<s>
Segment	B-Protocol
routing	I-Protocol
,	O
a	O
form	O
of	O
computer	B-Architecture
networking	I-Architecture
,	O
is	O
a	O
modern	O
variant	O
of	O
source	B-Protocol
routing	I-Protocol
that	O
is	O
being	O
developed	O
within	O
the	O
and	O
IPv6	B-Protocol
working	O
groups	O
of	O
the	O
IETF	O
.	O
</s>
<s>
In	O
a	O
segment	B-Protocol
routed	O
network	O
,	O
an	O
ingress	O
node	O
may	O
prepend	O
a	O
header	B-General_Concept
to	O
packets	B-Protocol
that	O
contain	O
a	O
list	O
of	O
segments	O
,	O
which	O
are	O
instructions	O
that	O
are	O
executed	O
on	O
subsequent	O
nodes	O
in	O
the	O
network	O
.	O
</s>
<s>
These	O
instructions	O
may	O
be	O
forwarding	O
instructions	O
,	O
such	O
as	O
an	O
instruction	O
to	O
forward	O
a	O
packet	B-Protocol
to	O
a	O
specific	O
destination	O
or	O
interface	O
.	O
</s>
<s>
Segment	B-Protocol
routing	I-Protocol
works	O
either	O
on	O
top	O
of	O
a	O
MPLS	B-Protocol
network	O
or	O
on	O
an	O
IPv6	B-Protocol
network	O
.	O
</s>
<s>
In	O
an	O
MPLS	B-Protocol
network	O
,	O
segments	O
are	O
encoded	O
as	O
MPLS	B-Protocol
labels	B-Protocol
.	O
</s>
<s>
Under	O
IPv6	B-Protocol
,	O
a	O
new	O
header	B-General_Concept
called	O
a	O
Segment	B-Protocol
Routing	I-Protocol
Header	B-General_Concept
(	O
SRH	O
)	O
is	O
used	O
.	O
</s>
<s>
Segments	O
in	O
a	O
SRH	O
are	O
encoded	O
in	O
a	O
list	O
of	O
IPv6	B-Protocol
addresses	O
.	O
</s>
