3Com CoreBuilder 7000, Operation Manual

Page: 148 / 264

148 C
HAPTER
7: LAN E
MULATION
V
ERSIONS
1.0
AND
2.0
standard addressing protocol. This is discussed in more detail in the next
section.
When the connection of LEC to LECS is established, the LECS identifies an
appropriate LES using the search policies discussed below and transfers
the LES address to the LEC. A LECS database within the CoreBuilder 7000
stores the network structure.
LECS Address Access A LEC can access the LECS address in two ways: by ILMI or directly to the
LECS “well-known” address. If the ILMI channel (VPI/VCI = 0/16) is
connected between LEC and LECS and if the LEC device supports
enquiries of the ILMI MIB “atmSrvcRegistryGroup”, then it is the
preferred channel of communication. If not, then the LEC communicates
with the LECS by the LECS “well-known” address.
The type of communication between LEC and LECS is set by management
via a parameter called “LECS via ILMI”. For communication by ILMI this
parameter is set to enable. Otherwise it is disabled (see “Update
LECS-Address Access Status” on page 135 in the Management Guide).
Note that the ILMI channel can be continuously verified (polled) so that
the manager will know if the channel has failed (see “Display ILMI
Channel Polling Status” on page 136 in the Management Guide and
following commands). In that event, he will need to disable the “LECS via
ILMI” parameter.
LECS Connect Phase
During the LECS Connect phase, the LEC establishes its connection with
the LECS. If use of the LECS is not required, a LEC may skip this phase.
The mechanisms used to locate the configuration service are as follows,
in order:
1 Get the LECS address via ILMI
2 Use the well-known LECS address
3 Use the LECS PVC (not supported by the CoreBuilder 7000)
LECS Search Policy
When a LEC requests to join an ELAN it can supply the following
information to assist the LECS in finding the appropriate LES: