3Com CoreBuilder 7000, Руководство по эксплуатации

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158 C
HAPTER
7: LAN E
MULATION
V
ERSIONS
1.0
AND
2.0
:
The LECS has determined that the primary LES, LES 1, is operational by
connecting to it and has assigned it to be the active LES in the ELAN. The
connection has reported 20 LECs attached.
Failure Recovery - Transferring Control to the Redundant LES
A failure of an active LES is sensed by the switch in two steps:
1 The ATM connection between the LECS and the active LES is released.
The release is sent either because of a LES failure or a physical link failure.
2 The LECS fails to re-establish the connection with the LES.
Note that you can control the speed with which the link-failure
mechanism reports a link failure by setting the link-failure sensitivity (see
“Update Link-Failure Indicator Sensitivity” on page 126 in the
Management Guide).
When a connection between active LES and LECS is terminated, the LECS
first responds by assuming that a link between it and the LES is
temporarily down and tries to re-establish the connection. If it is unable
to re-establish the connection, the LECS assumes that the active LES has
failed and declares the secondary LES in the ELAN topology database to
be the active LES. From then on, LECs requesting to join the ELAN are
referred to the newly active LES. In this way, LECs that were released from
the failed primary LES are directed by the LECS to the newly active LES
and the ELAN re-establishes itself.
Note that the newly activated secondary LES remains active even after the
failed primary LES becomes operational again. You can cause the primary
LES to become the active LES again by using an LMA command (see
“Make Primary LES Active” on page 311 in the Management Guide). You
need to perform this command on all CoreBuilder 7000 switches with
active LECS and verify the result.
Normally, since their topology database is identical, all LECS in the
network respond in the same way to a LES failure; they each assign the
Table 42 LES Information in LECS Topology Base
LES ID Priority
Is LES
Operational? Assigned to be
active LES Number of
LECs attached
LES 1 Primary Yes Yes 20
LES 2 Secondary Yes No 0