Cell Relay Archive

[dattap <dattap@future.futsoft.com>]

Hi Eike

>A connection is being established from a source device across a privte
>network where switches are connected via P-NNI to a destination device.
>Will P-NNI signaling or routing part change the routing tables of a
>switch?

It is the responsibility of PNNI Routing to change the routing tables of a 
switch. Routing Tables are updated according to some well defined criteria 
at some regular intervals. PNNI Signaling just obeys the end to end optimal 
route to a destination while sending the SETUP message from the DTL in the 
SETUP. Thus the outgoing ports from each ATM device are obtained from this 
optimal route table which I think solves a doubt of urs w.r.t. one of ur 
previous mails.

>And if, when (upon receiving a SETUP message, or ...)?

Upon receiving s SETUP message PNNI Signaling just fills up the DTL 
according to the optimal route already obtained and just forwards the 
message through the outgoing CES specified in the DTL. Thus at this point 
there is no question of changing the route table of the switch, only the per 
port VPI VCI table is updated.

>When are these routing table entries deleted again (upon receiving a 
RELEASE
>message)?  Or are routing tables entries not changed in connection setup
>phase at all and I should think of them as beeing permanent physical
>connections, that means predefined?

As discussed above already the deletion of routing tables is independent of 
arrival of any RELEASE message for e.g. Routing table Generation is a 
constant background process. Any request of a connection setup just reads 
the routing table for generating DTLs (for source node )and updating the 
same (for entry border node ) in the SETUP message.  Similarly a release 
request also modifies the per port VCI table at an ATM device which is 
nothing to do with the route table.

Hope this clarifies.

Regards

Prabir Datta
Future Software Private Ltd
Madras, India



>Thanx,
>Eike
>