[lvs-users] LVS-DR stuck in SYN packets?

Tiago sytker at gmail.com
Mon Mar 24 20:00:33 GMT 2014


Hello all,

I'm trying to setup an LVS-DR here for a couple of webservers. My scenario
is:

Eth1 and eth0 are in separated vlans.

   1. My realservers ips: 10.56.213.31-10.56.213.32 at eth0
   2.
   3. myrealip** at eth1 (its a public IP)
   4.
   5.
   6. root at lvs1:~# ipvsadm
   7. IP Virtual Server version 1.2.1 (size=4096)
   8. Prot LocalAddress:Port Scheduler Flags
   9.   -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
   10. TCP  myrealip**:http wlc
   11.   -> 10.56.213.31:http            Route   1      0          0
   12.   -> 10.56.213.32:http            Route   1      0          0
   13.
   14. On realservers:
   15. lo:0      Link encap:Local Loopback
   16.           inet addr:myrealip**  Mask:255.255.255.255
   17.           UP LOOPBACK RUNNING  MTU:16436  Metric:1
   18.
   19. route -n:
   20. myrealip**  0.0.0.0         255.255.255.255 UH    0      0        0
   lo
   21.
   22.
   23. When someone try to access myrealip**:80 I have:
   24.   -> 10.56.213.31:http            Route   1      0          1
   25.   -> 10.56.213.32:http            Route   1      0          0
   26.
   27. And on realserver 10.56.213.31:
   28.
   29. root at web1:/var/log/apache2# tcpdump -ni eth0 host 216.5.78.123 (my
   source ip)
   30. tcpdump: WARNING: eth0: no IPv4 address assigned
   31. tcpdump: verbose output suppressed, use -v or -vv for full protocol
   decode
   32. listening on eth0, link-type EN10MB (Ethernet), capture size 65535
   bytes
   33. 13:40:35.267880 IP 216.5.78.123.37026 > myrealip**.80: Flags [S],
   seq 2186878409, win 14600, options [mss 1460,sackOK,TS val 164050646 ecr
   0,nop,wscale 7], length 0
   34. 13:40:36.270371 IP 216.5.78.123.37026 > myrealip**.80: Flags [S],
   seq 2186878409, win 14600, options [mss 1460,sackOK,TS val 164051646 ecr
   0,nop,wscale 7], length 0
   35. 13:40:38.276806 IP 216.5.78.123.37026 > myrealip**.80: Flags [S],
   seq 2186878409, win 14600, options [mss 1460,sackOK,TS val 164053646 ecr
   0,nop,wscale 7], length 0
   36. 13:40:42.294667 IP 216.5.78.123.37026 > myrealip**.80: Flags [S],
   seq 2186878409, win 14600, options [mss 1460,sackOK,TS val 164057646 ecr
   0,nop,wscale 7], length 0
   37. 13:40:50.328756 IP 216.5.78.123.37026 > myrealip**.80: Flags [S],
   seq 2186878409, win 14600, options [mss 1460,sackOK,TS val 164065646 ecr
   0,nop,wscale 7], length 0
   38.
   39. But I can't see the answer going back to me in any interface I have
   at these realservers. I don't get any HTTP HIT at apache either.

Obviously it seems I'm missing something here, however, I can't see clearly
what is it.

Can you help on this?

Thanks in advance!


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