Re: SETSOCKOPT question

TCP_MAXSEG is a read-only value. You can read it with getsockopt(), but you cannot change it with setsockopt().

IIRC, the MSS is set on a per-interface basis. That means, you set it as part of the configuration of your network interface (which is usually a NIC) and it affects all traffic that flows over that interface.

Ethernet (which is the most common type of network used nowadays) must have an MTU of 1518 or smaller. So the idea of having an MSS of 4096 doesn't make much sense. Unless you're trying to implement something like TSO?? Or jumbo frames on a gigabit network?? But, in either of these cases, you have to have the appropriate hardware, and then you have to configure *that* *hardware* -- not your application -- to support the larger segments.

But, in any case, setsockopt() doesn't support TCP_MAXSEG. To see what it DOES support, please read the following page in the Information Center:
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/topic/apis/ssocko.htm

I'm really curious as to why you'd want to mess with this setting.

I want to override the maximum segment size of my socket server
program. I added the following code and when I run the program and
view the stats via netstat it still shows the maximum segment size of
1380. Is the following code correct or am I missing something?

D FourK S 10I 0 INZ(4096)

c callp setsockopt(sock: IPPROTO_TCP: c TCP_MaxSeg: %addr(FourK): %size(FourK))