Re: WG last calls - exclude route ID

[Cheng-Yin Lee <Cheng-Yin.Lee@alcatel.com>]

Hi Arthi,
Thanks for your comments.

Arthi Ayyangar wrote:

> Hi,
>
> Here are a few comments on this ID. Sorry for the delay.
> Also, in case some of these comments are a repetition, please ignore
> those.
>
> thanks,
> -arthi
> ----------------
> 1)
> Section 2.
>
> To convey these constructs within the signaling protocol, a new
> RSVP object and a new ERO subobject are introcuded respectively.
>                                        ^^^^^^^^^^^
> - Typo
>
> 2)
> Section 4.2
> The number of introduced exlicit nodes or abstract nodes with
>                         ^^^^^^^^^^
> the L flag set to "avoid" should be minimised.
>
> - Typo

Ok, we should run spell check.

>
> 3)
> 5.2
> Each EXRS may carry multiple exclusions.  The exclusion is encoded
> ---------------------------------------
> exactly as for XRO subobjects and prefixed by an additional Type and
> Length.
>
> <AA> Did you mean, there can be multiple EXRS per ERO, which I see or
>      multiple exclusions per EXRS ?
>      From the format of the EXRS it looks like one exclusion per EXRS.
>      Did I miss something ?

there can be multiple EXRS per ERO
multiple subobjects can  be specified in an EXRS

>
>
> 4)
> Thus, an EXRO subobject for an IP hop might look as follows:
>      ^^^^^^^^^^^^^^^^^
> <AA> EXRS ?

Yes.

> Also the S in EXRS already means sub-object, so you could get
> rid of sub-object following EXRS.

ok.

> 5)
> The subobjects in the ERO and EXRS SHOULD not contradict each other.
> If they do contradict, the subobjects with the L bit not set, strict
> or MUST be excluded, respectively, in the ERO or XRO MUST take pre-
> cedence.  If there is still a conflict, the subobjects in the ERO
> MUST take precedence.
>
> <AA> You may want to state explicitly what you mean by contradict for
> EXRS. Is the scope of contradiction just the previous and next ERO
> sub-objects ?

Yes. This may not be a contradiction. We will think of some text to clarify
this.

>
> 6)
> If the presence of EXRO Subobjects precludes further forwarding of
>                     ^^^^^^^^^^^^^^^^^
> the Path message, the node should return a PathErr with the error
> code "Routing Problem" and error value of "Route blocked by Exclude
> Route"
>
> 7)
> <AA> With respect to EXRS, it might be useful to clarify what does EXRS
> provide that cannot be achieved by XRO. Basically give some hints as to
> where EXRS may be useful versus XRO.

EXRS - If we need to exclude a resource between A and B only (could be a
policy thing), but may want to use the resource elsewhere  in the path.

> Also, can there be conflicts between
> EXRS and XRO ? If yes, then how is that dealt with ?

I can't think of conflicts between EXRS and XRO, if X is excluded by EXRS and
XRO, then it is just redundant to specify X in EXRS.

>
> 8) Section 6
>
> The IPv6 Prefix subobject MUST be supported with a prefix
>           length of 128, and an attriubute value of "interface" and
>                               ^^^^^^^^^^^^
>           "node".
> - Typo
>
> -----------------

Thanks
Cheng-Yin