<s>
Multicast	B-Protocol
router	I-Protocol
discovery	I-Protocol
(	O
MRD	O
)	O
provides	O
a	O
general	O
mechanism	O
for	O
the	O
discovery	O
of	O
multicast	O
routers	O
on	O
an	O
IP	B-Protocol
network	I-Protocol
.	O
</s>
<s>
For	O
IPv4	B-Protocol
,	O
the	O
mechanism	O
is	O
based	O
on	O
IGMP	B-Protocol
.	O
</s>
<s>
For	O
IPv6	B-Protocol
the	O
mechanism	O
is	O
based	O
on	O
MLD	B-Protocol
.	O
</s>
<s>
Multicast	B-Protocol
router	I-Protocol
discovery	I-Protocol
is	O
defined	O
by	O
RFC	O
4286	O
.	O
</s>
