Optional BR per Rule within a domain. Deployment considerations. Flexible Assigment of Port Sets. Traffic Classification. Prefix Delegation Deployment. Coexisting Deployment. Friendly to Network Provisioning.
Enable privacy addresses. Facilitating 4v6 Service. Independency with IPv6 Routing Planning. Optimized Routing Path. Guidelines for Operators. Additional terms. Understanding address formats: their difference and relevance. Residual deployment with MAP. Given an IPv6 packet with an destination address with an embedded IPv4 address, a node could automatically tunnel this packet by extracting the IPv4 tunnel end- point address from the IPv6 destination address.
RFC discusses the transport of the port set information in an IPv4-embedded IPv6 address but the conclusion was the following excerpt from [ RFC ] : "There have been proposals to complement stateless translation with a port range feature.
Instead of mapping an IPv4 address to exactly one IPv6 prefix, the options would allow several IPv6 nodes to share an IPv4 address, with each node managing a different set of ports. If a port set extension is needed, could be defined later, using bits currently reserved as null in the suffix. Likewise for translation, an IPv4 address can be calculated from an IPv6 destination address and vice versa.
This document describes a more generic mapping of IPv4 to IPv6 that can be used both for encapsulation IPv4 over IPv6 and for translation between the two protocols. The unified mapping scheme described here supports translation mode, encapsulation mode, in both mesh and hub and spoke topologies. This document describes delivery of IPv4 unicast service across an IPv6 infrastructure. IPv4 multicast is not considered further in this document. Other work that has motivated the work on a unified mapping mechanism for translation and encapsulation are: [ I-D.
In particular the architecture of a shared IPv4 address by distributing the port space is described in [ RFC ]. The appendixes are in no way to be considered normative.
Each MAP node in the domain has the same set of rules. Each node has a separate part of the transport layer port space; denoted as a port set.
Only ports that belong to the assigned port set can be used for communication. Mapping rules are used differently depending on their function. Every MAP node must be provisioned with a Basic mapping rule. This same basic rule can also be used for forwarding, where an IPv4 destination address and optionally a destination port is mapped into an IPv6 address or prefix.
Additional mapping rules can be specified to allow for e. Traffic outside of the domain IPv4 address not matching using longest matching prefix any Rule IPv4 prefix in the Rules database will be forward using the Default Rule. There are three types of mapping rules: 1.
Basic Mapping Rule - used for IPv4 prefix, address or port set assignment. Forwarding Mapping Rule - used for forwarding. The rule is then used for IPv4 prefix, address or shared address assignment. In the hub and spoke mode, all traffic should be forwarded using the Default Mapping Rule. Port mapping algorithm Several port mapping algorithms have been proposed with their own set of advantages and disadvantages.
The port mapping algorithm proposed here is called generalized modulus algorithm GMA and supports both these cases. For a given sharing ratio R and the maximum number of contiguous ports M , the GMA algorithm is defined as: 1. For any port number, the PSID can be obtained by bit mask operation. Note that in above figure there is a PSID prefix length c. The port mapping algorithm in [ I-D. Figure 2: Example 4. The defaults are: o Excluded ports : o Offset bits A : 6 The defaults of Offset bits A , which determines excluded ports, remains to be chosen.
Comparative merits of R-4 compliance and full optimization of port-set sizes remain to be evaluated. There is no waste of the port numbers, except the well-known ports. The algorithm is flexible, the control parameters are sharing ratio R , the continue port range M and PSID prefix length c. The algorithm is simple to perform effectively. It allows Service Providers to define their own address sharing ratio, the theoretical value is from to and a more practical value is from to It supports deployments using differentiated port ranges.
It could support differentiated port ranges within a single shared IPv4 address, depending on the IPv6 format chosen see Appendix A. It support excluding the well known ports It supports assigning well known ports to a CE. The number of IPv4 address bits p in the EA bits is given by 32 - r bits. The PSID bits are used to create a port set. PSID: 0x Example: Given: IPv4 destination address: Traffic using this rule will be sent from a CE to a BR.
Which is used is dependent on the mode used. For example translation requires that the IPv4 destination address is encoded in the BR IPv6 address, so only a prefix is used in the DMR to allow for a generated interface identifier. To satisfy this requirement a BR IPv4 address is included in the rule. Giving a default route in the RIB: 0. As long as the interface-id is well known or provisioned and the same for all MAP nodes, it can be any interface identifier.
When translating, the destination IPv4 address is translated into a corresponding IPv6 address. Troan, Ed. Internet-Draft cisco Intended status: Standards Track November 25, Expires: May 28, Mapping of Address and Port MAP draft-mdt-softwire-mapping-address-and-port Abstract This document describes a generic mechanism for mapping between an IPv4 prefix, address or parts thereof, and transport layer ports and an IPv6 prefix or address. Note that other groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress. All rights reserved. Please review these documents carefully, as they describe your rights and restrictions with respect to this document.
Mapping Rules. Port mapping algorithm. Bit Representation of the Algorithm. GMA examples. GMA Provisioning Considerations. Features of the Algorithm. Basic mapping rule BMR. Forwarding mapping rule FMR. Default mapping rule DMR. The IPv6 Interface Identifier. IANA Considerations.
Security Considerations. Normative References. Informative References. Given an IPv6 packet with an destination address with an embedded IPv4 address, a node could automatically tunnel this packet by extracting the IPv4 tunnel end- point address from the IPv6 destination address.
RFC discusses the transport of the port set information in an IPv4-embedded IPv6 address but the conclusion was the following excerpt from [ RFC ] : "There have been proposals to complement stateless translation with a port range feature.
Instead of mapping an IPv4 address to exactly one IPv6 prefix, the options would allow several IPv6 nodes to share an IPv4 address, with each node managing a different set of ports.
If a port set extension is needed, could be defined later, using bits currently reserved as null in the suffix. The motivation for work is described in [ I-D. Deployment considerations are described in [I-D. Troan, et al. Each MAP node in the domain has the same set of rules. Port-set: Each node has a separate part of the transport layer port space; denoted as a port-set.
Only ports that belong to the assigned port-set can be used for communication. Also known as a Port-Restricted IPv4 address. It is unique for each CE. Address and Port aware datastructure, supporting longest match lookups. While it is theoretically possible to make host stacks and applications port- aware, that is considered a too drastic change to the IP model [ RFC ].
The forwarding function uses the MRT to make forwarding decisions. The table consist of the mapping rules. The normal best matching prefix algorithm is used. Mapping rules are used differently depending on their function. Every MAP node must be provisioned with a Basic mapping rule. This same basic rule can also be used for forwarding, where an IPv4 destination address and optionally a destination port is mapped into an IPv6 address or prefix.
Additional mapping rules can be specified to allow for e. Traffic outside of the domain IPv4 address not matching using longest matching prefix any Rule IPv4 prefix in the Rules database will be forward using the Default mapping rule. There are three types of mapping rules: 1.
Basic Mapping Rule - used for IPv4 prefix, address or port set assignment. Forwarding Mapping Rule - used for forwarding. The rule is then used for IPv4 prefix, address or shared address assignment. The two extreme cases are: 1 the port numbers are not contiguous for each PSID, but uniformly distributed across the port range ; 2 the port numbers are contiguous in a single range for each PSID.
The port mapping algorithm proposed here is called the Generalized Modulus Algorithm GMA and supports both these cases. For a given sharing ratio R and the maximum number of contiguous ports M , the GMA algorithm is defined as: 1. For any port number, the PSID can be obtained by bit mask operation. This ensures that the algorithm excludes the system ports [ I-D. GMA examples Troan, et al.
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