3Com CoreBuilder 7000 Operation Manual page 156

156 C 7: LAN E V 1.0 2.0
HAPTER MULATION ERSIONS AND
about the LESs associated with each ELAN and can take over as the active
LECS at any time.
LMA Commands
To enter the primary LES by LMA, see "Add ELAN" on page 301 in the
Management Guide; to enter a secondary LES, see "Assign Redundant
LES to ELAN" on page 308 in the Management Guide.
Shared LES
You are allowed to assign a LES to two different ELANs: as a primary LES
for the first ELAN and as the secondary LES for the second ELAN or as a
secondary LES for more than one ELAN. Such a LES is called shared
between the two ELANs.
Using shared LESes is not recommended unless there are insufficient
ELAN resources in the network. Shared LESes can, in certain
circumstances, cause two ELANs to collapse into one or make it difficult
to recover from a split ELAN.
Assigning the Active LES for an ELAN — Monitoring LES Status
On-line
Before assigning the primary or secondary LES of an ELAN to be active,
the LECS determines if they are operational. For this purpose, each LECS
continuously monitors the operating status of all LESes in its topology
database by trying to establish an ATM point-to-point connection with
the LES as shown in Figure 51. If the connection is successful, the LES is
marked operational. If the attempted connection is not successful, or if
an established connection is released by the LES, the LES is identified as
not operational. If the attempted connection to a LES is not successful at
first, the LECS keeps trying to establish the connection.