Hi Pete,
please see inline:
On 16/11/18 14:45 , Pete Resnick wrote:
Reviewer: Pete Resnick
Review result: Ready with Issues
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Document: draft-ietf-ospf-ospfv3-segment-routing-extensions-18
Reviewer: Pete Resnick
Review Date: 2018-11-16
IETF LC End Date: 2018-11-16
IESG Telechat date: Not scheduled for a telechat
Summary: One serious concern, one minor issue, and some nits.
Major issues:
In 3.1:
I get worried when I see this:
SID/Label: If length is set to 3, then the 20 rightmost bits
represent a label.
So, the Length is not a length, but rather a flag. This seems like it has the
potential for an interop problem. If a general implementation treats it as a
length, it's going to get the left-most 24 bits when the value is 3. Even if
the implementation chooses the right-most 24 bits, it's only supposed to take
the right-most 20 bits and mask off the extra 4 bits. Or are you going to
specify that implementations must always set the extra 4 bits to 0?
no. We have other documents that use the same and none of them enforces
the other bits to 0. When we say we only use specific bits, the rest can
be set to anything.
Maybe this sort of thing is the way things have always been done for TLVs, and
if so feel free to ignore me, but from an code implementation perspective, this
seems like an accident waiting to happen. (Known sometimes as a "foot-gun".)
Minor issues:
In 4.4:
The SRMS Preference TLV MAY only be advertised once in the OSPFv3
Router Information Opaque LSA and has the following format:
You mean MUST, not MAY there.
sure, I will change to MUST.
In 7.1 and 7.2:
If SID/Index/Label is a label, is it using the low 20 bits of the first 3 bytes
of the field (i.e., bits 4-23)?
right.
Is there a requirement that the high 4 bits and
the low 8 bits must be cleared by the implementation?
there is no such requirement really.
Some clarification would be useful.
In 8.1:
You talk about setting the IA-flag, but this version of the document doesn't
define the IA-flag anymore. Is it defined elsewhere?
my bad, we have removed IA in last version, but I forgot to remove this
part. I removed it.
Nits/editorial comments:
In 3.1:
Ignoring the issue stated above, I also found this text a bit confusing:
Length: Variable, 3 or 4 octets
Obviously you mean that the value of Length is either 3 or 4. At first I read
it as the value of Length was variable, and that it took up 3 or 4 octets in
the Sub-TLV. If this is the way you've always written these things, fine, but
it seems to me it would be clearer to say.
Length: Either 3 or 4
Done.
In 5:
s/we need a single advertisement/a single advertisement is needed
Just being pedantic. If you like it, use it. If not, don't.
Done.
Please let me know if you agree or disagree with my responses.
thanks,
Peter
.
