On Tue, 19 Apr 2016, Lou Berger wrote:
Paul,
You have a valid point on absolutes. One never should say never :-)
Agreed. And I agree with you we should get to standards compliance..
That said, we're not talking some obscure feature here . Does any
non-quagga based vendor, major or otherwise, support the non standard
behavior as the default? If so , there may be some basis for this
discussion. If not , and in my experience , then the current behavior
should be viewed as a bug.
Just one persons (my) opinion...
Right. The specifics of this are:
- At some point in the future, hopefully not too far off (IANA have
re-allocated the relevant OSPF option bit to the H-bit) there will be
a standards compliant way to signal "no-transit". So Quagga will be
able to signal "no-transit" and "transit discouraged, but still OK".
The "no-transit" signalling (H-bit) will be recognised by:
- old Quagga
- all H-bit recognising routers (inc new Quagga)
Non-H-bit, RFC2328 routers will not recognise this, so it'd be the
same issue as with Quagga and other routers today (but, at least
configurable on both the originating Quagga side, and on the SPF side
on any updated Quagga)
The "transit discouraged, but OK" signalling of 0xfffe (or lower) will
be recognised universally as such:
- old Quagga
- new Quagga
- RFC1247, 1583, 2328, OSPF
- For doing the right thing by other routers, we need to change the SPF
behaviour.
The implications are:
- We need a UI for admins to indicate between whether they want
"no-transit" or "transit still OK". This would be the case regardless
of the past, if we wanted to support the H-bit.
- As we will be able to get to a point where the current behaviour will
work in a standards compatible way, and as "old Quagga" will
interpret the H-bit signalling as "no-transit" anyway (cause it
requires 0xffff link metrics) it makes little sense to break
that behaviour.
Otherwise we will just piss off another group of unsuspecting
operators, to fix an issue that affects another (who, if they know
they're affected by this, may already be pissed off). Both sets may be
small, and which set would be larger we can not know.
- The first step to changing the SPF default is to add the option to
control it, and print out the state of that config option explicitly,
and document things so admins can be aware and make a choice.
Why object to that??
So, yes, RFC compliance - great. That _is_ what this patch set is
_aiming for_ while trying to avoid upsetting any _further_ operators.
Read the patch, get stuck into the details, come up with constructive
suggestions on how to improve the transition. That kind of thing would
help. :)
regards,
--
Paul Jakma [email protected] @pjakma Key ID: 64A2FF6A
Fortune:
The best defense against logic is ignorance.
_______________________________________________
Quagga-dev mailing list
[email protected]
https://lists.quagga.net/mailman/listinfo/quagga-dev
