DIAMETER: What does 1 * [ AVP] signifies ?

Question

I found 1 * [vendor-id] as a single AVP in rfc3588. Can someone please explain means of 1 * [AVP] ?

Answer 1

I didn't understand it completely. I feel there is no AVP like 1* [Vendor-Id]. It may be a syntax to define an AVP multiple times.

This is what ABNF says:

repeat = 1*DIGIT / (*DIGIT "*" *DIGIT)

So it means the vendor-id avp will repeat one more time in message.

Same with the AVP code. if you want to repeat an AVP more than one time you can use the above syntax to do it.
ABNF for diameter

Comments

thanks for your answer. Please check this AVP definition in rfc3588.

AVP Format

   <Vendor-Specific-Application-Id> ::= < AVP Header: 260 >
                                     1* [ Vendor-Id ]
                                     0*1{ Auth-Application-Id }
                                     0*1{ Acct-Application-Id }


I am asking the meaning of 1 * [] ?

I kow 1 * means repetition of AVP but there are two things as follows:
1 * {AVP}  and 1 * [AVP] . I am looking for difference between these two.

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n * {AVP}  means AVP mandatory and it can repeat, and should be present for n times.

n * [AVP]  means AVP is optional and it can repeat, and should be present for n times if it is present (I stress only if it is present)

Answer 2

1 * [AVP] means.
AVP is a optional sequence ([] signifies the optional) and it can repeat but should be available for at-least 1 time.