Priscilla Oppenheimer wrote: > > 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.
That's interesting. I always thought a source quench was reserved for scenarios where the receiver was getting hammered (maybe a server on an FE port drowning a PC on a 10 Mbps port). I would think it would be just as costly to generate a source quench response as it would be to generate an ICMP echo reply. Or is the pinging device supposed to immediately stop repeated pings altogether, thereby ensuring that the receiver was only going to need to send one response vs. possibly many? If so, does that really happen in practice? > > 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? > > > > > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=57891&t=57870 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
