<s>
Reliable	B-Protocol
Event	I-Protocol
Logging	I-Protocol
Protocol	I-Protocol
(	O
RELP	O
)	O
,	O
a	O
networking	O
protocol	O
for	O
computer	B-Application
data	I-Application
logging	I-Application
in	O
computer	O
networks	O
,	O
extends	O
the	O
functionality	O
of	O
the	O
syslog	B-Protocol
protocol	O
to	O
provide	O
reliable	O
delivery	O
of	O
event	O
messages	O
.	O
</s>
<s>
RELP	O
uses	O
TCP	B-Protocol
for	O
message	O
transmission	O
.	O
</s>
<s>
When	O
a	O
connection	O
aborts	O
,	O
TCP	B-Protocol
cannot	O
reliably	O
detect	O
whether	O
the	O
last	O
messages	O
sent	O
have	O
actually	O
reached	O
their	O
destination	O
.	O
</s>
<s>
Unlike	O
the	O
syslog	B-Protocol
protocol	O
,	O
RELP	O
works	O
with	O
a	O
backchannel	B-Protocol
which	O
conveys	O
information	O
back	O
to	O
the	O
sender	O
about	O
messages	O
processed	O
by	O
the	O
receiver	O
.	O
</s>
<s>
RELP	O
was	O
developed	O
in	O
2008	O
as	O
a	O
reliable	O
protocol	O
for	O
rsyslog-to-rsyslog	O
communication	O
.	O
</s>
<s>
As	O
RELP	O
designer	O
Rainer	O
Gerhards	O
explains	O
,	O
the	O
lack	O
of	O
reliable	O
transmission	O
in	O
industry-standard	O
syslog	B-Protocol
was	O
a	O
core	O
motivation	O
to	O
create	O
RELP	O
.	O
</s>
<s>
Originally	O
,	O
RFC	O
3195	O
syslog	B-Protocol
was	O
considered	O
to	O
take	O
up	O
this	O
part	O
in	O
rsyslog	B-Protocol
,	O
but	O
it	O
suffered	O
from	O
high	O
overhead	O
and	O
missing	O
support	O
for	O
new	O
IETF	O
syslog	B-Protocol
standards	O
(	O
which	O
have	O
since	O
been	O
published	O
as	O
RFC	O
5424	O
,	O
but	O
were	O
not	O
named	O
at	O
that	O
time	O
)	O
.	O
</s>
<s>
While	O
RELP	O
was	O
initially	O
meant	O
solely	O
for	O
rsyslog	B-Protocol
use	O
,	O
it	O
became	O
adopted	O
more	O
widely	O
.	O
</s>
<s>
While	O
RELP	O
is	O
still	O
not	O
formally	O
standardized	O
,	O
it	O
has	O
evolved	O
into	O
an	O
industry	O
standard	O
for	O
computer	O
logging	B-Application
.	O
</s>
<s>
RELP	O
is	O
inspired	O
by	O
RFC	O
3195	O
syslog	B-Protocol
and	O
RFC	O
3080	O
.	O
</s>
<s>
The	O
current	O
version	O
of	O
RELP	O
does	O
not	O
specify	O
native	O
TLS	B-Protocol
support	O
.	O
</s>
