Specifications

ALAXALA Ring Configuration Guide (Edition 1)
Copyright © 2008, ALAXALA Networks Corporation. All rights reserved.
65
4. Notes
4.1 Prohibited Ring Protocol configurations
(1) Configuration with multiple master nodes in the same ring
If one ring has multiple master nodes (Figure 4.1
-1), depending on the positions of the logically blocked
secondary ports of the master nodes, communication might be blocked or a failure might not be detected
properly.
Figure 4.1-1 Configuration with multiple master nodes in the same ring
(2) Multi-ring configuration with multiple shared link monitoring rings
In a multi-ring configuration, the configuration must have only one shared link monitoring ring (O-shaped
ring). Otherwise, in some cases, a ring failure cannot be detected properly, as shown in Figure 4.
1-2.
Figure 4.1-2 Configuration with multiple shared link monitoring rings
M1 T1
T2 M2
M1 M2
T1 T2
T1 cannot
communicate with
other nodes due
to logical blocking
by the two master
nodes.
Because two
master nodes
exist, they can
always receive
their HC frame in
one direction
even if a line
failure occurs.
M1 and M2:
Ring master node, T1 and T2: Ring transit node
S1, S2, S3, and
S4 send HC(S)s
to M2.
When a failure
occurs, M2 cannot
receive HC(S)s
from S3 and S4.
However, M2 can
receive HC(S)s
from S1 and S2,
so M2 does not
detect the failure.
Shared link non-monitoring ring
(C-shaped ring)
Shared link monitoring ring
(O-shaped ring)
Shared link monitoring ring
(O-shaped ring)
M1 S1 M2
T1 S3 T2
HC(M)
HC(M)
HC(S)
HC(S)
S2 M3
S4 T3
HC(M)
HC(S)
HC(S)
A fault occurred
here.
M1 S1 M2
T1 S3 T2
HC(M)
HC(M)
HC(S)
HC(S)
M3
S4 T3
HC(M)
HC(S)
HC(S)
S2
M1 - M3: Ring master node, T1 - T3: Ring transit node, S1 - S4: Ring shared node