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I have a very basic question about IPv6 prefix. Taking a very simple example about prefix notation:

"2001:db8:abcd:0012::0/64"

My question is: Do we call the whole thing under quote as prefix or just the value after back slash?

In general term, I understand that prefix is a way to tell how many bits of the IPv6 address is actually the network part. In above example, it is clearly that first 64 bits (8 octets) are Network address and remaining 64 bits(8 octets) will be Host Identifier. But, to be precise, when we talk about prefix, do we end up calling that number after back slash(i.e 64 in above example) as prefix or the whole thing (entire thing under double quotes)as prefix ? I would like to get 100% clear about the terminology and its interpretation? Please share your kind response.

Glorfindel
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Network_starter
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    The number after / is called prefix length – manish ma Nov 23 '21 at 14:15
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    *Network address* and *prefix* are the very same thing. – Zac67 Nov 23 '21 at 15:46
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    This question, of course, applies equally well to IPv4 prefixes, e.g. `203.0.113.0/24`. There is nothing different for IPv6 or IPv4 prefix terminology. The difference in terminology is about IPv4 octets and IPv6 hexadecimal, variously called words, 16-bit fields, hexadecimal fields or parts, etc. in various RFCs. – Ron Maupin Nov 23 '21 at 15:50
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    Nitpick: "/" is a "forward slash" (or just "slash"). "\" is a "back slash". – Roger Lipscombe Nov 24 '21 at 09:40

1 Answers1

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From RFC4291 section 2.3:

An IPv6 address prefix is represented by the notation:

  ipv6-address/prefix-length

The whole thing is called prefix.

First part up to / is called address.

Second part after / is called prefix-length.

manish ma
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