We have a problem with SnapMirror operations in NetApp, we are replicating volumes from 1 filer to a 2nd filer located on a different site. The connection goes through 2 FW's and several routers/switches. The problem is that the connection is established, data is being transferred, and at some random point (could be after 5GB of data transfer or 15 GB, doesn't matter), the data replication fails.
After consulting with NetApp tech support, I've run a packet trace (pktt) and from the results (viewed in wireshark) netapp concluded that the problem is with MSS, something on the way is modifying the packets and causing the MSS to be lowered from 1460 to 1406, here are the lines from the trace log:
X.X.X.X = Destination FW, the destination netapp filer to which the data is replicated is behind that FW.
172.16.0.13 = source filer located behind a different FW on a different site.
I would like to consult with a network specialist here if there's any sense in NetApp claim regarding the packet modification according to the different MSS values seen in the trace logs, this is what, according to NetApp, is causing the failures.