Number of PID

[Ghassane Aniba <Ghassane.Aniba@sophia.inria.fr>]

Thomas 'Dent' Mirlacher wrote:
> 
> On Tue, 23 Apr 2002, Patrick Cipiere wrote:
> 
> >
> > "Kearney" <clausen@cosy.sbg.ac.at> wrote:
> >
> > > I think this is absolute overkill - to address 2^28 multicast groups or
> > > individual stations in ONE PID stream is unrealistic. And remember: every
> > > bit counts.
> >
> > How many addresses do you think is realistic?
> > I don't understand why we should not allow the full IP adresses scope
> > on one PID.
> 
> another related question would be:
> 
> how does the correct scheme for segmenting the IP-address space
> into PIDs look like.
> 
> and there are a couple of possible solutions (also remember there
>         are receivers out there which are not capable of filtering
>         2^13 PIDs)

We will not use 2^13 PID. In the first time we'll use just 4 bits from
13 bits (20 PID), as you say, the receivers, until now, could only
filter 20 PID.
That's why i've said, we will have 2^28 connection (4 bits from PID and
24 from @link_sat)

> 
> 1) put all the traffic in one PID
>         + simple implementation on the receiver side (just filter a
>                 single PID)
>         - load on the receiver

We won't profit from the PID if we do like this.
In fthe future if the receivers, will be able to filter more PID, it
will be profitable for us, and we won't need any change in our schema.

> 
> 2) put unicast inside one PID
>    group multicast in several other PIDs
>         + (see above - at least for P2P connections)
>         - for the unicast case, there's no easy way to
>                 do fast filtering (ar HW/FW level, without
>                 looking at the IP address - so the work
>                 needs to be done in the IP stack)

Another problem, there isn't enough PID to do it.2^13.

> 
> 3) put every connection into a single PID (like PVCs)
>         - PID space exhaustion: possible problems with OBPs (like skyplex)
>         - most existing receivers cannot HW-filter more than n-PIDs

This is why we will just use i20 PID n the first time.

> 
> all the above points share the need for an IP->PID table.
> 
It's clear.

>         tm
> --
> in some way i do, and in some way i don't.

Aniba.

-- 
Ghassane ANIBA
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