Subject: Re: ICMP handling for a fragmented packet.
To: Charles M. Hannum <root@ihack.net>
From: Rohit Dhawan <rohit@samsung.com>
List: tech-net
Date: 03/19/2001 20:13:56
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Dear Charles & everyone,
I am developing a light weight protocol stack for a real time =
application. As one of the features of the stack, I need to develop a =
mechanism, wherein I can report to the application, which had sent a =
message to another task (on another card), if any errors occured in =
transmission.
Can somebody suggest an existing protocol which does a similar =
function or anything which might be helpful in this case.
Thx=20
Regards,
Rohit.
----- Original Message -----=20
From: "Charles M. Hannum" <root@ihack.net>
To: "Rohit Dhawan" <rohit@samsung.com>
Cc: "Charles M. Hannum" <root@ihack.net>; <tech-net@netbsd.org>
Sent: Monday, March 19, 2001 12:03 PM
Subject: Re: ICMP handling for a fragmented packet.
>=20
> On Mon, Mar 19, 2001 at 11:51:44AM +0530, Rohit Dhawan wrote:
> >=20
> > > You're thinking too hard. ICMP TIME EXCEEDED is basically ignored =
by
> > > a host, so the presence or absence of connection information in =
the
> > > packet is irrelevant.
> > >
> > TLL was just an example, my real concern is regarding the handling =
of ICMP
> > messages associated with fragments other than the first fragment, as =
they
> > donot have any information of the higher layer protocol.
>=20
> And the answer is the same. The ones we respond to are all either MTU
> related (and are used for host-based MTU discovery) or generate a
> host-specific response rather than a connection-specific response. =
The
> TCP/UDP/RDP header is not needed. I believe other systems follow the
> same rules.
>=20
Thx for your help - It has helped me improve my understanding of ICMP !
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<DIV><FONT face=3DArial size=3D2>Dear Charles & =
everyone,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2> I am developing a =
light weight=20
protocol stack for a real time application. As one of the features of =
the stack,=20
I need to develop a mechanism, wherein I can report to the application, =
which=20
had sent a message to another task (on another card), if any errors =
occured in=20
transmission.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2> Can somebody suggest =
an existing=20
protocol which does a similar function or anything which might be =
helpful=20
in this case.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Thx </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Regards,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Rohit.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>----- Original Message ----- </FONT>
<DIV><FONT face=3DArial size=3D2>From: "Charles M. Hannum" <</FONT><A =
href=3D"mailto:root@ihack.net"><FONT face=3DArial=20
size=3D2>root@ihack.net</FONT></A><FONT face=3DArial =
size=3D2>></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>To: "Rohit Dhawan" <</FONT><A=20
href=3D"mailto:rohit@samsung.com"><FONT face=3DArial=20
size=3D2>rohit@samsung.com</FONT></A><FONT face=3DArial =
size=3D2>></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Cc: "Charles M. Hannum" <</FONT><A=20
href=3D"mailto:root@ihack.net"><FONT face=3DArial=20
size=3D2>root@ihack.net</FONT></A><FONT face=3DArial size=3D2>>; =
<</FONT><A=20
href=3D"mailto:tech-net@netbsd.org"><FONT face=3DArial=20
size=3D2>tech-net@netbsd.org</FONT></A><FONT face=3DArial =
size=3D2>></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Sent: Monday, March 19, 2001 12:03 =
PM</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Subject: Re: ICMP handling for a =
fragmented=20
packet.</FONT></DIV></DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>> <BR>> On Mon, Mar 19, 2001 at =
11:51:44AM=20
+0530, Rohit Dhawan wrote:<BR>> > <BR>> > > You're =
thinking too=20
hard. ICMP TIME EXCEEDED is basically ignored by<BR>> > > =
a host,=20
so the presence or absence of connection information in the<BR>> > =
>=20
packet is irrelevant.<BR>> > ><BR>> > TLL was just an =
example, my=20
real concern is regarding the handling of ICMP<BR>> > messages =
associated=20
with fragments other than the first fragment, as they<BR>> > donot =
have=20
any information of the higher layer protocol.<BR>> <BR>> And the =
answer is=20
the same. The ones we respond to are all either MTU<BR>> =
related (and=20
are used for host-based MTU discovery) or generate a<BR>> =
host-specific=20
response rather than a connection-specific response. The<BR>>=20
TCP/UDP/RDP header is not needed. I believe other systems follow=20
the<BR>> same rules.<BR>> </FONT></DIV>
<DIV> </DIV>
<DIV><FONT color=3D#800000 face=3DArial size=3D2><EM><STRONG>Thx for =
your help - It=20
has helped me improve my understanding of ICMP =
!</STRONG></EM></FONT></DIV>
<DIV> </DIV></BODY></HTML>
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