dbs/mss/packet_size is a SAP Parameter attribute which is used to control size of network packet information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Size of each network packet. Limits are 512 <(><<)>= packet_size <(><<)>= 16k Can affect performance depending on the type of network traffic being generated.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.