Does a ping of 1496 work, but not 1497? Remember in Q-in-Q the four-byte overhead, on our 3560s we need to set the system MTU to 1504. Not sure if that is the same problem or not, but you should define exactly where the break in size first as part of your troubleshooting.
Les On Sun, May 12, 2013 at 5:55 PM, Eric campbell <[email protected]>wrote: > First I would apologize to the other poster for inadvertently Hijacking > his thread. > > > I will start a new thread at this point and maybe That will work. > > > Folks, > > I just want to start off by saying thanks to all of the regulars in the > group for the consistent knowledge sharing. > > I am a long time Lurker, but I have stumbled onto something which has me > puzzled to say the least. > > I am attempting to create a bridge domain between two interfaces on an > ASR 1006 and am running into a strange MTU issue. > > > Everything is working fine I am tunneling my q-in-q/802.1q traffic > popping and pushing the necessary tags and what not, however when I try > to ping accross it using a 1500 byte packet with the df bit set i > cannot. I can ping across it with a 1400 byte packet but of course this > is not the magic number. > > I have tried setting the MTU at the > interfaces involved (gig interfaces) but cannot for the life of me > figure out why this is happening. This happens with a single tag as well > as a stack of them. I do not have a BDI interface at the moment, but I > am not sure i really need one since I am transiting the box. The only > thing that i am able to think of at the moment is some sort of system > wide MTU setting. This may become a no duh moment for me in the end, but > I cannot find the command if it exists. Any guidance would be > appreciated. If there is any information that is lacking let me know and > i will get it out here. > > > This is a rather small test environment at the moment. > > I have an Adtran 8044 - directly to the ASR on gig 0/1/1 the ASR then > bridges this traffic to the interface Gig 0/1/2 - which then places it on > the wire as a single tagged trunk going into a 6509 trunk port and finally > terminating on an SVI. On the other side of the Adtran is a simple laptop > connected to the 8044 which is where I am originating the 1500 byte pings > that terminate to the SVI on the 6509. > > The 8044 simply takes the packet in as a native packet in this case, > applies a 802.1q tag to it, and then ships it out a trunk port to the ASR. > The 8044 has a MTu set at 2000 on this port, The ASR has an interface level > MTU of 1600 and the 6509 has an MTU of 1500. Also I have tried it with the > MTu set at Max on the 6509 as well. Like I said I am sure that in a setup > as small as this the answer is staring me in the eye. > > Since the 6509 is receiving a trunk port off of the ASR with a single tag > applied I feel the problem is probably not there. The Adtran takes the > taffic in from the laptop at 1500 MTU and then applies its tag then > shipping it out. > > I have also tried performing this ping from a 7206 I have that is spare > set up like the laptop in this case using the same parameters. > > Thanks for assisting > > > > Thanks to all, > Eric > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > > http://onlinestudylist.com/mailman/listinfo/ccie_rs > -- Les Waller, Network Engineer ..:|:..:|:.. Home Page: *http://www.facebook.com/groups/325762454132531/* * *MBA, CISSP, CCNP/CCDA _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
