Re: [RTG-DIR] Routing Directorate Early Review of draft-li-arch-sat-04.txt - "A Routing Architecture for Satellite Networks"

[Tony Li <[e-mail]>]

Hi Acee,


> I think I understand what you are saying. An IS-IS L1L2 adjacency provides  a more natural way for an L1 area to provide transit for inter-area traffic. In OSPF, you’d need to use virtual links. 


Exactly.


>> Ah. The distinction here is that I’m assuming that the overall connectedness of the stripe is stable, not that any given ISL is stable.  I think I can clarify this a bit.
> 
> That would be good - you’re saying that the stripe is designed such that the probability of the L1 area partitioning is very low even though there will be inter-area link changes. 


Exactly.


>> As stated, each inter-area L2 adjacency should be listed.  So if an inter-area link changes, both of the proxy LSPs that are relevant for that link would change.  Again, this seems tolerable.
> 
> Ok - I guess the L2 link costs stay constant independent of L1 area  changes? 


Yes.  At this point, you’ll observe that this effectively makes the L2 metric for any area 0.  This is absolutely correct. In this architecture, this isn’t an issue as we’re doing everything by traffic engineering anyways.


> No - I think it is valuable. I was just suggesting to explain why this is the case. 


Ok, I will try to do that.

Tony