Cell Relay Archive

["Greg Sack" <greg_sack@neca.nec.com.au>]

I would like an opinion on the correct interpretation of the LANE 1.0
standard with regard to how the LECS should respond in the following
circumstance.

A LEC with SOURCE-ATM-ADDRESS S and SOURCE-LAN-DESTINATION MAC1 is already
joined to ELAN E.

A configure request is then sent to the LECS with SOURCE-ATM-ADDRESS S,
SOURCE-LAN-DESTINATION MAC2 and ELAN-NAME E.  

>From 5.4.2.6, I believe it would be illegal for the LES for ELAN E to
accept a join request for a LEC with SOURCE-ATM-ADDRESS S and
SOURCE-LAN-DESTINATION MAC2 at the same time it already has that
SOURCE-ATM-ADDRESS already joined with a different SOURCE-LAN-DESTINATION
(MAC1).  My assumption here is that different SOURCE-LAN-DESTINATIONs for
the the same SOURCE-ATM-ADDRESS represent different LEC instantiations with
respect to a join request, and therefore these cannot be the subject of
separate join requests to the same ELAN concurrently (note this is
different to subsequently using the registration protocol to register
multiple local or non-local MAC addresses against a joined LEC).  (But even
if I am wrong in this interpretation, I don't think it weakens my argument
below.)

However, my interpretation of the standard is that the LECS itself should
*NOT* reject the *configure* request above, even if a subsequent join
attempt using those parameters would fail. 

In 5.3.2 the standard says "The LE Configuration Server uses the
information provided in the LE_CONFIGURE_REQUEST to generate an
LE_CONFIGURE_RESPONSE.  This response may indicate success or failure
depending on whether the prospective LE Client is to be allowed to attempt
to join an LE Server".  

To me, the key words are "allowed to attempt to join", which is not the
same as "allowed to join"!!  That is, as far as I can tell, the LECS should
make its decisions totally based on its local configuration database,
independently of the current state of the LESs in the network.  So as long
as the LECS configuration database otherwise permits a LEC with
SOURCE-ATM-ADDRESS S and SOURCE-LAN-DESTINATION MAC2 to belong to ELAN E,
my interpretation is that the LECS should respond with success status and
the LES address and other configuration parameters for  ELAN E.  It would
then be up to the LES to reject a subsequent join request if it believed
the requested parameters were in conflict with an already-joined LEC.

Can anyone provide a more authoritative statement of the correct LECS
behaviour in these circumstances?

-- 
Greg Sack
Systems Engineer
NEC Australia

ph:    +61 3 9262 1009
fax:   +61 3 9262 1399
email: greg_sack@neca.nec.com.au