ISC link

[chloi]

Pls view the attached JPG for the setup.

I had 2 CSS with VIP Stateful failover configured. An ISC link was use to link up two css for this purpose.

if lets say, my CSS-1 connected to Server-1 & Server-2, CSS-2 connected to Server-1 & Server-2 also.

If the link between CSS-1 and Server1 down, How does the Client connected to Server-1 react? would it try to connect back to Server-1 thru the ISC link? or would it drop the connection and initiate a connection again?

thanks.

[Gilles Dufour]

The ISC link is not being used [and can't be] to send traffic. It's only purpose is for CSS to share flow information so the backup CSS is aware of what the primary CSS does.

If the primary CSS goes down and the secondary takes over, the client will still send traffic to the vip and the new active CSS will forward it to the same server as originally selected by the first CSS.

This means the ip address of the server needs to be reachable by both CSS.

Regarding your connectivity make sure your servers have a system to share the same ip on both link and a system to have 1 interface and the other one standby.

Personally I do not like this kind of connectivity.

I prefer to introduce another L2 switch to connect the servers and the CSS.

[let the network decide how to handle failover and not the server].

Regards,

Gilles.

[chloi]

Hi Gilles,

Thanks for the response. I do not like this kind of connectivity as well. but, I do not have an extra switch for this purpose... too bad...

If I still want my theory to work, which is, if link between css-1 and ldap-1 down, the traffic still go thru css-2 and back to ldap-1. What should i do?

Should I setup a cross cable in between the CSSes and let them carry the traffic?

[Gilles Dufour · Accepted solution]

Indeed you should add an extra link between the CSS and put it in the same circuit vlan as the servers.

Also add the command 'ip uncond-bridging' on both CSS to guarantee that the backup CSS forwards the server traffic to the primary CSS.

Regards,

Gilles.