Does anyone understand tcpdump output?

Hi

I'm trying to figure out why a client PC can't connect to our MRP system. I
have done some tcpdump testing, but I don't know enough about the output. It
always produces something similar to the following before the client gives
up. Can anyone explain all the R0:0(0) and nop,nop,sackOK type stuff? Does
this output explain why it might be failing?

12:05:30.749224 192.168.100.2.873 > 192.168.101.17.1831: F 545:545(0) ack
866 win 6432 (DF)
12:05:30.782964 192.168.101.17.1831 > 192.168.100.2.873: . ack 546 win 16016
(DF)
12:05:31.543809 192.168.100.2.32815 > 192.168.101.17.1832: S
2868601612:2868601612(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 0>
(DF)
12:05:31.584487 192.168.101.17.1832 > 192.168.100.2.32815: R 0:0(0) ack
2868601613 win 0

The 100 and 101 networks are connected via a VPN.

TIA
Tim