<s>
An	O
edge	B-Device
device	I-Device
is	O
a	O
device	O
that	O
provides	O
an	O
entry	O
point	O
into	O
enterprise	O
or	O
service	O
provider	O
core	O
networks	O
.	O
</s>
<s>
Examples	O
include	O
routers	B-Protocol
,	O
routing	O
switches	O
,	O
integrated	O
access	O
devices	O
(	O
IADs	O
)	O
,	O
multiplexers	O
,	O
and	O
a	O
variety	O
of	O
metropolitan	O
area	O
network	O
(	O
MAN	O
)	O
and	O
wide	O
area	O
network	O
(	O
WAN	O
)	O
access	O
devices	O
.	O
</s>
<s>
Edge	B-Device
devices	I-Device
also	O
provide	O
connections	O
into	O
carrier	O
and	O
service	O
provider	O
networks	O
.	O
</s>
<s>
An	O
edge	B-Device
device	I-Device
that	O
connects	O
a	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
to	O
a	O
high	O
speed	O
switch	B-Protocol
or	O
backbone	O
(	O
such	O
as	O
an	O
ATM	O
switch	B-Protocol
)	O
may	O
be	O
called	O
an	O
edge	B-Device
concentrator	I-Device
.	O
</s>
<s>
In	O
general	O
,	O
edge	B-Device
devices	I-Device
are	O
normally	O
routers	B-Protocol
that	O
provide	O
authenticated	O
access	O
(	O
most	O
commonly	O
PPPoA	B-Protocol
and	O
PPPoE	B-Protocol
)	O
to	O
faster	O
,	O
more	O
efficient	O
backbone	O
and	O
core	O
networks	O
.	O
</s>
<s>
The	O
trend	O
is	O
to	O
make	O
the	O
edge	B-Device
device	I-Device
smart	O
and	O
the	O
core	O
device(s )	O
"	O
dumb	O
and	O
fast	O
"	O
,	O
so	O
edge	B-Protocol
routers	I-Protocol
often	O
include	O
quality	O
of	O
service	O
(	O
QoS	O
)	O
and	O
multi-service	O
functions	O
to	O
manage	O
different	O
types	O
of	O
traffic	O
.	O
</s>
<s>
Consequently	O
,	O
core	O
networks	O
are	O
often	O
designed	O
with	O
switches	O
that	O
use	O
routing	O
protocols	O
such	O
as	O
Open	B-Protocol
Shortest	I-Protocol
Path	I-Protocol
First	I-Protocol
(	O
OSPF	B-Protocol
)	O
or	O
Multiprotocol	B-Protocol
Label	I-Protocol
Switching	I-Protocol
(	O
MPLS	B-Protocol
)	O
for	O
reliability	O
and	O
scalability	O
,	O
allowing	O
edge	B-Protocol
routers	I-Protocol
to	O
have	O
redundant	O
links	O
to	O
the	O
core	O
network	O
.	O
</s>
<s>
Links	O
between	O
core	O
networks	O
are	O
different	O
—	O
for	O
example	O
,	O
Border	B-Protocol
Gateway	I-Protocol
Protocol	I-Protocol
(	O
BGP	B-Protocol
)	O
routers	B-Protocol
are	O
often	O
used	O
for	O
peering	O
exchanges	O
.	O
</s>
<s>
Edge	B-Device
devices	I-Device
may	O
translate	O
between	O
one	O
type	O
of	O
network	O
protocol	O
and	O
another	O
.	O
</s>
<s>
For	O
example	O
,	O
Ethernet	O
or	O
Token	B-Device
Ring	I-Device
types	O
of	O
local	B-General_Concept
area	I-General_Concept
networks	I-General_Concept
(	O
LANs	B-General_Concept
)	O
or	O
xDSL	O
equipment	O
may	O
use	O
an	O
Asynchronous	O
Transfer	O
Mode	O
(	O
ATM	O
)	O
backbone	O
to	O
other	O
core	O
networks	O
.	O
</s>
<s>
Some	O
new	O
types	O
of	O
optical	B-Architecture
fibre	I-Architecture
use	O
a	O
passive	B-Architecture
optical	I-Architecture
network	I-Architecture
subscriber	O
loop	O
such	O
as	O
GPON	B-Architecture
,	O
with	O
the	O
edge	B-Device
device	I-Device
connecting	O
to	O
Ethernet	O
for	O
backhaul	B-General_Concept
(	O
telecommunications	O
)	O
.	O
</s>
<s>
An	O
edge	B-Device
switch	I-Device
for	O
a	O
WAN	O
may	O
be	O
a	O
multiservice	O
unit	O
,	O
meaning	O
that	O
it	O
supports	O
a	O
wide	O
variety	O
of	O
communication	O
technologies	O
,	O
including	O
Integrated	B-Protocol
Services	I-Protocol
Digital	I-Protocol
Network	I-Protocol
(	O
ISDN	B-Protocol
)	O
,	O
T1	O
circuits	O
,	O
Frame	B-Protocol
Relay	I-Protocol
,	O
and	O
ATM	O
.	O
</s>
<s>
An	O
edge	B-Device
device	I-Device
may	O
provide	O
enhanced	O
services	O
,	O
such	O
as	O
virtual	B-Application
private	I-Application
networking	I-Application
(	O
VPN	B-Application
)	O
support	O
,	O
Voice	B-Application
over	I-Application
IP	I-Application
,	O
and	O
QoS	O
services	O
.	O
</s>
