Behavior during OSPF premature aging

Olivier Benghozi olivier.benghozi at
Mon Jul 14 12:07:29 CEST 2014

Hi Lennard,

Damn, I also have Fortinet stuff and I was thinking about replacing Quagga by BIRD for the same use (announcing service loopbacks as tagged external routes - Quagga knows nothing about LSA type 5/7 tag) :P
Another case to open...

On Ericsson's side, the bug is only in OSPFv3; OSPFv2 is OK (two different processes, and two different codes for the same LS SeqNum comparison...).


Le 14 juil. 2014 à 10:42, Lennard Klein <Lennard.Klein at> a écrit :

> Hi Olivier,
> I was having problems with a Fortinet device. In my environment, I've simply removed the line I mentioned in my original e-mail. I don't think this has had any adverse effects, though I can't be quite sure (I am having some other issues which seem to be unrelated).
> Lennard Klein
> Special Projects, Netherlands
> lennard.klein at 
> -----Original Message-----
> From: owner-bird-users at [mailto:owner-bird-users at] On Behalf Of Olivier Benghozi
> Sent: zaterdag 12 juli 2014 18:33
> To: bird-users at
> Subject: Re: Behavior during OSPF premature aging
> Hi guys,
> Ondrej Zajicek wrote:
>> On Tue, Jun 24, 2014 at 08:46:20AM +0100, Lennard Klein wrote:
>>> When premature aging an LSA, bird seems to increase the LSA sequence number to its maximum (proto/ospf/lsupd.c line 616, in 1.4.3).
>>> While I think the main fault lies with the other vendor, my question
>>> at this time is: what is the reasoning behind updating the sequence
>>> number to its maximum, even though the RFC says to leave it as-is?
>> This is done mainly to compensate other problems/quirks/hacks in BIRD
>> OSPF implementation. One reason is that if you flush LSA using MaxSeqNo,
>> you could forget old LSA sequence number, and when you originate a new
>> one later, you could safely start from InitSeqNo.
>> Currently i am finishing OSPF revision that removes most of these BIRD
>> quirks and problems related to LSA flood and makes BIRD much better in
>> RFC compliance.
> I've just hit the wall with that on Redback/Ericsson gears; for their code, signed 0x80000005 is more recent than signed 0x7fffffff according to the debugs (while I've no problem at all with a Juniper router).
> For my use (announcing anycast service loopbacks as tagged N2 routes) I guess I could push the metric to Infinite to see the route disappear (but not the LSA), while it's not very satisfying.
> However I must say that I'm more than interested by such a code revision (since manually replacing LSA_MAXSEQNO to 0xffffffff in ospf/lsupd.c line 616 would be a horrible hack) :)
> Lennard, which vendor do you have problem with?
> On my side I've opened a bug at Eric&Son's TAC.
> -- 
> regards,
> Olivier Benghozi
> Wifirst
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