Cell Relay Archive

[Mukul Katiyar <mukul@cplane.com>]

erze9119@my-deja.com wrote:
> 
> Hi folks!
> 
> Thank you for your comments on the N square problem.
> 
> Now I understand that the N square problem concerns
> only networks with PVC connections and not SVC capable
> networks like PNNI for example.

 Well that's just because with a signalled (svc)  mechanism
setup. teardown, reroute, etc are automatic where as in 
a PVC enviornment there is need to manage these functions
by management procedures which invariably needs
operator intervention slowing down making the task enormous.

> 
> BTW, in  the IP over ATM (overlay model) is the assumption
> PVC connected ATM network, 

It could be either.

>or is it possible to use SVC
> connected network as well, and thus avoid the N square
> problem?

No,you have got it wrong, the N square problem doesnot disapper
with svcs, it just gets a bit automated to set up these
"square" ordered connections when you use svc signalled connections.

-mukul

> 
> Regards,
> 
> erze
> 
> In article <8tb684$4da$1@nntp.teliafi.net>,
>   jorma.mellin@telia.fi (Jorma Mellin) wrote:
> > In article <8t9k0u$l7l$1@nnrp1.deja.com>, erze9119@my-deja.com says...
> >  >I am reading some MPLS docs, and in one doc. they calim that
> >  >MPLS avoids the N-square problem associated with the over-lay
> >  >problem. What I don't understand is that ATM creates N*(N-1)/2
> >  >switched virtual conns. (SVCs), between N edge routers. MPLS
> >  >also creates equal nr. of LSPs; how are these two different?
> >  >Doesn't MPLS also suffer from the same problem? Can somebody
> >  >knowledgeable explain this to me please?
> >
> > Well, I don't see the problem here. If you use SVC's on your
> > ATM network, why should you care how many connections there
> > are active? Connections are setup and teared down automaticly,
> > and you always follow the fastest path (with PNNI). The amount
> > of SVC's possible on a NNI link is huge, if I remember correctly
> > there are 14-bits available for SVC numbers (short amount is reserved
> though).
> >
> > I am not an expert with MPLS, but I remember that you don't have
> > all LSP's at all PE devices (provider edge). However, keep in mind
> > that if you think using MPLS VPN's, the VPN doesn't reach the customer
> > edge (CE). The VPN terminates at PE.
> > With ATM the "VPN" goes all the way to the CPE.
> > Both of these (VPN's) are non-crypted by def, although there might be
> > a little more security when the data are in cells, rather than in
> packets.
> >
> > Jorma
> >
> >
> 
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