Re: Question about IGMP host implementation

"Beeram, Suresh KumarReddy" <[email protected]> Wed, 12 Oct 2011 11:46:53 +0100
Newsgroups gmane.ietf.magma
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Hi Indranil,
Why the Query coming from VLAN-A has to be forwarded to VLAN-B?
In general switch should forward the Query packets to all the ports in same=
 VLAN(VLAN-A). Hosts receiving the Query can reply to the query even the so=
urce address of the Query is in different subnet.
Is there anything I am missing in your reply???
Thanks
B S  Reddy

From: [email protected] [mailto:[email protected]] On Behalf Of I=
ndranil Bhattacharya
Sent: Wednesday, October 12, 2011 2:06 PM
To: Kunal Shah
Cc: [email protected]
Subject: Re: [magma] Question about IGMP host implementation

Hi Kunal,

             Yes it should. The scenario that I have in mind is a switch wh=
ose mrouter interface is in vlanA and igmp joins are received on an interfa=
ce in vlanB. In this case, query coming from vlanA(different subnet) has to=
 be answered by hosts in vlanB.

Thanks,
Indranil
On Wed, Oct 12, 2011 at 6:08 AM, Kunal Shah <[email protected]<mailto=
:[email protected]>> wrote:
Hi all,

Can an IGMPv2 host respond to a general query originated from a subnet othe=
r then its own?? RFC 2236 states:

""query received" occurs when the host receives either a valid
     General Membership Query message, or a valid Group-Specific
     Membership Query message.  To be valid, the Query message must be
     at least 8 octets long, and have a correct IGMP checksum.  The
     group address in the IGMP header must either be zero (a General
     Query) or a valid multicast group address (a Group-Specific Query)"

There is no requirement for the source address to be on the same subnet as =
the host.

Thanks,
Kunal


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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-US link=3Dblue vli=
nk=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span style=3D'f=
ont-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Indran=
il,<o:p></o:p></span></p><p class=3DMsoNormal><span style=3D'font-size:11.0=
pt;font-family:"Calibri","sans-serif";color:#1F497D'>Why the Query coming f=
rom VLAN-A has to be forwarded to VLAN-B?<o:p></o:p></span></p><p class=3DM=
soNormal><span style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif"=
;color:#1F497D'>In general switch should forward the Query packets to all t=
he ports in same VLAN(VLAN-A). Hosts receiving the Query can reply to the q=
uery even the source address of the Query is in different subnet.<o:p></o:p=
></span></p><p class=3DMsoNormal><span style=3D'font-size:11.0pt;font-famil=
y:"Calibri","sans-serif";color:#1F497D'>Is there anything I am missing in y=
our reply???<o:p></o:p></span></p><p class=3DMsoNormal><span style=3D'font-=
size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks<o:p></=
o:p></span></p><p class=3DMsoNormal><span style=3D'font-size:11.0pt;font-fa=
mily:"Calibri","sans-serif";color:#1F497D'>B S&nbsp; Reddy<o:p></o:p></span=
></p><p class=3DMsoNormal><span style=3D'font-size:11.0pt;font-family:"Cali=
bri","sans-serif";color:#1F497D'><o:p>&nbsp;</o:p></span></p><div style=3D'=
border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p cl=
ass=3DMsoNormal><b><span style=3D'font-size:10.0pt;font-family:"Tahoma","sa=
ns-serif"'>From:</span></b><span style=3D'font-size:10.0pt;font-family:"Tah=
oma","sans-serif"'> [email protected] [mailto:[email protected]] =
<b>On Behalf Of </b>Indranil Bhattacharya<br><b>Sent:</b> Wednesday, Octobe=
r 12, 2011 2:06 PM<br><b>To:</b> Kunal Shah<br><b>Cc:</b> [email protected]<br=
><b>Subject:</b> Re: [magma] Question about IGMP host implementation<o:p></=
o:p></span></p></div><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><div><p clas=
s=3DMsoNormal>Hi Kunal,<o:p></o:p></p></div><div><p class=3DMsoNormal>&nbsp=
;<o:p></o:p></p></div><div><p class=3DMsoNormal>&nbsp;&nbsp;&nbsp;&nbsp;&nb=
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Yes it should. The scenario t=
hat I have in mind is a switch whose mrouter interface is in vlanA and igmp=
 joins are received on an interface in vlanB. In this case, query coming fr=
om vlanA(different subnet) has to be answered by hosts in vlanB.<o:p></o:p>=
</p></div><div><p class=3DMsoNormal>&nbsp;<o:p></o:p></p></div><div><p clas=
s=3DMsoNormal>Thanks,<o:p></o:p></p></div><div><p class=3DMsoNormal style=
=3D'margin-bottom:12.0pt'>Indranil<o:p></o:p></p></div><div><p class=3DMsoN=
ormal>On Wed, Oct 12, 2011 at 6:08 AM, Kunal Shah &lt;<a href=3D"mailto:kun=
[email protected]">[email protected]</a>&gt; wrote:<o:p></o:p></p>=
<div><div><p class=3DMsoNormal><span style=3D'font-size:10.0pt;font-family:=
"Arial","sans-serif"'>Hi all,<o:p></o:p></span></p></div><div><p class=3DMs=
oNormal><span style=3D'font-size:10.0pt;font-family:"Arial","sans-serif"'>&=
nbsp;<o:p></o:p></span></p></div><div><p class=3DMsoNormal><span style=3D'f=
ont-size:10.0pt;font-family:"Arial","sans-serif"'>Can an IGMPv2 host respon=
d to a general query originated from a subnet other then its own?? RFC 2236=
 states: <o:p></o:p></span></p></div><div><p class=3DMsoNormal><span style=
=3D'font-size:10.0pt;font-family:"Arial","sans-serif"'>&nbsp;<o:p></o:p></s=
pan></p></div><div><p class=3DMsoNormal><span style=3D'font-size:10.0pt;fon=
t-family:"Arial","sans-serif"'>&quot;</span><span style=3D'font-size:10.0pt=
;font-family:"Courier New"'>&quot;query received&quot; occurs when the host=
 receives either a valid<br>&nbsp;&nbsp;&nbsp;&nbsp; General Membership Que=
ry message, or a valid Group-Specific<br>&nbsp;&nbsp;&nbsp;&nbsp; Membershi=
p Query message.&nbsp; To be valid, the Query message must be<br>&nbsp;&nbs=
p;&nbsp;&nbsp; at least 8 octets long, and have a correct IGMP checksum.&nb=
sp; The<br>&nbsp;&nbsp;&nbsp;&nbsp; group address in the IGMP header must e=
ither be zero (a General<br>&nbsp;&nbsp;&nbsp;&nbsp; Query) or a valid mult=
icast group address (a Group-Specific Query)</span><span style=3D'font-size=
:10.0pt;font-family:"Arial","sans-serif"'>&quot; <o:p></o:p></span></p></di=
v><div><p class=3DMsoNormal><span style=3D'font-size:10.0pt;font-family:"Ar=
ial","sans-serif"'>&nbsp;<o:p></o:p></span></p></div><div><p class=3DMsoNor=
mal><span style=3D'font-size:10.0pt;font-family:"Arial","sans-serif"'>There=
 is no requirement for the source address to be on the same subnet as the h=
ost.<o:p></o:p></span></p></div><div><p class=3DMsoNormal><span style=3D'fo=
nt-size:10.0pt;font-family:"Arial","sans-serif"'>&nbsp;<o:p></o:p></span></=
p></div><div><p class=3DMsoNormal><span style=3D'font-size:10.0pt;font-fami=
ly:"Arial","sans-serif"'>Thanks,<o:p></o:p></span></p></div><div><p class=
=3DMsoNormal><span style=3D'font-size:10.0pt;font-family:"Arial","sans-seri=
f"'>Kunal<o:p></o:p></span></p></div><div><p class=3DMsoNormal><span style=
=3D'font-size:10.0pt;font-family:"Arial","sans-serif"'>&nbsp;<o:p></o:p></s=
pan></p></div></div><p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><br=
>_______________________________________________<br>magma mailing list<br><=
a href=3D"mailto:[email protected]">[email protected]</a><br><a href=3D"https://w=
ww.ietf.org/mailman/listinfo/magma" target=3D"_blank">https://www.ietf.org/=
mailman/listinfo/magma</a><o:p></o:p></p></div><p class=3DMsoNormal><o:p>&n=
bsp;</o:p></p></div></body></html>=

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