Why are you blocking ICMP? No need and really provides no protection.
Im betting those are ICMP Port/Destination Unreachable messages being returned from a router.
TCMP is Internet Control Message Protocol
It provides useful info to systems on the internet.
If you stop blocking it Tixati would know right away to stop trying to connect to that client and move on, with it block tixati has to wait for the connection to time out.
There are many other messages that are part of ICMP including Path MTU Discovery (
http://en.wikipedia.org/wiki/Path_MTU_Discovery ) that break if you simply block all ICMP.