Folks,

I am running multicast benchmark on RHEL5 systems. One RHEL5 system sends multicast packets and other RHEL5 system is the receiver. I use "netstat -su" to look at the counters and I noticed that whenever I have packet loss the "packet receive errors" is always increased by factor of two (i.e., if 100 packets are lost the counter is increased by 200).

Is this a bug or does it increase once for multicast and once to udp?

Thanks.

I would check to see what type of packets you are seeing on the wire with either tcpdump or wireshark.

Also which error count are you looking at? This the output of a machine at work.

[me@myhost]$ netstat -su
IcmpMsg:
InType0: 2325
InType3: 91
InType8: 17
OutType0: 17
OutType3: 248
OutType8: 8752
OutType13: 1
Udp:
4656889 packets received
235 packets to unknown port received.
12 packet receive errors
3527864 packets sent
IpExt:
InMcastPkts: 200639
OutMcastPkts: 36
InBcastPkts: 5688689

Also which kernel are you running from RHEL5?

I am looking at "packet receive errors". This is a benchmark environment to nothing much is going on. I can run "netstat -su" all day long and the receive errors counter does not increase. When I run my multicast program and when there is a packet loss this counter is always increased by twice the number of packets lost.

I am running RHEL 5.4 (Tikanga), 2.6.18-164.20.1.el5 kernel.