Software changes

Unanswered Question
Apr 23rd, 2008


Since I've upgraded software from 7.5 to 8.2 I've noticed more ISC link UP and DOWN whose lead CSS to fastly flip backup->master->backup all virtual routers. It seems to not have any incident on availability of hosted applications.

Anyway, does upgrade from version 7 to 8 change anything to ISC link protocol?

Thanks for help!


NB : css are connected through layer 2 devices

I have this problem too.
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jsivulka Tue, 04/29/2008 - 06:01

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.

sniff the traffic at the different catalyst.

Are you trunking this vlan with others ?

you might one to use a dedicated vlan between your catalysts.

David Coupez Sun, 05/04/2008 - 23:17

Hello, thanks for your interest in my problem.

I'm sure the link is correctly used. No traffic is sent through it (even if I wanted to I'm pretty sure it cant be done).

Anyway, the CSS are separated by two cisco switch series 6000 ruled by HSRP. A dedicated VLAN is used for each CSS pair.

A problem is also that Cisco doesnt provide any docs on its ISC protocol so I cannot understand the content of ISC messages.


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