[f-nsp] dns keepalive checks on "unknown" ports

[David J. Hughes]

A better idea for aliased ports is to associate them with a
master port.  If you have X aliased ports then you are generating
  X + 1 healthchecks (if you could get them to work in your setup
that is :).  This is not only an excessive load but also provides
a window during which 1 VIP may believe a real server is fine
while another knows it's failed a healthcheck.

If you associate the aliased port with a master port then it
just uses the current state of the master port without re-testing
the service's health.  You can set it up using something like
the following fragment.

---
server port 1110
  connection-log all
  session-sync
  tcp keepalive 5 3
  tcp keepalive use-master-state
---

In this situation, port 1110 is an alias to 110 and is bound using
a "no port 110 translate" on the VIP.  Works like a charm.


David
...


On 12/11/2004, at 4:48 AM, Michael Renner wrote:

> Hi,
>
> I currently have a "Many-to-one" setup [1] on a Foundry ServerIron XL 
> running 07.4.00T12, with 2 virtual servers pointing to 3 real servers, 
> but I'm not able to enable keepalive on the "aliased" port as 
> suggested in the documentation [2].
>
[ ..... ]
>
> ---
>
> server port 53
>   udp keepalive 3 2
>
> server port 153
>   udp keepalive 3 2
>   udp keepalive protocol 53
>
> server real www1 1.1.1.1
>   port 153
>   port 153 keepalive
>   port dns
>   port dns keepalive
>   port dns addr_query "www.domain.com"
>
> [repeat for www2 and www3]
>
> server virtual a.ns.domain.com 1.2.1.1
>   port dns
>   bind dns www1 dns www2 dns www3 dns
>
> server virtual b.ns.domain.com 1.3.1.1
>   port dns
>   no port dns translate
>   bind dns www1 153 www2 153 www3 153
>
> ---