On 07/22/2014 02:08 PM, Brian Haberman wrote:
Hi Tom,
On 7/22/14 2:51 PM, Tom Henderson wrote:
Brian,
You left the following DISCUSS comments on draft-ietf-hip-rfc5201-bis
which I would like to address below:
I have no objection to the publication of this document, but I do
have two small points to discuss in section 5.2.3.
1. The R1_COUNTER parameter was labeled as optional in RFC 5201, but
made mandatory in this revision. However, the text says it SHOULD be
included in R1. If it is not included in R1 (violates the SHOULD),
where will it be included given it is mandatory?
Support for it is mandatory (if the Responder sends it, the Initiator
must echo it back), but the inclusion by the responder is optional.
To try to clarify this, I edited it (for version -15) to read:
Support for the R1_COUNTER parameter is mandatory although
its inclusion in the R1 packet is optional. It SHOULD be
included in the R1 ...
The above is fine. If this parameter is sent by the Responder, what
packets could it be sent in (i.e., violate the SHOULD) and still be useful?
The above question is just something for you to think about. I will not
hold a discuss on it.
R1_COUNTER can be sent in the R1 and I2 packets (Sections 5.3.2 and
5.3.3) but is not found in any of the other packets.
2. The Type value of R1_COUNTER was 128 in 5201 and is now 129. Is
that correct?
Yes, by making its support mandatory, it is now deemed a "critical"
parameter and the LSB of the type value must be 1. This necessitated
the change from 128 to 129.
Is there a need to discuss any backwards compatibility issues with this
change?
I don't know whether any need exists. If a legacy implementation
provides 128, it also likely provides HIP version 1, in which case an
ICMP packet with Parameter Problem should be generated (section 5.4.2).
If HIP version 2 is indicated but this parameter is encoded with 128,
it will probably be covered by an implementation with the INVALID_SYNTAX
notification (Section 5.2.19).
- Tom
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