OSPF route selection

[Olivier Benghozi]

Hi ,

it should be noted that the RFC 2328 explains in its annex C.1 that the "RFC1583Compatibility" flag must be "Set to enabled by default".

Most OSPF deployments in the world using hardware equipments are indeed using RFC 1583 behavior set by default (Cisco, Juniper, Brocade, Ericsson, Alcatel...) with some exceptions for some firewalls (Fortinet, Check Point...).
However the main and newer software engines set it to off by default (BIRD, Quagga... and appliances using them in their products).

So if someone is expecting a "usual" behavior (usual from the hardware routers world), the change can be hard to understand.

The critical thing is having that configuration consistant across the network (default values sometimes suck), and understanding what is done (if set to off, the particular loop case design must be avoided).
That particular case of OSPF RFC1583 failure is described by example at https://live.paloaltonetworks.com/docs/DOC-5561


regards,
Olivier


On 8 oct. 2014 at 11:58, Ondrej Zajicek <santiago at crfreenet.org> wrote :

> You could enable 'RFC1583Compatibility' option, but that is generally
> discouraged unless you know exactly what you are doing (as it may lead
> to persistent routing loops).


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