Clarification Required regarding the Context Replication
Anil Maguluri <[email protected]> Fri, 25 Jun 2010 17:39:13 +0530
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Hi All,
I am implementing the Context Replication mechanism for TCP (ROHCv2 Profil=
e-6).
Please clarify me whether my understanding is right or not.
1. When Base CID will be same as CID ?
As per my understanding the scenario will be: All the CID's are used at th=
e compressor
and it received a new flow. At that time compressor will check which CID i=
s idle, so that
it can use that CID for the new flow instead of sending as Profile-4 or Pr=
ofile-0 based on
the supported profiles.
a. Is my understanding is right?
b. Is there any other scenario where Base CID =3D CID?
c. Should I reset the compressor/decompressor context (Mode, State, =
Counters) if the
Base CID =3D CID?
As per my understanding, we should not reset the context (Mode, State, Cou=
nters).
"RFC 4996,
6.1.1. Master Sequence Number (MSN):
When the MSN is initialized, it SHOULD be initialized to a random value. T=
he compressor should
only initialize a new MSN for the initial IR or IR-CR packet sent for a CI=
D that corresponds to a
context that is not already associated with this profile. In other words, =
if the compressor reuses
the same CID to compress many TCP flows one after the other, the MSN is no=
t reinitialized but
rather continues to increment monotonically.
For context replication, the compressor does not use the MSN of the base c=
ontext when sending
the IR-CR packet, unless the replication process overwrites the base conte=
xt (i.e., Base CID =3D=3D CID).
Instead, the compressor uses the value of the MSN if it already exists in =
the ROHC-TCP context
being associated with the new flow (CID); otherwise, the MSN is initialize=
d to a new value.
"
d. Should we start the Heuristics for the new flow if BCID =3D CID?
As per my understanding, we should not start the Heuristics in case of BCI=
D =3D CID, but we should do the Heuristics is BCID !=3D CID?
Is my understanding is right?
Thanks for your support.
Regards,
Anil Kumar Maguluri
________________________________
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<p class=3D"MsoNormal">Hi All,<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p> </o:p></p>
<p class=3D"MsoNormal">I am implementing the Context Replication mechanism=
for TCP (ROHCv2 Profile-6).<o:p></o:p></p>
<p class=3D"MsoNormal">Please clarify me whether my understanding is right=
or not.<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p> </o:p></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in;text-indent:-.25i=
n;
mso-list:l0 level1 lfo1">
<![if !supportLists]><span style=3D"mso-list:Ignore">1.<span style=3D"font=
:7.0pt "Times New Roman"">
</span></span><![endif]>When Base CID will be same as CID ?<o:p></o:p></p>=
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in">As per my unders=
tanding the scenario will be: All the CID’s are used at the compress=
or<o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in">and it received =
a new flow. At that time compressor will check which CID is idle, so that<=
o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in">it can use that =
CID for the new flow instead of sending as Profile-4 or Profile-0 based on=
<o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in">the supported pr=
ofiles. <o:p>
</o:p></p>
<p class=3D"MsoListParagraph" style=3D"text-indent:-.25in;mso-list:l1 leve=
l1 lfo2"><![if !supportLists]><span style=3D"mso-list:Ignore">a.<span styl=
e=3D"font:7.0pt "Times New Roman"">  =
;
</span></span><![endif]>Is my understanding is right? <o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"text-indent:-.25in;mso-list:l1 leve=
l1 lfo2"><![if !supportLists]><span style=3D"mso-list:Ignore">b.<span styl=
e=3D"font:7.0pt "Times New Roman"">  =
;
</span></span><![endif]>Is there any other scenario where Base CID =3D CID=
?<o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"text-indent:-.25in;mso-list:l1 leve=
l1 lfo2"><![if !supportLists]><span style=3D"mso-list:Ignore">c.<span styl=
e=3D"font:7.0pt "Times New Roman"">  =
;
</span></span><![endif]>Should I reset the compressor/decompressor context=
(Mode, State, Counters) if the
<o:p></o:p></p>
<p class=3D"MsoListParagraph">Base CID =3D CID? <o:p></o:p></p>
<p class=3D"MsoListParagraph">As per my understanding, we should not reset=
the context (Mode, State, Counters).<o:p></o:p></p>
<p class=3D"MsoListParagraph"><i>“RFC 4996, <o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>6.1.1. Master=
Sequence Number (MSN):<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i><o:p> </=
o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>When the MSN =
is initialized, it SHOULD be initialized to a random value. The compressor=
should
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>only initiali=
ze a new MSN for the initial IR or IR-CR packet sent for a CID that corres=
ponds to a
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>context that =
is not already associated with this profile. In other words, if the
<b>compressor reuses <o:p></o:p></b></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><b><i>the same C=
ID to compress many TCP flows one after the other, the MSN is not reinitia=
lized but
<o:p></o:p></i></b></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><b><i>rather con=
tinues to increment monotonically</i></b><i>.
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i><o:p> </=
o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>For context r=
eplication, the compressor does not use the MSN of the base context when s=
ending
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>the IR-CR pac=
ket, unless the replication process overwrites the base context (i.e., Bas=
e CID =3D=3D CID).
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>Instead, the =
compressor uses the value of the MSN if it already exists in the ROHC-TCP =
context
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:1.0in"><i>being associa=
ted with the new flow (CID); otherwise, the MSN is initialized to a new va=
lue.
<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in;text-indent:.25in=
"><i>“<o:p></o:p></i></p>
<p class=3D"MsoListParagraph" style=3D"text-indent:-.25in;mso-list:l1 leve=
l1 lfo2"><![if !supportLists]><span style=3D"mso-list:Ignore">d.<span styl=
e=3D"font:7.0pt "Times New Roman"">  =
;
</span></span><![endif]>Should we start the Heuristics for the new flow if=
BCID =3D CID?<o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in;text-indent:.25in=
">As per my understanding, we should not start the Heuristics in case of B=
CID =3D CID, but we should do the Heuristics is BCID !=3D CID?
<o:p></o:p></p>
<p class=3D"MsoListParagraph" style=3D"margin-left:.25in;text-indent:.25in=
">Is my understanding is right?<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p> </o:p></p>
<p class=3D"MsoNormal"><o:p> </o:p></p>
<p class=3D"MsoNormal">Thanks for your support.<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p> </o:p></p>
<p class=3D"MsoNormal">Regards,<o:p></o:p></p>
<p class=3D"MsoNormal">Anil Kumar Maguluri<o:p></o:p></p>
</div>
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