In the past Cisco has been shipping two line of Loadbalancing products
First line ( modules dedicated for 6500/7600 chassis ) includes CSM & CSM-S & SSLSM (for ssl offloading)
The other line comprises of appliance based CSS series products.
ACE module is a next generation module replacing CSM modules that fits into 6500/7600 chassis.
It gives you upto 16Gbps throughput (versus CSM's 4Gbps throughput).
ACE appliance is a next gen replacement of CSS line of appliance based products.
CSS appliances were used to come in different Hardware models with varied
performance capacities. ACE appliance is a single hardware with various licenses
used to scale the performance/features.Ace appliance supports upto 4Gbps of throughput.
Previously CSS & CSM code terminologies & command set was different. For example a real server
was termed as "service" in CSS & was called "real" in CSM . Similarly "probe" in CSM was "keepalive"
in CSS.
With ACE line of products you get the same terminologies & command sets for both
modules & Appliances.
ACE Appliance & ACE modules are functionality vise coming closer with every new release but
still there are some differences.
For example following ACE appliance features are not available in ACE module:
Appl optimization (flash forward, Delta Encoding)
Embedded Device manager
Http compression
Which one is better than the other really depends on your requirement
From Performance perspective Module give you much higher performance then Appliance.
SO if performance is your criteria the ACE module is better than ACE appliance.(Some performance metrics at the end of the post).
If you are looking for Application optimization & HTTP compression along with Loadbalancing
then it can only be achieved with ACE appliance.
If you are not using 6500/7600 series chassis in your environment then you can only use ACE appliance
(unless you are open to buy module+chassis due to performance requirement).
Some performance metrics
Ace Appliance supports 1 Million concurrent connections where as Ace Module supports 4 Million.
Ace Appliance supports 120K L4 conn/sec where as Ace Module supports 380K L4 conn/sec.
Ace Appliance supports 40K L7 conn/sec where as Ace Module supports 133K L7 conn/sec.
Ace Appliance supports upto 4Gbps throughput where as Ace Module supports 16Gbps throughput .
HTH
Syed Iftekhar Ahmed
