Simon, Thank you very much, this would be very beneficial for us to get working.. I did try the timeout value as you suggested and if I only send one request every second (since that appears to be as low as I can make it) then everything works fine, one DHCP packet is sent to one real server, the next DHCP packet is sent to the next real server.. unfortunately I am running tests at about 500 DHCP ACKs per second, so the timeout never happens and all the packets still go to a single real server.
What can I do to help get "Julian Anastasov's" one packet scheduler patches into the 2.6 kernel as this appears to be exactly what we need? Thanks again, Brian Carpio -----Original Message----- From: Simon Horman [mailto:ho...@verge.net.au] Sent: Saturday, March 27, 2010 5:22 PM To: Brian Carpio Cc: linux-ha@lists.linux-ha.org Subject: Re: [Linux-HA] UDP / DHCP / LDIRECTORD On Fri, Mar 26, 2010 at 12:57:36PM -0700, Brian Carpio wrote: > Hi, > > Currently I have a very unique situation where I need to load balance DHCP > ACKs to two different real servers, my issue (and this hopefully is just a > simple configuration issue) is that when we test our ldirectord load balacner > all the DHCP ACKs go to a single "real server" if the source port is not > randomized, we solved this problem in our test lab by changing our test > application to randomize the source port if this is done then one DHCP ACK > goes to one real server, the next DHCP ACK goes to the other real server, > everything is perfectly load balanced, the problem is that in our production > environment the device which sends us the DHCP ACKs is not randomizing the > ports, all the DHCP ACKs come from the same source port 8000 so ldirectord > sends all the requests to the same "real server" (even if I send 1,000,000 > DHCP ACKs in two hours) here is a look at my config: > > checktimeout=10 > checkinterval=2 > autoreload=yes > logfile="/var/log/ldirectord.log" > quiescent=yes > virtual=lbvip01:67 > real=server01:67 masq > real=server02:67 masq > protocol=udp > checktype=ping > #persistent=1 > scheduler=rr > virtual=lbvip01:68 > real=server01:68 masq > real=server02:68 masq > protocol=udp > checktype=ping > #persistent=1 > scheduler=rr > > > I have tried to set and comment out the persistent setting but it doesn't > seem to make any difference. > > Hopefully I am missing something. Hi Brian, I think that the problem that you are seeing is that LVS regards a series of packets with the same SRC_HOST:SRC_PORT and DST_HOST:DST_PORT as a connection of sorts and thus sends them to the same real-server. This is separate from the behaviour of persistence which broadends the rule by ignoring the SRC_PORT. You may be able to mitigate this behaviour to some extent by setting a very low timeout on UDP "connections" using ipvsadm --set. However I suspect that due to implementation details of LVS that very short timeouts won't work as well as one might hope. A better solution to this problem is Julian Anastasov's one packet scheduler patches[1,2]. Unfortunately it seems to be rather out of date, based on the 2.4 kernel. I would be happy to work with you on getting it into the mainline 2.6 kernel. [1] http://docs.huihoo.com/hpc-cluster/linux-virtual-server/HOWTO/LVS-HOWTO.ipvsadm.html#one_packet_scheduler [2] http://www.ssi.bg/~ja/#lvs_patches No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.791 / Virus Database: 271.1.1/2771 - Release Date: 03/29/10 00:32:00 _______________________________________________ Linux-HA mailing list Linux-HA@lists.linux-ha.org http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
