[anonsec] question: ID payload in BTNS IKE negotiation

[shinta at sfc.wide.ad.jp (Shinta Sugimoto)]

Hello,

I have a basic question about BTNS IKE negotiation.

In BTNS IKE negotiation, what should ID payload (IDi/IDr) be?
I understand that public key is the instance which represents
identity of the host in BTNS.  But reading the spec, I did not fully
understand how IKE negotiation is done in particular usage of ID
payload.  My interpretation of the spec is that an identity of
a peer (=public key) is represented by the CERT payload.  If so,
what is the role of ID payload in BTNS IKE negotiation?
And what should be included in the IDi, IDr?

Thank you in advance.

Regards,
Shinta