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6. Notes on Combining IPv6 Addresses with Port Numbers

6. Notes on Combining IPv6 Addresses with Port Numbers​

There are many different ways to combine IPv6 addresses and port numbers that are represented in text. Examples are shown below.

  • 2001:db8::1:80
  • 2001:db8::1.80
  • 2001:db8::1 port 80
  • 2001:db8::1p80
  • 2001:db8::1#80

The situation is not much different in IPv4, but the most ambiguous case with IPv6 is the second bullet. This is due to the "::" usage in IPv6 addresses. This style is NOT RECOMMENDED because of its ambiguity. The [] style as expressed in [RFC3986] SHOULD be employed, and is the default unless otherwise specified. Other styles are acceptable when there is exactly one style for the given context and cross-platform portability does not become an issue. For URIs containing IPv6 address literals, [RFC3986] MUST be followed, as well as the rules defined in this document.

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