In most cases, migrating hosts and networks in an enterprise to IPv6 is expected to be a gradual process. Compatibility with the existing IPv4 applications and hosts needs to be maintained during this transition period. It is also expected that
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Most or all remote hosts that are IPv6-capable are dual-stack.
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Edge routers (if not the complete network) are dual-stack in most cases, at least in the initial transition period.
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ClearPath MCP applications will be modified or newly written to be IPv6-capable as needed. These applications must be capable of operating on both IPv4 and IPv6 networks.
Given the preceding conditions
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IPv6-capable MCP applications communicate with remote IPv4 hosts using the IPv4 layer, with IPv6 hosts using the IPv6 layer, and with dual-stack hosts using either the IPv4 or IPv6 layer with preference given to IPv6 for active opens.
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All existing unchanged MCP applications communicate with remote IPv4 hosts using the IPv4 layer.
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Existing unchanged applications that are not IP address-aware communicate with IPv6 hosts using the IPv6 layer, and with dual-stack hosts using either the IPv4 or IPv6 layer with preference given to IPv6 for active opens.
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Existing unchanged applications that are IP address-aware communicate with dual-stack hosts using the IPv4 layer. If the remote host is IPv6-only, a network-based translation device can be used to facilitate the conversion between IPv4 and IPv6, transparently to hosts; the protocol used is NAT-PT.
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All applications using the MCP Sockets API and those using the user datagram protocol (UDP) need to be modified for IPv6.
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Applications using the Logical I/O and Co-op APIs over TCP connections are affected if one of the following is true:
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The applications need to be capable of connecting to remote hosts using explicit IP addresses.
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The applications handle (store, parse, generate, or display) IP addresses.
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