Service Virtualization

How to control TCP response Packet Frame size? I receive from live system response divided to group of 1514 byte frames. But from VSE response is send in one or two frames with size of 45594 bytes. (see screenshot dump from wireshark) How to change that frame size??

My first question would be is the consuming application misbehaving when it receives the response?

If the consuming application is not complaining, I would not be overly concerned about what Wireshark is reporting.

I am no expert in this area -- and maybe one of the TCP gurus will chime in --, but TCP is a byte stream protocol.  So, the stream is being chunked into transmittable pieces of data, transmitted over the wire, and then reassembled on the other side. 

In the attached picture, I believe the 1514 packet size you are seeing is an Ethernet packet that is wrapping the actual a TCP packet data.  From what I understand, Ethernet packets are rarely larger than 1518 bytes.  Ethernet usually has a 14-byte header, IPv4 header is at least 20 and the TCP header should be about 20 bytes.  This leaves 1460 for the actual data. 1514 - (14+20+20) = 1460 which is consistent with the LEN=1460.

I see 'Unknown 100 OML' rather than TCP in the virtual service response. Also, the sequence numbers that are used to reassemble the packets (and/or request that a packet be resent) are missing.

When you created your TCP service, what Delimiters and Data Protocols did you use?  

Also, are these communications using A-bis over IP.  I found a reference to OML messages while trying to figure out what the response is.  If this is some type of vendor-specific protocol, you may need to develop a custom transport protocol handler.

Of course. I know very well how TCP works. Real length of body in frame it's not important. That's only an example of what i want to achieve. And the name OML is not relevant because wireshark just try name everything... The point is that only size of frames are different between connection without vs and with vs. When i put together body from lot of small frames (from connection without vs) and do the same with body from couple of big frames (vs between with DPH and Delimiter), i get same result. Same size. Everything exactly the same. It appears only with very big messages. And not appear in medium and small. So there is a problem with socket maximum buffer size I think.

All I can say is that your best course of action is open a ticket with CA Support and ask if there are properties for controlling VSE's TCP send & receive default and max buffer sizes.   I am not aware of any but that does not mean they do not exist.