Re: [Cbor] I-D Action: draft-ietf-cbor-network-addresses-04.txt

Carsten Bormann <cabo@tzi.org> Mon, 26 April 2021 05:15 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Mon, 26 Apr 2021 07:15:17 +0200
Cc: Ole Troan <otroan@employees.org>, cbor@ietf.org, 6man@ietf.org
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To: Michael Richardson <mcr+ietf@sandelman.ca>
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Subject: Re: [Cbor] I-D Action: draft-ietf-cbor-network-addresses-04.txt
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On 26. Apr 2021, at 02:06, Michael Richardson <mcr+ietf@sandelman.ca> wrote:
> 
>> - so you don’t want to support the commonly used shortcut of specifying
>> both and address and a prefix in one?
> 
> I don't understand your suggestion.
>    X - address
> [n,X] - prefix

Back in IPv4-land, we often said something like

“Configure the interface to 192.168.3.5/24”

Which is a short-cut for

“Configure the interface to address 192.168.3.5, prefix 192.168.3.0/24”

Since address/prefix is structurally similar to a prefix (but uses a full 32-bit address), it could be expressed by adding a third case

>    A - address
> [n,P] - prefix
> [A,n] - address/prefix

Where A is a 4-byte byte-string, P is a 0-to-4-byte byte string, and n is an unsigned integer 0 to 32.

This construct is less common in IPv6-land, because n is usually 64, so sending the address suffices, but there are exceptions to that here, too.

Grüße, Carsten