[LARTC] DGD patch not detecting dead gateway

[Manish Kathuria]

On 2/8/07, Tom Lobato <tomlobato at gmail.com> wrote:

>   Thank you for the script. I'm trying it.
>
>   Well, I made a simple modification and would like to hear opnions.
>   Until now, I just added one more TESTIP, so I'm pinging one IP for each link.
>   Also I'm using the IP instead name address, and used the DNS IP of each provider
> for the ping. I made this because the ping to external sites (yahoo, google) is too slow
> here, mainly when the link is under heavy load. So I'm afraid it can try ping
> without success and "think" the link is down.

I just used a popular external site because it may happen that
connectivity from your location to the provider's DNS is there but the
provider's link with the rest of the internet is down so even if you
get a successful ping reply, the link isn't working in the real sense.
Also, I preferred using a name instead of IP address because there
could be multiple IP addresses associated with the site name and they
can change too. But I don't see anything wrong in your approach. What
do you mean by slow ? I don't think ping reply time should be an
issue. We are more concerned with the success. Obviously, it should
not time out.

The ping reply times I get here for sites like www.yahoo.com and
www.google.com are to the tune of 300 ms.

You can increase the pin
>   Also, for don't get falses 'link down', did you tried to increase the number of 4
> ping fails before replace the route? What do you think about?
>

4 successful ping fails means that the link has been down for anywhere
between 40-50 seconds which I think was a sufficient time interval to
carry a failover. But you can increase it depending upon your
requirements. For restoring the link, the script doesn't wait for that
much time.

>   PS: although alteration be so simple, if someone want to see, tell me and I send a mail.
>   Tom Lobato

It would be great to see your final script.


-- 
Manish Kathuria
Tux Technologies
http://www.tuxtechnologies.co.in/