Re: ason-routing-reqts: issue 2 architecture

["Adrian Farrel" <adrian@olddog.co.uk>]

Lyndon,

 

> If you follow this through, is there a visible difference between

> the following cases:

 

 

Well, yes. I can see a difference.

But I suppose you are asking a deeper question.

 

Your B) shows only a decoupling of control plane and data plane such as one might achieve using GSMP (or TL1 or ...) in a standard configuration.

 

Your A) includes with this decoupling a centralization of control into a single controling entity. As Jonathan points out, this might be done in order to present the data plane resources (nodes and links) as a single entity, or might be done simply because there is a single centralized control plane node.

 

It was my intention to distinguish these cases using R1 and R2 on my figure.

 

NOTE WELL. None of these figures dwells on control plane connectivity. This is entirely a separate matter from TE connectivity.

 

Thanks,

Adrian

>  
>         A)                       B)
>            ------------------       ------   ------   ------
>           |R1                |     |R1    | |R2    | |R3    |
>           |  --    --    --  |     |  --  | |  --  | |  --  |
>           | |L1|  |L2|  |L3| |     | |L1| | | |L2| | | |L3| |
>           |  --    --    --  |     |  --  | |  --  | |  --  |
>           |   :     :     :  |     |   :  | |   :  | |   :  |
> Control    ---+-----+-----+--       ---+--   ---+--   ---+--
> Plane         :     :     :            :        :        :
> --------------+-----+-----+----    ----+--------+--------+----
> Data          :     :     :            :        :        :
> Plane        --     :    --           --        :       --
>         ----|P1|--------|P3|---   ---|P1|--------------|P3|---
>              -- \   :  / --           --    \   :  /    --
>                  \ -- /                      \ -- /
>                   |P2|                        |P2|
>                    --                          --
>
> > >              ------------------     ------   
> > >             |R1                |   |R2    |  
> > >             |  --    --    --  |   |  --  |    ------
> > >             | |L1|  |L2|  |L3| |   | |L4| |   |R3    |
> > >             |  --    --    --  |   |  --  |   |  --  |
> > >             |   :     :     :  |   |   :  |   | |L5| |
> > > Control      ---+-----+-----+--     ---+--    |  --  |
> > > Plane           :     :     :          :      |   :  |
> > > ----------------+-----+-----+----------+------+---+--+-
> > > Data            :     :     :          :      |   :  |
> > > Plane          --     :    --         --      |  --  |
> > >           ----|P1|--------|P3|-------|P4|-----+-|P5|-+-
> > >                -- \   :  / --         --      |  --  |
> > >                    \ -- /                     |      |
> > >                     |P2|                       ------
> > >                      --
> > >
> > > Pn is a physical (bearer/data/transport plane) node.
> > > Rn is a control plane "router"
> > > Ln is a logical control plane entity that manages a single
> > >    physical node.
> > >
> > > Thus:
> > > R3 represents an LSR with all components collocated.
> > > R2 shows how the "router" component may be disjoint from
> > >    the switch
> > > R1 shows how a single "router" may manage multiple switches