Application Delivery (ADX)

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Contributor
Posts: 39
Registered: ‎05-04-2009

My remote servers do not come up... health check problems with remote server?

Is there anything special talking about health checks for remote servers? I do have some local servers and they are all fine but I am not successful with my remote servers. I do not get them up for some reason. Where should I look at?

Super Contributor
Posts: 316
Registered: ‎05-01-2009

Re: My remote servers do not come up... health check problems with remote server?

It is hard to find the root cause for this problem based on the details available in your post. Are you sure everything is OK from a routing/L3 point of view? Have you tried to ping the remote server? Do you get the answer back?

Contributor
Posts: 39
Registered: ‎05-04-2009

Re: My remote servers do not come up... health check problems with remote server?

I am not able to ping the remote servers. There is a firewall in front of the remote servers and the firewall does not allow ICMP traffic. Nevertheless I am able to telnet to the remote servers and I am as well able to telnet to port 80 of the remote servers. Connectivity is therefore fine and I would expect my HTTP health check to be successful.

Super Contributor
Posts: 316
Registered: ‎05-01-2009

Re: My remote servers do not come up... health check problems with remote server?

There are some firewalls in between the ServerIrons and the remote servers and they do not allow ICMP traffic? This is bad - the health checking process is getting down in multiple steps talking about remote servers:

Step 1: route table lookup

Step 2: Layer 3 health check (ICMP echo request)

Step 3: Layer 4

Step 4: Layer 7

The ServerIron is not going to step 3 and step 4 without being able to finish step 2 successfully. You have two options from my point of view:

Option 1: allow ICMP traffic to the remote real server IP addresses coming from the physical IP addresses of the ServerIrons

Option 2: disable step 2 using "no-l3-check" below the remote real server configuration:

server real rsA a.b.c.d

  no-l3-check

  port http

 

Contributor
Posts: 39
Registered: ‎05-04-2009

Re: My remote servers do not come up... health check problems with remote server?

I have used "no-l3-check" just for a quick test and it is working.

THX!

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