ICMP & source quench message

[TOMAS BERNABEU]

We have detected in one of our machines with HP-ux 11,00, that are sent packages "source quench" like answer to packages ICMP_REQUEST. We are trying to find out the cause and we have found that it can be related to processes that listen to and open SOCKET_RAW.

1. - that source can cause the appearance of the messages quench?
2. - As we can find out that processes are listening in socket-raw?
3. - If he is some of these processes, as of them?

thanks

Tom

[Sebastian Galeski_1]

Some information for You about this message:
'Problem Description
Are these Source Quench Messages something that I need to worry about?
Solution
This problem has been identified and is addressed in SR 5003435396. This
problem will be fixed in the 11.01 version of the HP-UX operating
system. These messages can be safely ignored as they have absolutely no
impact on the operating system (performance or otherwise). Alternatively
these messages can be prevented by disabling source quench. For more information see
the sections below.
What is causing these messages?
At 11.0 the Streams Xport layer now passes the ICMP echo request to any
other process that has a socket open and bound to raw IP. The rpcd
rpcd/dced deamon opens a raw socket to listen to ICMP messages. This raw
socket is open by icmp_monitor routine of rpcd. The main function of
this routine is to check for error messages from dce servers registered
in endpoint database of the host and it checks the socket every 5
minutes. It does not respond to or use the ICMP echo requests However
the socket queue becomes filled during the 5 minute delay causing the
source quench message. The fix being implemented in 11.01 will be to
increase the buffer size to 128k and shorten the wait interval from 5
minutes to 2 minutes thereby flushing the queue of these unwanted
messages before the queue becomes filled.
Why is it safe to ignore these messages or to turn them off?
A good disscussion of this is in TCPIP Illustrated Volume 1 (by Richard
Stevens) page 160-162
Here is a Clip from page 161:
"Although RFC 1009 [Braden and Postal 1987] requires a router to
generate source quenches when it runs out of buffers, the new router
Requirements RFC [Almquist 1993] changes this and says that a router
must not originate source quench errors. The current feeling is to
deprecate the source quench error, since it consumes network bandwidth
and is an ineffective and unfair fix for congestion."
Also see RFC 1812 section 4.3.3.3 Source Quench (this is good
discussion)

Use next command to switch it off
ndd -set /dev/ip ip_send_source_quench 0'

or edit file /etc/rc.config.d/nddconf
and enter
TRANSPORT_NAME[0]=ip
NDD_NAME[0]=ip_send_source_quench
NDD_VALUE[0]=0

after reboot it will work
hope it help you

[MANOJ SRIVASTAVA]

Hi Tomas


Here it goes:

This problem has been identified and is addressed in SR 5003435396.
This problem will be fixed in the 11.01 version of the HP-UX operating
system. These messages can be safely ignored as they have absolutely no
impact on the operating system (performance or otherwise). Alternatively
these messages can be prevented by disabling source quench. For more
information see the sections below.

What is causing these messages?

At 11.0 the Streams Xport layer now passes the ICMP echo request to any
other process that has a socket open and bound to raw IP. The rpcd
rpcd/dced deamon opens a raw socket to listen to ICMP messages. This raw
socket is open by icmp_monitor routine of rpcd. The main function of
this routine is to check for error messages from DCE servers registered
in endpoint database of the host and it checks the socket every 5
minutes. It does not respond to or use the ICMP echo requests; however,
the socket queue becomes filled during the 5-minute delay causing the
source quench message. The fix being implemented in 11.01 will be to
increase the buffer size to 128 K and shorten the wait interval from 5
minutes to 2 minutes, thereby flushing the queue of these unwanted
messages before the queue becomes filled.

Why is it safe to ignore these messages or to turn them off?

A good disscussion of this is in TCPIP Illustrated Volume 1,
by Richard Stevens, pages 160-162.Here is an excerpt from page 161:

Although RFC 1009 [Braden and Postal 1987] requires a
router to generate source quenches when it runs out of
buffers, the new router requirements RFC [Almquist 1993]
changes this and says that a router must not originate
source quench errors. The current feeling is to deprecate
the source quench error, since it consumes network bandwidth
and is an ineffective and unfair fix for congestion.

Also, see RFC 1812, section 4.3.3.3 Source Quench for a good
discussion of the issues.

Also RFC 2001 has discussion on Congestion and why TCP should handle
this not ICMP:

Congestion avoidance and slow start are independent
algorithms with different objectives. But when congestion
occurs, TCP must slow down its transmission rate of packets
into the network and then invoke slow start to get things
going again. In practice, they are implemented together.

Exactly how do I disable source quench?

You can disable source quench in HP-UX 11.0 by executing this command:

ndd -set /dev/ip ip_send_source_quench 0

To disable Source Quench so that it can survive a reboot,

modify the /etc/rc.config.d/nddconf file as follows :
TRANSPORT_NAME[X]=ip
NDD_NAME[X]=ip_send_source_quench
NDD_VALUE[X]=0

Where X is the next logical numerical sequence in a table
of values, with X starting at 0.
--------------------------------------------------

DCE patch and dependencies:

3 PHCO_23651 fsck_vxfs(1M) cumulative patch
2 PHCO_23876 cumulative SAM/ObAM patch
1 PHCO_25883 cumulative 10.20 libc compatibility support
3 PHKL_18543 PM/VM/UFS/async/scsi/io/DMAPI/JFS/perf patch
3 PHKL_20016 2nd CPU not recognized in G70/H70/I70
3 PHKL_23956 Profile, virtual timers and disabling fix
3 PHKL_24027 VxFS 3.1 cumulative patch
1 PHKL_25906 Probe,IDDS,PM,VM,PA-8700,asyncio,T600,FS
1 PHKL_25999 syscall, msem_lock, umask cumulative patch
2 PHSS_21614 HP DCE/9000 1.7 Runtime cumulative patch


You may like to do like this
ndd -set /dev/ip ip_send_source_quench 0


this is solve the issue.

You may like to look at:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xe4727bb04b5cd611abdb0090277a778c,00.html


Manoj Srivastava