Unreasonable MTU configuration results in the error as copying files

Publication Date:  2012-07-27 Views:  92 Downloads:  0
Issue Description
Networking:
Server-8016--ne40--ne16--6503--client.

Phemomenon:client browses the files on the server,but as copying files from server,there is no responses for a long time, the copying fails.
NE40, NE16 are PEs,8016 transers at layer 2, NE40 established sub-interface to identify vlan,and the sub-interfac belongs to the private network VPN.
Alarm Information

None

Handling Process

1.It is normal for client to communicate with server 1471 byte packets via non-fragement mode, while 1472 cannot.
2.The mtu configuration for ne40 to communicate with server:
   interface Ethernet1/0/3.50
    vlan-type dot1q vid 50
     mtu 1499
     undo shutdown
    ip binding vpn-instance xzdcn_ziyuanguanli

The problem is solved after modify mtu to 1500.

Root Cause
Client browses the files of server, they are all the small packets,but as copying files from server, there will be 1500-bytes packets, surpassing the MTU of NE40 and are discarded by NE40. The copying fails.
Suggestions
None

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