Hi Tony, > The hierarchical arrangement of the control plane does NOT imply that the data plane is necessarily hierarchical.
Since Aijun posted his question I was trying to think of such model, but failed. While it is easy to envision this with DV protocols say BGP - do you have any pointer to a link state protocol architecture where data plane is non hierarchical (links do not belong to upper levels) while control plane used traverses multiple levels ? Thx, R. On Thu, Aug 15, 2019 at 4:40 PM <tony...@tony.li> wrote: > > Hi Aijun, > > 1. The size of network is increasing, but it is becoming more flat. Is it > the right direction to make the network more hierarchical? > > > > Well, given that we’re talking a link state protocol running SPF over a > database in O(n log n) time, it’s pretty clear that we don’t want to scale > the size of an area indefinitely. While modern processors are amazing > (especially to those of us that started off with KHz 8080’s), it’s pretty > clear that Moore’s law is over and that we cannot expect infinite compute > power anytime in the future. The alternative is to partition the network > in some way. Once partitioned, hierarchical arrangement seems like a > natural fit. It’s been said that the only real tool that we have over scale > is hierarchy. Divide and conquer. > > > 2. More hierarchical network means the traffic will also be traversed in > hierarchical way, is it more efficient? > > > > The hierarchical arrangement of the control plane does NOT imply that the > data plane is necessarily hierarchical. > > > 3. Is there any other methods to scale out the IS-IS deployment? > > > > If you’ve been following along, Dynamic Flooding ( > https://tools.ietf.org/html/draft-ietf-lsr-dynamic-flooding-03) allows us > to address the limitations that we have with flooding, allowing us to scale > the size of an area. However, it does not address the O(n log n) cost of > SPF that will still ultimately bound the growth of areas and in turn > necessitate more hierarchy. > > Regards, > Tony > > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr >
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