CSS Redundancy - Which one to use?

[pbarman]

I have two CSS 11503 and trying to decide which CSS Redundancy to use. I am pretty much thinking about ASR but still wanted to clear my understanding of what needs to be configured when.

1) VIP Redundancy -

a) I guess we will configure it when we need Active/Active CSS behaviour,i.e., both CSS processing flows for different VIPs and sharing the load.

b) Also as a prerequisite to configuring ASR.

c) When ASR or Box-to-Box redundancy cannot be configured because a direct connection between the two CSS boxes cannot be made.

2) ASR - Straight reason, when we need Stateful Session Redundancy.

3) Box-to-Box - This I am not sure why we would configure it ever. This also requires direct connection between the CSS for VRRP heartbeat exchange. If we can make a direct connection between the CSS boxes, why would I not use ASR and use Box-to-Box?? ASR would rather give me stateful session redundancy and Box-to-Box won't!!

Please help me understand this!

Thanks,

Partha

[Gilles Dufour · Accepted solution]

box-to-box is the only option with css11000.

There is no ASR on this older version of the CSS.

For compatibility purpose it does exist on the CSS11500 as well.

Another reason for box-to-box, is if you do firewall loadbalancing. It is much easier to deploy.

ASR can't be configured alone.

If you go for ASR, you need Vip and Interface redundancy.

Vip redundancy is required even if you do not go active-active.

Gilles.

[grlx]

Hi, I am moving towards a similar ASR deployment with a pair of CS11503 connected to redundant 6509 data center aggregation switches. I am also considering a pair of AVS 3120 accelerator appliances. Is it best to have each AVS 3120 directly connected to each CSS11503 or to have the AVS devices directly connected to the 6509 switches - maybe as a cluster on their own dedicated VLAN/SUBNET ?

According to the AVS User Guide doc'n, I have the option to use the built-in AVS Availability Manager, thus not requiring the load balancer?

Thank

Gilles

[Gilles Dufour]

you should physically connect your AVS to the cat6k and have them placed in the "server" subnet of the CSS.

If this is the only devices that you want to loadbalance, you definitely do not need the CSS - except if you prefer hardware loadbalancing for better performance.

The AVS guide clearly says you do not need any additional hardware for loadbalancing.

This means you can do it without CSS, but the CSS would give you more performance and the possibility to loadbalance other devices.

Gilles.

[grlx]

Merci Gilles for clarifying the positioning of AVS. Yes, I will still use pair of CSS for load balancing of servers in 3-tier server farm design. With the AVS pair directly on the 6509 pair (one AVS connected to each 6509), I should still have the flexibility to deploy multiple subnet/VLANs re the CSS/AVS solution? It appears the CSS as a layer 3 device will allow this design?

Thanks

Gilles Larivee