Problems with load balancing on slave server

Re: Problems with load balancing on slave server

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At 10:43 PM -0700 8/8/01, Noah Patton wrote:
>Alright, now that I am comfortable with the fact that load balancing
>is setup correctly (other that that odd TTL value on the slave
>server load balancing record), I have continued with some other
>troubleshooting and it appears that, as you said, the DNS load
>balancer is having difficulty contacting the primary web server.

I checked up on the TTL issue; it appears to be essentially only
cosmetic in nature.

>As you may recall, my primary web server is behind a IPNetRouter
>firewall. Is there some additional ports that I need to map
>specifically for the loadbalancer, or does it simply check port 80?

It just checks port 80. It establishes a connection; once the
connection is established, it counts that as a success and drops the
connection.

>I have found that if I run another (unused) web server directly on
>the gateway & dns server itself, load balancing works perfectly, as
>it verifies that the web server is up by checking the unused web
>server on the gateway/dns server itself, and then when an actual
>http request comes in IPNetRouter routes it to my actual web server
>behind the firewall.
>
>This leads me to belive that there are some additional ports that
>are being used for load balancing that could be portmapped to solve
>this issue.

No, it's just port 80. Therefore, it seems likely there's something
not quite right in how IPNetRouter handles port mapping. Perhaps IPNR
waits for some data before forwarding the connection; Load Balancer
doesn't send any data at all over the connection, it just establishes
the connection.

I'm guessing that the extra web server running on the gateway machine
works because then the gateway machine actually has a listener on
port 80, so it responds (acknowledges the connection attempt) when a
connection is requested.

>Which ports exactly are they, and which directions do they need to
>be portmapped in to allow proper communication between my internal
>web server, external web server, and both DNS/Loadbalancing servers?
>
>Again, my configuration is two servers at seperate locations, one
>server is out in the open and runs WebStar and QuickDNS 3.5, the
>other server is behind a IPNetRouter firewall. QuickDNS runs
>directly on the firewall itself, the web server is a seperate box
>behind the firewall. The purpose of this configuration is because we
>use FileMaker pro and Lasso extensively in our pages, and want the
>filemaker pro servers to be behind the firewall and still be
>accessable by the web server. This way, we only have to punch holes
>in the firewall for http and not filemaker.
>
>Would I be better off running the DNS server on a seperate internal
>box behind the firewall rather that on the gateway itself?

I don't see why that would make a difference. After all, the machine
on the firewall is the one that's able to contact both web servers,
right?

>When I began this setup I made the incorrect assumption that by
>placing the QuickDNS server on the gateway itself it would have full
>access to both servers.
>
>Perhaps if I had stayed with QuickDNS 2.2.1 and used the WebStar
>load balancing plugin instead this issue would be less complex?

I suppose that's possible, though setting up load balancing with
version 2 and the web server plug-ins was much more involved.

>Also, just so I follow your login on CNAMEs:
>
>Load balance one record, such as www.alpenlodge.com, and then make a
>CNAME for all other www records that points to www.alpenlodge.com.
>Thus, all records are effectively load balanced, as they all point
>to www.alpenlodge.com. Therefore, we only actually need seperate
>load balancing records for each physical server, not each domain.
>Correct?

You end up with just one load balance record which points to both servers.
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