[Users] Networkproblem: VE stops sending ACKs

[Konstantin Seiler]

Hi!
I've got a strange networkingproblem around here - the VE suddenly stops to 
send ACKs.

Setup is a VE with its own ip and proxyarp/iptables running on HN. Sometimes a 
tcp/ip-connection simply hangs and does not recover at all. I did look into 
it with ethereal and discovered the following situation:

The VE was downloading a larger file via http on a fast connection. Apparently 
a packet got lost, so the VE started to send dupACKs. Of course the sender 
kept sending packets, because the dupACKs hadn't arrived jet. So far so good.
However, after 155 (154 in another case) dupACKs, the VE simply stopped 
sending any ACKs whatsoever. The sender kept retransmitting the missing 
packet, but the VE simply stayed quiet.

Any idea about what's going on here and how to solve this problem?

Cheers,
Konstantin