<s>
Lollipop	B-Protocol
sequence	I-Protocol
numbering	I-Protocol
is	O
a	O
numbering	O
scheme	O
used	O
in	O
routing	B-Protocol
protocols	I-Protocol
.	O
</s>
<s>
This	O
path	O
can	O
be	O
visualized	O
as	O
a	O
line	O
with	O
a	O
circle	O
at	O
the	O
end	O
;	O
hence	O
a	O
lollipop	B-Application
.	O
</s>
<s>
Lollipop	B-Protocol
sequence	I-Protocol
numbering	I-Protocol
was	O
originally	O
believed	O
to	O
resolve	O
the	O
ambiguity	O
problem	O
in	O
cyclic	O
sequence	O
numbering	O
schemes	O
,	O
and	O
was	O
used	O
in	O
OSPF	B-Protocol
version	O
1	O
for	O
this	O
reason	O
.	O
</s>
<s>
Later	O
work	O
showed	O
that	O
this	O
was	O
not	O
the	O
case	O
,	O
like	O
in	O
the	O
ARPANET	O
sequence	O
bug	O
,	O
and	O
OSPF	B-Protocol
version	O
2	O
replaced	O
it	O
with	O
a	O
linear	O
numbering	O
space	O
,	O
with	O
special	O
rules	O
for	O
what	O
happens	O
when	O
the	O
sequence	O
numbers	O
reach	O
the	O
end	O
of	O
the	O
numbering	O
space	O
.	O
</s>
