<s>
Transparent	B-General_Concept
LAN	I-General_Concept
Service	I-General_Concept
(	O
TLS	O
)	O
is	O
a	O
service	O
from	O
a	O
carrier	O
linking	O
together	O
remote	O
Ethernet	O
networks	O
.	O
</s>
<s>
Its	O
primary	O
real	O
world	O
deployment	O
is	O
usually	O
limited	O
to	O
corporations	O
who	O
1	O
)	O
require	O
remote	O
office	O
or	O
back-end	O
data	B-Operating_System
center	I-Operating_System
connectivity	O
at	O
close	O
to	O
LAN	B-General_Concept
speed	O
,	O
and	O
2	O
)	O
do	O
not	O
have	O
in-house	O
expertise	O
in	O
WAN	O
management	O
,	O
as	O
TLS	O
is	O
usually	O
purchased	O
as	O
a	O
fully	O
managed	O
service	O
(	O
meaning	O
the	O
carrier	O
chosen	O
owns	O
,	O
configures	O
,	O
monitors	O
,	O
and	O
maintains	O
the	O
equipment	O
needed	O
for	O
the	O
service	O
to	O
function	O
)	O
.	O
</s>
<s>
In	O
most	O
cases	O
,	O
it	O
is	O
only	O
available	O
in	O
large	O
metropolitan	O
areas	O
and	O
office	O
buildings	O
,	O
campuses	O
,	O
or	O
data	B-Operating_System
centers	I-Operating_System
large	O
enough	O
to	O
warrant	O
the	O
proper	O
equipment	O
.	O
</s>
<s>
Transparent	B-General_Concept
LAN	I-General_Concept
service	I-General_Concept
between	O
two	O
sites	O
has	O
been	O
successful	O
,	O
but	O
multipoint	O
transparent	B-General_Concept
LANs	I-General_Concept
have	O
been	O
problematic	O
due	O
to	O
the	O
difference	O
in	O
architecture	O
between	O
the	O
broadcast-based	O
Ethernet	O
and	O
the	O
carrier	O
's	O
point-to-point	B-Architecture
network	O
.	O
</s>
<s>
The	O
VPLS	B-Application
(	O
a	O
type	O
of	O
VPN	B-Application
)	O
standard	O
was	O
developed	O
to	O
resolve	O
the	O
problem	O
using	O
IP	B-Protocol
and	O
MPLS	B-Protocol
routers	O
.	O
</s>
