exit

Return to global configuration mode.

Step 6

interface interface-id

Enter interface configuration mode, and specify the Layer 3 interface to configure.

Step 7

ipv6 ospf process-id area area-id [ instance instance-id ]

Enable OSPF for IPv6 on the interface.

  • instance instance-id— (Optional) Instance identifier.

Step 8

end

Return to privileged EXEC mode.

Step 9

show ipv6 ospf [ process-id ] [ area-id ] interface [ interface-id ]

or

show ipv6 ospf [ process-id ] [ area-id ]

Display information about OSPF interfaces.


 

Display general information about OSPF routing processes.

Step 10

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable an OSPF routing process, use the no ipv6 router ospf process-id global configuration command. To disable the OSPF routing process for an interface, use the no ipv6 ospf process-id area area-id interface configuration command.

For more information about configuring OSPF routing for IPv6, see the “Implementing OSPF for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Tuning LSA and SPF Timers for OSPFv3 Fast Convergence

Beginning in the privileged EXEC mode, follow these steps to tune LSA and SPF timers:

 

Command
Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

ipv6 router ospf process-id

Enables OSPFv3 router configuration mode.

Step 3

timers lsa arrival milliseconds

Sets the minimum interval at which the software accepts the same LSA from OSPFv3 neighbors.

Step 4

timers pacing flood milliseconds

Configures LSA flood packet pacing.

Step 5

timers pacing lsa-group seconds

Changes the interval at which OSPFv3 LSAs are collected into a group and refreshed, checksummed, or aged.

Step 6

timers pacing retransmission milliseconds

Configures LSA retransmission packet pacing in OSPFv3.

Configuring LSA and SPF Throttling for OSPFv3 Fast Convergence

Beginning in the privileged EXEC mode, follow these steps to configure LSA and SPF throttling:

 

Command
Purpose

Step 1

configure terminal

Enters global configuration mode.

Step 2

ipv6 router ospf process-id

Enables OSPFv3 router configuration mode.

Step 3

timers throttle spf spf-start spf-hold spf-max-wait

Turns on SPF throttling.

Step 4

timers throttle lsa start-interval hold-interval max-interval

Sets rate-limiting values for OSPFv3 LSA generation.

Step 5

timers lsa arrival milliseconds

Sets the minimum interval at which the software accepts the same LSA from OSPFv3 neighbors.

Step 6

timers pacing flood milliseconds

Configures LSA flood packet pacing.

For more information, see the “ Enabling Event Logging for LSA and SPF Rate Limiting ,” “ Verifying OSPFv3 Configuration and Operation ,” and “ Example: Configuring LSA and SPF Throttling for OSPFv3 Fast Convergence ” sections of the Implementing OSPFv3 chapter of the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring IPSec on OSPFv3


Note To enable authentication and encryption, configure the IP Security (IPsec) secure socket application program interface (API) on OSPFv3.


For information about configuring IPSec, see the following sections of the Cisco IOS IPv6 Configuration Library on Cisco.com:

Configuring EIGRP for IPv6

By default, EIGRP for IPv6 is disabled. You can configure EIGRP for IPv6 on an interface. After configuring the router and the interface for EIGRP, enter the no shutdown privileged EXEC command to start EIGRP.


Note If EIGRP for IPv6 is not in shutdown mode, EIGRP might start running before you enter the EIRGP router-mode commands to configure the router and the interface.


To set an explicit router ID, use the show ipv6 eigrp command to see the configured router IDs, and then use the router-id command.

As with EIGRP IPv4, you can use EIGRPv6 to specify your EIGRP IPv4 interfaces and to select a subset of those as passive interfaces. Use the passive-interface default command to make all interfaces passive, and then use the no passive-interface command on selected interfaces to make them active. EIGRP IPv6 does not need to be configured on a passive interface.

For more configuration procedures, see the “Implementing EIGRP for IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Configuring HSRP for IPv6

Hot Standby Router Protocol (HSRP) for IPv6 provides routing redundancy for routing IPv6 traffic not dependent on the availability of any single router.

When HSRP for IPv6 is enabled on a switch, IPv6 hosts learn of available IPv6 routers through IPv6 neighbor discovery router advertisement messages. An HSRP IPv6 group has a virtual MAC address that is derived from the HSRP group number. The group has a virtual IPv6 link-local address that is, by default, derived from the HSRP virtual MAC address. Periodic messages are sent for the HSRP virtual IPv6 link-local address when the HSRP group is active.

When configuring HSRP for IPv6, you must enable HSRP version 2 (HSRPv2) on the interface.

For configuration guidelines when configuring HSRP for IPv6 with HSRPv1 and HSRPv2, see the “Default HSRP Configuration” section and the “Troubleshooting HSRP for Mixed Stacks of Catalyst 3750-X, 3750-E and 3750 Switches” section.

For more information about HSRP for IPv6 and HSRPv2, see the Chapter1, “Configuring HSRP and VRRP”


Note Before configuring an HSRP for IPv6 group, you must enable the forwarding of IPv6 packets by using the ipv6 unicast-routing global configuration command and enable IPv6 on the interface on which you will configure an HSRP for IPv6 group.


Enabling HSRP Version 2

Beginning in privileged EXEC mode, follow these steps to enable HSRP version 2 on a Layer 3 interface.

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface interface-id

Enter interface configuration mode, and enter the Layer 3 interface on which you want to specify the standby version.

Step 3

standby version { 1 | 2 }

Enter 2 to change the HSRP version. The default is 1.

Step 4

end

Return to privileged EXEC mode.

Step 5

show standby

Verify the configuration.

Step 6

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Enabling an HSRP Group for IPv6

Beginning in privileged EXEC mode, follow these steps to create or enable HSRP for IPv6 on a Layer 3 interface.

 

Command
Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface interface-id

Enter interface configuration mode, and enter the Layer 3 interface on which you want to enable HSRP for IPv6.

Step 3

standby [ group-number ] ipv6 { link-local-address | autoconfig }

Create (or enable) the HSRP for IPv6 group.

  • (Optional) group-number —The group number on the interface for which HSRP is being enabled. The range is 0 to 4095. The default is 0. If there is only one HSRP group, you do not need to enter a group number.
  • Enter the link-local address of the Hot Standby router interface, or enable the link-local address to be generated automatically from the link-local prefix and a modified EUI-64 format interface identifier, where the EUI-64 interface identifier is created from the relevant HSRP virtual MAC address.

Step 4

standby [ group-number ] preempt [ delay {minimum seconds | reload seconds | sync seconds }]

Configure the router to preempt , which means that when the local router has a higher priority than the active router, it assumes control as the active router.

  • (Optional) group-number —The group number to which the command applies.
  • (Optional) delay —Set to cause the local router to postpone taking over the active role for the shown number of seconds. The range is 0 to 3600 (1 hour). The default is 0 (no delay before taking over).
  • (Optional) reload —Set the preemption delay, in seconds, after a reload. The delay period applies only to the first interface-up event after the router reloads.
  • (Optional) sync —Set the maximum synchronization period, in seconds, for IP redundancy clients.

Use the no form of the command to restore the default values.

Step 5

standby [ group-number ] priority priority

Set a priority value used in choosing the active router. The range is 1 to 255; the default priority is 100. The highest number represents the highest priority.

Use the no form of the command to restore the default values.

Step 6

end

Return to privileged EXEC mode.

Step 7

show standby [ interface-id [ group-number ]]

Verify the configuration.

Step 8

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no standby [ group-number ] ipv6 interface configuration command to disable HSRP for IPv6.

This example shows how to activate HSRP for IPv6 for group 1 on a port. The IP address used by the hot standby group is learned by using HSRP for IPv6.


Note This procedure is the minimum number of steps required to enable HSRP for IPv6. Other configurations are optional.


Switch# configure terminal
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# no switchport
Switch(config-if)# standby 1 ipv6 autoconfig
Switch(config-if)# end
Switch# show standby
 

For more information about configuring HSRP for IPv6, see the “Configuring First Hop Redundancy Protocols in IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Displaying IPv6

For complete syntax and usage information on these commands, see the Cisco IOS command reference publications.

 

Table 1-2 Commands for Monitoring IPv6

Command
Purpose

show ipv6 access-list

Display a summary of access lists.

show ipv6 cef

Display Cisco Express Forwarding for IPv6.

show ipv6 interface interface-id

Display IPv6 interface status and configuration.

show ipv6 mtu

Display IPv6 MTU per destination cache.

show ipv6 neighbors

Display IPv6 neighbor cache entries.

show ipv6 ospf

Display IPv6 OSPF information.

show ipv6 prefix-list

Display a list of IPv6 prefix lists.

show ipv6 protocols

Display IPv6 routing protocols on the switch.

show ipv6 rip

Display IPv6 RIP routing protocol status.

show ipv6 route

Display the IPv6 route table entries.

show ipv6 routers

Display the local IPv6 routers.

show ipv6 static

Display IPv6 static routes.

show ipv6 traffic

Display IPv6 traffic statistics.

 

Table 1-3 Commands for Displaying EIGRP IPv6 Information

Command
Purpose

show ipv6 eigrp [ as-number ] interface

Displays information about interfaces configured for EIGRP IPv6.

show ipv6 eigrp [ as-number ] neighbor

Displays the neighbors discovered by EIGRP IPv6.

show ipv6 eigrp [ as-number ] traffic

Displays the number of EIGRP IPv6 packets sent and received.

show ipv6 eigrp topology [ as-number | ipv6-address ] [ active | all-links | detail-links | pending | summary | zero-successors ]

Displays EIGRP entries in the IPv6 topology table.

 

Table 1-4 Commands for Displaying IPv4 and IPv6 Address Types

Command
Purpose

show ip http server history

Display the previous 20 connections to the HTTP server, including the IP address accessed and the time when the connection was closed.

show ip http server connection

Display the current connections to the HTTP server, including the local and remote IP addresses being accessed.

show ip http client connection

Display the configuration values for HTTP client connections to HTTP servers.

show ip http client history

Display a list of the last 20 requests made by the HTTP client to the server.

This is an example of the output from the show ipv6 interface privileged EXEC command:

Switch# show ipv6 interface
Vlan1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::20B:46FF:FE2F:D940
Global unicast address(es):
3FFE:C000:0:1:20B:46FF:FE2F:D940, subnet is 3FFE:C000:0:1::/64 [EUI]
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF2F:D940
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
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
<output truncated>