Cell Relay Archive

[anouch gharagozlou <anouch_c@yahoo.com>]

Thanks Afroz,

I agree with you that there is no traffic loss.
There is however a configuration problem that is not
signaled to the application.
Anouch

--- Afroz Lateef <afroz.lateef@fnc.fujitsu.com> wrote:
> Anouch,
> 
> In this case, the CAC should have been run on the
> output port of the
> unit that is connected to the I-port of the switch.
> Since this is a CPE
> and cannot have CAC implemented on it, there is no
> service affecting
> problem.
> Because, traffic cannot exceed more than the link
> capacity. So in TX
> side, there is no traffic loss.
> 
> Afroz Lateef
> 
> anouch gharagozlou wrote:
> 
> > Hi,
> >
> > Call/Connection Admition control (CAC)in a cell
> relay
> > switch is always acting on the ouput port. But
> what
> > happens if the input port is out of capacity and
> that
> > is not checked?
> >
> > Suppose a user connect to the input port (I-port)
> of a
> > switch and wants a connection with another user
> > located just behind the output port (O-port)of the
> > same switch.
> >
> > Assume I-port speed is 45Mbps and O-port speed is
> > 155Mbps.
> > The user asks for a 100Mbps connection. The CAC
> checks
> > if the O-port has enough bandwidth left and if
> it's ok
> > the connection is established (if no other
> connection
> > is using the O-port, 100Mbps being < 155Mbps, the
> call
> > succeeds).
> > But the user will never be able to send at 100Mbps
> > since the I-port where it is connected has a speed
> of
> > 45Mbps. The CAC doesn't check that and the
> > provisioning succeeds while the user isn't aware
> of
> > the configuration problem.
> >
> > This actually happens on a Nortel 7k/15k Passport
> but
> > may also happens on other switches. And it is more
> > problematic when dealing with asymetrical (e.g.
> ADSL)
> > connections.
> >
> > Is this a bug, or the CAC should never checks the
> > input port for incoming traffic?
> > In the latter case what is the solution?
> >
> > Thanks
> > Anouch
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Kick off your party with Yahoo! Invites.
> > http://invites.yahoo.com/
> 


__________________________________________________
Do You Yahoo!?
Kick off your party with Yahoo! Invites.
http://invites.yahoo.com/