RE : RE : RE : Proposed strategy for Inter-area/AS

["LE ROUX Jean-Louis FTRD/DAC/LAN" <jeanlouis.leroux@francetelecom.com>]

Hi Fabio and all,

I see what you suggest, but IMHO this would not be sufficient, as an LSP affinity can be a combination of colors inclusion/exclusion

Using your proposed advertisement, there is no mean to know that there is no path through the ABR, for
an LSP bw=50M and affinity = exclude red & blue.

Basically, IMHO in case you have N paths, each with a distinct adm-group, the only solution, if you want to
compute an optimal path using this approach, is to advertise N virtual links.
Note that an ABR would have to compute and advertise many paths to many potential destinations, 
This may generate higher flooding than the direct advertisement of TE-links...
and you are likely to loose all the interest for area partitionning.


Cheers,

JL


> -----Message d'origine-----
> De : ricciato [mailto:ricciato@coritel.it] 
> Envoyé : lundi 26 avril 2004 18:59
> À : LE ROUX Jean-Louis FTRD/DAC/LAN
> Cc : adrian@olddog.co.uk; ccamp@ops.ietf.org
> Objet : Re: RE : RE : Proposed strategy for Inter-area/AS
> 
> 
> Dear JL,
> 
> you´re right.
> 
> Just a quick proposal.
> In an attempt to limit the number of virtual link advertised, 
> would it make sense to advertise only K virtual links, where 
> K={number 
> of colors}, and for each of them  (say j) advertise the maximum 
> bandwdith over all links that have color j into their admin_group ?
> 
> For example, in your example (with Path 4 added)
> 
> Path 1: bw 100M admin group {green;blue}
> Path 2: bw 50M admin group {red; blue}
> Path 3: bw 5M admin group {red;green}
> Path 4: bw 50M admin group {red}
> 
> One should advertise 
> Virtual Link 1: bw 100M admin group {green} --->max(100M,5M) 
> Virtual Link 2: bw 50M admin group {red} --->max(50M,5M,50M) 
> Virtual Link 3: bw 100M admin group {gblue} --->max(100M,50M)
> 
> 
> Assuming that the number of colors << number of possible 
> links, this approach might cap the amount of advertisement.
> 
> But I´m not sure it works ... 
> 
> ciao
> fabio
> 
> LE ROUX Jean-Louis FTRD/DAC/LAN wrote:
> 
> >Hi Fabio,
> >
> >Advertising only a subset would improve scalability, but
> >this would not be enough to correclty select the best path.
> >
> >Let's assume that there are three paths from a given ABR X 
> to a given 
> >destination D Path 1: bw 100M admin group {green;blue} Path 
> 2: bw 50M 
> >admin group {red; blue} Path 3: bw 5M admin group {red;green}
> >
> >and a TE-LSP L : Destination D, bw= 4M, affinity= exlude blue
> >
> >If you advertise only Path 1 and Path 2 as virtual links, ABR X will 
> >never be selected as next ABR for this TE-LSP, while path 3 is a 
> >feasible path.
> >
> >Regards
> >
> >JL
> >
> >
> >
> >  
> >
> >>-----Message d'origine-----
> >>De : owner-ccamp@ops.ietf.org
> >>[mailto:owner-ccamp@ops.ietf.org] De la part de ricciato
> >>Envoyé : lundi 26 avril 2004 09:48
> >>À : LE ROUX Jean-Louis FTRD/DAC/LAN
> >>Cc : adrian@olddog.co.uk; ccamp@ops.ietf.org
> >>Objet : Re: RE : Proposed strategy for Inter-area/AS
> >>
> >>
> >>Hi JL,
> >>
> >>just a quick remark: would it make sense in this case to
> >>advertise only 
> >>a selected subset of the N virtual links (say the two with 
> >>most residual 
> >>bw) ?
> >>
> >>ciao
> >>fabio
> >>
> >>LE ROUX Jean-Louis FTRD/DAC/LAN wrote:
> >>
> >>    
> >>
> >>>Let's assume that there are N distinct paths from ABR A to a
> >>>destination X, each with a distinct bandwidth and distinct 
> >>>      
> >>>
> >>admin-group
> >>    
> >>
> >>>(a path admin group being expressed as a logical AND of the
> >>>      
> >>>
> >>link admin
> >>    
> >>
> >>>groups along the path) How can you summarize such topology ?
> >>>      
> >>>
> >>Actually
> >>    
> >>
> >>>you need to advertise N virtual links, each with a distinct
> >>>      
> >>>
> >>admin-group
> >>    
> >>
> >>>and available bandwidth.
> >>>
> >>>
> >>> 
> >>>
> >>> 
> >>>
> >>>      
> >>>
> >>
> >>    
> >>
> >
> >
> >  
> >
> 
>