Dear lvs-users We use LVS extensively with Keepalived for running redundant load balanced setups. As part of the load balancer we sometimes use what is called a sorry_server in Keepalived. This maps to a local real server in LVS speak.
In recent versions we have found a change in behaviour that seems to break that functionality of a local sorry_server. It boils down to LVS not setting the forward mode to "Local" for addresses for which there interfaces on the local node. See the following examples. First on a Ubuntu 10.04.4 LTS: # uname -a Linux ubuntuserver1004 2.6.32-54-server #116-Ubuntu SMP Tue Nov 12 19:37:57 UTC 2013 x86_64 GNU/Linux # ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.10.0.2:80 wlc -> 127.0.0.1:80 Local 1 0 0 In this example the forward mode is correctly set to "Local". In newer versions this doesn't seem to work any more: # uname -a Linux ubuntuserver1204 3.8.0-34-generic #49~precise1-Ubuntu SMP Wed Nov 13 18:05:00 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux # ipvsadm -A -t 10.10.0.2:80 # ipvsadm -a -t 10.10.0.2:80 -r 127.0.0.1 # ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.10.0.2:80 wlc -> 127.0.0.1:80 Route 1 0 0 Note that in this later cate the forward mode in the second example has *NOT* been set to "Local". This behaviour contradicts the documentation in the manual, which states: > Regardless of the packet-forwarding mechanism specified, real servers for > addresses for which there are interfaces on the local node will be use > the local forwarding method, then packets for the servers will be passed to > upper layer on the local node. This cannot be specified by ipvsadm, rather > it set by the kernel > as real servers are added or modified. Is the observed behaviour desired or a bug in LVS or even the Kernel? Regards Matías _______________________________________________ Please read the documentation before posting - it's available at: http://www.linuxvirtualserver.org/ LinuxVirtualServer.org mailing list - [email protected] Send requests to [email protected] or go to http://lists.graemef.net/mailman/listinfo/lvs-users
