Re: [Mipshop] Comments on RFC 5568 on Mobile IPv6 Fast Handovers
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Re: [Mipshop] Comments on RFC 5568 on Mobile IPv6 Fast Handovers
Hi David,
Thank you for taking a look. And, sorry for long the delay in
responding..
Please see below:
> #1
> -----------------------
> This error was introduced going from RFC 4068 to RFC 5268.
> RFC 5568 continued to carry forward the error.
>
> RFC 5568 page 29, 6.2.1.2, HAck
>
> "
> Upon receiving an HI message, the NAR MUST respond with a Handover
> Acknowledge message. If the 'S' flag is set in the HI message, the
> NAR SHOULD include the New Care-of Address option and a Code 3.
> "
>
> Code 3 in RFC 5268 and RFC 5568 means Handover Accepted, use PCoA.
> However in RFC 4068 it meant Handover Accepted, NCoA assigned.
>
> To me this implies Code 3 (three) needs to be changed to Code 2 (two).
>
> "
> Upon receiving an HI message, the NAR MUST respond with a Handover
> Acknowledge message. If the 'S' flag is set in the HI message, the
> NAR SHOULD include the New Care-of Address option and a Code 2.
> "
>
I agree with change #1.
For #2 (below), we simply intended to include an IPv6 address following
the Reserved field.
That is, not include the IPv6 Address/Prefix Option.
So, the change should be:
OLD:
2: NCoA is invalid, use the supplied NCoA. The supplied NCoA
(in the form of an IP Address Option) MUST be present following
the Reserved field.
NEW:
2: NCoA is invalid, use the supplied NCoA. The supplied NCoA (an IPv6
Address of 16 octets))
MUST be present following the Reserved field.
I can update the Errata with these changes.
Regards,
-Rajeev
>
> #2
> -------------------------
> What is the meaning of "(in the form of an IP Address Option)?"
> Does form mean format?
>
> RFC5568, Page 39, 6.4.6, NAACK
> "
> Length: 8-bit unsigned integer. Length of the option, in 8
> octets. The length is 1 when a new CoA is not supplied. The
> length is 3 when a new CoA is present (immediately following the
> Reserved field)
>
> Option-Code: 0
>
> Status: 8-bit unsigned integer indicating the disposition of the
> Unsolicited Neighbor Advertisement message. The
> following Status
> values are currently defined:
>
> 1: NCoA is invalid, perform address configuration
>
> 2: NCoA is invalid, use the supplied NCoA. The supplied NCoA
> (in the form of an IP Address Option) MUST be
> present following
> the Reserved field.
> "
>
> Since this option is using the ND space the length is in 8 octets.
> If no new CoA is present the length is 1 (indicating 8 octets
> from Type to Reserved, which is true) If a new CoA is present
> the length is stated to be 3, however this is confusing, if
> not wrong. The length would be 4, if the new CoA follows the
> IP Address / Prefix Option as defined in 6.4.1 because it
> contains 8 octets Type to Reserved plus 16 octets for the
> IPv6 address. Thus there are already 3 (x8 = 24 octets) in
> the IP Address / Prefix Option. Add this to the existing
> NAACK and that makes 32 octets (4 x 8).
>
> Unless the "(in the form of an IP Address Option)" does not
> mean to actually use the IP Address Option, but rather means
> just to append the 16 octets for the IPv6 address only. If
> this is the case perhaps the Figure 16 should be updated to
> reflect this. However, I do not see how you can have only
> the IPv6 address (16 octets) and have no prefix length.
>
> If the first solution is acceptable, then change (which
> includes two changes) "
> Length: 8-bit unsigned integer. Length of the option, in 8
> octets. The length is 1 when a new CoA is not supplied. The
> length is 4 when a new CoA is present (immediately following the
> Reserved field)
>
> Option-Code: 0
>
> Status: 8-bit unsigned integer indicating the disposition of the
> Unsolicited Neighbor Advertisement message. The
> following Status
> values are currently defined:
>
> 1: NCoA is invalid, perform address configuration
>
> 2: NCoA is invalid, use the supplied NCoA. The supplied NCoA
> (in the form of an IP Address / Prefix Option) MUST
> be present
> following the Reserved field.
> "
> What the figure might look like in this case.
> 0 1 2 3
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Type | Length=4 | Option-Code | Status |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Reserved |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Type | Length | Option-Code | Prefix Length |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Reserved |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | |
> + +
> | |
> + IPv6 Address +
> | |
> + +
> | |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> Figure 16: Neighbor Advertisement Acknowledgment Option
> (with NCoA as an IPv6 Address / Prefix option)
>
> If the second solution is what was intended, then change
> (which includes one change) "
> Length: 8-bit unsigned integer. Length of the option, in 8
> octets. The length is 1 when a new CoA is not supplied. The
> length is 3 when a new CoA is present (immediately following the
> Reserved field)
>
> Option-Code: 0
>
> Status: 8-bit unsigned integer indicating the disposition of the
> Unsolicited Neighbor Advertisement message. The
> following Status
> values are currently defined:
>
> 1: NCoA is invalid, perform address configuration
>
> 2: NCoA is invalid, use the supplied NCoA. The supplied NCoA
> (IPv6 Address (using 16 octets)) MUST be present
> following the
> Reserved field.
> "
> What the figure might look like for Length = 1.
> 0 1 2 3
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Type | Length=1 | Option-Code | Status |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Reserved |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> Figure 16: Neighbor Advertisement Acknowledgment Option
> (without NCoA)
>
>
> What the figure might look like for Length = 3. When the
> format of the IPv6 Address option is not used, only the IPv6
> address is present.
>
> 0 1 2 3
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Type | Length=3 | Option-Code | Status |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Reserved |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | |
> + +
> | |
> + IPv6 Address +
> | |
> + +
> | |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> Figure 16: Neighbor Advertisement Acknowledgment Option
> (with NCoA as an IPv6 Address only)
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