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That's the interesting rub with my setup... the realserver and database are not
on the same network, as they are on separate vlans. Both real servers, both
load balancers and the switch in between all this is vlan'd. The four Linux
servers use 802.1q trunks.
To diagram...
GW 1.1.1.1
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1.1.1.2 VIP 1.1.1.10 for http port
1.1.1.3
LB1----------------1.1.1.20 for mysql port------------------LB2
10.0.1.2 vlan 100 vlan 100 GW: 10.0.1.1 10.0.1.3 vlan
100
10.0.2.2 vlan 200 vlan 200 GW: 10.0.2.1 10.0.2.3 vlan
200
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----------------------------Cisco 2950----------------------------
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Real Server 1
Real Server 2
10.0.1.11 listen http vlan 100 10.0.1.12 listen http
vlan 100
10.0.2.11 listen mysql vlan 200 10.0.2.12 listen mysql
vlan 200
All networks are /24s.
As best as I understand... Both Real Servers are configured to use the
1.1.1.20 mysql server. Packet 10.0.1.11->1.1.1.20 via 10.0.1.1. I assume this
gets NAT'd as 1.1.1.2. The LB forwards this to one of the real mysql servers.
1.1.1.20->10.0.2.2, but the dest is the NAT address 1.1.1.2. It does its work
and sends the packet back... 10.0.2.2->1.1.1.2 via 10.0.2.1. Then it gets
unNAT'd back to the real server...
1.1.1.2->10.0.1.2.
Of course, this doesn't work.
I think the problem is that my NAT rule is not working due to the packet coming
from the inner interface... but I am likely wrong. ;-)
Stephen
> From: daniel.watson@xxxxxxxx> To: stephenamadei@xxxxxxxxxxx> Date: Wed, 20
> Aug 2008 11:46:48 -0700> Subject: Re: [lvs-users] Connecting to VIP from Real
> Servers> > >>I assume you have some sort of web application that uses a
> database. Why> >>not have you're both RS web apps using a MySQL connection to
> localhost.> >>Then you modify UltraMonkey to use not a simple tcp check, but
> a much> >>deeper app-levle check, that check as well the db connection. In
> case of> >>an issue with the DB, the RS will be de-activated, and will only
> remain> >>the RS that has a healthy DB connection.> > >Actually, that is what
> I am running right now... but I really wanted to> >be able to run MySQL
> separate from HTTP... just in case I end up with a> >situation where HTTP is
> broken on server A and MySQL is broken on server> >B.> >> >Stephen> > This is
> probably a routing issue.> From outside your network the data path looks
> like> Client -> vip -> loadbalancer -> realserver -> database> Client <- vip
> <-
LB <- Realserver <- database> When you try to load balance the database
server it goes like this> > Client -> vip -> LB -> RS -> vip -> LB -> Database>
Client x vip x lb x RS <- database> > Since the realserver and database are on
the same network the database is sending directly> to the realserver. While the
realserver is expecting a reply from the vip.> So this cannot work with nat,
and probably not work with most other configs.> They all rely on the load
balancer being the man in the middle to twiddle the packets.> > -dan
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