IGP routing protocols will not advertise any interface network address that
is physically down.
This example shows two routers running RIP between
each other.

Debugs
and Verification
Figure
shows
that interface Ethernet 0 is down.
Figure
shows the output
from the debug ip rip command. In this
debug, router R1 is not sending or receiving any RIP
updates because Layer 2 is down. There is no output from this
debug command because of this problem.
Solution
RIP cannot send or receive any routes if Layer 2 is
down. To correct this problem, Layer 2 or Layer 1 must be corrected.
Figure
shows the
interface Ethernet 0 after fixing the Layer 2 problem.
Figure
shows the
routing table of router R2.