Hello Erick, My understanding is that, with the ethernet MTU being 1500, pinging with the datagram size of bigger than 1500 byte (with the non-fragment bit set) won't leave my NIC card. I tried the command anyway, and I got an error message saying that the packet needs to be fragmented first but DF is set. When tryed the same from the router, it failed. But I am guessing it's probably because of the same reason. The packet has to go out the ethernet interface and 1500+ with NF set will not go out the interface because it exceeds the MTU.
Sean Erick B. wrote: > > Try this ping from the nodes: > > ping -f -l 1600 node-on-other-side-of-ATM > > If this doesn't ping, then the ATM connection is only > letting 1500 through. The Ethernet router interface is > fragmenting packets to 1500 bytes (1600 packet becomes > 2 packets) from the nodes. When doing a ping from the > router, if using ATM interface as source then it is > going across ATM as 1600 bytes. > > --- Sean Kim wrote: > > Hello Erick, > > > > If that's the case, than wouldn't I have problem > > pinging any nodes (with > > over 1500 byte datagram) across the ATM link? > > But I do not have pinging any other nodes. It only > > happens, when I am > > sitting on my router pinging the other router's > > interface and vice-versa... > > > > Sean > > > > > > > > Erick B. wrote: > > > > > > The ATM connection (provider) is probably limiting > > > payload size to 1500. They may doing some form of > > > traffic policing - common these days. Ethernet LAN > > MTU > > > is 1500 so there really isn't a need to send > > greater > > > than that across ATM in this case. > > > > > > --- Sean Kim wrote: > > > > Hello, > > > > > > > > My company has this 3rd party connection through > > > > ATM. The ATM TA has an > > > > ethernet outlet which is and connected to our > > core > > > > router. Our parner > > > > company is connected with anATM module on their > > > > router. > > > > > > > > Recently, I was told by our partner company that > > > > they were running ping test > > > > and they could not ping my ethernet interface > > (on > > > > the core router) with > > > > datagram over 1500 byte. > > > > > > > > From both the router itself and my workstation, > > I > > > > pinged my own interface > > > > with 1600 byte, and I was able to ping it. But > > when > > > > I pinged my partner > > > > company's interface with 1600 byte, it failed. > > > > > > > > In general it seems that pinging from other > > nodes, > > > > there is no problem, but > > > > sitting on the routers itself, pinging the other > > > > routers interface with the > > > > datagram size of over 1500 is failing. > > > > > > > > There isn't any problem with connection of > > > > performance. But I am very > > > > curious about why this is happening. > > > > Does anybody have any idea why this would > > happen? > > > > Or can anybody give me a > > > > clue as to how to approach this problem? > > > > > > > > Thank you in advance. > > > > > > > > Sean Kim > > > [EMAIL PROTECTED] > > > > > > > > > __________________________________________________ > > > Do you Yahoo!? > > > Yahoo! Shopping - Send Flowers for Valentine's Day > > > http://shopping.yahoo.com > [EMAIL PROTECTED] > > > __________________________________________________ > Do you Yahoo!? > Yahoo! Shopping - Send Flowers for Valentine's Day > http://shopping.yahoo.com > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=63143&t=63085 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
