Hi Peter,
On 5/26/20, 8:22 AM, "Peter Psenak" <[email protected]> wrote:
Hi Acee,
have you looked at the texts that I suggested in my response to Alvaro
earlier today?
I found it - let me reply to that Email.
Thanks,
Acee
Please see inline:
On 26/05/2020 13:49, Acee Lindem (acee) wrote:
> Hi Alvaro,
>
> See inline.
>
> On 5/22/20, 10:59 AM, "Alvaro Retana" <[email protected]> wrote:
>
> On May 21, 2020 at 3:39:03 PM, Benjamin Kaduk wrote:
>
>
> Peter:
>
> Hi!
>
>
> > With respect to Alvaro's clarification, your answer for (1) makes
sense;
> > thanks! I think Alvaro has offered to help work out what (if any)
> > additional text we might want to be sure that the answer to (2) is
clear in
> > the document.
>
> I think that #1 is where some clarification could be useful. :-)
>
>
> I'm including both ISIS and OSPF suggestions below to consolidate the
> discussion.
>
>
> ...
> > > My interpretation of Ben's question is two-fold:
> > >
> > > (1) Would ISIS routers normally propagate the information to a
> > > different level? The ELC is a new prefix attribute flag -- are
prefix
> > > attributes always propagated (unchanged) to other levels? If so,
then
> > > the requirement (MUST) is not needed. My reading of rfc7794 is
that
> > > the propagation is optional...
> >
> > depends on the attribute or a bit. Some are propagated some are
not.
> > That's why we are saying this one MUST be preserved.
>
> Right.
>
> For ISIS I think the current text is in line with the specification
of
> the other bits in rfc7794. No changes are needed.
>
> If anything, you may want to change the order of this sentence to
> address Ben's comment:
>
> OLD>
> When a router propagates a prefix between ISIS levels ([RFC5302],
it
> MUST preserve the ELC signaling for this prefix.
>
> NEW>
> The ELC signaling MUST be preserved when a router propagates a
prefix
> between ISIS levels ([RFC5302]).
>
> [Similar for OSPF.]
>
>
>
> I think that for OSPF it is not that simple...
>
> For OSPFv2: rfc7684 says that the "scope of the OSPFv2 Extended
Prefix
> Opaque LSA depends on the scope of the advertised prefixes", which I
> assume means that for intra-area prefixes the scope will be
> area-local...so the ABR wouldn't simply propagate it; it would have
to
> originate a new LSA.
>
> I agree with the changes but have suggested alternate text.
>
> Suggestion (Add to 3.1)>
> When an OSPFv2 Area Border Router (ABR) distributes information
between
> connected areas it SHOULD originate an OSPFv2 Extended Prefix
Opaque LSA
> [RFC7684] including the received ELC setting. If the received
information
> is included in an LSA with an AS-wide scope, then the new LSA is
not needed.
when would ABR do inter area propagation of what is advertised in AS
scope LSA? I can not think of such a case.
thanks,
Peter
>
> I'd suggest:
>
> When an OSPFv2 Area Border Router (ABR) advertises prefix
information between
> areas and ELC information is was advertised for the prefix in the
source area, the
> ABR SHOULD originate an OSPFv2 Extended Prefix Opaque LSA
[RFC7684] propagating
> the prefix's source area setting. If the ELC setting, is also
advertised in an OSPFv2
> Extended Prefix Opaque LSA with AS-wide scope, the additional LSA
origination
> Is not needed.
>
>
> For OSPFv3: The PrefixOptions are *in* the LSA, but I couldn't find
> anything in rfc5340 saying that the received values should be copied
> into the Inter-Area-Prefix-LSA (nor that they should not).
>
> Suggestion (Add to 3.2)>
> When an OSPFv3 Area Border Router (ABR) distributes information
between
> connected areas, the setting of the ELC Flag in the
Inter-Area-Prefix-LSA
> MUST be the same as the received value.
>
> I'd suggest:
>
> When an OSPFv3 Area Border Router (ABR) advertises information
between
> areas, the setting of the ELC flag in the Inter-area-prefix-LSA
MUST be the
> propagated unchanged.
>
> Thanks,
> Acee
>
>
>
>
> > > (2) If the propagation is not automatic, and the L1L2 router
doesn't
> > > support this specification, then what are the drawbacks/failure
> > > scenarios? IOW, for multi-level operation is it a requirement
that
> > > the L1L2 support this specification?
> >
> > drawback are identical to what is mentioned in the Security
> > Considerations section.
>
> I think that text is ok.
>
>
> Thanks!
>
> Alvaro.
>
>
>
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