I am currently writing LLD for a Data Center project and planning for the CSS redundancy design. The BoQ of CSS is given below:
Content Switches/Load Balancers: CSS11503 2
Cisco 11503 Content Services Switch SCM-2GE HD AC 2
WebNS 8.1X Enhanced Feature Set for CSS 11500 Platforms 2
WebNS Secure Management License: Enables Strong Encryption 2
CSS11500 SSL Module w/ Compression 2
WebNS License Claim Certificate: for V8.XX or higher 2
CSS11500 System Control Module 2GE HD, Order 0-2 CSS5-GBIC 2
CSS11500 Gigabit Ethernet IOM: 2 Port, Order 0-2 SFP 2
GE SFP, LC connector SX transceiver 12
Customer does not have given any specific requirement, but looking at BoQ is seems that two CSS are populated with SSL Module s/ Compression, so they might need SSL and Compression to be configured in future.
The best scenario is to configure these two CSS in Load Balance with Stateful failover. Since we have three Redundancy options in CSS:
1. VIP and Virtual Interface Redundancy - Can be configured in Load Balanced but no stateful failover.
2. ASR Redundancy - Can be configured in load balanced with stateful failover. It sounds ok, but the main disadvantage is that ASR & an SSL Module, and ASR & HTTP Compression cannot be configured on same Service.
3. Box-to-Box Redundancy - Cannot configured in load balanced, but I have no idea either it support stateful or stateless failover.
There are only two options left; one is VIP and Virtual Interface Redundancy and second is Box-to-Box Redundancy. What do you recommend in such scenario? Please note that I have two extra Gig ports available in CSS.