Re: [Idr] I-D Action: draft-ietf-idr-error-handling-03.txt

["Chris Hall" <[e-mail]>]

Jeff Wheeler wrote (on Mon 10-Dec-2012 at 16:13 +0000)
> On Mon, Dec 10, 2012 at 8:26 AM, Chris Hall
<[e-mail]> wrote:
>> However, given some way of determining the (likely ?) impact of
>> "unsafe" "treat-as-withdraw", then one could assess whether that is
>> better or worse than session-reset (under some  circumstances ?) --
in

> Why is the question not answerable by one of three options?
>  1# ignore
>  2# treat-as-withdraw
>  3# session-reset

> 1# IGNORE is hazardous but probably only to the prefixes in that
>    update (or withdraw) which means the scope of malfunction is
>    relatively small.  ....

I haven't considered IGNORE because the draft appears to vote against
that pretty strongly.

....
> 2# TREAT-AS-WITHDRAW is hazardous....
....
> The great risk is, how do you guess what the prefixes are,
> if the framing is wrong?

Absolutely.

> In my view, here is one way that is rather thorough for
> finding MP NLRIs:
>
> Beginning with or following the damaged Attribute (which one?),
> scan for MP_REACH_NLRI: AttrFlags AttrType AttrLen AFI
> SAFI NextHopLen NH 0x00 PfxLen Pfx (PfxLen Pfx){0,}

....snip further description of scanning attributes to find
....MP_REACH_NLRI and MP_UNREACH_NLRI.

Well, that's an interesting idea :-)  If the only important thing to
extract from a broken set of attributes is the NLRI, then why not scan
for it and assume that there is sufficient redundancy to effectively
rule out false positives.  Interesting :-)

Chris