[lvs-users] packet out-of-order in DR, dup ack, lots of retransmission

Fanzhou Zhao fanzhou at gmail.com
Tue Jul 26 04:05:10 BST 2011


I'm using LVS-DR and meet a serious performance issue. My LVS runs on a quad
core HP machine, ubuntu 10.04 x86-64, 4G Mem.

VIP: 192.168.1.100
Director: 192.168.1.10
RS: 192.168.1.11

Just a test, scp a file from remote client to RS:
(1) directly(RS IP): rate is about 100KB/s, a little packet retransmission.
(2) via Director(VIP): rate is less than 50KB/s, ant lots of dup ack and
retransmission. And it is more slow if the file is bigger.

Using TCPDump to capture packets in Director and RS, I find,
1. Packets Director received are normal with order
2. Packets Director forwared to RS are out of order.
3. Packets RS received are the same with Director sent.
So, it is Director forwarding packets out-of-order. But I don't know why and
how to fix it. Please help me.

Thanks a lot!

Fanzhou



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