IP/ICMP Translation Algorithm

Document Type Replaced Internet-Draft (individual)
Author Fred Baker 
Last updated 2009-07-06 (latest revision 2009-02-22)
Replaced by RFC 6145
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document specifies an update to the Stateless IP/ICMP Translation Algorithm (SIIT) described in RFC 2765. The algorithm translates between IPv4 and IPv6 packet headers (including ICMP headers). This specification addresses both a stateless and a stateful mode. In the stateless mode, translation information is carried in the address itself, permitting both IPv4->IPv6 and IPv6->IPv4 session establishment with neither state nor configuration in the IP/ICMP translator. In the stateful mode, translation state is maintained between IPv4 address/transport_port tuples and IPv6 address/ transport_port tuples, enabling IPv6 systems to open sessions with IPv4 systems. The choice of operational mode is made by the operator deploying the network and is critical to the operation of the applications using it. Significant issues exist in the stateless and stateful modes that are not addressed in this document, related to the address assignment and the maintenance of the translation tables, respectively. This document confines itself to the actual translation. Acknowledgement of previous work This document is a product of the 2008-2009 effort to define a replacement for NAT-PT. It is an update to and directly derivative from Erik Nordmark's [RFC2765], which similarly provides both stateless and stateful translation between IPv4 [RFC0791] and IPv6 [RFC2460], and between ICMPv4 [RFC0792] and ICMPv6 [RFC4443]. The original document was a product of the NGTRANS working group. The changes in this document reflect five components: 1. Redescribing the network model to map to present and projected usage. 2. Moving the address format to the framework document, to coordinate with other drafts on the topic. 3. Description of both stateful and stateless operation. 4. Some changes in ICMP. 5. Updating references.Requirements The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [RFC2119].


Fred Baker (fred@cisco.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)