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Stateless Source Network Prefix Translation for IPv6

Stateless Source Network Prefix Translation for IPv6 for IPv6

When an IPv6 packet is going from an internal network to the external network, Stateless Source Network Prefix Translation for IPv6 (NPTv6) maps the IPv6 prefix of the source address to an IPv6 prefix of an external network. When an IPv6 packet is coming from the external network to the internal network, NPTv6 maps the IPv6 prefix of the destination address to the IPv6 prefix of the internal network.

NPTv6 uses an algorithm to translate the addresses, and does not need to maintain the state for each node or each flow in the translator. NPTv6 also removes the need to recompute the transport layer checksum.

Benefits of Stateless Source Network Prefix Translation

  • For edge networks, you do not need to renumber the IPv6 addresses used inside the local network for interfaces, access lists, and system logging messages if:

    • The global prefixes used by the edge network are changed.

    • The IPv6 addresses are used inside the edge network or within other upstream networks (such as multihomed devices) when a site adds, drops, or changes upstream networks.

  • IPv6 addresses used by the edge network do not need ingress filtering in upstream networks and do not need their customer-specific prefixes advertised to upstream networks.

  • Connections that traverse the translation function are not disrupted by a reset or brief outage of an NPTv6 translator.

Configuring NPTv6 for Next Gen Services

Configuring the Source Pool

To configure the source pool for NPTv6:

  1. Create a source pool.
  2. Define the IPv6 prefix to which the IPv6 source address prefix is translated.

Configuring the NAT Rule

To configure the NAT source rule for NPTv6:

  1. Configure the NAT rule name.
  2. Specify the traffic direction to which the NAT rule set applies.
  3. Specify the IPv6 prefix of source addresses that are translated by the source NAT rule.

    To specify one address or prefix value:

  4. Configure the address-pooling paired feature if you want to ensure assignment of the same external IP address for all sessions originating from the same internal host.
  5. Specify the timeout period for address-pooling-paired mappings that use the NAT pool. The range is 120 through 86,400 seconds, and the default is 300. Mappings that are inactive for this amount of time are dropped.

    If you do not configure ei-mapping-timeout for endpoint independent translations, then the mapping-timeout value is used for endpoint independent translations.

  6. Specify the NAT pool that contains the IPv6 prefix for translated traffic.
  7. Configure the generation of a syslog when traffic matches the NAT rule conditions.

Configuring the Service Set

To configure the service set for NPTv6:

  1. Define the service set.
  2. Configure either an interface service set, which requires a single service interface, or a next-hop service set, which requires an inside and outside service interface.

    • To configure an interface service set:

    • To configure a next-hop service set:

  3. Specify the NAT rule sets to be used with the service set.
  4. Specify that ICMP error messages are sent if NPTv6 address translation fails.