Hale Nick wrote:
> 
> Scenario:
> Cat 6509 (SW 5.5(16)) with MSFC (Version 12.1(1)E). 
> The MSFC has over 15 vlans. 
> The vlan in question has over 60 active devices.
> There is one device that when pinged (datagram size does not
> change the result) it produces a source quench.

Source quench comes from the host (end device) that you're pinging. That
device is probably just too busy to respond to pings. This isn't necessarily
a problem. The definition of "too busy" is operating system and
version-dependent.

In the olden days, routers used to send source quench. That was determined
to be a useless feature. Per RFC 1812, "Requirements for IP Version 4
Routers," a router should not originate source quench messages. A host may
send source quench messages, however, per RFC 1122, "Requirements for
Internet Hosts."

What is the device that you're pinging? What's the operating system? What
version? Some operating systems send source quench almost immediately after
just a couple pings. For example, Mac OS used to do this. I can't remember
which version, but it's pre-Mac OS X, e.g. pre-UNIX.

> All other devices on the vlan respond to pings ok.
> From the command prompt on my desktop the result is the same.
> From a unix server the ping results are normal.

Are you saying that when you ping from a UNIX server to the device in
question, you don't get a source quench? That seems weird. But it could
happen if the UNIX ping sends less frequently and so doesn't trigger the
recipient to go into quenching mode.

> From the switch the ping results are normal. 

Pinging from the switch doesn't result in source quench either? Is it just
when you ping from the command prompt on your desktop? That ping must send
more quickly. Try telling the ping to let more time elapse between each
ping. If it's the DOS ping, you can't do this, though. The -w option is only
a timeout between unsuccessful pings, unfortunately.

> Specifications of the server are unknown.

What server? If you mean specifications of the ping recipient are unknown,
then the reason you're seeing this result will be unknown also. :-)

> The port that the device connects to is set to 100/full and has
> no errors.
> The MSFC and switch resources are fine
> The vlan interface does not have any errors.
> The switch and router module are both heavily used and it
> appears this issue is only happening to the one device.

Yes, it would be device-dependent. Source quench comes from the recipient.
It just means it's busy, as I mentioned.

_______________________________

Priscilla Oppenheimer
www.troubleshootingnetworks.com
www.priscilla.com

> 
> 
> Can anyone tell me why this is happening?
> 
> 




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