<s>
There	O
are	O
a	O
number	O
of	O
optional	O
parameters	O
that	O
may	O
be	O
present	O
in	O
an	O
Internet	B-Protocol
Protocol	I-Protocol
version	I-Protocol
4	I-Protocol
datagram	O
.	O
</s>
<s>
They	O
typically	O
configure	O
a	O
number	O
of	O
behaviors	O
such	O
as	O
for	O
the	O
method	O
to	O
be	O
used	O
during	O
source	B-Protocol
routing	I-Protocol
,	O
some	O
control	O
and	O
probing	O
facilities	O
and	O
a	O
number	O
of	O
experimental	O
features	O
.	O
</s>
<s>
Loose	O
Source	B-Protocol
Routing	I-Protocol
is	O
an	O
IP	B-Protocol
option	O
which	O
can	O
be	O
used	O
for	O
address	O
translation	O
.	O
</s>
<s>
LSR	O
is	O
also	O
used	O
to	O
implement	O
mobility	O
in	O
IP	B-Protocol
networks	O
.	O
</s>
<s>
Loose	O
source	B-Protocol
routing	I-Protocol
uses	O
a	O
source	B-Protocol
routing	I-Protocol
option	O
in	O
IP	B-Protocol
to	O
record	O
the	O
set	O
of	O
routers	B-Protocol
a	O
packet	B-Protocol
must	O
visit	O
.	O
</s>
<s>
The	O
destination	O
of	O
the	O
packet	B-Protocol
is	O
replaced	O
with	O
the	O
next	O
router	B-Protocol
the	O
packet	B-Protocol
must	O
visit	O
.	O
</s>
<s>
By	O
setting	O
the	O
forwarding	O
agent	O
(	O
FA	O
)	O
to	O
one	O
of	O
the	O
routers	B-Protocol
that	O
the	O
packet	B-Protocol
must	O
visit	O
,	O
LSR	O
is	O
equivalent	O
to	O
tunneling	B-Protocol
.	O
</s>
<s>
If	O
the	O
corresponding	O
node	O
stores	O
the	O
LSR	O
options	O
and	O
reverses	O
it	O
,	O
it	O
is	O
equivalent	O
to	O
the	O
functionality	O
in	O
mobile	B-Protocol
IPv6	I-Protocol
.	O
</s>
<s>
The	O
name	O
loose	O
source	B-Protocol
routing	I-Protocol
comes	O
from	O
the	O
fact	O
that	O
only	O
part	O
of	O
the	O
path	O
is	O
set	O
in	O
advance	O
.	O
</s>
<s>
Strict	O
source	B-Protocol
routing	I-Protocol
is	O
in	O
contrast	O
with	O
loose	O
source	B-Protocol
routing	I-Protocol
,	O
in	O
which	O
every	O
step	O
of	O
the	O
route	O
is	O
decided	O
in	O
advance	O
where	O
the	O
packet	B-Protocol
is	O
sent	O
.	O
</s>
<s>
Many	O
routers	B-Protocol
block	O
packets	B-Protocol
containing	O
these	O
options	O
.	O
</s>
