First let me say that even if there is ways to do this, it is complicated and the the drawbacks are more important that what you will gain by doing this.
So before going for this solution, ask yourself the following questions ?
- did you reach performance limitation of a CSS so that you need 2 ?
- Are you sure the limitation is the CSS ?
- Are you already using Gig ports with the chassis fully loaded [the more cards the better performance you get].
OK - if you really need 2 active CSS you can use either of these.
- use vip redundancy with 1 vip active on one side and the other vip active on the other side. [ only possible if you have multiple vip].
Problem is the return traffic.
You have to guarantee that the response goes back to the same CSS, so it usually requires client nat.
- you could use shared vip redundancy. However, this requires a device able to do flow based routing to guarantee that all packets of the same flow are sent to the same CSS.
Basically you need another CSS that will split the load between the other 2 - but this new one becomes a single point of failure and the bottleneck for your performance.
Conclusion - do not try active-active solution.
Regards,
Gilles.
