The Routing Over Large Clouds Mailing List Archive by date

[Sam Wilson <ercm20@tattoo.ed.ac.uk>]

> It seems to me that some ion members don't understand a CSR 
> correctly.

I think I had understood that but thank you for the information.

> The CSR is a router with cell-swithing fabric.

Or an ATM switch with an IP routing module attached.

> [ further description deleted ]
> (The only problem is that TTLs can not be discreased.)

Which could make for some interesting traffic loop damping behaviour,
presumably. 

> There exist, of course, no CSRs as commercial products.

Right...

> But you can implement them by combining a workstation 
> with a PVC/SVC ATM switch.
> The easiest implementation is as the following:
> 
>            workstation
>         +---------------+
>         |     gated     | 
>         +-------+-------+   
>         |ATM NIC|ATM NIC|
>         +-------+-------+   
>             |       |       
>         +---------------+
> --------|               |---------
>         +---------------+
>             ATM switch
> 
> The workstation controls the ATM swtich by a PVC interface
> via RS-232c.

Presumably it could also be implemented, with a recognisable bottleneck
but saving one NIC and one switch port, as:

           workstation
        +---------------+
        |     gated     | 
        +---------------+   
        |    ATM NIC    |
        +---------------+   
                |      
        +---------------+
--------|               |---------
        +---------------+
            ATM switch

This is beginning to look suspiciously like the setup we have, except
for the RS 232 connection and the workstation/gated, which in our case
will be a Cisco router.  Err...  any chance Cisco's IOS could configure
PVCs on a switch using the router's AUX port? I suppose I should add a
:-) to that last question...  

Actually one of my colleagues suggests that the obvious way to do this
is via SNMP rather than RS 232 and that some manufacturers are beginning
to do this kind of thing already, partly for administrative reasons so
that requests for ATM bandwidth can be filtered by a management station. 
I don't know details. 


Sam Wilson
Network Services Division
Computing Services, The University of Edinburgh
Edinburgh, Scotland, UK