Notes 6.x intermittently hangs "Network Operation did not complete..."

Can anyone explain in further detail the problem with Cisco routers described in technote# 1202982?

“In this particular case, Notes 6.x clients reaching a hang state appears to be related to the way Cisco routers handle TCP connections that are left open by Notes 6.x for multi-threading.”

What is the problem with Cisco routers and is there a fix on the router side (i.e. firmware upgrade)? Our customers contantly get an hourglass when using their Notes clients.