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Why TCP/IP Connection Breaking down?

SAP User || 01 Apr 2016 6:02 pm || 4

Hello Experts,

When we are sending or receiving larger data packets, running TCP/IP connections break down. And the data is about (2000 bytes up to 5000 bytes)

"connection to partner broken" at the sapgui

"Connection timed out" in the R/3-System

Kindly share the reason why we are getting this above scenario.

Thanks in advance.


  • 01 Apr 2016 6:06 pm Best Answer

    You are having this issue because applications send data-packets larger than the MTU-size of the underlying network these data-packets must be fragmented into serveral packets less than or equal MTU-size.

    These kind of problems belong to your specific TCP/IP configruation and are normally no SAP-Problems.

    In FDDI networks the normal MTU-Size is 4352 bytes. That can be verified using the command: netstat -i

    The normal ethernet packet size is about 1500 Bytes. So Routers between FDDI and Ethernet must fragment and defragment packets larger than 1500 Bytes. WAN-Lines may have other (smaller) MTU-Sizes.

    To check wether or not you have that problem you may use the niping program. (SAP Program)

    1. Start the niping server on the R/3-computer. (login as R/3-adm user)
    command: niping -s -I0 &
    2. Start the niping client on the frontend (PC)
    command: niping -c -B 5000 -H 

    You may vary the blocksize from 1000 Bytes up to 5000 Bytes. Please envolve your networking guys to solve that ploblem.

    It may be necessary to use network-analysers to check which component isn't able to do the fragmentation/defragmentation (IP-layer).

    May be the PC's TCP/IP-Stack isn't able to reassemble fragmented TCP/IP packets.

  • 01 Apr 2016 6:08 pm Helpful Answer

    There is One possibility is to set MTU-size to the smallest MTU of any data link that packets traverse between the PC and the R/3-Host.

    However the data sent by the SAP-applications depend on the amount of application-data and may vary in a wide range.

  • 06 Apr 2016 6:26 pm Helpful Answer

    The issue of TCP/IP break down is the result of the data packets sent by the application is larger than the MTU size of the underlying networks. The data packets must be fragmented into several packets whose size must be less than or equal to MTU-size.

    These problems belong to a specific TCP/IP configuration and are usually a no SAP Problem. In FDDI networks normal MTU-size is 4352 bytes and the normal Ethernet packet size is about 1500 bytes. So the routers between FDDI and Ethernet must fragment and defragment packets larger than 1500 bytes. We can use the NIPPING server to check if the problem persists or not.