Hi Acee,
Feb. 20, 2016 - [email protected]:
Hi Julien,
[snip]
What is more, I really think that the current wording is too loose in
"it is expected that the information in these LSA [sic] would be
identical". I do not see the drawback of having full alignment of
values
in case of duplication, but I see the operational risk of nightmare in
case they are not. As a result, I suggest to rephrase into: "If the
same
link attribute is advertised in both LSAs, the information in these
LSAs
MUST be identical."
given the OSPF protocol operation above can not be guaranteed. LSAs
arrive asynchronously and there can be intervals during which the
consistency of the information between two different LSAs can not be
guaranteed.
[JM] We fully agree on that. To make sure this is not creating an
ambiguity, you may rephrase as:
"If the same link attribute is advertised in both LSAs, the information
packed in these LSAs by advertising routers MUST be identical."
Are we sure on this? Today we can have an OSPF metric that is independent
of the OSPF TE Metric - why wouldn’t we want the same flexibility with
SRLG?
[JM] From my perspective, I concur. Metrics are purely administrative
parameters: it makes sense to allow operators to use different routing
decision between SPF and TE. Conversely, SRLGs are supposed to abstract
the underlying infrastructure to enable diverse routing: this gives a
clear semantic on the SRLG link parameter. I do not see any value in
using two different infrastructure descriptions, while I see some risk
of operational mess in case one forget to update one of the parameter sets.
I also believe that if double SRLG capability had been an operator's
requirement, we would have started from there and confronted that to
both IGPs. This is a different motivation here.
Cheers,
Julien
Thanks,
Acee
[snip]
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