<s>
Ethernet	B-Protocol
Automatic	I-Protocol
Protection	I-Protocol
Switching	I-Protocol
(	O
EAPS	O
)	O
is	O
used	O
to	O
create	O
a	O
fault	O
tolerant	O
topology	B-Architecture
by	O
configuring	O
a	O
primary	O
and	O
secondary	O
path	O
for	O
each	O
VLAN	B-General_Concept
.	O
</s>
<s>
The	O
idea	O
is	O
to	O
provide	O
highly	O
available	O
Ethernet	O
switched	O
rings	O
(	O
commonly	O
used	O
in	O
Metro	B-Protocol
Ethernet	I-Protocol
)	O
to	O
replace	O
legacy	O
TDM	O
based	O
transport	O
protection	O
fiber	O
rings	O
.	O
</s>
<s>
The	O
EAPS/EPSR	O
are	O
the	O
basis	O
of	O
the	O
ITU	O
G.8032	B-Protocol
Ethernet	O
Protection	O
recommendation	O
.	O
</s>
<s>
Under	O
normal	O
operation	O
,	O
the	O
secondary	O
port	O
on	O
the	O
master	O
is	O
blocked	O
for	O
all	O
protected	O
vlans	B-General_Concept
.	O
</s>
<s>
When	O
a	O
shared	O
link	O
goes	O
down	O
,	O
the	O
configured	O
Controller	O
will	O
open	O
only	O
one	O
segment	O
port	O
for	O
each	O
of	O
the	O
protected	O
VLANs	B-General_Concept
,	O
keeping	O
all	O
other	O
segment	O
ports	O
in	O
a	O
blocking	O
state	O
.	O
</s>
