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As per RFC 3927 it states that

There will be cases when devices with a configured Link-Local address will need to communicate with a device with a routable address configured on the same physical link, and vice versa. This allows, for example, a laptop computer with only a routable address to communicate with web servers world-wide using its globally-routable address while at the same time printing those web pages on a local printer that has only an IPv4 Link-Local address.

Is it that they are talking about 2 interfaces here - one that has routable address and other that has Link Local Address or about only one interface but using 2 IPs - I am not sure how?

Programmer
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  • Note that a single interface *can* have multiple IPs. There isn't usually all that much point, but the IP protocol allows it. That's definitely what that part of the RFC is talking about. – Harry Johnston Jun 27 '18 at 09:38
  • For those like me wondering what a "routable" address is, see [Link Local Addressing](https://serverfault.com/q/918222/368698) – askewchan Dec 12 '18 at 19:03

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I guess they are talking about one physical interface with two IPv4 addresses assigned. This thought is undermined by the fact that printers have only one physical interface for data. There might anyway be another interface dedicated to management only.

This would mean that you have to assign a link-local address as well as a routable address to this interface.

Anyway, the RFC does not recommend doing so within it's own abstract IPv4 Link-Local addresses are not suitable for communication with devices not directly connected to the same physical (or logical) link, and are only used where stable, routable addresses are not available (such as on ad hoc or isolated networks). This document does not recommend that IPv4 Link-Local addresses and routable addresses be configured simultaneously on the same interface.

Kevin K.
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