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> IPVSADM, IPVSADM Real server configuration
fqberful
 Posted: Oct 21 2014, 06:24 PM
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Hi All,

I have a question for the network experts :

Using IPVSADM on SL 6.5 to set up a basic load balancer,

I have the director set up for direct routing [ DR ]

I have the director configuerd for ipv4 and the 2 real servers also set up for ipv4 and the LB works as advertised. Note here I'm using the lo:1 interface on the real servers as opposed to the iptables method for arp management.

I set up ipv6 on the director and both real servers.

I can see the ipv6 requests hit the director and the real servers, BUT [ always a but biggrin.gif ] I can't get a response to the client from the real server.

What do I have to do to the real server(s) to get the response to the client. Note that DR mode bypasses the director on all responses from the real servers.

I'm really stumped on this one.

Thanks!

--Ed
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helikaon
 Posted: Oct 22 2014, 06:39 AM
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Hi,
so basically ivp4 traffic is configured and working while the ipv6 does not?
Hard to guess, if there is not much detail.
Do you get response when going directly client -> server bypassing LB?

cheers
















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fqberful
 Posted: Oct 22 2014, 06:26 PM
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QUOTE (helikaon @ Oct 22 2014, 01:39 AM)
Hi,
so basically ivp4 traffic is configured and working while the ipv6 does not?
Hard to guess, if there is not much detail.
Do you get response when going directly client -> server bypassing LB?

cheers



Hi,

The the Ipv4 traffic works 100% as it's supposed to.

Yes the IPv6 works direct from client to real server ... When the client access the LB via the virtual ip/port the LB shows the traffic, the real server shows the inbound connection.

However, because the LB is being run in DR mode the response from the real server goes direct to the client and that's not happening with IPv6.

To make this work with IPv4 you have to change ipv4 to forwarding, make the LO interface not respond to ARP and add a route to lo:1 for IPv4 from the LB .. This method as opposed to the iptables method which also works for IPv4. [ there's no nat table for IPv6 -- ip6tables ]

I just can't quite put my finger on how / what to configure for IPv6 on the 'real server' to make the responses go directly back to the client like it does with IPv4.

Can't find any 'real server' examples on the net and not on ipvsadm site for IPv6 other than how to formulate an IPv6 addr4ess for the LB which I have done and it works fine.

--Ed
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fqberful
 Posted: Oct 23 2014, 05:38 PM
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Hi All,

I found the answer in of all places, a kernel/ipvsadm bug report http://dl.dropbox.com/u/2835777/BangHead1.gif

All I had to do was add this line to /etc/rc.d/rc.local on the REAL SERVERS

ip -o -6 addr add xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx/128 dev lo

where the x's are the IP of the LB / director.

And away we go ! Now ipvsadm works fine in DR mode with ipv6.

Which BTW makes my little 2.8ghz Pentium R&D server better than the $14k Foundry load balancing switches we use ... Hmmm. Go SL !
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helikaon
 Posted: Oct 23 2014, 08:40 PM
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There you go, fantastic :]

I'm glad you solved it, ipv6 isn't something i feel i should be advising anyone with, as i need to study much more about it in the 1st place myself :]

cheers,

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