<s>
In	O
commercial	O
network	B-Protocol
routing	I-Protocol
between	O
autonomous	B-Architecture
systems	I-Architecture
which	O
are	O
interconnected	O
in	O
multiple	O
locations	O
,	O
hot-potato	B-Protocol
routing	I-Protocol
is	O
the	O
practice	O
of	O
passing	O
traffic	O
off	O
to	O
another	O
autonomous	B-Architecture
system	I-Architecture
as	O
quickly	O
as	O
possible	O
,	O
thus	O
using	O
their	O
network	O
for	O
wide-area	B-Application
transit	I-Application
.	O
</s>
<s>
Cold-potato	B-Protocol
routing	I-Protocol
is	O
the	O
opposite	O
,	O
where	O
the	O
originating	O
autonomous	B-Architecture
system	I-Architecture
holds	O
onto	O
the	O
packet	O
until	O
it	O
is	O
as	O
near	O
to	O
the	O
destination	O
as	O
possible	O
.	O
</s>
<s>
This	O
is	O
called	O
hot-potato	B-Protocol
routing	I-Protocol
,	O
since	O
ISP	O
A	O
hands	O
off	O
the	O
packet	O
at	O
the	O
earliest	O
opportunity	O
,	O
as	O
in	O
a	O
game	O
of	O
hot	B-Device
potato	I-Device
.	O
</s>
<s>
This	O
is	O
called	O
cold-potato	B-Protocol
routing	I-Protocol
by	O
symmetry	O
,	O
since	O
ISP	O
A	O
keeps	O
the	O
packet	O
in	O
its	O
internal	O
network	O
as	O
long	O
as	O
possible	O
.	O
</s>
<s>
Hot-potato	B-Protocol
routing	I-Protocol
is	O
the	O
normal	O
behavior	O
of	O
most	O
settlement-free	O
peering	O
agreements	O
.	O
</s>
<s>
Hot-potato	B-Protocol
routing	I-Protocol
has	O
the	O
effect	O
that	O
the	O
network	O
receiving	O
the	O
data	O
bears	O
the	O
cost	O
of	O
carrying	O
it	O
between	O
cities	O
.	O
</s>
<s>
The	O
marginal	O
cost	O
of	O
carrying	O
traffic	O
between	O
cities	O
depends	O
on	O
how	O
the	O
network	O
has	O
purchased	O
those	O
links	O
;	O
some	O
networks	O
own	O
dark	B-Protocol
fiber	I-Protocol
,	O
which	O
can	O
be	O
upgraded	O
by	O
merely	O
replacing	O
the	O
equipment	O
on	O
each	O
end	O
of	O
the	O
fiber	O
,	O
and	O
possibly	O
the	O
amplifiers	O
along	O
the	O
path	O
between	O
cities	O
.	O
</s>
<s>
Cold-potato	B-Protocol
routing	I-Protocol
,	O
on	O
the	O
other	O
hand	O
,	O
is	O
more	O
expensive	O
to	O
do	O
,	O
but	O
keeps	O
the	O
traffic	O
under	O
the	O
network	O
administrator	O
's	O
control	O
for	O
longer	O
,	O
allowing	O
operators	O
of	O
well-provisioned	O
networks	O
to	O
offer	O
a	O
higher	O
quality	O
of	O
service	O
to	O
their	O
customers	O
.	O
</s>
<s>
It	O
can	O
also	O
be	O
preferred	O
when	O
connecting	O
to	O
content	O
providers	O
;	O
if	O
content	O
providers	O
use	O
cold-potato	B-Protocol
routing	I-Protocol
,	O
they	O
may	O
escape	O
from	O
paying	O
for	O
the	O
cost	O
of	O
links	O
between	O
cities	O
.	O
</s>
<s>
Cold-potato	B-Protocol
routing	I-Protocol
is	O
prone	O
to	O
misconfiguration	O
as	O
well	O
as	O
poor	O
coordination	O
between	O
two	O
networks	O
.	O
</s>
<s>
In	O
such	O
scenarios	O
,	O
packets	O
can	O
be	O
routed	B-Protocol
further	O
distances	O
and	O
can	O
allow	O
another	O
autonomous	B-Architecture
system	I-Architecture
to	O
manipulate	O
routing	B-Protocol
in	O
a	O
network	O
for	O
various	O
purposes	O
.	O
</s>
<s>
Cold-potato	B-Protocol
routing	I-Protocol
requires	O
a	O
level	O
of	O
trust	O
between	O
two	O
networks	O
that	O
either	O
side	O
will	O
not	O
attempt	O
to	O
"	O
cheat	O
"	O
the	O
other	O
.	O
</s>
<s>
Some	O
content	O
networks	O
favor	O
the	O
use	O
of	O
cold-potato	B-Protocol
routing	I-Protocol
(	O
multi	O
exit	O
discriminator	O
exchange/honoring	O
)	O
in	O
order	O
to	O
deliver	O
content	O
from	O
replicated	O
server	O
farms	O
closer	O
to	O
the	O
end-user	O
.	O
</s>
<s>
The	O
terms	O
can	O
also	O
be	O
used	O
to	O
describe	O
the	O
route	O
announcement	O
policy	O
of	O
a	O
network	O
:	O
by	O
choosing	O
to	O
announce	O
their	O
network	O
at	O
a	O
large	O
number	O
of	O
points	O
at	O
the	O
periphery	O
of	O
another	O
autonomous	B-Architecture
system	I-Architecture
,	O
a	O
provider	O
can	O
pull	O
incoming	O
traffic	O
onto	O
their	O
network	O
as	O
soon	O
as	O
possible	O
,	O
ensuring	O
that	O
the	O
traffic	O
stays	O
on	O
their	O
network	O
all	O
the	O
way	O
to	O
their	O
customer	O
's	O
connection	O
.	O
</s>
