Hi Fabien, Sorry for delay reply. pls see inline. > > Hi Mach, > > Thanks for the fast answer. > I still have some comments: > > >Mach>> Yes, for inter-AS TE link, the AS number attribute is essential, as > > I pointed out in my previous message, the AS number is needed in the PCE- > > based path computation senario. > > To be more precise, my question is not to know if the AS number sub TLV is > useful cause I agree that it is. > But rather is it madatory to encode such sub TLV in each inter domain TE > link. > There are some scenario where it is useful (e.g. PCE based path > computation), maybe it is not in some other scenarios. > > For instance RFC3630 states that " The Link Type and Link ID sub-TLVs are > mandatory, i.e., must appear exactly once", and I think the same kind > statement should be done to explicitly indicate if the AS number sub TLV is > mandatory or optional in case of inter domain TE link. Yes, we will make such statement in the next revision. As to mandatory or optional, although the AS number attribute of an inter-AS TE links is very useful for many computation scenarios, but only if there is one scenario that does not need the AS number attribute, the AS number sub-TLV should not be mandatory, so optional is more reasonable for the AS number sub-TLV. > > Note that if it is optional it is even more important to have a different > link type. > > >Mach>> Since there is no OSPF adjancy runing on the inter-AS TE links, to > >advertise both directions of the TE link can make sure that the inter-AS TE > >link is valid for path computation. As Vishwas Manral said, CSPF > >implementations will do a two way check before using the TE link for path > >computation. > > Ok. But then if the only purpose of having 2 links LSA is to be able to do 2 > way connectivity check, why not rather stating that the inter domain TE link > is bidirectional (unlike intra domain link). > That is, this TE link would be advertised only if the advertising routers > has checked the 2-way connectivity. A bidirectional inter-AS link is an option. But, IMO, from the aspect of implementing (especially CSPF), using 2 link LSAs as current intra-area TE does is simpler than using a new bidirectional inter-AS LSA. Anyway, there should be mechanism to advertise the backward directions of an inter-AS links, the ASBR within local AS will do the "proxy" advertisement. So, no matter which option is adopted, the objective is to make few changes to the current mechanisms. We would like to hear suggestion from implementers.
> > Thanks > Fabien > > > Best regards, Mach _______________________________________________ OSPF mailing list [email protected] https://www1.ietf.org/mailman/listinfo/ospf
