A
Glossary of Terms
193
PSK
Pre
‐
Shared
Key.
With
pre
‐
shared
key
authentication,
an
identical
symmetric
key
must
be
manually
configured
on
both
systems.
The
shared
key
is
a
secret
passphrase,
normally
a
string
of
ASCII
characters
or
a
set
of
random
Hexadecimal
numbers.
Both
endpoints
need
to
have
the
same
key
defined
and
the
key
must
be
kept
secret.
The
pre
‐
shared
key
is
used
only
for
the
primary
authentication;
the
two
negotiating
entities
then
generate
dynamic
shared
session
keys
for
the
IKE
SAs
and
IPsec
SAs.
Public
key
In
public
‐
key
cryptography
the
public
key,
which
is
included
in
the
certificate,
can
be
used
to
verify
signatures
and
encrypt
messages.
Public
‐
key
cryptography
In
contrast
to
symmetric
(secret
‐
key)
cryptography
with
just
one
cipher
key,
in
public
‐
key
cryptography
each
person
or
host
has
two
keys.
One
is
the
private
key,
which
is
used
for
signing
outgoing
messages
and
decrypting
incoming
messages,
the
other
is
the
public
key,
which
is
used
by
others
to
confirm
the
authenticity
of
a
signed
message
coming
from
that
person
and
for
encrypting
messages
addressed
to
that
person.
The
private
key
must
not
be
available
to
anyone
but
its
owner,
but
the
public
key
is
spread
via
trusted
channels
to
anyone.
RADIUS
Remote
Authentication
for
Dial
in
User
Service.
An
Internet
protocol
providing
authentication,
authorization
and
accounting.
It
is
primarily
used
for
dial
access.
RADIUS
is
defined
in
RFC
2138
and
RFC
2139.
Rijndael
Designed
by
Joan
Daemen
and
Vincent
Rijmen,
Rijndael
is
a
symmetric
block
cipher
with
a
variable
block
size
of
128,
192,
or
256
bits
and
a
variable
key
length
of
128,
192,
or
256
bits.
Rijndael
is
the
algorithm
used
in
the
U.S.
Advanced
Encryption
Standard
(AES),
however,
in
AES
only
the
128
‐
bit
block
size
is
used.
Round
‐
Robin
A
round
robin
is
an
arrangement
of
choosing
all
elements
in
a
group
equally
in
some
rational
order,
usually
from
the
top
to
the
bottom
of
a
list
and
then
starting
again
at
the
top
of
the
list
and
so
on.
A
simple
way
to
think
of
round
robin
is
that
it
is
about
“taking
turns.”
Used
as
an
adjective,
round
robin
becomes
“round
‐
robin.”
Route
Failover
The
route
failover
feature
can
be
used
when
there
is
two
or
more
routes
to
a
destination.
For
example,
in
a
scenario
where
two
ISPs
are
available
for
connection
to
the
Internet,
one
ISP
(the
primary)
is
normally
used
and
a
backup
ISP
is
used
when
the
primary
is
down.
Router
priority
The
Router
Priority
which
is
configurable
on
a
per
‐
interface
basis
is
the
parameter
that
controls
the
election.
The
router
with
the
highest
priority
number
becomes
DR
and
the
next
highest
one
becomes
BDR.
